vendredi 8 mai 2015

May 8, 2015 0600 UTC Day 1 Convective Outlook



DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT FRI MAY 08 2015

   VALID 081200Z - 091200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER SW OK AND FAR NW TX...

   ...THERE IS AN ENH RISK OF SVR TSTMS FROM SERN CO TO MOST OF OK AND
   PARTS OF N TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN GREAT
   PLAINS...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE MIDWEST TO THE
   CNTRL/SRN GREAT PLAINS...

   ...SUMMARY...
   SCATTERED TO PERHAPS WIDESPREAD SEVERE THUNDERSTORMS MAY DEVELOP
   ACROSS PORTIONS OF THE SOUTHERN HIGH PLAINS TO ALONG THE RED
   RIVER...MAINLY FROM MIDDAY THROUGH THIS EVENING. VERY LARGE
   HAIL...DAMAGING WINDS...AND TORNADOES WILL BE POSSIBLE.

   ...SYNOPSIS...
   INITIALLY VIGOROUS SHORTWAVE TROUGH OVER SRN CA WILL DAMPEN AS IT
   EJECTS TOWARDS THE FOUR CORNERS AREA THROUGH EARLY SAT. A SUBTLE
   MID-LEVEL IMPULSE EVIDENT IN WATER-VAPOR IMAGERY OVER AZ TO NW
   MEXICO SHOULD REACH THE SRN HIGH PLAINS BY EARLY TO MID AFTERNOON
   WITH AN ASSOCIATED JET STREAK FROM THE TRANS-PECOS TO NW TX.
   GUIDANCE VARIES MARKEDLY WITH THE EVOLUTION OF THE DRYLINE BY
   AFTERNOON IN THE WAKE OF AN ONGOING MCS FROM ERN OK TO N-CNTRL TX
   AND POTENTIAL MORNING CONVECTION N OF THE TRAILING MCS OUTFLOW THAT
   EXTENDS TOWARDS THE CONCHO VALLEY. THE DRYLINE SHOULD MIX INTO PARTS
   OF WRN TX BEFORE RETREATING WWD TONIGHT WITH A LOW-LEVEL MOISTURE
   SURGE TOWARDS THE TX/NM BORDER IN ADVANCE OF THE FOUR CORNERS
   TROUGH.

   ...SRN GREAT PLAINS...
   CONFIDENCE IS LOWER THAN PREVIOUS FORECAST WITH A POTENTIALLY
   COMPLEX/MESSY CONVECTIVE EVOLUTION THAT COULD LIMIT THE OVERALL
   RISK. CONSIDERED A CATEGORICAL DOWNGRADE THIS OUTLOOK...BUT A
   HIGHER-END SCENARIO CANNOT BE COMPLETELY DISCOUNTED AT THIS TIME.

   MOISTURE RETURN IS ONGOING ACROSS THE EDWARDS PLATEAU WITH UPPER 60S
   TO LOWER 70S SURFACE DEW POINTS S OF THE TRAILING OUTFLOW BOUNDARY
   OVER THE CONCHO VALLEY WITHIN A 40-KT LLJ. ISENTROPIC ASCENT N OF
   THIS BOUNDARY COUPLED WITH DIFLUENT HIGH-LEVEL FLOW AND MID-LEVEL
   DCVA ASSOCIATED WITH THE LEAD MID-LEVEL IMPULSE SHOULD RESULT IN
   CONVECTION DEVELOPING LATER THIS MORNING FROM THE TX S PLAINS
   TOWARDS THE PANHANDLE. THIS TIMING APPEARS UNFAVORABLE FOR ROBUST
   DIURNAL DESTABILIZATION WITHIN THIS CORRIDOR AND ALSO APPEARS
   QUESTIONABLE FARTHER E IN THE WAKE OF EXTENSIVE CONVECTIVE
   OVERTURNING ON THU.

   MORNING CONVECTION MAY GROW UPSCALE INTO AN MCS BY MIDDAY IN
   SOMEWHAT SIMILAR FASHION TO THU OWING TO THE LACK OF A VERY STRONG
   EML RELATIVE TO THE DEGREE OF TROPICAL MOISTURE...CHARACTERIZED BY
   MEAN MIXING RATIOS OF 15-17 G/KG IN 08/00Z RAOBS ALONG THE WRN GULF
   COAST. STRENGTHENING MID-LEVEL SWLYS SHOULD FAVOR EMBEDDED SUPERCELL
   AND BOWING/LEWP STRUCTURES AS ACTIVITY PROBABLY DEVELOPS E/S THROUGH
   THE AFTERNOON. LARGE HAIL /SOME SIGNIFICANT/...DAMAGING WINDS AND A
   FEW TORNADOES ARE ALL POSSIBLE ALONG THE LEADING EDGE OF THE
   MCS...AND POTENTIAL REDEVELOPMENT SWWD ALONG TRAILING
   OUTFLOW/DRYLINE INTERSECTION. LOW-LEVEL FLOW SHOULD REMAIN MODEST
   THROUGH MUCH OF THE AFTERNOON...PRIOR TO INCREASING TOWARDS 00Z.
   WITH EXTENSIVE CONVECTION AND MESSY CONVECTIVE MODE PROBABLY ONGOING
   BY THIS TIME...THE EXTENT OF HIGHER-END TORNADO POTENTIAL MAY BE
   SUBDUED.

   ADDITIONAL STORMS SHOULD FORM WITHIN THE LOW-LEVEL UPSLOPE REGIME
   ACROSS THE HIGH PLAINS FROM SERN CO INTO PARTS OF THE TX PANHANDLE.
   DEEP-LAYER WIND PROFILES WOULD SUPPORT ALL SEVERE HAZARDS...BUT THE
   OVERALL RISK WILL LIKELY BE DEPENDENT ON THE DEGREE OF
   BOUNDARY-LAYER MOISTURE WHICH MAY BE TEMPERED BY MORNING CONVECTION
   TO THE SE. ANOTHER ROUND OF NOCTURNAL STORMS MAY FORM BY 12Z/SAT AS
   MID-LEVEL HEIGHT FALLS OVERSPREAD A SURGE OF LOW-LEVEL MOISTURE
   APPROACHING THE TX/NM BORDER. ISOLATED SEVERE HAIL SHOULD BE THE
   MAIN RISK.

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