SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT THU SEP 09 2010 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE NRN HIGH PLAINS... ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT... NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING. A HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN TO THE NRN HIGH PLAINS BY EARLY FRIDAY. THE MIDLEVEL TROUGH WILL BE PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE TROUGH. THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE WY/SD BORDER. DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS. A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS. THE SEVERE STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL DAKOTAS. ...CENTRAL/NRN AR THIS AFTERNOON... THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR I-40 ACROSS AR. SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF 200 M2/S2. THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING. AT THIS TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA. ..THOMPSON/ROGERS.. 09/09/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT THU SEP 09 2010 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE NRN HIGH PLAINS... ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT... NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING. A HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN TO THE NRN HIGH PLAINS BY EARLY FRIDAY. THE MIDLEVEL TROUGH WILL BE PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE TROUGH. THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE WY/SD BORDER. DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS. A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS. THE SEVERE STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL DAKOTAS. ...CENTRAL/NRN AR THIS AFTERNOON... THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR I-40 ACROSS AR. SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF 200 M2/S2. THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING. AT THIS TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA. ..THOMPSON/ROGERS.. 09/09/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT THU SEP 09 2010 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE NRN HIGH PLAINS... ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT... NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING. A HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN TO THE NRN HIGH PLAINS BY EARLY FRIDAY. THE MIDLEVEL TROUGH WILL BE PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE TROUGH. THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE WY/SD BORDER. DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS. A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS. THE SEVERE STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL DAKOTAS. ...CENTRAL/NRN AR THIS AFTERNOON... THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR I-40 ACROSS AR. SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF 200 M2/S2. THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING. AT THIS TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA. ..THOMPSON/ROGERS.. 09/09/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT THU SEP 09 2010 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE NRN HIGH PLAINS... ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT... NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING. A HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN TO THE NRN HIGH PLAINS BY EARLY FRIDAY. THE MIDLEVEL TROUGH WILL BE PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE TROUGH. THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE WY/SD BORDER. DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS. A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS. THE SEVERE STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL DAKOTAS. ...CENTRAL/NRN AR THIS AFTERNOON... THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR I-40 ACROSS AR. SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF 200 M2/S2. THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING. AT THIS TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA. ..THOMPSON/ROGERS.. 09/09/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT THU SEP 09 2010 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE NRN HIGH PLAINS... ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT... NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING. A HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN TO THE NRN HIGH PLAINS BY EARLY FRIDAY. THE MIDLEVEL TROUGH WILL BE PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE TROUGH. THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE WY/SD BORDER. DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS. A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS. THE SEVERE STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL DAKOTAS. ...CENTRAL/NRN AR THIS AFTERNOON... THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR I-40 ACROSS AR. SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF 200 M2/S2. THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING. AT THIS TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA. ..THOMPSON/ROGERS.. 