May 2, 2012 1630 UTC Day 1 Convective Outlook
Updated: Wed May 2 16:34:27 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the mid missouri valley this evening and overnight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20120502 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120502 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20120502 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20120502 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 021630
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CDT WED MAY 02 2012
   
   VALID 021630Z - 031200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER MUCH OF EASTERN/NORTHEAST
   NEBRASKA INTO SOUTHEAST SOUTH DAKOTA...EXTREME SOUTHWEST MINNESOTA
   AND A SMALL PORTION OF NORTHWEST IOWA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
   FROM THE CNTRL HIGH PLAINS EAST ACROSS THE UPPER MIDWEST AND
   SOUTHEAST TO THE MID ATLANTIC...
   
   ...CNTRL PLAINS LATE...
   MORNING SURFACE/UA ANALYSIS REVEALS DEEP-LAYER FRONTAL ZONE
   EXTENDING SW TO NE OVER THE CNTRL PLAINS TO A SURFACE LOW PRESSURE
   CENTER IN SRN ONTARIO. THE FRONT IS EMBEDDED WITHIN A BAND OF MODEST
   40-50KT SWLY FLOW AT MID LEVELS AND...AT THE SURFACE...THE FRONT IS
   INTERSECTED BY AN OUTFLOW BOUNDARY OVER ERN NEB. MID/UPPER LEVEL
   FLOW OBSERVED ON WATER VAPOR DEPICTS A SHORT WAVE TROUGH MOVING
   ACROSS MT BUT OTHERWISE CAN BE DESCRIBED AS NON-DESCRIPT WITH REGARD
   TO MORE PROMINENT SHORT WAVE FEATURES THAT MAY AID ASCENT ACROSS THE
   PLAINS TODAY. IN FACT...MOST GUIDANCE INDICATES WEAK MID LEVEL
   HEIGHT RISES WILL OCCUR ACROSS MUCH OF THE REGION THROUGH THE
   DAYLIGHT HOURS. IN ADDITION...SUBSTANTIAL CAPPING ACROSS THE GREAT
   PLAINS...ESPECIALLY SOUTH OF THE FRONT/OUTFLOW INTERSECTION...WILL
   LIKELY LIMIT STORM INITIATION AND SUBSEQUENT SEVERE THREAT ACROSS
   THE MDT RISK AREA UNTIL THIS EVENING.
   
   WHILE ENVIRONMENT IS CURRENTLY HOSTILE TO MORE ROBUST TSTM
   DEVELOPMENT...THAT DOES NOT MEAN THAT A TREMENDOUS AMOUNT OF
   INSTABILITY CANNOT DEVELOP. IT SEEMS REASONABLE TO EXPECT SBCAPE TO
   CLIMB TO AROUND 5000 J/KG LATER THIS AFTERNOON BASED ON MORNING
   SOUNDINGS AND FORECAST HIGH TEMPERATURES IN AREAS EXPERIENCING
   MAXIMUM HEATING. IT IS POSSIBLE THAT PERSISTENT MESOSCALE
   CONVERGENCE/LIFT NEAR THE FRONT AND ALONG AND NORTH OF
   OUTFLOW...FROM ERN NEB ACROSS IA...COULD RESULT IN TSTM DEVELOPMENT
   IN THESE AREAS BY LATER AFTERNOON. ANY STORMS THAT CAN BREAK THE CAP
   IN THESE AREAS WILL POSE A THREAT OF LARGE HAIL AND DAMAGING
   WINDS...AND PERHAPS EVEN A TORNADO...GIVEN THE MAGNITUDE OF
   INSTABILITY AND EFFECTIVE SHEAR ON THE ORDER OF 40-50KT. WHILE SOME
   GUIDANCE DOES FORECAST THIS POTENTIAL NEAR THE IA/MN/WI BORDERS BY
   LATE AFTERNOON...OTHER GUIDANCE DOES NOT. THUS...RELATIVELY HIGH
   UNCERTAINTY EXISTS IN THIS SCENARIO.
   
   MORE CONFIDENCE EXISTS THAT STORMS WILL INITIATE OVER THE CNTRL HIGH
   PLAINS LATE TODAY THROUGH A COMBINATION OF DIABATIC INFLUENCES AND
   GREATER LARGE SCALE SUPPORT WITH THE UPPER TROUGH APPROACHING FROM
   MT. THE ACTIVITY WILL TRACK EAST INTO THE INSTABILITY AXIS FROM NRN
   KS INTO NEB THIS EVENING AND SHOULD INTENSIFY AND EXPAND INTO ONE OR
   TWO FORWARD-PROPAGATING STORM COMPLEXES. VERY LARGE HAIL POTENTIAL
   WILL EXIST WITH EARLY DEVELOPMENT. INCREASE IN NOCTURNAL LOW LEVEL
   JET SHOULD FURTHER SUSTAIN MASS INFLOW AND KINEMATIC REGIME APPEARS
   SUPPORTIVE OF WIDESPREAD SEVERE WIND GUSTS SPREADING EAST ACROSS
   NEB/SERN SD AND PARTS OF SWRN MN AND WRN IA THROUGH LATE TONIGHT.
   
