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  
   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.


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