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    Day 2 Outlook >
Jul 27, 2016 2000 UTC Day 1 Convective Outlook
Updated: Wed Jul 27 19:50:32 UTC 2016 (Print Version | 20160727 2000Z Day 1 shapefile | 20160727 2000Z Day 1 KML)
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 Forecast Discussion
   SPC AC 271950

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0250 PM CDT WED JUL 27 2016

   VALID 272000Z - 281200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS LATE THIS AFTERNOON AND EVENING
   ACROSS PARTS OF THE NORTHERN AND CENTRAL HIGH PLAINS...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF SERN MINNESOTA
   INTO WESTERN WISCONSIN...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF NRN MAINE...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL
   APPALACHIANS INTO MID ATLANTIC COAST...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF SERN ARIZONA
   AND ADJACENT SWRN NM...

   ...SUMMARY...
   WIDELY SCATTERED STRONG STORMS ARE POSSIBLE ACROSS PARTS OF THE
   NORTHERN AND CENTRAL HIGH PLAINS...THE VIRGINIA/NORTH CAROLINA
   AREA...SOUTHEAST ARIZONA...NORTHERN MAINE...AND SOUTHEAST MINNESOTA
   INTO A PORTION WISCONSIN LATE THIS AFTERNOON AND EVENING.  THESE MAY
   BE ACCOMPANIED BY SOME RISK FOR SEVERE WEATHER.

   ...20Z OUTLOOK UPDATE...
   SOME ADJUSTMENTS HAVE BEEN MADE TO CATEGORICAL AND PROBABILISTIC
   LINES...MOSTLY IN AN ATTEMPT TO BETTER ACCOUNT FOR ONGOING AND
   ANTICIPATED CONVECTIVE TRENDS.  

   PERHAPS THE MOST SUBSTANTIVE CHANGE HAS BEEN TO ADD LOW SEVERE
   PROBABILITIES TO PORTIONS OF NORTHWESTERN MAINE.  LIFT AHEAD OF A
   CLOSED LOW/TROUGH WITHIN THE MID-LATITUDE WESTERLIES IS CONTRIBUTING
   TO INCREASING VIGOROUS THUNDERSTORM DEVELOPMENT ACROSS PARTS OF
   SOUTHERN QUEBEC...CURRENTLY NEAR OR JUST NORTHWEST OF THE ST.
   LAWRENCE RIVER.  THIS IS WHERE AT LEAST MODEST PRE-COLD FRONTAL
   BOUNDARY LAYER DESTABILIZATION /CAPE UP TO 1000 J PER KG/ HAS
   OCCURRED...IN THE PRESENCE OF SHEARED...30-40 KT WEST NORTHWESTERLY
   DEEP LAYER MEAN FLOW.  AIDED BY AN AREA OF ENHANCED FORCING FOR
   ASCENT...IT APPEARS AT LEAST POSSIBLE THAT STORMS COULD SPREAD INTO
   PARTS OF NORTHERN MAINE WITH SOME RISK FOR SEVERE WIND OR HAIL
   BEFORE WEAKENING THIS EVENING.

   ..KERR.. 07/27/2016

   .PREV DISCUSSION... /ISSUED 1130 AM CDT WED JUL 27 2016/

   ...SERN MN THROUGH WRN WI...

