Jun 13, 2009 2000 UTC Day 1 Convective Outlook
Updated: Sat Jun 13 22:37:29 UTC 2009
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Public Severe Weather Outlook

The SPC is forecasting ...significant severe thunderstorms expected over parts of the southern plains high plains this afternoon into tonight....   Please read the latest public statement about this event.

Categorical Graphic
20090613 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20090613 2000 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20090613 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20090613 2000 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 132232
   
   DAY 1 CONVECTIVE OUTLOOK AMEND 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0532 PM CDT SAT JUN 13 2009
   
   VALID 132000Z - 141200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF THE TX AND OK
   PANHANDLE REGION...AND INTO WRN OK/WRN N TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL AND SRN HIGH
   PLAINS SEWD INTO KS/OK/TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SOUTHEAST
   AND THE LWR MS VALLEY...
   
   AMENDED FOR SLIGHT RISK ADDITION IN THE LWR MS VALLEY
   
   ...LWR MS VALLEY...
   PLEASE REFER TO SPC MESOSCALE DISCUSSION 1098 FOR DETAILS.
   
   ...SRN HIGH PLAINS...
   STORMS HAVE BEGUN DEVELOPING FROM THE TX SOUTH PLAINS REGION SWWD
   INTO THE TRANSPECOS REGION...AS DAYTIME HEATING HAS PUSHED
   TEMPERATURES INTO THE 90S/LOW 100S S OF THE SURFACE FRONT NOW LYING
   ACROSS NRN PORTIONS OF THE TX SOUTH PLAINS AND INTO THE RED RIVER
   VALLEY REGION.  WITH DEWPOINTS GENERALLY IN THE 60S OVER THE HIGH
   PLAINS...MIXED-LAYER CAPE IN EXCESS OF 1500 J/KG HAS DEVELOPED THIS
   AFTERNOON.
   
   STORMS SHOULD CONTINUE TO DEVELOP ACROSS THIS REGION...AND
   EVENTUALLY NWD INTO THE TX PANHANDLE WHERE ELY UPSLOPE FLOW
   PERSISTS.  STORMS WILL BECOME SUPERCELLULAR GIVEN FAVORABLE
   VEERING/SHEAR WITH HEIGHT IN PLACE ACROSS THIS REGION...WITH LARGE
   HAIL AND DAMAGING WINDS ANTICIPATED ALONG WITH AN ISOLATED TORNADO
   OR TWO.  LATER...STORMS SHOULD DEVELOP/INCREASE NEAR AND N OF THE
   SURFACE FRONT ACROSS N TX/OK...WHERE VERY MOIST/STRONGLY-UNSTABLE
   AIRMASS IS EVIDENT.  STORMS DEVELOPING/SPREADING EWD INTO OK/N TX
   MAY POSE A GREATER TORNADO POTENTIAL...GIVEN GREATER BOUNDARY-LAYER
   MOISTURE AND A MORE UNSTABLE AIRMASS.  OVERNIGHT...STORMS SHOULD
   EVOLVE INTO A LARGE MCS...MOVING ACROSS OK AND VICINITY THROUGH THE
   END OF THE PERIOD -- ACCOMPANIED BY A CONTINUED THREAT FOR
   HAIL/DAMAGING WINDS.
   
   ...CENTRAL HIGH PLAINS...
   LOW-LEVEL MOISTURE CONTINUES ADVECTING NWWD INTO THE HIGH
   PLAINS...IN BROAD ZONE OF ELY/SELY FLOW W OF A SURFACE HIGH OVER THE
   MID MO VALLEY AND TO THE COOL SIDE OF THE SURFACE FRONT LYING FROM
   THE FRONT RANGE SWD INTO NERN NM.  WITH 500 TO 1500 J/KG NOW
   INDICATED ALONG THE HIGH PLAINS...STORMS SHOULD CONTINUE TO INCREASE
   THROUGH THE AFTERNOON AND EVENING...EVENTUALLY SHIFTING INTO THE
   LOWER PLAINS OVERNIGHT AS THE LOW-LEVEL JET INCREASES.
   
