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    Day 2 Outlook >
Apr 27, 2015 1630 UTC Day 1 Convective Outlook
Updated: Mon Apr 27 16:18:24 UTC 2015 (Print Version | 20150427 1630Z Day 1 shapefile | 20150427 1630Z Day 1 KML)
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 Forecast Discussion
   SPC AC 271618

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1118 AM CDT MON APR 27 2015

   VALID 271630Z - 281200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM N-CNTRL TX TO THE CNTRL
   GULF COAST...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK
   OVER THE GENERAL AREA...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER THE SOUTHEAST FLORIDA
   PENINSULA...

   ...SUMMARY...
   A BAND OF SEVERE THUNDERSTORMS WITH LOCALLY DAMAGING WINDS AND
   POSSIBLY A COUPLE TORNADOES WILL AFFECT FAR SOUTHEAST LOUISIANA LATE
   THIS MORNING INTO EARLY AFTERNOON.  DURING THE AFTERNOON...OTHER
   STRONG TO SEVERE STORMS WITH HAIL...LOCALLY DAMAGING WIND...AND
   PERHAPS A TORNADO OR TWO MAY AFFECT PARTS OF NORTH-CENTRAL INTO
   EASTERN TEXAS AND PERHAPS SOUTHWEST LOUISIANA.  A FEW STRONG TO
   POSSIBLY SEVERE AFTERNOON STORMS ALSO MAY OCCUR OVER CENTRAL AND
   SOUTHERN FLORIDA.

   ...SYNOPSIS...

   A MID TO UPPER-LEVEL LOW WILL EDGE SLOWLY EWD ACROSS THE SRN PLAINS
   IN RESPONSE TO AN AMPLIFYING UPSTREAM RIDGE OVER THE GREAT BASIN
   INTO NRN ROCKIES.  A MID-LEVEL JET STREAK OBSERVED WITHIN THE BASE
   OF THE UPPER LOW PER 12Z OBSERVED SOUNDINGS WILL PROGRESS GENERALLY
   EWD INTO THE CNTRL GULF COAST.

   AT THE SURFACE...AN AREA OF LOW PRESSURE OVER N-CNTRL TX WILL
   DEVELOP SEWD INTO SRN LA ALONG A COLD FRONT ADVANCING SEWD THROUGH
   CNTRL AND SRN PARTS OF TX.  MEANWHILE...VISIBLE SATELLITE AND
   SURFACE OBSERVATIONS AS OF MID MORNING INDICATE AN OUTFLOW BOUNDARY
   ASSOCIATED WITH THE BOW ECHO OVER SERN LA EXTENDING WWD THROUGH THE
   UPPER TX COAST BEFORE CURVING NWWD ALONG A BAZ-SEP LINE WHERE IT
   LINKS WITH THE SURFACE LOW AND ASSOCIATED COLD FRONT.

   ...SERN TX INTO THE CNTRL GULF COAST TODAY INTO TONIGHT...

   A WELL-DEFINED BOW ECHO WITH A HISTORY OF FAIRLY WIDESPREAD DAMAGING
   WINDS SHOULD CONTINUE ESEWD THROUGH THE REMAINDER OF FAR SERN LA
   LATE THIS MORNING INTO EARLY AFTERNOON WITH A RISK FOR DAMAGING
   WINDS AND PERHAPS A TORNADO OR TWO OVER THOSE LOCATIONS.  IN THE
   WAKE OF THIS MCS...IT APPEARS THAT WAA/ISENTROPIC ASCENT ATOP THE
   TRAILING OUTFLOW BOUNDARY COUPLED WITH DEEPER-LAYER FORCING FOR
   ASCENT RELATED TO THE ABOVE-MENTIONED MID-LEVEL JET STREAK MAY
   SUPPORT THE DEVELOPMENT OF TSTMS THIS AFTERNOON INTO TONIGHT FROM
   SERN TX EWD INTO LA.  

   BASED ON THE 12Z SOUNDINGS AT CRP AND BRO...AMPLE LOW-LEVEL MOISTURE
   SURMOUNTED BY A WELL-DEFINED EML WILL SUPPORT MODERATE AFTERNOON
   INSTABILITY AND THE POTENTIAL FOR ORGANIZED STORM MODES INCLUDING
   SUPERCELLS GIVEN 40-50 KT OF DEEP-LAYER SHEAR.  WHILE LARGE HAIL
   APPEARS TO BE THE PRIMARY HAZARD...LOCALLY DAMAGING WINDS AND
   PERHAPS A BRIEF TORNADO OR TWO ARE POSSIBLE.

   ...N-CNTRL INTO ERN TX THIS AFTERNOON/EVENING...

   AS MENTIONED ABOVE...CONSIDERABLE OVERTURNING OF THE AIR MASS HAS
   OCCURRED OVER ERN INTO N-CNTRL TX IN THE WAKE OF THE MCS NOW OVER
   LA.  HOWEVER...COLD MID-LEVEL TEMPERATURES COUPLED WITH A WARMING
   BOUNDARY LAYER SHOULD SUPPORT AIR MASS DESTABILIZATION BY AFTERNOON
   AHEAD OF THE SURFACE LOW AND COLD FRONT WITH MLCAPE APPROACHING
   1000-1500 J/KG.  FORCING FOR ASCENT IN ADVANCE OF THE DEEP-LAYER
   CYCLONE IS EXPECTED TO FOSTER THE DEVELOPMENT OF SURFACE-BASED
   STORMS BY AFTERNOON AMIDST A KINEMATIC ENVIRONMENT FEATURING
   VERTICALLY VEERING AND STRENGTHENING WINDS WITH HEIGHT.  AS
   SUCH...SUPERCELLS ARE POSSIBLE WITH THE RISK FOR LARGE
   HAIL...DAMAGING WINDS AND A COUPLE OF TORNADOES SPREADING SEWD INTO
   PARTS OF ERN TX.  THIS SEVERE WEATHER THREAT SHOULD BEGIN TO WANE BY
   MID TO LATE EVENING AS THE BOUNDARY LAYER BEGINS TO COOL AND
   STABILIZE.

   ...FL PENINSULA THIS AFTERNOON...

   PRONOUNCED WLY DEEP-LAYER FLOW OBSERVED BY 12Z SOUNDINGS WILL
   PERSIST TODAY WITH DIURNAL STORM DEVELOPMENT LIKELY REMAINING
   CONFINED TO THE EAST COAST SEA BREEZE.  WHILE MID-LEVEL LAPSE RATES
   WILL REMAIN POOR...DAYTIME HEATING COUPLED WITH A MOIST BOUNDARY
   LAYER WILL YIELD MODERATE AFTERNOON INSTABILITY AND THE POTENTIAL
   FOR A FEW STRONG TO MARGINALLY SEVERE STORMS THIS AFTERNOON WITH A
   RISK FOR LOCALLY DAMAGING WIND GUSTS.

   ..MEAD/HART.. 04/27/2015

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z

        
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