09/09/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT THU SEP 09 2010 VALID 091300Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PART OF THE NRN INTO CNTRL HIGH PLAINS... ...NRN INTO CNTRL HIGH PLAINS... POTENT VORTICITY MAXIMUM AND ASSOCIATED 100+ KT UPPER-LEVEL JET STREAK CURRENTLY ROUNDING THE LARGE-SCALE TROUGH BASE OVER NV WILL TRANSLATE NEWD INTO THE REGION...RESULTING IN A CONSIDERABLE INCREASE IN DYNAMIC FORCING FOR ASCENT DURING THE LATTER HALF OF THE DIURNAL HEATING CYCLE. THIS WILL HASTEN THE DEEPENING OF A LEE CYCLONE OVER NERN WY/SERN MT TODAY...PRIOR TO THE LOW ACCELERATING NNEWD INTO SERN SASKATCHEWAN OVERNIGHT. AN ASSOCIATED LEE TROUGH OR DRYLINE WILL REMAIN QUASI-STATIONARY OVER ERN PARTS OF WY/CO WHILE A WARM FRONT SLOWLY LIFTS NWD THROUGH THE DAKOTAS. FARTHER W...A COLD FRONT WILL STRENGTHEN WHILE PROGRESSING EWD/SEWD THROUGH THE NRN HIGH PLAINS. THE DEEPENING SURFACE CYCLONE WILL SERVE TO ENHANCE SELY LOW-LEVEL FLOW...MAINTAINING AN AXIS OF UPPER 50S/LOWER 60S BOUNDARY LAYER DEW POINTS E OF THE SHARPENING LEE TROUGH/DRYLINE. THIS MOISTURE AXIS WILL COINCIDE WITH A STEEP MIDLEVEL LAPSE RATE/EML PLUME PRECEDING WRN U.S. UPPER TROUGH...SUPPORTING AFTERNOON MLCAPE VALUES OF 1000-2000 J/KG. LATEST MODEL GUIDANCE IS CONSISTENT IN SUGGESTING THAT THE COMBINED EFFECTS OF THE ABOVE-MENTIONED INCREASE IN LARGE-SCALE FORCING AND SUSTAINED SURFACE CONVERGENCE ALONG LEE TROUGH/DRYLINE WILL ERODE THE CAP WITHIN A NARROW N-S CORRIDOR OVER THE WRN DAKOTAS INTO THE NEB PNHDL...ALLOWING FOR ISOLATED TO SCATTERED STORM FORMATION BY LATE AFTERNOON OR EARLY EVENING. SWLY MIDLEVEL FLOW STRENGTHENING TO 45-55 KT ATOP A SELY LOW-LEVEL WIND FIELD WILL RESULT IN VERTICAL SHEAR MORE THAN SUFFICIENT FOR SUPERCELLS CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS. A TORNADO OR TWO IS POSSIBLE WITH ANY SUPERCELLS THAT CAN REMAIN FULLY SURFACE-BASED BEYOND 10/00Z WHEN LOW-LEVEL SHEAR WILL NOTABLY INCREASE IN CONJUNCTION WITH THE DEVELOPMENT OF A 40-50 KT LLJ. ADDITIONAL DIURNALLY-ENHANCED STORMS WILL BE POSSIBLE FARTHER W ALONG OR IN WAKE OF COLD FRONT OVER MT WHERE SHEAR WILL BE STRONG...BUT INSTABILITY SOMEWHAT MARGINAL. ISOLATED HAIL AND/OR DAMAGING WIND EVENTS MAY ACCOMPANY ANY MORE SUSTAINED STORMS IN THIS AREA. ...OZARK PLATEAU... THE REMNANT CIRCULATION OF TROPICAL STORM HERMINE CURRENTLY OVER N-CNTRL OK WILL UNDERGO CONSIDERABLE WEAKENING TODAY AS SYSTEM IS ENTRAINED INTO THE WESTERLIES AND SUBSEQUENTLY ACCELERATES NEWD THROUGH THE OZARKS. HOWEVER...AREA PROFILER AND VWP DATA SHOW THAT A BELT OF MODERATELY STRONG /40-50 KT/ LOW TO MID-TROPOSPHERIC FLOW HAS BEEN MAINTAINED WITHIN ERN SEMICIRCLE OF LARGE-SCALE CIRCULATION. SIMILAR TO THE PAST COUPLE OF DAYS...THIS ENHANCED WIND FIELD COMBINED WITH A MOIST BOUNDARY LAYER AND THE ONSET OF DAYTIME HEATING MAY YIELD AN ENVIRONMENT SUPPORTIVE OF A FEW SUPERCELLS CAPABLE OF A BRIEF TORNADO OR TWO...DESPITE THE OVERALL WEAKENING AND TRANSITION OF SYSTEM TO EXTRATROPICAL. ..MEAD/GRAMS.. 09/09/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT THU SEP 09 2010 VALID 091300Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PART OF THE NRN INTO CNTRL HIGH PLAINS... ...NRN INTO CNTRL HIGH PLAINS... POTENT VORTICITY MAXIMUM AND ASSOCIATED 100+ KT UPPER-LEVEL JET STREAK CURRENTLY ROUNDING THE LARGE-SCALE TROUGH BASE OVER NV WILL TRANSLATE NEWD INTO THE REGION...RESULTING IN A CONSIDERABLE INCREASE IN DYNAMIC FORCING FOR ASCENT DURING THE LATTER HALF OF THE DIURNAL HEATING CYCLE. THIS WILL HASTEN THE DEEPENING OF A LEE CYCLONE OVER NERN WY/SERN MT TODAY...PRIOR TO THE LOW ACCELERATING NNEWD INTO SERN SASKATCHEWAN OVERNIGHT. AN ASSOCIATED LEE TROUGH OR DRYLINE WILL REMAIN QUASI-STATIONARY OVER ERN PARTS OF WY/CO WHILE A WARM FRONT SLOWLY LIFTS NWD THROUGH THE DAKOTAS. FARTHER W...A COLD FRONT WILL STRENGTHEN WHILE PROGRESSING EWD/SEWD THROUGH THE NRN HIGH PLAINS. THE DEEPENING SURFACE CYCLONE WILL SERVE TO ENHANCE SELY LOW-LEVEL FLOW...MAINTAINING AN AXIS OF UPPER 50S/LOWER 60S BOUNDARY LAYER DEW POINTS E OF THE SHARPENING LEE TROUGH/DRYLINE. THIS MOISTURE AXIS WILL COINCIDE WITH A STEEP MIDLEVEL LAPSE RATE/EML PLUME PRECEDING WRN U.S. UPPER TROUGH...SUPPORTING AFTERNOON MLCAPE VALUES OF 1000-2000 J/KG. LATEST MODEL GUIDANCE IS CONSISTENT IN SUGGESTING THAT THE COMBINED EFFECTS OF THE ABOVE-MENTIONED