lundi 13 octobre 2014

Oct 13, 2014 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT MON OCT 13 2014

   VALID 131200Z - 141200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NRN LA...AR...SE
   MO...NW MS...WRN TN...WRN KY AND FAR SRN IL...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...OZARKS...LOWER MS VALLEY...MID MS VALLEY...CNTRL GULF COAST
   STATES...TN VALLEY AND OH VALLEY...

   ...SUMMARY...
   NUMEROUS STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TODAY AND
   TONIGHT FROM EAST TEXAS THROUGH THE LOWER AND MIDDLE MISSISSIPPI
   VALLEY INTO PARTS OF THE TENNESSEE VALLEY...OHIO VALLEY AND GULF
   COAST STATES. WIDESPREAD DAMAGING WINDS...SOME TORNADOES AND HAIL
   WILL LIKELY OCCUR.

   ...LOWER TO MID MS VALLEY...
   AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE SRN PLAINS
   TODAY AS A 65 TO 80 KT MID-LEVEL JET ROUNDS THE BASE OF THE
   UPPER-LEVEL TROUGH AND MOVES ACROSS THE ARKLATEX AND OZARKS. AT THE
   SFC...A LOW WILL MOVE NEWD ACROSS MO AS A COLD FRONT ADVANCES
   QUICKLY EWD ACROSS ERN OK AND EAST TX. A SQUALL-LINE WILL BE ONGOING
   AHEAD OF THE FRONT AT THE START OF THE PERIOD FROM SW MO SWD ACROSS
   WRN AR AND EXTENDING SWWD INTO NE TX. THIS SQUALL-LINE WILL MOVE
   QUICKLY EWD INTO THE LOWER TO MID MS VALLEY TODAY RESULTING IN
   WIDESPREAD SEVERE WEATHER.

   AHEAD OF THE SQUALL-LINE...A WELL-DEVELOPED 50 TO 65 KT LOW-LEVEL
   JET WILL HELP REINFORCE A CORRIDOR OF LOW-LEVEL MOISTURE EXTENDING
   NWD ACROSS THE ERN HALF OF AR INTO SERN MO THIS MORNING. SFC
   DEWPOINTS ALONG THIS CORRIDOR WILL INCREASE INTO THE MID TO UPPER
   60S F ALLOWING MODERATE INSTABILITY TO DEVELOP ACROSS PARTS OF SRN
   AND ERN AR THIS MORNING. WARMING SFC TEMPS DURING THE DAY AND
   INCREASING LOW-LEVEL MOISTURE SHOULD ENABLE THE SQUALL-LINE TO
   GRADUALLY INTENSIFY PRODUCING A WIDESPREAD WIND DAMAGE THREAT. A
   POTENTIAL FOR WIND GUSTS OF GREATER THAN 65 KNOTS WILL EXIST THIS
   MORNING INTO THIS AFTERNOON AS THE LINE MOVES ACROSS THE MODERATE
   RISK AREA. TORNADOES MAY ALSO OCCUR WITH ROTATING CELLS EMBEDDED IN
   THE LINE. THE GREATEST TORNADO THREAT SHOULD DEVELOP ACROSS ERN
   AR...NW MS AND FAR WRN TN LATE THIS MORNING INTO EARLY AFTERNOON AS
   SFC TEMPS WARM AND THE LOW- AND MID-LEVEL JETS BECOME COUPLED AHEAD
   OF THE APPROACHING UPPER-LEVEL TROUGH. ALTHOUGH THE MODERATE RISK
   AREA IS DRIVEN BY WIND...A STRONG TORNADO OR TWO CAN NOT BE RULED
   OUT WITH SUPERCELLS THAT CAN FORM IN OR AHEAD OF THE LINE. 

   ...LOWER OH VALLEY/SRN GREAT LAKES...
   SOUTHWEST MID-LEVEL FLOW WILL BE IN PLACE TODAY ACROSS THE LOWER OH
   VALLEY AND SRN GREAT LAKES REGION AS A SHORTWAVE RIDGE MOVES NEWD
   AWAY FROM THE REGION THIS AFTERNOON. AT THE SFC...WINDS WILL BE
   SSELY...HELPING TO REINFORCE A CORRIDOR OF LOW-LEVEL MOISTURE
   LOCATED FROM THE MID MS VALLEY NNEWD INTO THE SRN GREAT LAKES REGION
   WHERE INSTABILITY WILL INCREASE AROUND MIDDAY. NAM FORECASTS SUGGEST
   THAT SBCAPE COULD REACH THE 1000 TO 1500 J/KG RANGE AS FAR NORTH AS
   CNTRL INDIANA. ALTHOUGH A SQUALL-LINE WILL MOVE INTO WRN PARTS OF
   THE REGION THIS MORNING...SOME THUNDERSTORM ACTIVITY MAY DEVELOP
   WELL AHEAD OF THE LINE AS INSTABILITY INCREASES. 

   FORECAST SOUNDINGS AT SPRINGFIELD IL AND INDIANAPOLIS AT 18Z SHOW 40
   KT OF DEEP LAYER SHEAR WITH LOW-LEVEL LAPSE RATES APPROACHING 7.0
   C/KM. THIS MAY BE ENOUGH FOR A WIND DAMAGE THREAT WITH THE STRONGER
   MULTICELLS THIS MORNING. AS A SFC LOW MOVES INTO THE MID MS VALLEY
   THIS AFTERNOON...THE NRN END OF A SQUALL-LINE IS EXPECTED TO MOVE
   INTO THE LOWER OH VALLEY. THIS WILL LIKELY RESULT IN A WIND DAMAGE
   THREAT THIS AFTERNOON WITH A FEW WIND GUSTS GREATER THAN 65 KT
   POSSIBLE.

   ...GULF COAST...
   AN UPPER-LEVEL TROUGH WILL MOVE ACROSS THE SRN PLAINS TODAY AS A
   COLD FRONT MOVES QUICKLY EWD INTO CNTRL AND ERN TX. A SQUALL-LINE
   WILL LIKELY BE ONGOING AHEAD OF THE FRONT ACROSS ECNTRL TX AT THE
   START OF THE PERIOD WITH THIS FEATURE MOVING EWD INTO LA THIS
   AFTERNOON. FORECAST SOUNDINGS FOR BATON ROUGE AT 18Z SHOW SFC
   DEWPOINTS NEAR 70 F...MLCAPE NEAR 1500 J/KG AND 45 KT OF 0-6 KM
   SHEAR. THIS SHOULD SUPPORT A WIND DAMAGE THREAT WITH BOWING LINE
   SEGMENTS EMBEDDED IN THE SQUALL-LINE. DUE TO THE INSTABILITY...HAIL
   WILL ALSO BE POSSIBLE WITH THE MORE INTENSE PARTS OF THE LINE.
   LOW-LEVEL FLOW WILL BE STRONGER WITH NWD EXTENT MAKING THE GREATEST
   WIND DAMAGE THREAT ACROSS NRN PARTS OF THE REGION FROM CNTRL AND NRN
   LA EWD INTO CNTRL MS.

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