   WITH MODERATE MID-LEVEL WLYS ATOP LOW-LEVEL VEERING...SHEAR WILL
   SUPPORT SUPERCELLS...WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE IN
   ADDITION TO THE POTENTIAL FOR ISOLATED TORNADOES.  
   
   OVERNIGHT...STORMS SHOULD CONTINUE SEWD -- MERGING INTO ONE OR MORE
   MCS WITH ASSOCIATED HAIL/WIND POTENTIAL THROUGH THE END OF THE
   PERIOD.
   
   ...SERN AL/SRN GA/NRN FL AND THE FL PANHANDLE...
   STORMS HAVE DEVELOPED IN A ROUGHLY W-E ARC ACROSS NRN FL...WHILE
   STORMS ONGOING EARLIER ACROSS AL HAVE MOVED SEWD INTO SERN AL/SWRN
   GA.  WHILE DEEP-LAYER WIND FIELD REMAINS RELATIVELY WEAK...MODERATE
   INSTABILITY ACROSS THIS REGION SUGGESTS A CONTINUED THREAT FOR
   ISOLATED SEVERE STORMS THROUGH MID-EVENING.
   
   ..SELECT A FORECASTER.. 06/13/2009
   
   .PREV DISCUSSION... /ISSUED 1126 AM CDT SAT JUN 13 2009/
   
   ...SYNOPSIS...
   LITTLE OVERALL CHANGE IN LARGE SCALE PATTERN AS TROUGH PERSIST OVER
   WRN U.S...RIDGE ACROSS SRN PLAINS/LWR MS VALLEY AND TROUGH IN THE
   NORTHEAST. COMPOSITE OF A FRONTAL ZONE/CONVECTIVE OUTFLOW BOUNDARIES
   EXTENDS WWD FROM TN VALLEY THRU CENTRAL OK ACROSS TX PANHANDLE INTO
   ERN NM. A VERY MOIST AND POTENTIALLY EXTREMELY UNSTABLE AIR MASS
   RESIDES S OF SRN PLAINS PORTION OF SURFACE BOUNDARIES. ADDITIONALLY
   LOW LEVEL MOISTURE RETURNING NWD E OF FRONT RANGE CENTRAL HI PLAINS
   IN ADVANCE OF A SIGNIFICANT UPPER TROUGH CURRENTLY EJECTING FROM WRN
   TROUGH POSITION.
   
   ...WRN OK INTO NWRN TX AND THE TX PANHANDLE...
   WHILE THIS AREA WILL GENERALLY BY CAPPED THRU MID AFTERNOON UNDER
   THE RIDGE POSITION...VERY STRONG HEATING ALONG AND S OF FRONTAL ZONE
   WILL RAISE SFC TEMPS TO NEAR 100 F NWRN TX WHICH ALONG WITH
   DEWPOINTS NEAR OF ABOVE 70F BOTH VICINITY AND N OF BOUNDARY AND TO
   THE E OF WHERE DRY LINE IS ABLE TO MIX WILL PUT IN PLACE AN
   EXTREMELY UNSTABLE AIR MASS WITH MLCAPES AOA 4500 J/KG.  GIVEN THE
   LACK OF AVAILABLE LARGE SCALE LIFT AS AREA IN THE RIDGE
   POSITION...SURFACE BASED STORMS EXPECTED TO FORM IN LOW LEVEL
   CONVERGENCE BOTH VICINITY E/W BOUNDARY AND THE INTERFACE OF THE
   STRONGLY HEATED/STEEP LAPSE RATE ENVIRONMENT VICINITY N/S DRY LINE
   WCENTRAL TX.
   
