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    Day 2 Outlook >
Aug 2, 2015 0600 UTC Day 1 Convective Outlook
Updated: Sun Aug 2 06:00:35 UTC 2015 (Print Version | 20150802 1200Z Day 1 shapefile | 20150802 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 020600

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT SUN AUG 02 2015

   VALID 021200Z - 031200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS THIS AFTERNOON AND EVENING
   ACROSS MUCH OF CENTRAL AND EASTERN WISCONSIN AND LOWER MICHIGAN INTO
   ADJACENT AREAS OF NORTHEASTERN ILLINOIS...NORTHERN INDIANA AND
   NORTHWEST OHIO...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SURROUNDING AREAS OF THE
   UPPER MIDWEST AND GREAT LAKES REGION...

   ...THERE IS A MRGL RISK OF SVR TSTMS AS FAR SOUTHWEST AS PORTIONS OF
   THE CENTRAL PLAINS...AND AS FAR EAST AS THE LOWER GREAT LAKES
   REGION...

   ...SUMMARY...
   SEVERE STORMS ARE EXPECTED ACROSS THE GREAT LAKES REGION TODAY. 
   THIS MAY INCLUDE ONE OR TWO ORGANIZED STORM CLUSTERS CAPABLE OF
   GENERATING SWATHS OF POTENTIALLY DAMAGING WIND GUSTS...IN ADDITION
   TO SEVERE HAIL...AND PERHAPS A COUPLE OF TORNADOES.

   ...SYNOPSIS...
   MODELS CONTINUE TO INDICATE AMPLIFICATION WITHIN THE MID-LATITUDE
   WESTERLIES ACROSS SOUTHERN CANADA AND THE NORTHERN TIER OF THE U.S.
   DURING THIS PERIOD.  WITHIN THIS REGIME...THE CENTER OF A FAIRLY
   BROAD AND DEEP MID-LEVEL CLOSED LOW IS FORECAST TO SHIFT SOUTH OF
   HUDSON BAY INTO NORTHERN ONTARIO...AS A SIGNIFICANT PERTURBATION
   CONTINUES PIVOTING AROUND ITS SOUTHWESTERN AND SOUTHERN PERIPHERY. 
   IN ASSOCIATION WITH THESE DEVELOPMENTS...MID/UPPER FLOW APPEARS
   LIKELY TO STRENGTHEN WHILE BECOMING INCREASINGLY CYCLONIC ACROSS THE
   CENTRAL CANADIAN/U.S. BORDER AREA...INCLUDING THE UPPER GREAT LAKES
   REGION...EARLY TODAY...AND THROUGH MUCH OF THE REMAINDER OF THE
   GREAT LAKES REGION BY LATE TONIGHT.

   UPSTREAM...A LESS PROMINENT SHORT WAVE TROUGH...AND EMBEDDED
   MID-LEVEL CLOSED LOW...IS FORECAST TO GRADUALLY PROGRESS INLAND
   ACROSS THE BRITISH COLUMBIA COAST. BETWEEN THIS FEATURE AND THE
   DOWNSTREAM SYSTEM...SHORT WAVE RIDGING MAY BUILD TO THE EAST OF THE
   CANADIAN ROCKIES.  MEANWHILE...IN LOWER  LATITUDES...SUBTROPICAL
   RIDGING WILL CONTINUE TO PREVAIL OVER MUCH OF NORTHERN MEXICO AND
   THE SOUTHERN TIER OF THE U.S...BUT ITS CENTER MAY CONTINUE TO
   GRADUALLY WEAKEN AS ONE OR TWO PERTURBATIONS MIGRATE AROUND ITS
   NORTHWESTERN PERIPHERY...ACROSS THE GREAT BASIN INTO CENTRAL
   ROCKIES.

