Jun 20, 2010 0600 UTC Day 1 Convective Outlook
Updated: Sun Jun 20 08:20:45 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the central and northern plains...and over the lower missouri and mid mississippi valleys...this afternoon through early monday....   Please read the latest public statement about this event.

Categorical Graphic
20100620 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100620 1200 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100620 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100620 1200 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 200600
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT SUN JUN 20 2010
   
   VALID 201200Z - 211200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF SD/NEB/IA AND
   SOUTHWEST MN/NORTHWEST MO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NORTHERN ROCKIES TO
   THE MIDWEST/OH VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SOUTHERN NEW ENGLAND AND
   SOUTHERN NY/NJ...
   
   ...SYNOPSIS...
   A BROAD/CONSIDERABLE WESTERN STATES UPPER TROUGH WILL MIGRATE
   EAST-NORTHEASTWARD THROUGH THE PERIOD...WITH THE BRUNT OF THE UPPER
   TROUGH OVERSPREADING THE NORTHERN ROCKIES THIS AFTERNOON/TONIGHT. A
   BELT OF MODERATELY STRONG MID-HIGH LEVEL FLOW WILL EXIST FROM THE
   GREAT BASIN AND CENTRAL/NORTHERN ROCKIES TO THE GREAT LAKES
   REGION/NORTHEAST STATES...WITH MULTIPLE LOW AMPLITUDE SHORTWAVE
   TROUGHS/REMNANT CONVECTIVE VORTICIES EMBEDDED WITHIN THIS FLOW
   REGIME.
   
   ...NORTHERN/CENTRAL PLAINS TO MIDWEST...
   A REMNANT MCS/LARGE CLUSTER OF THUNDERSTORMS SHOULD BE ONGOING AT
   THE BEGINNING OF THE PERIOD FROM EASTERN PORTIONS OF IA/MO INTO
   IL...WHILE ADDITIONAL CONVECTIVE CLUSTERS/POTENTIAL SEVERE MCS MAY
   BE ONGOING ACROSS SOUTHEAST SD/NORTHEAST NEB INTO IA THIS MORNING.
   AHEAD OF THIS ACTIVITY...POTENTIAL MCV/RESIDUAL OUTFLOWS MAY
   CONTRIBUTE TO A REINVIGORATION OF TSTMS DURING THE DAY ACROSS THE
   MIDWEST...WITH THE POSSIBILITY OF MODERATE/STRONG DESTABILIZATION
   TODAY ALONG/SOUTH OF A WEST-EAST SYNOPTIC FRONT. THIS INCLUDES
   PORTIONS OF IL/INDIANA AND THE ADJACENT OHIO VALLEY.
   
   FARTHER WEST...OUTFLOW SOLIDIFIED EFFECTIVE FRONTAL ZONE ALONG THE
   NEB/KS BORDER VICINITY SHOULD GRADUALLY RETREAT NORTHWARD DURING THE
   DAY...AND ULTIMATELY SERVE AS A FOCUS FOR VIGOROUS DEEP CONVECTION
   LATER THIS AFTERNOON/EARLY EVENING IN A POTENTIALLY VOLATILE AIRMASS
   ALONG/NORTH OF THIS SURFACE BOUNDARY. SUPERCELLS CAPABLE OF LARGE
   HAIL AND A FEW TORNADOES WILL BE POSSIBLE ESPECIALLY DURING THE LATE
   AFTERNOON/EARLY EVENING HOURS. AIDED BY A STRENGTHENING LOW LEVEL
   JET/MOISTURE TRANSPORT REGIME...STORMS WILL LIKELY GROW UPSCALE INTO
   A SEVERE QUASI-LINEAR MCS WITH EAST-SOUTHEASTWARD FORWARD
   PROPAGATION DURING THE EVENING/OVERNIGHT. THE POTENTIAL FOR
   CONSIDERABLE WIND DAMAGE WILL LIKELY INCREASE ACCORDINGLY...MOST
   LIKELY ACROSS PORTIONS OF EASTERN NEB INTO IA/NORTHERN MO.
   