INCREASE IN LARGE-SCALE FORCING AND SUSTAINED SURFACE CONVERGENCE ALONG LEE TROUGH/DRYLINE WILL ERODE THE CAP WITHIN A NARROW N-S CORRIDOR OVER THE WRN DAKOTAS INTO THE NEB PNHDL...ALLOWING FOR ISOLATED TO SCATTERED STORM FORMATION BY LATE AFTERNOON OR EARLY EVENING. SWLY MIDLEVEL FLOW STRENGTHENING TO 45-55 KT ATOP A SELY LOW-LEVEL WIND FIELD WILL RESULT IN VERTICAL SHEAR MORE THAN SUFFICIENT FOR SUPERCELLS CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS. A TORNADO OR TWO IS POSSIBLE WITH ANY SUPERCELLS THAT CAN REMAIN FULLY SURFACE-BASED BEYOND 10/00Z WHEN LOW-LEVEL SHEAR WILL NOTABLY INCREASE IN CONJUNCTION WITH THE DEVELOPMENT OF A 40-50 KT LLJ. ADDITIONAL DIURNALLY-ENHANCED STORMS WILL BE POSSIBLE FARTHER W ALONG OR IN WAKE OF COLD FRONT OVER MT WHERE SHEAR WILL BE STRONG...BUT INSTABILITY SOMEWHAT MARGINAL. ISOLATED HAIL AND/OR DAMAGING WIND EVENTS MAY ACCOMPANY ANY MORE SUSTAINED STORMS IN THIS AREA. ...OZARK PLATEAU... THE REMNANT CIRCULATION OF TROPICAL STORM HERMINE CURRENTLY OVER N-CNTRL OK WILL UNDERGO CONSIDERABLE WEAKENING TODAY AS SYSTEM IS ENTRAINED INTO THE WESTERLIES AND SUBSEQUENTLY ACCELERATES NEWD THROUGH THE OZARKS. HOWEVER...AREA PROFILER AND VWP DATA SHOW THAT A BELT OF MODERATELY STRONG /40-50 KT/ LOW TO MID-TROPOSPHERIC FLOW HAS BEEN MAINTAINED WITHIN ERN SEMICIRCLE OF LARGE-SCALE CIRCULATION. SIMILAR TO THE PAST COUPLE OF DAYS...THIS ENHANCED WIND FIELD COMBINED WITH A MOIST BOUNDARY LAYER AND THE ONSET OF DAYTIME HEATING MAY YIELD AN ENVIRONMENT SUPPORTIVE OF A FEW SUPERCELLS CAPABLE OF A BRIEF TORNADO OR TWO...DESPITE THE OVERALL WEAKENING AND TRANSITION OF SYSTEM TO EXTRATROPICAL. ..MEAD/GRAMS.. 09/09/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT THU SEP 09 2010 VALID 091300Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PART OF THE NRN INTO CNTRL HIGH PLAINS... ...NRN INTO CNTRL HIGH PLAINS... POTENT VORTICITY MAXIMUM AND ASSOCIATED 100+ KT UPPER-LEVEL JET STREAK CURRENTLY ROUNDING THE LARGE-SCALE TROUGH BASE OVER NV WILL TRANSLATE NEWD INTO THE REGION...RESULTING IN A CONSIDERABLE INCREASE IN DYNAMIC FORCING FOR ASCENT DURING THE LATTER HALF OF THE DIURNAL HEATING CYCLE. THIS WILL HASTEN THE DEEPENING OF A LEE CYCLONE OVER NERN WY/SERN MT TODAY...PRIOR TO THE LOW ACCELERATING NNEWD INTO SERN SASKATCHEWAN OVERNIGHT. AN ASSOCIATED LEE TROUGH OR DRYLINE WILL REMAIN QUASI-STATIONARY OVER ERN PARTS OF WY/CO WHILE A WARM FRONT SLOWLY LIFTS NWD THROUGH THE DAKOTAS. FARTHER W...A COLD FRONT WILL STRENGTHEN WHILE PROGRESSING EWD/SEWD THROUGH THE NRN HIGH PLAINS. THE DEEPENING SURFACE CYCLONE WILL SERVE TO ENHANCE SELY LOW-LEVEL FLOW...MAINTAINING AN AXIS OF UPPER 50S/LOWER 60S BOUNDARY LAYER DEW POINTS E OF THE SHARPENING LEE TROUGH/DRYLINE. THIS MOISTURE AXIS WILL COINCIDE WITH A STEEP MIDLEVEL LAPSE RATE/EML PLUME PRECEDING WRN U.S. UPPER TROUGH...SUPPORTING AFTERNOON MLCAPE VALUES OF 1000-2000 J/KG. LATEST MODEL GUIDANCE IS CONSISTENT IN SUGGESTING THAT THE COMBINED EFFECTS OF THE ABOVE-MENTIONED INCREASE IN LARGE-SCALE FORCING AND SUSTAINED SURFACE CONVERGENCE ALONG LEE TROUGH/DRYLINE WILL ERODE THE CAP WITHIN A NARROW N-S CORRIDOR OVER THE WRN DAKOTAS INTO THE NEB PNHDL...ALLOWING FOR ISOLATED TO SCATTERED STORM FORMATION BY LATE AFTERNOON OR EARLY EVENING. SWLY MIDLEVEL FLOW STRENGTHENING TO 45-55 KT ATOP A SELY LOW-LEVEL WIND FIELD WILL RESULT IN VERTICAL SHEAR MORE THAN SUFFICIENT FOR SUPERCELLS CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS. A TORNADO OR TWO IS POSSIBLE WITH ANY SUPERCELLS THAT CAN REMAIN FULLY SURFACE-BASED BEYOND 10/00Z WHEN LOW-LEVEL SHEAR WILL NOTABLY INCREASE IN CONJUNCTION WITH THE DEVELOPMENT OF A 40-50 KT LLJ. ADDITIONAL DIURNALLY-ENHANCED STORMS WILL BE POSSIBLE FARTHER W ALONG OR IN WAKE OF COLD FRONT OVER MT WHERE SHEAR WILL BE STRONG...BUT INSTABILITY SOMEWHAT MARGINAL. ISOLATED HAIL AND/OR DAMAGING WIND EVENTS MAY ACCOMPANY ANY MORE SUSTAINED STORMS IN THIS AREA. ...OZARK PLATEAU... THE REMNANT CIRCULATION OF TROPICAL STORM HERMINE CURRENTLY OVER N-CNTRL OK WILL UNDERGO CONSIDERABLE WEAKENING TODAY AS SYSTEM IS ENTRAINED INTO THE WESTERLIES AND SUBSEQUENTLY ACCELERATES NEWD THROUGH THE OZARKS. HOWEVER...AREA PROFILER AND VWP DATA SHOW THAT A BELT OF MODERATELY STRONG /40-50 KT/ LOW TO MID-TROPOSPHERIC FLOW HAS BEEN MAINTAINED WITHIN ERN SEMICIRCLE OF LARGE-SCALE CIRCULATION. SIMILAR TO THE PAST COUPLE OF DAYS...THIS ENHANCED WIND FIELD COMBINED WITH A MOIST BOUNDARY LAYER AND THE ONSET OF DAYTIME HEATING MAY YIELD AN ENVIRONMENT SUPPORTIVE OF A FEW SUPERCELLS CAPABLE OF A BRIEF TORNADO OR TWO...DESPITE THE OVERALL WEAKENING AND TRANSITION OF SYSTEM TO EXTRATROPICAL. ..MEAD/GRAMS.. 