SPC AC 052000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT FRI JUN 05 2009
VALID 052000Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL/SOUTHERN
HIGH PLAINS...
...CENTRAL HIGH PLAINS...
BENEATH AMPLE HIGH LEVEL CLOUD COVER THIS AFTERNOON...SPECIAL
VORTEX2 SOUNDINGS ACROSS THE SOUTHWEST NEB PANHANDLE AND NORTHEAST
CORNER OF CO CONFIRM A RESIDUAL CAP BETWEEN 700-800 MB AS OF
18Z...BUT IMPLY THAT SURFACE BASED CINH SHOULD WANE AS TEMPERATURES
WARM THROUGH THE UPPER 70S F...WITH POTENTIAL REALIZATION OF AROUND
2000 J/KG OF MLCAPE. WITH STRENGTHENING LOW LEVEL SOUTHEASTERLY
UPSLOPE FLOW NOTED IN EARLY-MID AFTERNOON SURFACE OBSERVATIONS AND
THE GOODLAND WSR-88D VWP...THE MOST LIKELY SCENARIO APPEARS TO BE
FOR TSTMS TO INITIATE ACROSS FAR SOUTHEAST WY/NORTHEAST CO AND THE
SOUTHERN NEB PANHANDLE BY LATE AFTERNOON. WITH EAST-SOUTHEAST
TRAJECTORIES IN THE BOUNDARY LAYER...STRENGTHENING MID-HIGH LEVEL
WINDS /INCREASING TREND NOTED 5 KM AND ABOVE PER PLATTEVILLE CO AND
MEDICINE BOW WY PROFILERS/ WILL BE WELL-SUPPORTIVE OF SUPERCELLS
CAPABLE OF LARGE HAIL AND SOME TORNADOES. WITH A STEADILY INCREASING
SOUTHERLY LOW LEVEL JET THIS EVENING ACROSS WESTERN KS...THE SEVERE
THREAT WILL LIKELY CONTINUE TO DEVELOP EASTWARD ALONG THE SHARPENING
WEST-EAST FRONTAL ZONE TONIGHT...WITH A CONTINUED RISK FOR SEVERE
HAIL/DAMAGING WINDS.
...FL/SOUTHEAST STATES TO SOUTHEAST VA...
OBSERVED MCV ALONG THE NC/VA BORDER IN TANDEM WITH REMNANT FRONTAL
ZONE ACROSS THE REGION MAY PROVIDE A FOCUS FOR A FEW ROTATING STORMS
OVER THE NEXT FEW HOURS. ACROSS THE FL PENINSULA...MAINLY ISOLATED
SEVERE TSTMS WILL CONTINUE TO BE FOCUSED ALONG/SOUTH OF OUTFLOW
BOUNDARY CURRENTLY ACROSS THE CENTRAL FL PENINSULA. OVERALL...SEVERE
THREAT IN THE FORM OF DAMAGING WINDS/POSSIBLE TORNADO SHOULD REMAIN
RATHER LOCALIZED/MARGINAL ACROSS THE REGION.
SEE PREVIOUS DAY 1 OUTLOOK DISCUSSION AND LATEST SPC
WATCHES/MESOSCALE DISCUSSIONS FOR ADDITIONAL GUIDANCE.
..GUYER.. 06/05/2009
.PREV DISCUSSION... /ISSUED 1127 AM CDT FRI JUN 05 2009/
...CENTRAL HIGH PLAINS THIS AFTERNOON INTO TONIGHT...
ON THE LARGER SCALE...SHORTWAVE RIDGING WILL PERSIST OVER THE
CENTRAL HIGH PLAINS INTO THIS AFTERNOON...PRIOR TO THE ARRIVAL OF A
NEWD EJECTING SPEED MAX EMANATING FROM THE SRN GREAT BASIN. IN THE
LOW LEVELS...A WEAK LEE CYCLONE WILL REMAIN ACROSS ERN CO...WHILE
ANOTHER COLD FRONT PROGRESSES SWD INTO NRN NEB AND ERN WY. S OF THE
COLD FRONT AND N OF THE LEE CYCLONE...UPSLOPE FLOW OF LOW-MID 50S
BOUNDARY LAYER DEWPOINTS WILL BE MAINTAINED INVOF ANOTHER/WEAKER
BAROCLINIC ZONE FROM NW KS/SW NEB NWWD INTO SE WY. SURFACE HEATING
W OF AN INITIAL CIRRUS BAND AND UPSLOPE FLOW WILL SUPPORT
THUNDERSTORM DEVELOPMENT THIS AFTERNOON ONCE SURFACE TEMPERATURES
APPROACH 70-72 F IN SE WY AND 78-80 F IN NE CO...WITH INITIAL
DEVELOPMENT POSSIBLE FROM AREAS N OF THE PALMER DIVIDE TO THE
CHEYENNE RIDGE AND LARAMIE MOUNTAINS. CONVECTION WILL THEN SPREAD
EWD THIS EVENING INTO AN ENVIRONMENT WITH MODERATE INSTABILITY
/MLCAPE VALUES AROUND 1500 J/KG/.
