May 18, 2010 2000 UTC Day 1 Convective Outlook
Updated: Tue May 18 20:00:24 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100518 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100518 2000 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100518 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100518 2000 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 181957
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0257 PM CDT TUE MAY 18 2010
   
   VALID 182000Z - 191200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
   PARTS OF ERN CO...NERN NM...PARTS OF THE OK/TX PNHDLS INTO THE TX S
   PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN CO/WRN KS INTO THE ERN
   NM AND WRN INTO N-CNTRL TX...
   
   ...CNTRL/SRN HIGH PLAINS...
   
   THE PRIMARY CHANGES TO THE CURRENT FORECAST ARE AS FOLLOWS: 1) A
   SLIGHT NWD SHIFT OF THE CATEGORICAL SLIGHT RISK OVER SWRN TX...2) A
   SLIGHT EWD SHIFT IN THE CATEGORICAL SLIGHT RISK ALONG THE RED RIVER
   VALLEY OF SWRN OK/NWRN TX...3) A SWD EXTENSION OF THE TEN PERCENT
   TORNADO PROBABILITY LINE IN THE TX PNHDL...AND 4) THE ADDITION OF A
   30 PERCENT PROBABILITY WIND CONTOUR OVER PARTS OF THE OK/TX PNHDLS
   INTO WRN OK.
   
   TSTMS ARE EXPECTED TO INCREASE IN AREAL COVERAGE AND INTENSITY
   THROUGH THE REMAINDER OF THE AFTERNOON INTO THIS EVENING FROM ERN CO
   SWD THROUGH ERN NM INTO THE OK/TX PNHDLS AND WRN TX.  HERE...
   DIABATIC HEATING COUPLED WITH EWD PROGRESSION OF EML PRECEDING
   MIDLEVEL TROUGH AND DEW POINTS IN THE 50S ARE CONTRIBUTING TO AIR
   MASS DESTABILIZATION WITH MLCAPE APPROACHING 2000 J/KG BY LATE
   AFTERNOON.  
   
   AT THE SAME TIME...A 40-50/50-70 KT MID/HIGH-LEVEL JET WILL DEVELOP
   EWD THROUGH NM INTO THE SRN HIGH PLAINS...RESULTING IN STEADILY
   STRENGTHENING VERTICAL SHEAR.  AS SUCH...THE SETUP WILL BECOME
   INCREASINGLY FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL AND
   TORNADOES.  THE THREAT FOR TORNADOES MAY INCREASE NEAR OR SHORTLY
   AFTER 00Z FROM FAR SERN CO SEWD INTO THE OK/TX PNHDLS IN CONCERT
   WITH A STRENGTHENING...SELY LLJ.  
   
   BY LATE EVENING...STORMS MAY GROW UPSCALE INTO A MCS WITH AN
   INCREASED THREAT FOR DAMAGING WINDS OVER THE OK/TX PNHDLS.  THE
   CONVECTIVE SYSTEM WILL LIKELY BE MAINTAINED OVERNIGHT EWD INTO
   OK...SUPPORTED BY STRONG WAA TO THE N OF WARM FRONT RETREATING NWD
   INTO NRN TX.
   
   ..MEAD.. 05/18/2010
   
   .PREV DISCUSSION... /ISSUED 1119 AM CDT TUE MAY 18 2010/
   
   ...CENTRAL AND SRN HIGH PLAINS...
   S/W TROUGH CURRENTLY SRN INTERMOUNTAIN REGION MOVES EWD ACROSS SRN
   ROCKIES INTO HIGH PLAINS BY 12Z WED. BAND OF STRONGER MID/UPR LEVEL
   WINDS ASSOCIATED WITH TROUGH NRN AZ/NM WILL BRING FAVORABLE DEEP
   LAYER SHEAR AND LARGE SCALE ASCENT INTO HIGH PLAINS OF CO AND NE NM
   BY LATER THIS AFTERNOON. SURFACE RESPONSE TO APPROACHING TROUGH IS
   LEE LOW DEVELOPMENT SERN CO WITH ADDITIONAL SMALLER SCALE CYCLONIC
   FORMATION TO N OF PALMER DIVIDE.
   