09/09/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT THU SEP 09 2010 VALID 091300Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PART OF THE NRN INTO CNTRL HIGH PLAINS... ...NRN INTO CNTRL HIGH PLAINS... POTENT VORTICITY MAXIMUM AND ASSOCIATED 100+ KT UPPER-LEVEL JET STREAK CURRENTLY ROUNDING THE LARGE-SCALE TROUGH BASE OVER NV WILL TRANSLATE NEWD INTO THE REGION...RESULTING IN A CONSIDERABLE INCREASE IN DYNAMIC FORCING FOR ASCENT DURING THE LATTER HALF OF THE DIURNAL HEATING CYCLE. THIS WILL HASTEN THE DEEPENING OF A LEE CYCLONE OVER NERN WY/SERN MT TODAY...PRIOR TO THE LOW ACCELERATING NNEWD INTO SERN SASKATCHEWAN OVERNIGHT. AN ASSOCIATED LEE TROUGH OR DRYLINE WILL REMAIN QUASI-STATIONARY OVER ERN PARTS OF WY/CO WHILE A WARM FRONT SLOWLY LIFTS NWD THROUGH THE DAKOTAS. FARTHER W...A COLD FRONT WILL STRENGTHEN WHILE PROGRESSING EWD/SEWD THROUGH THE NRN HIGH PLAINS. THE DEEPENING SURFACE CYCLONE WILL SERVE TO ENHANCE SELY LOW-LEVEL FLOW...MAINTAINING AN AXIS OF UPPER 50S/LOWER 60S BOUNDARY LAYER DEW POINTS E OF THE SHARPENING LEE TROUGH/DRYLINE. THIS MOISTURE AXIS WILL COINCIDE WITH A STEEP MIDLEVEL LAPSE RATE/EML PLUME PRECEDING WRN U.S. UPPER TROUGH...SUPPORTING AFTERNOON MLCAPE VALUES OF 1000-2000 J/KG. LATEST MODEL GUIDANCE IS CONSISTENT IN SUGGESTING THAT THE COMBINED EFFECTS OF THE ABOVE-MENTIONED INCREASE IN LARGE-SCALE FORCING AND SUSTAINED SURFACE CONVERGENCE ALONG LEE TROUGH/DRYLINE WILL ERODE THE CAP WITHIN A NARROW N-S CORRIDOR OVER THE WRN DAKOTAS INTO THE NEB PNHDL...ALLOWING FOR ISOLATED TO SCATTERED STORM FORMATION BY LATE AFTERNOON OR EARLY EVENING. SWLY MIDLEVEL FLOW STRENGTHENING TO 45-55 KT ATOP A SELY LOW-LEVEL WIND FIELD WILL RESULT IN VERTICAL SHEAR MORE THAN SUFFICIENT FOR SUPERCELLS CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS. A TORNADO OR TWO IS POSSIBLE WITH ANY SUPERCELLS THAT CAN REMAIN FULLY SURFACE-BASED BEYOND 10/00Z WHEN LOW-LEVEL SHEAR WILL NOTABLY INCREASE IN CONJUNCTION WITH THE DEVELOPMENT OF A 40-50 KT LLJ. ADDITIONAL DIURNALLY-ENHANCED STORMS WILL BE POSSIBLE FARTHER W ALONG OR IN WAKE OF COLD FRONT OVER MT WHERE SHEAR WILL BE STRONG...BUT INSTABILITY SOMEWHAT MARGINAL. ISOLATED HAIL AND/OR DAMAGING WIND EVENTS MAY ACCOMPANY ANY MORE SUSTAINED STORMS IN THIS AREA. ...OZARK PLATEAU... THE REMNANT CIRCULATION OF TROPICAL STORM HERMINE CURRENTLY OVER N-CNTRL OK WILL UNDERGO CONSIDERABLE WEAKENING TODAY AS SYSTEM IS ENTRAINED INTO THE WESTERLIES AND SUBSEQUENTLY ACCELERATES NEWD THROUGH THE OZARKS. HOWEVER...AREA PROFILER AND VWP DATA SHOW THAT A BELT OF MODERATELY STRONG /40-50 KT/ LOW TO MID-TROPOSPHERIC FLOW HAS BEEN MAINTAINED WITHIN ERN SEMICIRCLE OF LARGE-SCALE CIRCULATION. SIMILAR TO THE PAST COUPLE OF DAYS...THIS ENHANCED WIND FIELD COMBINED WITH A MOIST BOUNDARY LAYER AND THE ONSET OF DAYTIME HEATING MAY YIELD AN ENVIRONMENT SUPPORTIVE OF A FEW SUPERCELLS CAPABLE OF A BRIEF TORNADO OR TWO...DESPITE THE OVERALL WEAKENING AND TRANSITION OF SYSTEM TO EXTRATROPICAL. ..MEAD/GRAMS.. 09/09/2010 Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0453 AM CDT THU SEP 09 2010 VALID 101200Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... ...SYNOPSIS... AN UPPER-LEVEL SHORT WAVE TROUGH OVER THE NRN HIGH PLAINS WILL SHIFT E/NEWD ACROSS THE SRN CANADIAN PRAIRIE PROVINCES AND THE NRN PLAINS. PRIMARY SURFACE CYCLONE WILL MOVE NWD AND OCCLUDE ACROSS SRN MANITOBA...WHILE AN ATTENDANT COLD FRONT PROGRESSES EWD ACROSS THE NRN/CNTRL PLAINS. ...FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... MARGINAL TO LOCALIZED LOW-END CRITICAL CONDITIONS SHOULD DEVELOP FRI ALONG THE LEE OF THE FRONT RANGE IN SERN WY/N-CNTRL CO EWD INTO THE NEB PANHANDLE. LOCALLY GUSTY WLY WINDS MAY BE ONGOING AT 12Z/FRI ACROSS THE FOOTHILLS. THE 06Z NAM REMAINS THE MOST BULLISH OPERATIONAL MODEL IN TEMPORAL EXTENT AND MAGNITUDE OF LOW-LEVEL FLOW LATE DAY 1. HOWEVER...IT DOES DEPICT AT LEAST FAIR RH RECOVERY OCCURRING FRI MORNING WHICH SUGGESTS THE PROBABILITY OF ONGOING CRITICAL CONDITIONS TO BE LOW. AS DAYTIME HEATING ENSUES...A DEEPENING MIXED BOUNDARY LAYER WILL POTENTIALLY SUPPORT MORE WIDESPREAD GUSTS TO REACH THE SURFACE. NEVERTHELESS...CONSENSUS OF MODEL GUIDANCE INDICATES LOW/MID-LEVEL FLOW WILL WEAKEN THROUGH THE DAY. SUSTAINED SURFACE WINDS SHOULD AVERAGE AROUND 15 TO 20 MPH WITH GUSTS OF 30 TO 40 MPH ACROSS SERN WY INTO NEB PANHANDLE AND EXTREME NRN CO...WHERE AFTERNOON RH VALUES SHOULD BECOME MARGINALLY LOW /FROM 15 TO 20 PERCENT/. FARTHER S IN N-CNTRL CO...SUSTAINED WINDS SHOULD BE MODERATE AROUND 15 MPH WITH RH VALUES NEAR 15 PERCENT. ...E-CNTRL NM... LATEST MODEL FORECASTS ARE HIGHLY CONSISTENT THAT A ZONE OF ENHANCED LOW-LEVEL WLYS /AROUND 30 TO 35 MPH AT 700 MB/ WILL DEVELOP BETWEEN THE SANGRE DE CRISTO AND SACRAMENTO MTNS FRI MORNING. AS DAYTIME HEATING COMMENCES...MIXING OF THIS MODERATELY STRONG FLOW TO THE SURFACE WILL SUPPORT