   HAVE INTRODUCED A MARGINAL RISK FOR THIS REGION THIS AFTERNOON WHERE
   A FEW STORMS HAVE UNDERGONE A MODEST INCREASE OVER SERN MN. ACTIVITY
   IS DEVELOPING IN RESPONSE TO ASCENT ASSOCIATED WITH A PROGRESSIVE
   MCV OVER SRN/CNTRL MN. SFC ANALYSIS SHOWS A WEAK SFC LOW OVER CNTRL
   MN WITH A COLD FRONT EXTENDING SWWD INTO THE CNTRL PLAINS. A WEAK
   WARM FRONT EXTENDS EWD FROM THE LOW THROUGH ECNTRL MN...BUT A LARGE
   SWD-ADVANCING OUTFLOW BOUNDARY IS LOCATED ACROSS CNTRL WI.
   WIDESPREAD CLOUDS ARE LIMITING DIABATIC WARMING...BUT WITH SFC
   DEWPOINTS NEAR 70...ANY CLOUD BREAKS WILL SUPPORT MLCAPE NEAR 1500
   J/KG. MINNEAPOLIS VWP ALSO INDICATES A LOCAL ENHANCEMENT IN WIND
   PROFILES RESULTING FROM THE MCV CIRCULATION...WITH 35 KT 0-6 KM
   SHEAR. THIS ENVIRONMENT MIGHT SUPPORT OCCASIONAL MARGINAL SUPERCELL
   STRUCTURES/BOWING SEGMENTS CAPABLE OF PRODUCING A FEW INSTANCES HAIL
   AND GUSTY WINDS THIS AFTERNOON. REF SWOMCD 1405 FOR FURTHER DETAILS.


   ...NRN THROUGH CNTRL HIGH PLAINS AREAS...

   WEAK ELY UPSLOPE FLOW IS EVOLVING IN POST FRONTAL REGIME OVER THE
   NRN/CNTRL HIGH PLAINS THIS AFTERNOON WHERE DEWPOINTS GENERALLY IN
   THE 50S WILL RESIDE BENEATH STEEP LAPSE RATES...RESULTING IN
   1000-1500 J/KG MLCAPE. A COUPLE OF MCVS ARE OBSERVED MOVING THROUGH
   THE NRN/CNTRL HIGH PLAINS THIS MORNING WITH ASSOCIATED ONGOING
   CONVECTION FROM WRN/CNTRL NEB INTO SERN MT. STORMS ARE EXPECTED TO
   REDEVELOP LATER THIS AFTERNOON AND EVENING WITHIN THE WEAK UPSLOPE
   REGIME OVER THE HIGHER TERRAIN OVER THE CNTRL/NRN HIGH PLAINS AS
   WELL AS ALONG TRAILING FRONT FROM NERN CO INTO NWRN KS. WEAK ELY
   LOW-LEVEL FLOW BENEATH MODEST NWLY FLOW ALOFT WILL SUPPORT POTENTIAL
   FOR UPDRAFT ROTATION WITH A THREAT FOR MAINLY LARGE HAIL AND
   DOWNBURST WINDS. WEAK DEEPER FORCING IN WAKE OF MCVS DURING THE DAY
   LOWERS CONFIDENCE IN WHERE MORE THAN VERY ISOLATED STORM COVERAGE
   WILL OCCUR. THEREFORE WILL MAINTAIN SLIGHT RISK THIS OUTLOOK AND
   REEVALUATE FOR A POSSIBLE SLIGHT RISK IN UPCOMING 20Z UPDATE. 

   ...VA/NC VICINITY...

   STRONG SURFACE HEATING AMID 70S SURFACE DEW POINTS SHOULD AGAIN
   CONTRIBUTE TO MODERATE BUOYANCY AND SCATTERED AFTERNOON STORMS.
   MODEST MID-LEVEL WESTERLIES PERSISTING NORTH OF THE SOUTH ATLANTIC
   COAST ANTICYCLONE COULD SUPPORT LOOSELY ORGANIZED MULTICELLS.
   HOWEVER...STORM MERGERS AND THE HIGH PW AIR MASS SHOULD PRIMARILY BE
   RESPONSIBLE FOR GENERATING A WET MICROBURST WIND THREAT.

   ...SOUTHEAST AZ...

   15-25 KT 500-MB NORTHEASTERLIES ARE EXPECTED LATE AFTERNOON TO
   EVENING ACROSS SOUTHERN NM/SOUTHEAST AZ. THIS SHOULD AID IN
   CONVECTION PROPAGATING OFF THE HIGHER TERRAIN WITH A RISK FOR
   ISOLATED SEVERE WIND GUSTS OVER LOWER ELEVATIONS.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z

        
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