SPC AC 171927
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 PM CDT SUN MAY 17 2009
VALID 172000Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...SERN STATES...
TSTMS HAVE BECOME FAIRLY WIDESPREAD THIS AFTERNOON ALONG COLD FRONT
AS WELL AS WITHIN PRE-FRONTAL WARM SECTOR...FOCUSED ALONG RESIDUAL
OUTFLOW AND SEA BREEZE BOUNDARIES. WARM SECTOR AIR MASS REMAINS
QUITE MOIST WITH DEWPOINTS IN THE 60S. THIS MOISTURE IN CONJUNCTION
WITH RELATIVELY STRONG DAYTIME HEATING IS RESULTING IN A MODERATELY
UNSTABLE AIR MASS WITH MLCAPE OF 1000-2000 J/KG. PLAN VIEW VWP DATA
INDICATE THAT STRONGER MID/HIGH-LEVEL FLOW REMAINS DISPLACED TO THE
N OF SURFACE FRONT WITH GENERALLY WEAK FLOW ACROSS WARM SECTOR. AS
SUCH...EXPECT ABOVE-MENTIONED BOUNDARIES AND DEEPER ASCENT
ASSOCIATED WITH MIDLEVEL IMPULSE MOVING THROUGH MS/AL TO MAINTAIN
CLUSTERS OF MULTICELL/PULSE TSTMS INTO THIS EVENING. THE STRONGER
ACTIVITY WILL REMAIN CAPABLE OF SOME HAIL AND LOCALLY STRONG WIND
GUSTS.
...AZ...
TSTMS ARE BEGINNING TO DEVELOP THIS AFTERNOON ALONG THE MOGOLLON RIM
AND HIGHER TERRAIN OF SERN AZ WITHIN STEEP LAPSE RATE ENVIRONMENT
WHERE SBCAPE HAS INCREASED TO 1000 J/KG. CURRENT TUCSON AND PHOENIX
VWPS INDICATE RATHER WEAK WIND FIELDS...AND THIS WILL LIMIT THE
POTENTIAL FOR STORM ORGANIZATION. NONETHELESS...GIVEN THE PRESENCE
OF THE STEEP LAPSE RATES...DEEPLY MIXED BOUNDARY LAYER CONDITIONS
AND DCAPE APPROACHING 1500 J/KG...THE POTENTIAL WILL EXIST FOR A FEW
STRONG STORMS CAPABLE OF STRONG DOWNBURST WINDS THROUGH THIS
EVENING.
..MEAD.. 05/17/2009
.PREV DISCUSSION... /ISSUED 1119 AM CDT SUN MAY 17 2009/
...GA/FL INTO THE EASTERN CAROLINAS...
ANOTHER ACTIVE CONVECTIVE DAY IS EXPECTED ACROSS THE SERN U.S. AHEAD
OF BROAD MID/UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT
SHIFTING STEADILY ESEWD. AFTERNOON HEATING AND CONVERGENCE INVOF
NUMEROUS SURFACE BOUNDARIES/SEA BREEZE CIRCULATIONS PERSISTING
WITHIN THE WARM SECTOR WILL SUPPORT SCATTERED THUNDERSTORMS THROUGH
THE AFTERNOON. MID LEVEL TEMPERATURES REMAIN SEASONABLY COOL AND
SHOULD SUPPORT MODERATE SBCAPE AND SOME HAIL POTENTIAL WITH THE
STRONGER CORES...ALONG WITH ISOLATED STRONG DOWNBURSTS. ACTIVITY
WILL REMAIN WEAKLY ORGANIZED AND ANY ENSUING SEVERE THREAT SHOULD BE
BRIEF-LIVED UNDER WEAK FLOW ALOFT. OVERALL THREAT SHOULD WANE
QUICKLY THIS EVENING.
...SWRN STATES...
WV IMAGERY INDICATES WEAK SHORTWAVE TROUGH ROTATING N-NWWD ACROSS
THE NRN GULF CA AND NWRN MEXICO THIS MORNING AS LARGER MID/UPPER
LEVEL LOW RETROGRADES WWD OFF THE MEXICAN/SRN CA COAST. IN
ADDITION...NARROW PLUME OF .5-.75 INCH PW IS EXPECTED TO PERSIST IN
A W-E BAND ALONG THE AZ/SWRN NM-MEXICAN BORDER TODAY. MODELS ARE
CONSISTENT IN GENERATING AFTERNOON THUNDERSTORMS BOTH WITHIN THIS
BAND AND NEAR THE HIGHER TERRAIN OF CENTRAL/ERN AZ AND WRN NM WHERE
NEAR RECORD HEAT WILL DEVELOP OVER THE DESERTS. WITH WEAK ENELY
STEERING FLOW...A FEW OF THESE HIGH-BASED STORMS MAY SURVIVE FOR A
SHORT PERIOD WWD ACROSS LOWER ELEVATIONS SUPPORTING AT LEAST A LOW
PROBABILITY RISK OF ISOLATED DAMAGING WINDS.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
|