SUSTAINED WINDS AROUND 15 TO 20 MPH BY EARLY AFTERNOON. THIS WILL BE JUXTAPOSED WITH RH VALUES FALLING TO BETWEEN 8 AND 15 PERCENT...LIKELY RESULTING IN AN ENHANCED TO LOCALIZED CRITICAL THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0453 AM CDT THU SEP 09 2010 VALID 101200Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... ...SYNOPSIS... AN UPPER-LEVEL SHORT WAVE TROUGH OVER THE NRN HIGH PLAINS WILL SHIFT E/NEWD ACROSS THE SRN CANADIAN PRAIRIE PROVINCES AND THE NRN PLAINS. PRIMARY SURFACE CYCLONE WILL MOVE NWD AND OCCLUDE ACROSS SRN MANITOBA...WHILE AN ATTENDANT COLD FRONT PROGRESSES EWD ACROSS THE NRN/CNTRL PLAINS. ...FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... MARGINAL TO LOCALIZED LOW-END CRITICAL CONDITIONS SHOULD DEVELOP FRI ALONG THE LEE OF THE FRONT RANGE IN SERN WY/N-CNTRL CO EWD INTO THE NEB PANHANDLE. LOCALLY GUSTY WLY WINDS MAY BE ONGOING AT 12Z/FRI ACROSS THE FOOTHILLS. THE 06Z NAM REMAINS THE MOST BULLISH OPERATIONAL MODEL IN TEMPORAL EXTENT AND MAGNITUDE OF LOW-LEVEL FLOW LATE DAY 1. HOWEVER...IT DOES DEPICT AT LEAST FAIR RH RECOVERY OCCURRING FRI MORNING WHICH SUGGESTS THE PROBABILITY OF ONGOING CRITICAL CONDITIONS TO BE LOW. AS DAYTIME HEATING ENSUES...A DEEPENING MIXED BOUNDARY LAYER WILL POTENTIALLY SUPPORT MORE WIDESPREAD GUSTS TO REACH THE SURFACE. NEVERTHELESS...CONSENSUS OF MODEL GUIDANCE INDICATES LOW/MID-LEVEL FLOW WILL WEAKEN THROUGH THE DAY. SUSTAINED SURFACE WINDS SHOULD AVERAGE AROUND 15 TO 20 MPH WITH GUSTS OF 30 TO 40 MPH ACROSS SERN WY INTO NEB PANHANDLE AND EXTREME NRN CO...WHERE AFTERNOON RH VALUES SHOULD BECOME MARGINALLY LOW /FROM 15 TO 20 PERCENT/. FARTHER S IN N-CNTRL CO...SUSTAINED WINDS SHOULD BE MODERATE AROUND 15 MPH WITH RH VALUES NEAR 15 PERCENT. ...E-CNTRL NM... LATEST MODEL FORECASTS ARE HIGHLY CONSISTENT THAT A ZONE OF ENHANCED LOW-LEVEL WLYS /AROUND 30 TO 35 MPH AT 700 MB/ WILL DEVELOP BETWEEN THE SANGRE DE CRISTO AND SACRAMENTO MTNS FRI MORNING. AS DAYTIME HEATING COMMENCES...MIXING OF THIS MODERATELY STRONG FLOW TO THE SURFACE WILL SUPPORT SUSTAINED WINDS AROUND 15 TO 20 MPH BY EARLY AFTERNOON. THIS WILL BE JUXTAPOSED WITH RH VALUES FALLING TO BETWEEN 8 AND 15 PERCENT...LIKELY RESULTING IN AN ENHANCED TO LOCALIZED CRITICAL THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0453 AM CDT THU SEP 09 2010 VALID 101200Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... ...SYNOPSIS... AN UPPER-LEVEL SHORT WAVE TROUGH OVER THE NRN HIGH PLAINS WILL SHIFT E/NEWD ACROSS THE SRN CANADIAN PRAIRIE PROVINCES AND THE NRN PLAINS. PRIMARY SURFACE CYCLONE WILL MOVE NWD AND OCCLUDE ACROSS SRN MANITOBA...WHILE AN ATTENDANT COLD FRONT PROGRESSES EWD ACROSS THE NRN/CNTRL PLAINS. ...FAR SERN WY/N-CNTRL CO/SWRN NEB PANHANDLE... MARGINAL TO LOCALIZED LOW-END CRITICAL CONDITIONS SHOULD DEVELOP FRI ALONG THE LEE OF THE FRONT RANGE IN SERN WY/N-CNTRL CO EWD INTO THE NEB PANHANDLE. LOCALLY GUSTY WLY WINDS MAY BE ONGOING AT 12Z/FRI ACROSS THE FOOTHILLS. THE 06Z NAM REMAINS THE MOST BULLISH OPERATIONAL MODEL IN TEMPORAL EXTENT AND MAGNITUDE OF LOW-LEVEL FLOW LATE DAY 1. HOWEVER...IT DOES DEPICT AT LEAST FAIR RH RECOVERY OCCURRING FRI MORNING WHICH SUGGESTS THE PROBABILITY OF ONGOING CRITICAL CONDITIONS TO BE LOW. AS DAYTIME HEATING ENSUES...A DEEPENING MIXED BOUNDARY LAYER WILL POTENTIALLY SUPPORT MORE WIDESPREAD GUSTS TO REACH THE SURFACE. NEVERTHELESS...CONSENSUS OF MODEL GUIDANCE INDICATES LOW/MID-LEVEL FLOW WILL WEAKEN THROUGH THE DAY. SUSTAINED SURFACE WINDS SHOULD AVERAGE AROUND 15 TO 20 MPH WITH GUSTS OF 30 TO 40 MPH ACROSS SERN WY INTO NEB PANHANDLE AND EXTREME NRN CO...WHERE AFTERNOON RH VALUES SHOULD BECOME MARGINALLY LOW /FROM 15 TO 20 PERCENT/. FARTHER S IN N-CNTRL CO...SUSTAINED WINDS SHOULD BE MODERATE AROUND 15 MPH WITH RH VALUES NEAR 15 PERCENT. ...E-CNTRL NM... LATEST MODEL FORECASTS ARE HIGHLY CONSISTENT THAT A ZONE OF ENHANCED LOW-LEVEL WLYS /AROUND 30 TO 35 MPH AT 700 MB/ WILL DEVELOP BETWEEN THE SANGRE DE CRISTO AND SACRAMENTO MTNS FRI MORNING. AS DAYTIME HEATING COMMENCES...MIXING OF THIS MODERATELY STRONG FLOW TO THE SURFACE WILL SUPPORT SUSTAINED WINDS AROUND 15 TO 20 MPH BY EARLY AFTERNOON. THIS WILL BE JUXTAPOSED WITH RH VALUES FALLING TO BETWEEN 8 AND 15 PERCENT...LIKELY RESULTING IN AN ENHANCED TO LOCALIZED CRITICAL THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0343 AM CDT THU SEP 09 2010 VALID 091200Z - 101200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WY...NWRN/N-CNTRL CO... