SWODY1
SPC AC 181953
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT TUE OCT 18 2011
VALID 182000Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND TONIGHT
ACROSS MUCH OF FLORIDA INTO THE COASTAL CAROLINAS...
...20Z OUTLOOK UPDATE...
...FLORIDA...
ALTHOUGH IT MAY BE MUCH SLOWER THAN EARLIER THOUGHT...MODELS STILL
INDICATE SUBSTANTIAL STRENGTHENING OF SOUTHERLY LOW-LEVEL WIND
FIELDS /IN EXCESS OF 50 KT AT 850 MB/ ACROSS MUCH OF THE FLORIDA
PENINSULA LATE THIS AFTERNOON THROUGH THE EVENING HOURS. THIS
SHOULD OCCUR AS A DEEPENING SURFACE LOW OVER THE EASTERN GULF OF
MEXICO MIGRATES INLAND...NORTHEASTWARD ACROSS PARTS OF NORTHERN
FLORIDA. SUPERCELLULAR STRUCTURES WITHIN THE LINE OF STORMS NOW
APPROACHING WEST CENTRAL AND SOUTHWESTERN COASTAL AREAS PROBABLY
WILL POSE THE PRIMARY INITIAL SEVERE THREAT...WITH A RISK FOR
ISOLATED TORNADOES AND DAMAGING WINDS. HOWEVER...ADDITIONAL STORM
DEVELOPMENT ASSOCIATED WITH AT LEAST POCKETS OF WEAK BOUNDARY LAYER
DESTABILIZATION OVER THE INTERIOR SOUTHERN AND CENTRAL PENINSULA IS
EXPECTED THIS EVENING...BEFORE LOW-LEVEL CONVERGENCE BECOMES FOCUSED
ALONG ATLANTIC COASTAL AREAS. THIS ACTIVITY WILL ALSO BE
ACCOMPANIED BY THE RISK FOR TORNADOES AND DAMAGING WIND GUSTS...IN
THE PRESENCE OF LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS AND HIGH
BOUNDARY LAYER DEW POINTS/RELATIVE HUMIDITY.
...MID SOUTH...
ONGOING PRE-FRONTAL CONVECTIVE DEVELOPMENT ACROSS PARTS OF NORTHERN
ALABAMA AND MIDDLE TENNESSEE APPEARS TO HAVE BEEN AIDED BY FORCING
FOR ASCENT ASSOCIATED WITH A SHORT WAVE IMPULSE LIFTING OUT OF THE
LOWER MISSISSIPPI VALLEY. THIS FORCING APPEARS LIKELY TO
WEAKEN/SHIFT NORTHEAST OF THE REGION INTO THE LOWER OHIO VALLEY AND
CENTRAL APPALACHIANS DURING THE 21-00Z TIME FRAME. AS THIS
OCCURS...STORM INTENSITIES MAY BEGIN TO LEVEL OFF/DECREASE...IN THE
PRESENCE OF SOMEWHAT MARGINAL/LIMITED INSTABILITY FOR STRONG/SEVERE
STORM DEVELOPMENT. SOME HAIL/WIND GUSTS APPROACHING OR BRIEFLY
EXCEEDING SEVERE LIMITS ARE POSSIBLE...BUT THE THREAT STILL SEEMS TO
REMAIN BELOW SLIGHT RISK PROBABILITIES.
..KERR.. 10/18/2011
.PREV DISCUSSION... /ISSUED 1120 AM CDT TUE OCT 18 2011/
...FL INTO CAROLINAS...
A LARGE UPPER TROUGH IS PRESENT TODAY OVER THE EASTERN UNITED
STATES...WITH TWO PRIMARY SHORTWAVE TROUGHS AFFECTING THE SOUTHEAST
STATES. ONE IMPULSE IS CURRENTLY OVER THE EASTERN GULF OF MEXICO
AND IS MOVING SLOWLY NORTHEASTWARD. MODELS SUGGEST THAT THIS SYSTEM
WILL ACCELERATE NORTHEASTWARD LATER THIS EVENING AND PROMOTE LOW
LEVEL CYCLOGENESIS FROM FL INTO THE CAROLINA COASTAL AREAS BY WED
MORNING. NUMEROUS ROTATING STORMS HAVE BEEN OBSERVED OFF THE
SOUTHWEST COAST OF FL THIS MORNING. THIS ACTIVITY WILL APPROACH THE
PENINSULA THIS AFTERNOON AND WILL POSE A RISK OF ISOLATED TORNADOES.
THE THREAT FARTHER NORTH ACROSS THE CENTRAL/NORTHERN FL PENINSULA IS
MUCH MORE COMPLEX DUE TO THE CONVECTIVE SYSTEM THAT WILL AFFECT THE
SOUTH. HOWEVER...MORNING MODEL SOLUTIONS CONTINUE TO SUGGEST STRONG
LOW LEVEL WIND FIELDS AND SUFFICIENT CAPE WILL MOVE ACROSS THIS AREA
THIS EVENING AND TONIGHT TO MAINTAIN THE ONGOING SLIGHT RISK. THE
THREAT SHOULD MOVE NORTHEASTWARD ALONG THE SURFACE WARM FRONT INTO
THE COASTAL CAROLINAS LATE TONIGHT.
...MID SOUTH...
THE SECOND STRONG SHORTWAVE TROUGH IS EVIDENT IN SATELLITE IMAGERY
OVER AR/LA/MS. THIS FEATURE WILL TRACK EASTWARD ACROSS THE CENTRAL
GULF COAST STATES...WITH THE ASSOCIATED COLD FRONT SWEEPING AS FAR
EAST AS GA BY WED MORNING. POCKETS OF STRONG HEATING AHEAD OF THE
FRONT...COUPLED WITH COOLING TEMPERATURES ALOFT AND ASCENT
ASSOCIATED WITH THE LEFT-EXIT REGION OF THE UPPER JET WILL PROMOTE
SCATTERED THUNDERSTORM DEVELOPMENT. FORECAST SOUNDINGS SUGGEST A
RISK OF HAIL AND GUSTY WINDS FROM THE STRONGEST STORMS...MAINLY THIS
AFTERNOON AND EARLY EVENING FROM CENTRAL KY/MIDDLE TN INTO CENTRAL
AL.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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