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Dec 21, 2014 1730 UTC Day 2 Convective Outlook
Updated: Sun Dec 21 17:27:03 UTC 2014 (Print Version | 20141221 1730Z Day 2 shapefile | 20141221 1730Z Day 2 KML)
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 Forecast Discussion

   SPC AC 211727

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1127 AM CST SUN DEC 21 2014

   VALID 221200Z - 231200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE LOWER MS
   VALLEY AND GULF COAST STATES...

   ...SUMMARY...
   ISOLATED SEVERE STORMS WILL BE POSSIBLE MONDAY NIGHT INTO EARLY
   TUESDAY ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY AND GULF COAST
   STATES.

   ...SYNOPSIS...
   ON THE LARGE-SCALE...MODEL CONSENSUS SUGGESTS THAT A BROAD
   UPPER-LEVEL TROUGH WILL AMPLIFY OVER THE CNTRL CONUS AS AN INTENSE
   MID-LEVEL JET /AOA 100 KT AT 500 MB/ DIGS SEWD TOWARDS THE BASAL
   PORTION OF THE TROUGH. AT THE SURFACE...PRIMARY CYCLONE SHOULD
   GRADUALLY SHIFT FROM ERN SD TO ERN IA DURING THE PERIOD. ATTENDANT
   COLD FRONT SHOULD ARC FROM IL TO S TX BY 12Z/TUE. WARM FRONT WILL
   ADVANCE N ACROSS PARTS OF THE CNTRL/ERN GULF COAST STATES AND DEEP
   SOUTH. 

   ...GULF COAST AND LOWER MS VALLEY...
   SUBSTANTIAL SPREAD EXISTS IN GUIDANCE WITH THE EVOLUTION OF
   SHORTWAVE IMPULSES EMBEDDED WITHIN THE BROADER CNTRL CONUS TROUGH.
   THIS YIELDS BELOW-AVERAGE CONFIDENCE IN THE AMPLITUDE AND
   SPATIOTEMPORAL DETAILS OF THE KINEMATIC AND THERMODYNAMIC
   ENVIRONMENT...MITIGATING A SLIGHT RISK ISSUANCE THIS OUTLOOK.
   PRIMARY CHANGE THIS OUTLOOK IS TO EXPAND COVERAGE OF LOW SEVERE
   PROBABILITIES.

   SLY LOW-LEVEL MOISTURE TRANSPORT WILL SUPPORT A BROADENING WARM
   SECTOR WITH SURFACE DEW POINTS AOA 60 DEG F BECOMING ESTABLISHED MON
   NIGHT FROM LA TO SRN AL. CONSISTENT WITH WPC PREFERRED NON-NCEP
   GUIDANCE...ONLY MINOR MID-LEVEL HEIGHT FALLS ARE EXPECTED LATE IN
   THE PERIOD AS A LEAD IMPULSE PIVOTS FROM THE LOWER MO TO THE UPPER
   MS VALLEY WHILE UPSTREAM VORTICITY MAXIMA REMAIN OVER NM/W TX.
   PRIMARY CONVECTIVE DEVELOPMENT SHOULD CONSIST OF ELEVATED PARCELS
   DRIVEN BY ISENTROPIC ASCENT N OF THE SURFACE WARM FRONT...BUT NEAR
   SURFACE-BASED TSTMS MAY DEVELOP INVOF THE TRIPLE POINT OVER THE
   LOWER MS VALLEY. STRONG EFFECTIVE SHEAR AMIDST WEAK BUOYANCY MAY
   SUPPORT A RISK FOR MARGINALLY SEVERE HAIL/LOCALLY DAMAGING WIND. 

   OF GREATER CONCERN IS THE POTENTIAL FOR A TORNADO/WIND RISK
   DEVELOPING TOWARDS 12Z/TUE ALONG THE WARM FRONT AND ADJACENT WARM
   SECTOR. STRENGTHENING LOW-LEVEL MASS RESPONSE TO THE SRN HIGH PLAINS
   PORTION OF THE MID-LEVEL TROUGH APPEARS TO HOLD OFF UNTIL AFTER
   12Z/TUE IN NON-NAM GUIDANCE. THE BULK OF SURFACE-BASED TSTM
   DEVELOPMENT ALIGNED WITH FAVORABLE LOW-LEVEL HODOGRAPHS FOR ROTATING
   UPDRAFTS WILL PROBABLY BE DELAYED UNTIL THE D3 TIME FRAME.

   ..GRAMS.. 12/21/2014

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0700Z

        
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Page last modified: December 21, 2014
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