   MOST FAVORED REGION FOR SUPERCELLS AND LARGE HAIL/WIND DAMAGE WILL
   BE ALONG AND ON THE COOL SIDE OF E/W FRONTAL ZONE WHERE GREATEST LOW
   LEVEL SHEAR WILL RESIDE. ADDITIONALLY SEVERE STORMS EXPECTED TO
   DEVELOP IN UPSLOPE REGION NERN NM AS MOIST LOW LEVEL AIRMASS SPREADS
   WWD. SUPERCELLS WOULD THEN LIKELY DEVELOP EWD ACROSS TX/OK PANHANDLE
   BY THIS EVENING WITH POTENTIAL FOR VERY LARGE HAIL...AT LEAST
   ISOLATED TORNADOES AS THIS AREA WILL HAVE A FAVORABLE VEERING LOW
   LEVEL SHEAR ENVIRONMENT/LARGE HODOGRAPHS AND RELATIVELY LOW LFC/S.
   
   HAVE SHIFTED THE ORIGINAL MDT TO THE N AND W BASED ON THESE
   REASONINGS WITH MORE ISOLATED SEVERE STORMS EXPECTED WITH SWD EXTENT
   INTO SWRN TX AS CAP WILL BE STRONGER UNDER RIDGE ALONG WITH WEAKER
   SHEAR.
   
   SEVERE STORMS DEVELOPING EWD ACROSS MDT RISK AREA THIS EVENING WILL
   LIKELY FORM ONE OR MORE MCS/S IN RESPONSE TO FORECASTED INCREASE IN
   THE LOW LEVEL JET TO 30-40KT AND ASSOCIATED WARM ADVECTION.  THIS
   WILL MAINTAIN A SEVERE THREAT INCLUDING DAMAGING WINDS/LARGE HAIL
   E/NEWD ACROSS OK/SRN KS TONIGHT.
   
   ...CENTRAL HIGH PLAINS...
   WITH LOW LEVEL MOISTURE RETURNING NWD IN ADVANCE OF UPPER TROUGH
   LIFTING NEWD ACROSS CENTRAL ROCKIES THIS AFTERNOON...EXPECT MORE
   THAN SUFFICIENT INSTABILITY AND SHEAR TO BE IN PLACE FOR SEVERE
   STORM DEVELOPMENT TODAY AS FAR N AS ERN WY.  AS 50 DEWPOINTS/STEEP
   LAPSE RATES AND INCREASING SHEAR WITH MID LEVEL SWLY FLOW OF 40-50
   KTS SPREADING ACROSS FRONT RANGE...SEVERE THUNDERSTORMS INCLUDING
   SUPERCELLS WILL DEVELOP ALONG AND E OF FRONT RANGE BASED ON THESE
   EXPECTED CONDITIONS NWD INTO SERN WY.
   
   FURTHER W INTO CENTRAL WY...THE AIR MASS WILL DESTABILIZE AND
   SUPPORT ACTIVE THUNDERSTORMS AHEAD OF UPPER TROUGH WHICH WILL
   INCLUDE BOTH HAIL AND DAMAGING WINDS BY MID AFTERNOON.  LOW LEVEL
   SHEAR/MOISTURE WILL BE A LITTLE LESS FAVORABLE THAN FURTHER E...BUT
   GIVEN THE LARGE SCALE ASCENT WITH TROUGH AT LEAST ISOLATED
   SUPERCELLS ARE LIKELY.
   
   ...MS/AL/GA/FL...
   SCATTERED THUNDERSTORMS ARE ONGOING THIS MORNING OVER PARTS OF
   MS/AL.  THIS ACTIVITY MAY INTENSIFY EARLY THIS AFTERNOON
   AS DAYTIME HEATING DESTABILIZES THE AIRMASS.  ISOLATED SEVERE STORMS
   CAPABLE OF HAIL AND DAMAGING WINDS ARE EXPECTED THROUGH THE DAY AS
   STORMS SPREAD EAST-SOUTHEASTWARD TOWARD GA/FL PANHANDLE.
   
   ...UPPER MS VALLEY...
   STEEP LOW LEVEL LAPSE RATES...COOL TEMPERATURE PROFILES AND MARGINAL
   INSTABILITY EXPECTED TO BE SUFFICIENT FOR A FEW STRONG/SEVERE
   THUNDERSTORMS ALONG/AHEAD OF FRONT MOVING SEWD ACROSS UPPER MS
   VALLEY THIS AFTERNOON.  PRIMARY THREAT WILL BE HAIL/GUSTY WINDS.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z