   LOW LEVEL MOISTURE IS SPREADING N/NNW IN 30-40KT LOW LEVEL JET FROM
   OK/TX PANHANDLE NWD THRU ERN CO/WRN KS.
   
   WHILE THERE IS CONSIDERABLE UPR CLOUDINESS WITH TROUGH ACROSS
   NM...CLEARING LEE OF CO ROCKIES WILL ALLOW GOOD SURFACE HEATING.
   
   WITH REGARDS TO THE MDT RISK...IT NOW LOOKS LIKE THE GREATEST
   LIKELIHOOD OF SUPERCELLS WITH LARGE HAIL AND TORNADO POTENTIAL WILL
   BE TIED TO THE LOW LEVEL CONVERGENCE VICINITY PALMER DIVIDE SWD THRU
   SERN CO/NERN NM INTO NRN TX PANHANDLE VICINITY AND N OF MID LEVEL
   WIND MAX CURRENTLY CROSSING NRN NM.
   
   INITIAL DEVELOPMENT EXPECTED IN ERN CO WHERE CINH WILL WEAKEN BY MID
   AFTERNOON. THEN EXPECT TO CONTINUE TO SEE AT LEAST SCATTERED STORMS
   INCLUDING SUPERCELLS SWD FAR ERN NM WHICH IS WHERE THE DRY LINE
   SHOULD HAVE MIXED EWD TO BY LATER THIS AFTERNOON.
   
   WITH LAPSE RATES IN EXCESS OF 8C/KM...MLCAPES TO 1500 J/KG AND 
   FAVORABLE VEERING HODOGRAPHS...CONDITIONS APPEAR FAVORABLE FOR VERY
   LARGE HAIL/TORNADOES WITHIN THE MDT AREA THAT WILL SHIFT EWD BY
   EARLY EVENING INTO SWRN KS SWD THRU THE TX PANHANDLE.
   
   FURTHER S WITH SOMEWHAT LESS FAVORABLE LAPSE RATES AND TO THE S OF
   THE LARGE SCALE ASCENT WITH THE TROUGH AND SOMEWHAT RETARDED SURFACE
   HEATING DUE TO OBSERVED MID LEVEL CLOUDS...STORMS WILL BE MORE
   WIDELY SCATTERED AND DEVELOP LATER AS WELL. HOWEVER ISOLATED
   SUPERCELLS ARE STILL LIKELY WITH POTENTIAL FOR PRIMARILY LARGE HAIL
   AS THEY PROPAGATE/MOVE EWD DURING THE EVENING.
   
   ...MT AND ADJACENT NORTHERN HIGH PLAINS THIS AFTN/EARLY EVE...
   MOISTURE WILL INCREASE TODAY OVER THE HI PLNS OF ERN MT...WITH PW
   RISING TO AOA .75 INCHES AS LEE SIDE TROUGH STRENGTHENS.  TSTMS
   SHOULD FORM THIS AFTN ALONG THE TROUGH AND/OR ALONG TERRAIN-INDUCED
   CIRCULATIONS AS HEATING BOOSTS SBCAPE TO 500-1000 J/KG /HIGHEST
   ACROSS SE MT/.  COUPLED WITH MODEST...DEEP...S TO SSELY FLOW AND
   STEEP LOW TO MID LVL LAPSE RATES...SETUP MAY SUPPORT A FEW SMALL
   CLUSTERS STG/SVR STMS.  HAIL SHOULD BE THE MAIN THREAT.
   
   ...FL THIS AFTN...
   SLIGHT COOLING/ASCENT WITH CYCLONIC MID/UPR LVL FLOW MAY
   CONTRIBUTE TO THERMODYNAMIC PROFILES FAVORABLE FOR ISOLD
   STRONG/SVR TSTMS THIS AFTN. A FEW DOWNBURSTS/MARGINALLY
   SVR HAIL WILL BE POSSIBLE...MAINLY ALONG THE E CST SEA BREEZE FRONT.
   
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