NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT SAT JUN 14 2014 VALID 141200Z - 151200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM NRN KS...CNTRL AND ERN NEB INTO WRN IA... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE SRN...CNTRL AND NRN PLAINS INTO THE UPPER MS VALLEY AREA... ...SUMMARY... VERY LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES ARE LIKELY ACROSS MUCH OF NEBRASKA...KANSAS...AND WESTERN IOWA SATURDAY AFTERNOON AND EVENING. SEVERE STORMS SHOULD ALSO OCCUR OVER NORTHEASTERN COLORADO...THE TEXAS AND OKLAHOMA PANHANDLES...AND THE EASTERN DAKOTAS INTO SRN MINNESOTA. ...SYNOPSIS... UPPER TROUGH CURRENTLY OVER THE NRN INTERMOUNTAIN REGION WILL MOVE EAST WITHIN A PROGRESSIVE FLOW REGIME...REACHING THE CNTRL AND NRN PLAINS SATURDAY NIGHT. SHORTWAVE TROUGH WITHIN BASE OF THIS UPPER LOW WILL EMERGE OVER THE CNTRL HIGH PLAINS LATE SATURDAY AFTERNOON OR SATURDAY EVENING AND CONTINUE INTO THE UPPER MS VALLEY REGION SATURDAY NIGHT. DRYLINE WILL SHARPEN FROM WRN TX THROUGH WRN KS TO THE SOUTH OF A LEE LOW. A COLD FRONT IS FORECAST TO ADVANCE SWD THROUGH THE NRN AND CNTRL HIGH PLAINS...EVENTUALLY MERGING WITH THE DRYLINE ACROSS SWRN NEB OR NWRN KS. ...SERN SD...SWRN MN...CNTRL AND ERN NEB...WRN AND CNTRL KS THROUGH WRN IA... POTENTIAL EXISTS FOR SIGNIFICANT SEVERE EVENTS IN THIS REGION INCLUDING VERY LARGE HAIL...WIDESPREAD WIND DAMAGING AND A FEW TORNADOES. STRONG SLY LOW-LEVEL JET WILL ADVECT RICHER MOISTURE NOW OVER THE SRN PLAINS NWD THROUGH THE WARM SECTOR INTO SATURDAY WITH BOUNDARY LAYER DEWPOINTS RISING INTO THE MID-UPPER 60S OVER ERN KS AND NEB. MEANWHILE...PLUME OF VERY STEEP LAPSE RATES /8.5 C/KM/ WILL SPREAD EWD ABOVE THE MOIST AXIS CONTRIBUTING TO VERY STRONG INSTABILITY WITH MLCAPE TO 4000 J/KG. A CAPPING INVERSION ASSOCIATED WITH WARM AIR AT BASE OF THE ELEVATED MIXED LAYER WILL LIKELY LIMIT SURFACE BASED DEVELOPMENT IN THIS REGION MUCH OF THE DAY. INITIAL STORMS WILL PROBABLY DEVELOP WITHIN ZONE OF DEEP MIXING ALONG THE DRYLINE FROM WRN KS INTO SWRN NEB. ADDITIONAL STORMS ARE LIKELY ALONG THE SEWD ADVANCING COLD FRONT AND THE COLD FRONT-DRYLINE MERGER FROM SCNTRL THROUGH CNTRL NEB. WINDS ALOFT WILL INCREASE AS A MID-LEVEL JET ROTATES THROUGH BASE OF THE UPPER TROUGH AND INTO THE CNTRL HIGH PLAINS WITH EFFECTIVE SHEAR APPROACHING 35-40 KT BY LATE AFTERNOON. THE ENVIRONMENT WILL BECOME VERY FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL WITH INITIAL STORMS THAT DEVELOP. THE LOW-LEVEL JET IS FORECAST TO SHIFT EAST DURING THE DAY RESULTING IN RELATIVELY SMALL HODOGRAPHS WHERE INITIATION OCCURS DURING THE AFTERNOON. HOWEVER...A SMALL WINDOW MAY EXIST FOR A FEW TORNADOES DURING THE LATE AFTERNOON AND EVENING...ESPECIALLY OVER ERN NEB WHERE THE LLJ WILL STRENGTHEN WITHIN MOIST AXIS AND BEFORE STORMS GROW UPSCALE. ISOLATED TORNADOES WILL ALSO BE POSSIBLE OVER WRN KS WITH STORMS INITIATING ALONG THE DRYLINE. EVENTUALLY STORMS WILL LIKELY EVOLVE INTO AN MCS FROM NRN KS INTO ERN NEB WITHIN ZONE OF INTENSE FORCING ALONG FRONT AND ON NOSE OF STRENGTHENING LLJ. THIS ACTIVITY COULD PRODUCE WIDESPREAD DAMAGING WIND AS IT CONTINUES THROUGH ERN NEB AND IA.
vendredi 13 juin 2014
Jun 14, 2014 0600 UTC Day 1 Convective Outlook,,,,,,,,,,,,,,,,,,,,,,http://www.spc.noaa.gov/products/outlook/day1otlk.html
DAY 1 CONVECTIVE OUTLOOK
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