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NERN AZ...FOUR CORNERS... ...SYNOPSIS... A POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE WRN GREAT BASIN WILL EJECT NEWD...REACHING THE NRN/CNTRL ROCKIES BY LATE EVENING. AT THE SURFACE...LEE CYCLOGENESIS WILL OCCUR ACROSS NRN HIGH PLAINS...WITH AN ATTENDANT COLD FRONT DRAPED SWWD THROUGH THE ERN GREAT BASIN THIS AFTERNOON. IN THE EAST...AN UPPER-LEVEL LOW WILL REMAIN ANCHORED OVER NRN NEW ENGLAND. ...PORTIONS OF WY...NWRN/N-CNTRL CO... A BELT OF INTENSE MID-LEVEL SWLYS /65 TO 75 MPH AT 500 MB/ WILL OVERSPREAD THE ERN GREAT BASIN AND CNTRL ROCKIES BY NOON IN ASSOCIATION WITH THE WRN CONUS UPPER-LEVEL TROUGH. THIS WILL HELP SHIFT RICHER SUB-TROPICAL MOISTURE E OF THE CNTRL ROCKIES...WITH A CORRIDOR OF DEEP VERTICAL MIXING DEVELOPING IN ITS WAKE FROM NWRN CO ACROSS CNTRL/ERN WY. THIS MIXING SHOULD LEAD TO VERY STRONG SUSTAINED SURFACE WINDS OF 25 TO 35 MPH AT PEAK HEATING...WITH GUSTS OF 45 TO 60 MPH PROBABLE. DESPITE SUBSTANTIAL DRYING...RH VALUES SHOULD ONLY BECOME MARGINALLY LOW /AROUND 12 TO 20 PERCENT/. HOWEVER...GIVEN THE STRENGTH OF THE WINDS...LOCALIZED EXTREMELY CRITICAL CONDITIONS MAY OCCUR. ALONG THE FOOTHILLS OF THE FRONT RANGE...A PERIOD OF STRONG GUSTY WLYS APPEARS LIKELY TO DEVELOP DURING THE EVENING. LATEST NAM FORECAST SOUNDINGS INDICATE 40 TO 50 MPH WLYS IN THE LOWEST 1000-3000 FT AGL WHICH WOULD LEAD TO LOCALLY INTENSE WIND GUSTS INVOF ONGOING FIRES. THE NAM REMAINS STRONGEST OF OPERATIONAL MODEL GUIDANCE IN TEMPORAL EXTENT OF THESE WINDS PERSISTING INTO THE OVERNIGHT...WHICH WOULD RESULT IN POOR RH RECOVERY. THE LATEST GFS/ECMWF SUGGEST STRONG WLYS WILL PRIMARILY RESIDE FARTHER N IN SERN WY DURING THE OVERNIGHT...WHICH BREEDS SOME UNCERTAINTY IN THE TEMPORAL EXTENT OF CRITICAL CONDITIONS IN N-CNTRL CO. ...PORTIONS OF NERN AZ...FOUR CORNERS... ON THE SRN PERIPHERY OF THE INTENSE MID-LEVEL SWLYS OVER THE ERN GREAT BASIN TO THE CNTRL ROCKIES...SUSTAINED SURFACE WINDS SHOULD LARGELY RANGE FROM 20 TO 25 MPH THIS AFTERNOON ACROSS THE FOUR CORNERS AREA. AS SUBSTANTIAL DRYING OVERSPREADS THE REGION...RH VALUES SHOULD BECOME LOW /AROUND 10 TO 15 PERCENT/...PRIMARILY ACROSS NERN AZ. FARTHER N/E...WIDESPREAD LIGHT TO AREAS OF MODERATE RAIN ON WED SHOULD MITIGATE THE OVERALL THREAT ACROSS MOST OF ERN UT/WRN CO/NWRN NM. ...CNTRL/ERN MD...DE...NERN VA...D.C.... NWLY LOW-LEVEL FLOW WILL RESULT IN COOLER TEMPERATURES THIS AFTERNOON COMPARED TO WED /PRIMARILY IN THE MIDDLE 70S TO LOWER 80S/. THIS WILL LEAD TO MORE MARGINAL RH VALUES...IN THE UPPER 20S TO MIDDLE 30S. SUSTAINED SURFACE WINDS WILL ALSO BE SLIGHTLY WEAKER /NEAR 15 MPH/ AS THE PRESSURE GRADIENT RELAXES. HOWEVER...POTENTIAL FOR GUSTS AROUND 25 MPH SHOULD CONTRIBUTE TO AN ELEVATED FIRE WEATHER THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0343 AM CDT THU SEP 09 2010 VALID 091200Z - 101200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WY...NWRN/N-CNTRL CO... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NERN AZ...FOUR CORNERS... ...SYNOPSIS... A POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE WRN GREAT BASIN WILL EJECT NEWD...REACHING THE NRN/CNTRL ROCKIES BY LATE EVENING. AT THE SURFACE...LEE CYCLOGENESIS WILL OCCUR ACROSS NRN HIGH PLAINS...WITH AN ATTENDANT COLD FRONT DRAPED SWWD THROUGH THE ERN GREAT BASIN THIS AFTERNOON. IN THE EAST...AN UPPER-LEVEL LOW WILL REMAIN ANCHORED OVER NRN NEW ENGLAND. ...PORTIONS OF WY...NWRN/N-CNTRL CO... A BELT OF INTENSE MID-LEVEL SWLYS /65 TO 75 MPH AT 500 MB/ WILL OVERSPREAD THE ERN GREAT BASIN AND CNTRL ROCKIES BY NOON IN ASSOCIATION WITH THE WRN CONUS UPPER-LEVEL TROUGH. THIS WILL HELP SHIFT RICHER SUB-TROPICAL MOISTURE E OF THE CNTRL ROCKIES...WITH A CORRIDOR OF DEEP VERTICAL MIXING DEVELOPING IN ITS WAKE FROM NWRN CO ACROSS CNTRL/ERN WY. THIS MIXING SHOULD LEAD TO VERY STRONG SUSTAINED SURFACE WINDS OF 25 TO 35 MPH AT PEAK HEATING...WITH GUSTS OF 45 TO 60 MPH PROBABLE. DESPITE SUBSTANTIAL DRYING...RH VALUES SHOULD ONLY BECOME MARGINALLY LOW /AROUND 12 TO 20 PERCENT/. HOWEVER...GIVEN THE STRENGTH OF THE WINDS...LOCALIZED EXTREMELY CRITICAL CONDITIONS MAY OCCUR. ALONG THE FOOTHILLS OF THE FRONT RANGE...A PERIOD OF STRONG GUSTY WLYS APPEARS LIKELY TO DEVELOP DURING THE EVENING. LATEST NAM FORECAST SOUNDINGS INDICATE 40 TO 50 MPH WLYS IN THE LOWEST 1000-3000 FT AGL WHICH WOULD LEAD TO LOCALLY INTENSE WIND GUSTS INVOF ONGOING FIRES. THE NAM REMAINS STRONGEST OF OPERATIONAL MODEL GUIDANCE IN TEMPORAL EXTENT OF THESE WINDS PERSISTING INTO THE OVERNIGHT...WHICH WOULD RESULT IN POOR RH RECOVERY. THE LATEST GFS/ECMWF SUGGEST STRONG WLYS WILL PRIMARILY RESIDE FARTHER N IN SERN WY DURING THE OVERNIGHT...WHICH BREEDS SOME UNCERTAINTY IN THE TEMPORAL EXTENT OF CRITICAL CONDITIONS IN N-CNTRL CO. ...PORTIONS OF NERN AZ...FOUR CORNERS... ON THE SRN PERIPHERY OF THE INTENSE MID-LEVEL SWLYS OVER THE ERN GREAT BASIN TO THE CNTRL ROCKIES...SUSTAINED SURFACE WINDS SHOULD LARGELY RANGE FROM 20 TO 25 MPH THIS AFTERNOON ACROSS THE FOUR CORNERS AREA. AS SUBSTANTIAL DRYING OVERSPREADS THE REGION...RH VALUES SHOULD