   ...UPPER MIDWEST/NRN IA ACROSS WI/NRN IL...
   FORECAST UNCERTAINTY ALREADY MENTIONED FOR STORMS ACROSS SOME OF
   THIS AREA LATER THIS AFTERNOON. A MORE LIKELY SCENARIO WOULD BE
   STORMS INCREASING ALONG/NORTH OF THE RETREATING OUTFLOW/WARM FRONT
   LATER THIS EVENING AHEAD OF THE BOWING/MCS COMPLEX FARTHER WEST.
   LARGE HAIL WOULD BE A THREAT WITH THIS DEVELOPMENT GIVEN MAGNITUDE
   OF UPSTREAM INSTABILITY. VERY HEAVY RAIN POTENTIAL WILL ALSO EXIST
   ACROSS SOME OF THE AREA GIVEN THE POSSIBILITY OF
   BACKBUILDING/TRAINING CONVECTION.
   
   ...SERN MI ACROSS OH/WRN PA...
   WATER VAPOR IMAGERY REFLECTS A LOW AMPLITUDE MID-LEVEL TROUGH
   PROGRESSING EASTWARD OVER LOWER MI/LAKE HURON VICINITY EARLY THIS
   AFTERNOON. ON THE SOUTHERN PERIPHERY OF THIS FEATURE...IT SEEMS
   LIKELY THAT TSTMS WILL INCREASE THIS AFTERNOON WITHIN AN
   INCREASINGLY WARM/UNSTABLE AIRMASS ALONG/SOUTH OF A WARM FRONT
   ACROSS THE REGION...WITH 2000-3000 J/KG MLCAPE LIKELY WITHIN THE
   WARM SECTOR. GIVEN THE DEGREE OF INSTABILITY...AND THAT THE
   REGION/WARM FRONTAL ZONE COINCIDES WITH THE SOUTHERN FRINGE OF
   MODERATELY STRONG MID-LEVEL WESTERLIES...SUFFICIENT VERTICAL SHEAR
   /25-35 KT/ WILL EXIST FOR SUSTAINED MULTICELLS/PERHAPS SOME
   SUPERCELLS. SEVERE HAIL/PERHAPS A BRIEF TORNADO WILL BE
   POSSIBLE...BUT MORE SO...STORMS SHOULD TEND TO CONGEAL/ORGANIZE AND
   MOVE EAST-SOUTHEASTWARD WITH A DAMAGING WIND THREAT INTO THIS
   EVENING.
   
   ...MID ATLANTIC...
   STRONG HEATING/DESTABILIZATION WILL OCCUR THIS AFTERNOON
   ALONG/SOUTHWEST OF A NEARLY STALLED FRONTAL ZONE FROM WV ACROSS NRN
   VA TO TIDEWATER...WITH THE MOST AGGRESSIVE DESTABILIZATION LIKELY TO
   OCCUR NEAR THE APPALACHIANS INTO SOUTHERN/WESTERN VA AND MUCH OF NC.
   THE STRONGEST WEST-NORTHWESTERLY FLOW ALOFT/VERTICAL SHEAR WILL BE
   RELATED TO NEAR THE AFOREMENTIONED FRONTAL ZONE...BUT THE DEGREE OF
   LAPSE RATES/DESTABILIZATION WILL AT LEAST SUPPORT AN
   ISOLATED/EPISODIC POTENTIAL FOR SEVERE WIND/HAIL THIS
   AFTERNOON/EARLY EVENING.
   
   ...MS DELTA...
   WEAK AND SLOW MOVING UPPER IMPULSE/MCV WILL AID IN TSTM DEVELOPMENT
   FROM THE DELTA INTO CNTRL MS AND SRN AL THROUGH THE AFTERNOON. WHILE
   FLOW IS WEAK...VERY WARM AND MOIST AIRMASS WILL BOOST INSTABILITY SO
   THAT A FEW STORMS IN THE FORM OF MULTICELLULAR CLUSTERS COULD POSE A
   THREAT OF SOME HAIL AND DAMAGING WET MICROBURSTS.
   
   ..CARBIN/MOSIER/GUYER.. 05/02/2012
   
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