SWODY1
SPC AC 181245
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT SUN SEP 18 2011
VALID 181300Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS IN EXTREME SW MO/NW AR SWWD TO
CNTRL TX...
...SYNOPSIS...
DAYBREAK WATER VAPOR IMAGERY SHOWS A FULL-LATITUDE UPR TROUGH
SITUATED ACROSS THE PLAINS STATES WITH NUMEROUS EMBEDDED IMPULSES.
STRONGEST OF SUCH DISTURBANCES WAS LOCATED OVER THE SRN HIGH PLAINS
AND IS EXPECTED TO TRANSLATE INTO THE LWR/MID-MS RVR VLY REGION BY
LATE TONIGHT. 12Z SFC ANALYSIS PLACES A 1011 MB LOW SW OF KICT WITH
A CONVECTIVELY ENHANCED FRONT SEWD INTO THE LWR MS RVR VLY. A CDFNT
WAS GAINING STRENGTH ACROSS NWRN OK AND THE TX PNHDL. THE LOW WILL
MIGRATE NEWD INTO ERN KS THIS AFTN WHILE WITH A WRMFNT DEVELOPING
ENE TOWARD THE OZARKS. THE CDFNT WILL SWEEP ESE INTO SW MO...ERN OK
AND CNTRL TX BY SUNSET...AND THE LWR OH VLY...CNTRL AR...TX HILL
COUNTRY BY 12Z MONDAY. THE FRONT WILL BE A FOCUS FOR TSTMS...SOME
PSBLY SVR THIS AFTN/EVE.
...EXTREME SW MO/NW AR SWWD INTO CNTRL TX...
WIDESPREAD CONVECTION/EMBEDDED TSTMS CONTINUE THIS MORNING FROM ERN
PARTS OF THE CNTRL PLAINS/MID-MS VLY SWWD INTO N TX. ACTIVITY
APPEARS LARGELY TIED TO MID/LOW-LVL WARM ADVECTION REGIME WITHIN A
BROAD SWLY H85-H7 JET AXIS...FAVORING AREAS ALONG/N OF THE
AFOREMENTIONED NW-SE ORIENTED FRONT LOCATED JUST N OF THE RED RVR
VLY/ARKLATEX REGIONS. MOST OF THE CONVECTION SHOULD PROGRESS ENE
TOWARD THE MID/LWR MS VLY THROUGH THE MORNING AND REMAIN SUB-SVR.
TO THE W...BOUNDARY LAYER REMAINS FAVORABLY MOIST AHEAD OF THE APCHG
CDFNT WITH DEW POINTS IN THE LWR-MID 60S FROM EXTREME SW MO SWWD
INTO CNTRL TX. AMPLE AMOUNTS OF DIABATIC HEATING COMBINED WITH
STEEP MID-LVL LAPSE RATES 7-7.5 DEG C PER KM/COOLING MID-LVL
TEMPERATURES WILL YIELD MLCAPES 1500-2500 J/KG IMMEDIATELY AHEAD OF
THE CDFNT THIS AFTN. STRONGEST FORCING FOR ASCENT WILL PASS LARGELY
N OF THE INSTABILITY AXIS...BUT AT LEAST WEAK HEIGHT FALLS/CYCLONIC
CURVATURE WILL REACH AS FAR S AS NRN/CNTRL TX AND AID IN MID TO LATE
AFTN TSTM DEVELOPMENT FROM SW MO...ERN OK INTO NCNTRL/CNTRL TX.
WLY H5 FLOW OF 30-35 KTS/STRONGEST VERTICAL SHEAR WILL GENERALLY BE
CONFINED TO AREAS N OF THE RED RVR VLY WHERE MULTICELL STORMS MAY
ACHIEVE BRIEF SUPERCELL CHARACTER. DESPITE WEAKER FLOW FARTHER
S...MORE ROBUST DESTABILIZATION WILL ALSO LIKELY SUPPORT PULSE
STG-SVR MULTICELL STORMS. LARGE HAIL AND DMGG WIND GUSTS WILL BE
THE PRIMARY SVR THREATS IN THE STRONGER STORM CLUSTERS/LINEAR
SEGMENTS.
ACTIVITY WILL MOVE EWD INTO THE OZARKS AND ARKLATEX REGIONS AMID
COMPARATIVELY WEAKER THERMODYNAMICS THIS EVE. FARTHER S...STORMS
ACROSS NRN/CNTRL TX WILL LIKELY BECOME UNDERCUT BY THE SURGING
CDFNT. IN ALL AREAS...THE SVR THREATS WILL DIMINISH BY MID/LATE
EVENING.
..RACY/COHEN.. 09/18/2011
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