Jul 26, 2011 2000 UTC Day 1 Convective Outlook
Updated: Tue Jul 26 20:04:11 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110726 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110726 2000 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
20110726 2000 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
20110726 2000 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 262000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT TUE JUL 26 2011
   
   VALID 262000Z - 271200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER NORTH CENTRAL/NERN SD AND
   SOUTH CENTRAL/SERN ND...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN/CENTRAL PLAINS
   INTO THE UPPER MS VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NERN STATES...
   
   ...NORTHERN/CENTRAL PLAINS...
   MADE MODEST SPATIAL CHANGES TO THE PRIOR OUTLOOK...WITH A GREATER
   INCORPORATION OF EASTERN MT INTO A SLIGHT RISK WHERE TSTMS HAVE BEEN
   INCREASING IN VICINITY OF A FRONTAL SEGMENT. OTHER STORMS ARE STILL
   EXPECTED TO DEVELOP/INCREASE IN VICINITY OF A SURFACE LOW AND
   NEAR/NORTH OF A WARM FRONT...AS WELL AS SURFACE TROUGH ACROSS
   SD/NEB...LATER THIS AFTERNOON/EARLY EVENING. SEE PRIOR OUTLOOK
   DISCUSSION BELOW AND SUBSEQUENT MESOSCALE DISCUSSIONS/WATCHES FOR
   ADDITIONAL DETAILS.
   
   ...NORTHEAST STATES...
   SCATTERED STRONG/SEVERE TSTMS...INCLUDING A FEW SUPERCELLS AND A
   CONGEALING/EVOLVING QUASI-LINEAR BAND OF TSTMS ACROSS SOUTHERN NEW
   ENGLAND...WILL CONTINUE TO POSE MAINLY A DAMAGING WIND/MARGINALLY
   SEVERE HAIL THREAT INTO THIS EVENING. ALSO SEE MESOSCALE DISCUSSION
   1750.
   
   ..GUYER.. 07/26/2011
   
   .PREV DISCUSSION... /ISSUED 1136 AM CDT TUE JUL 26 2011/
   
   ...NRN/CENTRAL PLAINS...
   UPPER VORTICITY MAX OVER SRN ALBERTA IS FORECAST TO MOVE EWD ACROSS
   THE SRN PRAIRIE PROVINCES WITH GRADUAL HEIGHT FALLS OVERSPREADING
   THE NRN PLAINS THROUGH TONIGHT.  ASSOCIATED COLD  FRONT FROM ERN MT
   SWWD ACROSS WY WILL MOVE EWD ACROSS PART SOD THE NRN
   PLAINS...REACHING A LINE FROM EXTREME ERN ND/CENTRAL SD/CENTRAL WY
   BY THE END OF THE PERIOD.  A WARM FRONT FROM SERN SD INTO A LOW OVER
   SERN MT WILL LIFT NWD TODAY...ALTHOUGH ITS PROGRESS MAY BE LIMITED
   BY CLOUD COVER SPREADING ENEWD OVER THE NRN TWO-THIRDS OF SD.
   
   VERY STEEP MID LEVEL LAPSE RATES AND ATTENDANT EML HAVE OVERSPREAD
   THE REGION...INDICATING THAT SURFACE-BASED STORMS WILL BE DELAYED
   UNTIL LATER THIS AFTERNOON AND EVENING.  CURRENT WIDELY SCATTERED
   ELEVATED STORMS FROM NWRN ND SEWD INTO NERN SD ARE ASSOCIATED WITH
   WARM ADVECTION IN THE 850-700 MB LAYER...AND ARE EXPECTED TO SLOWLY
   SPREAD EWD.  STRONGER CELLS MAY PRODUCE ISOLATED HAIL...SEE SWOMCD
   1746 FOR MORE NEAR-TERM DETAILS.
   
   AS LOW LEVEL MOISTURE CONTINUES TO SPREAD NWD THIS AFTERNOON AND
   HEATING OCCURS WITHIN BREAKS IN CLOUD COVER...ATMOSPHERE WILL BECOME
   INCREASINGLY UNSTABLE FROM SERN SD INTO CENTRAL/SERN ND...WITH
   MLCAPE OF 2000-3000 J/KG EXPECTED.  THE CAP IS EXPECTED TO GRADUALLY
   WEAKEN WITH NEW STORMS INITIATING OVER PARTS OF WRN ND INTO CENTRAL
   SD BY MID-LATE AFTERNOON.  VERTICAL WIND PROFILES ARE FORECAST TO
   EXHIBIT STRONG VEERING AND SPEED INCREASE IN THE LOWEST 3-4
   KM...WHICH WILL PROMOTE SUPERCELL DEVELOPMENT.  IF DISCRETE STORMS
   CAN BE MAINTAINED AFTER INITIATION...THERE WILL BE POTENTIAL FOR
   STRONGER CELLS TO PRODUCE VERY LARGE HAIL AND A FEW
   TORNADOES...SEVERAL OF WHICH COULD BE STRONG.  STORMS ARE EXPECTED
   TO MOVE EWD THROUGH THE EVENING HOURS...WITH THE POSSIBILITY OF SOME
   UPSCALE GROWTH INTO ONE OR TWO MCS/S MOVING TOWARD THE UPPER MS
   VALLEY.
   
   OTHER STORMS ARE EXPECTED TO DEVELOP SSWWD ALONG THE SURFACE TROUGH
   EXTENDING OVER WRN/CENTRAL NEB AND NERN CO.  STRONG DIABATIC HEATING
   AND STEEP LAPSE RATES COUPLED WITH SUFFICIENT VERTICAL SHEAR WILL BE
   FAVORABLE FOR SEVERE STORMS INCLUDING A FEW SUPERCELLS.  LARGE HAIL
   AND DAMAGING WINDS WILL BE THE PRIMARY THREATS.  STORMS WILL SPREAD
   ENEWD THROUGH THE EVENING HOURS BEFORE DIMINISHING AFTER 03-06Z.
   
   ...NERN STATES...
   STRONG/SEVERE STORMS WILL CONTINUE TO DEVELOP ALONG/AHEAD OF A COLD
   FRONT MOVING ACROSS THE LOWER GREAT LAKES AND ACROSS THE NERN
   STATES.  FAVORABLE JET LEVEL FORCING FOR ASCENT AND COLDER
   TEMPERATURES ALOFT WILL PROVIDE SUPPORT FOR SEVERE STORMS WITH
   POTENTIAL TO PRODUCE LARGE HAIL AND STRONG WIND GUSTS INTO THE
   EVENING HOURS.
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z