   FORCING FOR ASCENT ASSOCIATED WITH THESE LATTER FEATURES...IN
   ADDITION TO OROGRAPHY...ARE AGAIN EXPECTED TO CONTRIBUTE TO
   CONSIDERABLE THUNDERSTORM DEVELOPMENT IN THE PRESENCE OF MONSOONAL
   MOISTURE...ACROSS THE NORTHERN SIERRA NEVADA AND ADJACENT PORTIONS
   OF THE GREAT BASIN...AND THE EASTERN GREAT BASIN/COLORADO PLATEAU
   INTO THE CENTRAL AND SOUTHERN ROCKIES AND ADJACENT HIGH PLAINS. 
   SUBSTANTIAL THUNDERSTORM DEVELOPMENT IS ALSO EXPECTED WITHIN A
   PERSISTENT PLUME OF HIGH MOISTURE CONTENT AIR ALONG A WEAK REMNANT
   FRONTAL BAND ACROSS THE SOUTHWESTERN ATLANTIC AND NORTHERN FLORIDA
   INTO THE NORTHERN GULF OF MEXICO.  HOWEVER...SEVERE THUNDERSTORM
   POTENTIAL IS EXPECTED TO BE MOST PROMINENT IN ASSOCIATION WITH AN
   AREA OF INCREASING THUNDERSTORM DEVELOPMENT ACCOMPANYING THE UPPER
   TROUGH AMPLIFICATION OVER THE GREAT LAKES REGION.

   ...UPPER MIDWEST GREAT LAKES REGION...
   AT LEAST SCATTERED THUNDERSTORM ACTIVITY MAY BE ONGOING AT 12Z THIS
   MORNING ACROSS PARTS OF THE UPPER GREAT LAKES REGION... PRIMARILY
   SUPPORTED BY A ZONE OR ZONES OF LOWER/MID TROPOSPHERIC WARM
   ADVECTION...IN ADVANCE OF THE COLD FRONT ASSOCIATED WITH THE
   APPROACHING MID-LEVEL PERTURBATION.  THE PRIMARY WARM FRONTAL ZONE
   PROBABLY WILL EXTEND ACROSS PARTS OF NORTHERN WISCONSIN... THE UPPER
   MICHIGAN PENINSULA AND NORTHERN LOWER MICHIGAN PENINSULA EARLY
   TODAY.  GUIDANCE HAS BEEN SUGGESTIVE THAT THIS COULD BECOME THE
   FOCUS FOR AN INITIAL EVOLVING CLUSTER OF STORMS DURING THE
   DAY...GENERALLY ON THE NOSE OF A PLUME OF AT LEAST MODESTLY STEEP
   MID-LEVEL LAPSE RATES EMANATING FROM THE INTERMOUNTAIN WEST.

   BOUNDARY LAYER DESTABILIZATION AHEAD OF THIS INITIAL CONVECTIVE
   CLUSTER...ACROSS NORTHERN LOWER MICHIGAN...REMAINS A BIT UNCLEAR. 
   BUT...ALONG AND SOUTH OF ITS TRAILING OUTFLOW BOUNDARY...EXTENDING
   WESTWARD INTO NORTH CENTRAL WISCONSIN...MODERATE TO STRONG BOUNDARY
   LAYER DESTABILIZATION APPEARS LIKELY DURING THE DAY.  THIS WILL BE
   SUPPORTED BY BOUNDARY LAYER MOISTENING...WITH SURFACE DEW POINTS
   INCREASING THROUGH THE 60S /TO AROUND 70F+ OVER WISCONSIN/...BENEATH
   STEEPENING MID-LEVEL LAPSE RATES...AS WARMER ELEVATED MIXED LAYER
   AIR CONTINUES TO ADVECT EASTWARD BENEATH RELATIVELY COOL AND
   INCREASINGLY CYCLONIC NORTHWEST MID-LEVEL FLOW.

   IN THE PRESENCE OF INCREASINGLY SHEARED AND STRONG DEEP LAYER MEAN
   WESTERLY FLOW...UP TO AROUND 40 KT IN THE LOWER TO MID
   TROPOSPHERE...THE ENVIRONMENT SHOULD BECOME CONDUCIVE TO THE
   EVOLUTION OF ONE OR MORE ORGANIZED MESOSCALE CONVECTIVE SYSTEMS. 
   THIS MAY INCLUDE SUPERCELLS INITIALLY...PARTICULARLY NEAR THE
   INTERSECTION OF THE OUTFLOW BOUNDARY AND A SOUTHWARD ADVANCING COLD
   FRONT ACROSS PARTS OF NORTH CENTRAL WISCONSIN.  WHILE ACTIVITY GROWS
   UPSCALE AND DEVELOPS SOUTHEASTWARD ALONG THE OUTFLOW BOUNDARY
   INTO/THROUGH LOWER MICHIGAN...ADDITIONAL UPSCALE GROWTH IS POSSIBLE
   SOUTHWESTWARD...ALONG/AHEAD OF THE COLD FRONT...TOWARD THE
   MISSISSIPPI VALLEY.

   ..KERR/MARSH.. 08/02/2015

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
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