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Apr 20, 2015 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Mon Apr 20 07:26:32 UTC 2015 (Print Version | 20150420 0730Z Day 3 shapefile | 20150420 0730Z Day 3 KML)
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 Forecast Discussion
   SPC AC 200726

   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0226 AM CDT MON APR 20 2015

   VALID 221200Z - 231200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF CNTRL OK...SRN
   OK AND NRN TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...ARKLATEX AND LOWER MS VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH
   PLAINS...SRN PLAINS...ARKLATEX AND LOWER TO MID MS VALLEY...

   ...SUMMARY...
   THUNDERSTORMS WITH WIND DAMAGE AND LARGE HAIL ARE EXPECTED TO
   DEVELOP FROM THE SOUTHERN PLAINS SOUTHEASTWARD ACROSS THE ARKLATEX
   AND INTO THE LOWER MISSISSIPPI VALLEY. MARGINALLY SEVERE
   THUNDERSTORMS MAY DEVELOP ACROSS PARTS OF THE SOUTHERN AND CENTRAL
   HIGH PLAINS AND IN SOUTH CENTRAL TEXAS. THUNDERSTORM DEVELOPMENT MAY
   ALSO OCCUR ACROSS PARTS OF THE CENTRAL TO NORTHERN ROCKIES AND
   SIERRA NEVADA.

   ...SRN PLAINS/ARKLATEX
   AN UPPER-LEVEL RIDGE IS FORECAST TO MOVE EWD ACROSS THE SRN ROCKIES
   ON WEDNESDAY AS SFC LOW PRESSURE IN THE SRN HIGH PLAINS DEEPENS AND
   MOVES SEWD. A WARM FRONT MAY BE PRESENT ACROSS SRN OK EXTENDING
   ESEWD INTO AR. ALONG AND SOUTH OF THE BOUNDARY...SFC DEWPOINTS
   SHOULD BE IN THE LOWER TO MID 60S WITH MODERATE INSTABILITY
   DEVELOPING ACROSS MUCH OF THE WARM SECTOR BY AFTERNOON. AS A CAP
   WEAKENS DURING THE DAY...THUNDERSTORM DEVELOPMENT APPEARS POSSIBLE
   ALONG THE WARM FRONT AND FURTHER SOUTHEASTWARD ACROSS THE ARKLATEX
   NEAR THE ERN EDGE OF THE STRONGEST INSTABILITY. AN MCS WILL BE
   POSSIBLE ACROSS THE REGION LATE WEDNESDAY AFTERNOON WITH COLD-POOL
   ORGANIZATION ALSO POSSIBLE BY EVENING.

   NAM FORECAST SOUNDINGS FROM OKLAHOMA CITY SEWD TO NEAR THE RED RIVER
   AT 00Z/THU SHOW MLCAPE IN THE 2000 TO 2500 J/KG RANGE WITH 0-6 KM
   SHEAR OF 45 TO 50 KT. THIS WOULD SUPPORT SEVERE STORMS WITH LARGE
   HAIL AND WIND DAMAGE. THE MAIN QUESTION IS WHAT STORM MODE WILL
   DOMINANT. IF CELLS REMAIN DISCRETE...THEN SUPERCELLS WOULD BE THE
   MOST FAVORED STORM TYPE. HOWEVER...THE PATTERN WOULD SUGGEST
   COLD-POOL ORGANIZATION WHICH WOULD FAVOR A LINEAR STRUCTURED MCS
   WITH ENHANCED WIND DAMAGE POTENTIAL. EITHER WAY...SOME TORNADOES CAN
   BE EXPECTED WITH ROTATING CELLS ASSOCIATED WITH THE BETTER ORGANIZED
   STORM CLUSTERS. WILL ADD A 30 PERCENT SEVERE PROBABILITY FROM NEAR
   AND SOUTH OF OKC SEWD TO NEAR AND EAST OF DALLAS.

   FURTHER TO THE SOUTH ACROSS SE TX AND LA...FORECAST SOUNDINGS AT 21Z
   ON WEDNESDAY SHOW MODERATE INSTABILITY AND STRONG DEEP-LAYER SHEAR.
   DUE TO THIS ENVIRONMENT...CELLS THAT CAN INITIATE ALONG LOCALIZED
   CONVERGENCE ZONES COULD ROTATE AND POSE A THREAT FOR WIND DAMAGE AND
   HAIL. A SEVERE THREAT COULD ALSO DEVELOP DURING THE LATE EVENING OR
   IN THE OVERNIGHT PERIOD AS AN MCS APPROACHES THE REGION FROM THE
   NORTHWEST.

   ...ERN CO/SW KS/TX AND OK PANHANDLES...
   AN UPPER-LEVEL RIDGE IS FORECAST TO MOVE EWD ACROSS THE SRN ROCKIES
   WEDNESDAY AS SFC LOW PRESSURE DEEPENS ACROSS THE SRN HIGH PLAINS.
   UPSLOPE FLOW IS FORECAST FROM NEAR THE SFC LOW EXTENDING NWD ACROSS
   THE CNTRL HIGH PLAINS. THUNDERSTORM DEVELOPMENT MAY TAKE PLACE BY
   AFTERNOON ALONG A SFC TROUGH IN THE TX PANHANDLE AND IN ERN CO.
   FORECAST SOUNDINGS FOR LAMAR CO AND THE OK PANHANDLE AT 00Z/THU SHOW
   MLCAPE AROUND 1500 J/KG WITH 0-6 KM SHEAR NEAR 40 KT. THIS COMBINED
   WITH A RELATIVELY DRY BOUNDARY LAYER...SFC DEWPOINTS IN THE UPPER
   40S F...WOULD SUPPORT MARGINALLY SEVERE STORMS WITH WIND DAMAGE AND
   HAIL POSSIBLE MAINLY DURING THE LATE AFTERNOON AND EARLY EVENING.

   ..BROYLES.. 04/20/2015

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z

        
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Page last modified: April 20, 2015
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