SWODY1
SPC AC 141943
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CDT MON SEP 14 2009
VALID 142000Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF UT...
...UT...
THE CURRENT FORECAST APPEARS ON TRACK. STRONG TO SEVERE STORMS ARE
DEVELOPING ACROSS UT WITHIN ZONE OF DEEP LIFT AND UPPER DIVERGENCE
ATTENDING THE EWD MOVING SHORTWAVE TROUGH. COOL TEMPERATURES ALOFT
WITH -12 TO -13C AT 500 MB...STEEP LAPSE RATES...AND DEEPLY MIXED
BOUNDARY LAYERS ARE PROMOTING A RISK FOR ISOLATED LARGE HAIL AND
STRONG TO DAMAGING WIND GUSTS. SEVERE THREAT SHOULD DIMINISH EARLY
THIS EVENING AS THE BOUNDARY LAYER BEGINS TO STABILIZE.
...GULF COASTAL STATES...
EARLY THIS EVENING A FRONTAL BOUNDARY EXTENDS FROM THE NRN GULF OF
MEXICO NWWD TO A WEAK SURFACE LOW OVER THE LOWER MS VALLEY. LARGE
CLUSTER OF STORMS CONTINUE WITHIN PLUME OF DEEP SUBTROPICAL MOISTURE
FROM THE FL PANHANDLE NWD THROUGH AL. FARTHER WEST MORE ISOLATED
DEVELOPMENT IS OCCURING WITHIN DRY SLOT AND ZONE OF POSSIBLE UPPER
LEVEL SUBSIDENCE. IN BOTH THESE REGIONS CONSIDERABLE LOW LEVEL
VEERING EXISTS IN VICINITY OF THE FRONT...BUT LOW LEVEL AND DEEP
LAYER SHEAR REMAIN WEAK . STRONG DIABATIC HEATING HAS DESTABILIZED
THE BOUNDARY LAYER IN DRY SLOT REGION. HOWEVER...WEAK MID LEVEL
LAPSE RATES...WARM AIR ALOFT AND WEAK VERTICAL SHEAR WILL CONTINUE
TO BE A LIMITING FACTOR FOR A MORE ROBUSTS SEVERE THREAT.
..DIAL.. 09/14/2009
.PREV DISCUSSION... /ISSUED 1102 AM CDT MON SEP 14 2009/
...UT...
UPPER TROUGH HAS MOVED INLAND OVER CA THIS AM AND BY 12Z TUE
FORECASTED TO BE A CLOSED LOW CENTRAL UT. MOISTURE HAS SPREAD NEWD
AHEAD OF THE TROUGH THRU THE INTERMOUNTAIN REGION OVERNIGHT. THE
LARGE SCALE ASCENT AND COOL AIR ALOFT/STEEP LAPSE RATES/ WITH
APPROACHING TROUGH HAVE INITIATED THUNDERSTORMS VICINITY UT/NV
BORDER THIS AM. HEATING COMBINED WITH THE AVAILABLE MOISTURE...WILL
LEAD TO AN INCREASE IN INSTABILITY ACROSS MUCH OF UT BY MID
AFTERNOON WITH MLCAPES RANGING UPWARD FROM 500-1000 J/KG. WITH DEEP
LAYER SHEAR TO 30KT...SURFACE BASED STORMS WILL INCREASE DURING THE
AFTERNOON...POSSIBLY DEVELOP CLUSTERS AND SHORT LINES. WITH A
DEEPLY MIXED BOUNDARY LAYER...GUSTY WINDS...BRIEFLY SEVERE WILL
DEVELOP E AND NE ACROSS CENTRAL/UT THIS AFTERNOON. IN ADDITION HAIL
WILL BE LIKELY WITH STRONGEST UPDRAFTS GIVEN THE COOL AIR ALOFT AND
STEEP LAPSE RATES...THEREFORE HAVE INTRODUCED A LOW END SLIGHT RISK
FOR THIS AFTERNOON/EVENING.
...CENTRAL GULF COAST STATES...
A TROPICAL AIR MASS RESIDES ACROSS LOWER MS VALLEY IN ADVANCE OF THE
WEAK SURFACE/UPPER LOW CURRENTLY OVER ERN TX. SVR/TOR POTENTIAL AS
OVER THE WEEKEND WILL BE LIMITED BY THE RELATIVELY WEAKLY SHEARED
ENVIRONMENT. HOWEVER TODAY THERE WILL BE MORE HEATING EWD ACROSS LA
AND SRN MS...LEADING TO THE THREAT FOR DISCRETE STORM DEVELOPMENT
AND POSSIBLY WEAK ROTATION.
HAVE CONTINUED A MARGINAL RISK OF BRIEF TORNADOES AND WET MICRO
BURSTS...BUT WITH THE MARGINAL SHEAR...DO NOT EXPECT STORMS TO BE
ORGANIZED OR OF LONG DURATION.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment