SWODY1
SPC AC 181920
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0220 PM CDT SUN APR 18 2010
VALID 182000Z - 191200Z
...NO SVR TSTM AREAS FORECAST...
...S FL...
FORECAST REMAINS ON TRACK FOR THIS REGION SUCH THAT NO CHANGES ARE
NEEDED IN THE SEVERE PROBABILITIES. FOR ADDITIONAL MESOSCALE
DETAILS...REFER TO SPC MESOSCALE DISCUSSION 322.
..PETERS.. 04/18/2010
.PREV DISCUSSION... /ISSUED 1114 AM CDT SUN APR 18 2010/
...S FL AND SE TX TODAY...
SPLIT FLOW REGIME CONTINUES ACROSS THE CONUS WITH A SRN STREAM FROM
THE SW STATES/NRN MEXICO EWD TO FL...AND A MORE PRONOUNCED NRN
STREAM FROM THE PAC NW TO CENTRAL CANADA TO NEW ENGLAND. WITHIN THE
SRN STREAM...ONE SHORTWAVE TROUGH IS MOVING SEWD OVER THE MIDDLE TX
COAST...AND A DOWNSTREAM WAVE IS EJECTING NEWD FROM THE SE GULF OF
MEXICO TO S FL. A FEW THUNDERSTORMS WILL CONTINUE IN THE SMALL
INLAND WARM SECTOR ACROSS SE TX...AS WELL AS ACROSS S FL. LOCAL
VWP/S AND FORECAST SOUNDINGS FOR THIS AFTERNOON SHOW A MARGINALLY
FAVORABLE WIND PROFILE FOR ROTATING STORMS ACROSS S FL IN ADVANCE OF
THE SE GULF WAVE. GIVEN THE BOUNDARY LAYER DEWPOINTS NEAR 70 F AND
A FEW CLOUD BREAKS WITHIN THE MIDLEVEL DRY SLOT...THE STRONGEST
STORMS MAY PRODUCE VERY ISOLATED STRONG WIND GUSTS...AND PERHAPS A
BRIEF/WEAK TORNADO.
...HIGH PLAINS THIS AFTERNOON/EVENING FROM MT TO NM...
WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON/EVENING
ACROSS THE HIGH PLAINS FROM CENTRAL MT SWD TO NM. DESPITE MARGINAL
MOISTURE ACROSS MT...A WEAKENING MIDLEVEL TROUGH WILL INTERACT WITH
THE SURFACE LEE TROUGH AND PROMOTE AT LEAST ISOLATED/HIGH-BASED
THUNDERSTORM DEVELOPMENT ACROSS CENTRAL MT LATER THIS AFTERNOON.
FARTHER S...AN INITIAL MIDLEVEL TROUGH IS MOVING E OF THE WY/CO HIGH
PLAINS TO WRN SD/NEB/KS. HOWEVER...A WEAK SURFACE LEE TROUGH WILL
HELP FOCUS THUNDERSTORM DEVELOPMENT THIS AFTERNOON IMMEDIATELY E OF
THE FRONT RANGE IN CO/NE NM. HERE...AFTERNOON TEMPERATURES IN THE
60S AND BOUNDARY LAYER DEWPOINTS OF 35-40 F /BENEATH MIDLEVEL LAPSE
RATES OF 7.5-8 C PER KM/ WILL SUPPORT MLCAPE VALUES OF 500-750 J/KG
AND ONLY WEAK CONVECTIVE INHIBITION.
WEAK SURFACE SELY FLOW BENEATH 20-30 KT WNWLY MIDLEVEL FLOW WILL
RESULT EFFECTIVE BULK SHEAR NEAR 30 KT. THE COMBINATION OF
INSTABILITY AND VERTICAL SHEAR WILL BE MARGINALLY SUFFICIENT FOR
ORGANIZED/ROTATING STORMS. HOWEVER...THREAT FOR HAIL AOA 1 INCH IN
DIAMETER IS SMALL GIVEN THE LIMITED MOISTURE...SO NO HAIL
PROBABILITIES WILL BE ADDED IN THIS UPDATE.
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