   ADDITIONAL STRONG/SEVERE TSTM DEVELOPMENT IS EXPECTED BY MID/LATE
   AFTERNOON IN A NORTH-SOUTH CORRIDOR ACROSS THE NORTH-CENTRAL HIGH
   PLAINS...AIDED BY THE ARRIVAL OF LARGE SCALE HEIGHT FALLS AHEAD OF
   THE WESTERN STATES UPPER TROUGH. MODERATELY STRONG FLOW
   ALOFT/VEERING WIND PROFILES AND AMPLE MOISTURE/INSTABILITY WILL
   SUPPORT AN INITIAL MODE OF SUPERCELLS CAPABLE OF LARGE HAIL AND A
   COUPLE OF TORNADOES. THESE STORMS WILL PROBABLY ALSO GROW UPSCALE
   DURING THE EVENING/OVERNIGHT AND CONTINUE TO POSE A SEVERE THREAT
   EASTWARD ACROSS MUCH OF SD/NORTHERN NEB INTO IA/SOUTHERN MN.
   
   ...NORTHERN INTERMOUNTAIN WEST...
   IMMEDIATELY AHEAD OF THE UPPER TROUGH OVER THE PACIFIC
   NORTHWEST...AMPLE MOISTURE/PRECIPITABLE WATER IN CONJUNCTION WITH
   STEEP LAPSE RATES/STRONG SOUTHWESTERLY FLOW ALOFT WILL SUPPORT
   ORGANIZED STORMS CAPABLE OF SEVERE HAIL/WIND THIS AFTERNOON/EVENING.
   THIS WILL INITIALLY BE THE CASE ACROSS PORTIONS OF ID/ADJACENT
   EASTERN WA INTO WESTERN MT...WITH A SEVERE THREAT DEVELOPING INTO
   THE TERRAIN-ADJACENT HIGH PLAINS OF NORTH CENTRAL/EASTERN MT DURING
   THE LATE AFTERNOON/EARLY EVENING HOURS.
   
   ...NEW ENGLAND AND SOUTHERN NY/NJ TODAY...
   AHEAD OF EARLY DAY ONGOING SHOWERS/TSTMS...MODERATE DESTABILIZATION
   /PERHAPS 1000-2000 J PER KG MLCAPE/ IS PROBABLE ACROSS SOUTHERN NEW
   ENGLAND AND THE SOUTHERN NY/NJ VICINITIES THIS AFTERNOON.
   ACCORDINGLY...AN UPSWING IN TSTM COVERAGE/INTENSITY IS PROBABLE
   AHEAD OF A COLD FRONT AND/OR IN VICINITY OF A PREFRONTAL
   TROUGH...AIDED BY A PASSING SHORTWAVE TROUGH OVER NEW ENGLAND. WITH
   30-35 KT OF WESTERLY MID LEVEL FLOW...VERTICAL SHEAR WILL BE
   SUPPORTIVE OF MULTICELLS/PERHAPS SOME MARGINAL SUPERCELLS...WITH
   DAMAGING WINDS/SOME SEVERE HAIL POSSIBLE THROUGH AROUND SUNSET.
   
   ...GULF COAST/SOUTHEAST STATES TO CAROLINAS THIS AFTERNOON...
   ISOLATED STRONG/SEVERE TSTMS WILL BE POSSIBLE ACROSS THE CAROLINAS
   TODAY IN THE GENERAL VICINITY OF A SURFACE TROUGH...WITH ADDITIONAL
   STRONG/SEVERE TSTMS ACROSS THE SOUTHEAST STATES/GULF COAST
   REGION...POTENTIALLY AIDED BY SUBTLE MID LEVEL PERTURBATIONS
   SPREADING SOUTHWARD OVER THE REGION/ROUNDING THE SOUTHERN PLAINS
   ANTICYCLONE. WITH STEEP LOW LEVEL LAPSE RATES AND CORRIDORS OF
   MODERATE INSTABILITY BY AFTERNOON...PERIODIC DOWNBURSTS CAPABLE OF
   DAMAGING WINDS WILL BE POSSIBLE THROUGH AROUND SUNSET.
   
   ...SOUTHERN HIGH PLAINS LATE THIS AFTERNOON/EARLY EVENING...
   ISOLATED SEVERE TSTMS CAPABLE OF LARGE HAIL/SEVERE WIND WILL BE
   POSSIBLE ACROSS PORTIONS OF EASTERN NM/WEST TX THIS AFTERNOON/EARLY
   EVENING. CURRENTLY ANTICIPATED ISOLATED NATURE OF THE SEVERE RISK
   PRECLUDES A CATEGORICAL SLIGHT RISK AT THIS TIME.
   
   ..GUYER/HURLBUT.. 06/20/2010
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z