50-60 KT WLY FLOW ALOFT ABOVE THE LOW-LEVEL ELY/ESELY FLOW WILL
RESULT IN FAVORABLE VERTICAL SHEAR FOR SUPERCELLS /EFFECTIVE BULK
SHEAR OF 45-55 KT/. RELATIVELY STRAIGHT HODOGRAPHS COULD SUPPORT
STORM SPLITS INITIALLY...WHILE A TENDENCY FOR INCREASED CLOCKWISE
CURVATURE AND HODOGRAPH LENGTH WITH EWD EXTENT AND LATER THIS
EVENING SHOULD BE MORE FAVORABLE FOR TORNADIC SUPERCELLS. ISOLATED
VERY LARGE HAIL COULD ALSO OCCUR WITH THE MORE INTENSE SUPERCELLS
THIS AFTERNOON/EVENING. BY EARLY TONIGHT...CONVECTION WILL BEGIN TO
TRANSITION INTO MORE ELEVATED THUNDERSTORM CLUSTERS IN ASSOCIATION
WITH INCREASING WAA... WITH A LARGE HAIL AND DAMAGING WIND THREAT
CONTINUING OVERNIGHT INTO NEB.
...SRN HIGH PLAINS THIS AFTERNOON/EVENING...
REGIONAL 12Z SOUNDINGS INDICATE THAT AFTERNOON TEMPERATURES IN THE
UPPER 80S TO LOWER 90S WILL REDUCE CONVECTIVE INHIBITION AND SUPPORT
WIDELY SCATTERED THUNDERSTORM DEVELOPMENT ALONG THE LEE
TROUGH/DRYLINE FROM SW KS INTO TX PANHANDLE/W CENTRAL TX. MODERATE
INSTABILITY AND VERTICAL SHEAR COULD BE MARGINALLY FAVORABLE FOR
HIGH-BASED SUPERCELLS CAPABLE OF PRODUCING ISOLATED LARGE HAIL AND
STRONG OUTFLOW WINDS.
...NE NC/SE VA THIS AFTERNOON...
A REMNANT MCV IS MOVING NEWD ACROSS CENTRAL NC TOWARD SE VA...ALONG
A STALLED NE-SW ORIENTED FRONT. A BAND OF 25-30 KT LOW-MID LEVEL
FLOW E/SE OF THE MCV AND SOMEWHAT STRONGER LOW-LEVEL SHEAR ALONG THE
FRONT MAY BE SUFFICIENT FOR ISOLATED ROTATING STORMS. AN
ISOLATED/BRIEF TORNADO COULD OCCUR ALONG THE FRONT AND IMMEDIATELY
IN ADVANCE OF THE MCV FROM N CENTRAL/NE NC INTO SE VA THIS
AFTERNOON.
...NRN GREAT BASIN THIS AFTERNOON...
SURFACE HEATING AND A BROAD REGION OF ASCENT IN THE EXIT REGION OF A
SPEED MAX ROTATING AROUND THE CA/NV CLOSED LOW WILL PROMOTE
SCATTERED THUNDERSTORM DEVELOPMENT THROUGH THE AFTERNOON FROM NRN
NV/UT NWD INTO SRN ID. THE STRONGER VERTICAL SHEAR WILL BE LOCATED
FARTHER E TOWARD NW UT AND SE ID WHERE CLOUDS WILL MORE LIKELY
INTERFERE WITH SURFACE HEATING...AND THE STRONGER SURFACE HEATING
WILL OCCUR FARTHER W/NW TOWARD S/SW ID WHERE VERTICAL SHEAR WILL BE
WEAKER. A FEW STORMS MAY PRODUCE MARGINALLY SEVERE HAIL AND STRONG
OUTFLOW WINDS...BUT THE SEVERE THREAT SHOULD REMAIN RELATIVELY
MARGINAL AND/OR ISOLATED.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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