BECOME LOW /AROUND 10 TO 15 PERCENT/...PRIMARILY ACROSS NERN AZ. FARTHER N/E...WIDESPREAD LIGHT TO AREAS OF MODERATE RAIN ON WED SHOULD MITIGATE THE OVERALL THREAT ACROSS MOST OF ERN UT/WRN CO/NWRN NM. ...CNTRL/ERN MD...DE...NERN VA...D.C.... NWLY LOW-LEVEL FLOW WILL RESULT IN COOLER TEMPERATURES THIS AFTERNOON COMPARED TO WED /PRIMARILY IN THE MIDDLE 70S TO LOWER 80S/. THIS WILL LEAD TO MORE MARGINAL RH VALUES...IN THE UPPER 20S TO MIDDLE 30S. SUSTAINED SURFACE WINDS WILL ALSO BE SLIGHTLY WEAKER /NEAR 15 MPH/ AS THE PRESSURE GRADIENT RELAXES. HOWEVER...POTENTIAL FOR GUSTS AROUND 25 MPH SHOULD CONTRIBUTE TO AN ELEVATED FIRE WEATHER THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0348 AM CDT THU SEP 09 2010 VALID 121200Z - 171200Z ...DISCUSSION... 00Z ECMWF/GEFS CONTINUE TO REFLECT A NEARLY ZONAL/LOW AMPLITUDE LARGE SCALE REGIME INTO EARLY NEXT WEEK...ALTHOUGH GUIDANCE DISCREPANCIES BEGIN TO EXIST BY MID WEEK. THIS IS MAINLY DUE TO INDICATIONS OF AN INCREASINGLY AMPLIFIED PATTERN /LARGELY VIA AN EASTERN STATES TROUGH/ PER 00Z GEFS/DETERMINISTIC GFS...WHEREAS THE 00Z ECMWF REMAINS MORE ZONAL THROUGH EARLY NEXT WEEK. REGARDLESS...LIMITED POTENTIAL AND PREDICTABILITY...GIVEN THE INITIALLY LOW AMPLITUDE NATURE OF THE LARGE SCALE REGIME...PRECLUDE CONSIDERATION OF ANY SEVERE RISK AREAS. Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0348 AM CDT THU SEP 09 2010 VALID 121200Z - 171200Z ...DISCUSSION... 00Z ECMWF/GEFS CONTINUE TO REFLECT A NEARLY ZONAL/LOW AMPLITUDE LARGE SCALE REGIME INTO EARLY NEXT WEEK...ALTHOUGH GUIDANCE DISCREPANCIES BEGIN TO EXIST BY MID WEEK. THIS IS MAINLY DUE TO INDICATIONS OF AN INCREASINGLY AMPLIFIED PATTERN /LARGELY VIA AN EASTERN STATES TROUGH/ PER 00Z GEFS/DETERMINISTIC GFS...WHEREAS THE 00Z ECMWF REMAINS MORE ZONAL THROUGH EARLY NEXT WEEK. REGARDLESS...LIMITED POTENTIAL AND PREDICTABILITY...GIVEN THE INITIALLY LOW AMPLITUDE NATURE OF THE LARGE SCALE REGIME...PRECLUDE CONSIDERATION OF ANY SEVERE RISK AREAS. Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0348 AM CDT THU SEP 09 2010 VALID 121200Z - 171200Z ...DISCUSSION... 00Z ECMWF/GEFS CONTINUE TO REFLECT A NEARLY ZONAL/LOW AMPLITUDE LARGE SCALE REGIME INTO EARLY NEXT WEEK...ALTHOUGH GUIDANCE DISCREPANCIES BEGIN TO EXIST BY MID WEEK. THIS IS MAINLY DUE TO INDICATIONS OF AN INCREASINGLY AMPLIFIED PATTERN /LARGELY VIA AN EASTERN STATES TROUGH/ PER 00Z GEFS/DETERMINISTIC GFS...WHEREAS THE 00Z ECMWF REMAINS MORE ZONAL THROUGH EARLY NEXT WEEK. REGARDLESS...LIMITED POTENTIAL AND PREDICTABILITY...GIVEN THE INITIALLY LOW AMPLITUDE NATURE OF THE LARGE SCALE REGIME...PRECLUDE CONSIDERATION OF ANY SEVERE RISK AREAS. Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0343 AM CDT THU SEP 09 2010 VALID 091200Z - 101200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WY...NWRN/N-CNTRL CO... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NERN AZ...FOUR CORNERS... ...SYNOPSIS... A POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE WRN GREAT BASIN WILL EJECT NEWD...REACHING THE NRN/CNTRL ROCKIES BY LATE EVENING. AT THE SURFACE...LEE CYCLOGENESIS WILL OCCUR ACROSS NRN HIGH PLAINS...WITH AN ATTENDANT COLD FRONT DRAPED SWWD THROUGH THE ERN GREAT BASIN THIS AFTERNOON. IN THE EAST...AN UPPER-LEVEL LOW WILL REMAIN ANCHORED OVER NRN NEW ENGLAND. ...PORTIONS OF WY...NWRN/N-CNTRL CO... A BELT OF INTENSE MID-LEVEL SWLYS /65 TO 75 MPH AT 500 MB/ WILL OVERSPREAD THE ERN GREAT BASIN AND CNTRL ROCKIES BY NOON IN ASSOCIATION WITH THE WRN CONUS UPPER-LEVEL TROUGH. THIS WILL HELP SHIFT RICHER SUB-TROPICAL MOISTURE E OF THE CNTRL ROCKIES...WITH A CORRIDOR OF DEEP VERTICAL MIXING DEVELOPING IN ITS WAKE FROM NWRN CO ACROSS CNTRL/ERN WY. THIS MIXING SHOULD LEAD TO VERY STRONG SUSTAINED SURFACE WINDS OF 25 TO 35 MPH AT PEAK HEATING...WITH GUSTS OF 45 TO 60 MPH PROBABLE. DESPITE SUBSTANTIAL DRYING...RH VALUES SHOULD ONLY BECOME MARGINALLY LOW /AROUND 12 TO 20 PERCENT/. HOWEVER...GIVEN THE STRENGTH OF THE WINDS...LOCALIZED EXTREMELY CRITICAL CONDITIONS MAY OCCUR. ALONG THE FOOTHILLS OF THE FRONT RANGE...A PERIOD OF STRONG GUSTY WLYS APPEARS LIKELY TO DEVELOP DURING THE EVENING. LATEST NAM FORECAST SOUNDINGS INDICATE 40 TO 50 MPH WLYS IN THE LOWEST 1000-3000 FT AGL WHICH WOULD LEAD TO LOCALLY INTENSE WIND GUSTS INVOF ONGOING FIRES. THE NAM REMAINS STRONGEST OF OPERATIONAL MODEL GUIDANCE IN TEMPORAL EXTENT OF THESE WINDS PERSISTING INTO THE OVERNIGHT...WHICH WOULD RESULT IN POOR RH RECOVERY. THE LATEST GFS/ECMWF SUGGEST STRONG WLYS WILL PRIMARILY RESIDE FARTHER N IN SERN WY DURING THE OVERNIGHT...WHICH BREEDS SOME UNCERTAINTY IN THE TEMPORAL EXTENT OF CRITICAL CONDITIONS IN N-CNTRL CO. ...PORTIONS OF NERN AZ...FOUR CORNERS... ON THE SRN PERIPHERY OF THE INTENSE MID-LEVEL SWLYS OVER THE ERN GREAT BASIN TO THE CNTRL ROCKIES...SUSTAINED SURFACE WINDS SHOULD LARGELY RANGE FROM 20 TO 25 MPH THIS AFTERNOON ACROSS THE FOUR CORNERS AREA. AS SUBSTANTIAL DRYING OVERSPREADS THE REGION...RH VALUES SHOULD BECOME LOW /AROUND 10 TO 15 PERCENT/...PRIMARILY ACROSS NERN AZ. FARTHER N/E...WIDESPREAD LIGHT TO AREAS OF MODERATE RAIN ON WED SHOULD MITIGATE THE OVERALL THREAT ACROSS MOST OF ERN UT/WRN CO/NWRN NM. ...CNTRL/ERN MD...DE...NERN VA...D.C.... NWLY LOW-LEVEL FLOW WILL RESULT IN COOLER TEMPERATURES THIS AFTERNOON COMPARED TO WED /PRIMARILY IN THE MIDDLE 70S TO LOWER 80S/. THIS WILL LEAD TO MORE MARGINAL RH VALUES...IN THE UPPER 20S TO MIDDLE 30S. SUSTAINED SURFACE WINDS WILL ALSO BE SLIGHTLY WEAKER /NEAR 15 MPH/ AS THE PRESSURE GRADIENT RELAXES. HOWEVER...POTENTIAL FOR GUSTS AROUND 25 MPH SHOULD CONTRIBUTE TO AN ELEVATED FIRE WEATHER THREAT. ..GRAMS.. 09/09/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1239 AM CDT THU SEP 09 2010 VALID 091200Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN HIGH PLAINS... ...SYNOPSIS... PV-ANOMALY AT THE BASE OF THE WRN STATES TROUGH WILL TRANSLATE ENE AND REACH THE NRN HIGH PLAINS THURSDAY NIGHT. DOWNSTREAM LEE TROUGH/LOW WILL STRENGTHEN DURING THE AFTERNOON ACROSS ERN PARTS OF MT AND WY WITH SUBSEQUENT MOVEMENT INTO THE WRN DAKOTAS AND NEB PANHANDLE THURSDAY EVENING. ...NRN HIGH PLAINS... MID-LEVEL HEIGHT FALLS ON THE ORDER OF 30-60 METERS/12 HR ASSOCIATED WITH THE ADVANCING UPPER TROUGH WILL INDUCE INCREASING SSELY LLVL FLOW OVER THE HIGH PLAINS ON THURSDAY. THIS WILL TRANSPORT UPR 50S/MID 60S SURFACE DEW POINTS NWWD INTO ERN MT AND TO THE E OF THE LEE TROUGH OVER NEB AND THE DAKOTAS. MID-LEVEL LAPSE RATES OF 7.5-8 DEG C PER KM ATOP THIS RETURNING MOISTURE WILL CONTRIBUTE TO MLCAPES OF 1000-2000 J/KG BY AFTERNOON. BAND OF ASCENT AHEAD OF THE PRIMARY PV-ANOMALY WILL BE IMPETUS FOR HIGH-BASED CONVECTIVE INITIATION BY MID-AFTERNOON NEAR THE WY/NEB/SD BORDER AS HEATING/MOISTENING WEAKENS INHIBITION. STORMS WILL GROW STRONGER BY EARLY EVENING AS THEY ENCOUNTER COMPARATIVELY MORE ROBUST INSTABILITY OVER SWRN ND...WRN SD AND THE NEB PANHANDLE. OTHER STORMS WILL FORM FARTHER NW DURING THE EARLY EVENING OVER ERN MT AND ROTATE ENE INTO WRN ND IN ASSOCIATION WITH THE PRIMARY UPPER IMPULSE. INITIAL STORMS WILL LIKELY EVOLVE INTO SUPERCELLS OWING TO 40-45 KTS OF EFFECTIVE SHEAR AND MAGNITUDE OF MID-LEVEL LAPSE RATES. LARGE HAIL...UP TO GOLFBALL SIZE...WILL BE THE PRIMARY THREAT AND STORMS WILL TEND TO REMAIN DISCRETE THE LONGEST FROM WRN SD SWD INTO THE NEB PANHANDLE. EVENTUALLY LOOSELY ORGANIZED LINE SEGMENTS WILL BECOME THE PRIMARY MODE AS STORMS CONTINUE EWD ONTO THE LOWER PLAINS. THE SEVERE THREAT SHOULD GRADUALLY WANE OVERNIGHT AS ACTIVITY BECOMES MORE ELEVATED AND FARTHER REMOVED FROM THE INSTABILITY. ..RACY/SMITH.. 09/09/2010 Read more

SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1239 AM CDT THU SEP 09 2010 VALID 091200Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN HIGH PLAINS... ...SYNOPSIS... PV-ANOMALY AT THE BASE OF THE WRN STATES TROUGH WILL TRANSLATE ENE AND REACH THE NRN HIGH PLAINS THURSDAY NIGHT. DOWNSTREAM LEE TROUGH/LOW WILL STRENGTHEN DURING THE AFTERNOON ACROSS ERN PARTS OF MT AND WY WITH SUBSEQUENT MOVEMENT INTO THE WRN DAKOTAS AND NEB PANHANDLE THURSDAY EVENING. ...NRN HIGH PLAINS... MID-LEVEL HEIGHT FALLS ON THE ORDER OF 30-60 METERS/12 HR ASSOCIATED WITH THE ADVANCING UPPER TROUGH WILL INDUCE INCREASING SSELY LLVL FLOW OVER THE HIGH PLAINS ON THURSDAY. THIS WILL TRANSPORT UPR 50S/MID 60S SURFACE DEW POINTS NWWD INTO ERN MT AND TO THE E OF THE LEE TROUGH OVER NEB AND THE DAKOTAS. MID-LEVEL LAPSE RATES OF 7.5-8 DEG C PER KM ATOP THIS RETURNING MOISTURE WILL CONTRIBUTE TO MLCAPES OF 1000-2000 J/KG BY AFTERNOON. BAND OF ASCENT AHEAD OF THE PRIMARY PV-ANOMALY WILL BE IMPETUS FOR HIGH-BASED CONVECTIVE INITIATION BY MID-AFTERNOON NEAR THE WY/NEB/SD BORDER AS HEATING/MOISTENING WEAKENS INHIBITION. STORMS WILL GROW STRONGER BY EARLY EVENING AS THEY ENCOUNTER COMPARATIVELY MORE ROBUST INSTABILITY OVER SWRN ND...WRN SD AND THE NEB PANHANDLE. OTHER STORMS WILL FORM FARTHER NW DURING THE EARLY EVENING OVER ERN MT AND ROTATE ENE INTO WRN ND IN ASSOCIATION WITH THE PRIMARY UPPER IMPULSE. INITIAL STORMS WILL LIKELY EVOLVE INTO SUPERCELLS OWING TO 40-45 KTS OF EFFECTIVE SHEAR AND MAGNITUDE OF MID-LEVEL LAPSE RATES. LARGE HAIL...UP TO GOLFBALL SIZE...WILL BE THE PRIMARY THREAT AND STORMS WILL TEND TO REMAIN DISCRETE THE LONGEST FROM WRN SD SWD INTO THE NEB PANHANDLE. EVENTUALLY LOOSELY ORGANIZED LINE SEGMENTS WILL BECOME THE PRIMARY MODE AS STORMS CONTINUE EWD ONTO THE LOWER PLAINS. THE SEVERE THREAT SHOULD GRADUALLY WANE OVERNIGHT AS ACTIVITY BECOMES MORE ELEVATED AND FARTHER REMOVED FROM THE INSTABILITY. ..RACY/SMITH.. 09/09/2010 Read more