SWODY2
SPC AC 231730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CST MON NOV 23 2009
VALID 241200Z - 251200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
SERIES OF PROGRESSIVE SHORTWAVES WILL HELP TO SHIFT SYNOPTIC
TROUGHING EWD FROM HIGH PLAINS TOWARD MS VALLEY REGION THROUGH DAY-2
PERIOD. STG SHORTWAVE TROUGH -- NOW ANALYZED OVER FRONT/LARAMIE/BIG
HORN RANGES OF CO/WY -- IS FCST TO STRENGTHEN WITH 500 MB CLOSED LOW
DEVELOPING OVERNIGHT DAY-1 OVER KS. THIS LOW SHOULD MOVE ENEWD FROM
NRN MO TOWARD SRN LM AND WEAKEN SOMEWHAT DAY-2...AS UPSTREAM
PERTURBATION APCHS/INTENSIFIES. LATTER TROUGH -- NOW EVIDENT IN
MOISTURE CHANNEL IMAGERY APCHG BC COAST -- IS FCST TO MOVE THROUGH
LARGE SCALE RIDGE POSITION OVER WRN CANADA DAY-1...THEN TURN SEWD
ACROSS SWRN PORTIONS OF PRAIRIE PROVINCES AND NRN U.S. HIGH PLAINS
DAY-2. BY 25/12Z...THIS FEATURE SHOULD EVOLVE INTO CLOSED CYCLONE
WITHIN 500-300 MB LAYER...OVER ERN DAKOTAS AND WRN MN...WITH
POSITIVELY TILTED TROUGH SWWD ACROSS NEB.
AT SFC...LOW NOW EVIDENT OVER SWRN KS IS EXPECTED TO MOVE NEWD ALONG
BAROCLINIC ZONE TO VICINITY STJ BY START OF PERIOD...THEN DEEPEN
SLIGHTLY AND BECOME MORE CLOSELY COLLOCATED WITH LEADING MID-UPPER
PERTURBATION INVOF SRN LM. TRAILING COLD FRONT WILL MOVE EWD ACROSS
LOWER-MID MS VALLEY...AND SEWD FROM TX/LA ACROSS NWRN GULF.
MEANWHILE...OLDER FRONTAL ZONE ACROSS CENTRAL/SRN FL PENINSULA IS
EXPECTED TO DECELERATE...BECOMING MORE DIFFUSE WITH TIME THROUGHOUT
PERIOD.
...S TX...
ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE...BEGINNING AT START
OF PERIOD AS CARRY-OVER FROM POTENTIAL DISCUSSED IN DAY-1 OUTLOOK.
REGIME SHOULD BE CHARACTERIZED BY STG LOW LEVEL WAA AND MOISTURE
TRANSPORT...WHICH WILL COMBINE WITH POCKETS OF ENHANCED SFC HEATING
TO DESTABILIZE PREFRONTAL BOUNDARY LAYER THROUGH MUCH OF AFTERNOON.
AS PREFRONTAL SFC DEW POINTS UPPER 60S F BECOME MORE COMMON...MLCAPE
MAY RISE INTO 2000-2500 J/KG RANGE IN AREAS OF RELATIVELY SUSTAINED
CLOUD BREAKS. FRONTAL LIFT IMPINGING ON THIS ALREADY WEAKLY CAPPED
AIR MASS SHOULD BOOST CONVECTIVE COVERAGE INTO SCATTERED-NUMEROUS
RANGES AS FRONT MOVES SWD/SEWD OVER THIS REGION. MAJOR LIMITING
FACTOR FOR ANY ORGANIZED SVR POTENTIAL WILL BE LACK OF SHEAR...WITH
WEAK LOW-MID LEVEL WINDS LIMITING BOTH HODOGRAPH SIZE AND BULK WIND
DIFFERENCE THROUGH DEEP-LAYER SAMPLES.
...NRN MO TO WI/IL BORDER REGION...
WIDELY SCATTERED AND SHALLOW TSTMS ARE POSSIBLE IN ZONE OF STRONG
DEEP-LAYER ASCENT...STEEPENING LOW-MID LEVEL LAPSE RATES
SUFFICIENTLY TO SUPPORT RELATIVELY UNCAPPED AND MRGL BUOYANCY.
MODIFIED FCST SOUNDINGS SUGGEST LOW LEVEL FRONTOGENETIC/CYCLOGENETIC
FORCING AND WEAK CINH WILL SUPPORT MLCAPE UP TO ABOUT 250 J/KG AND
MUCAPE APCHG 500 J/KG FOR REASONABLY PROGGED SFC TEMPS 50S F AND DEW
POINTS UPPER 40S. LACK OF MORE ROBUST SHEAR...LOW LEVEL THETAE AND
CAPE PRECLUDE SVR THREAT.
...CENTRAL/SRN FL...
ISOLATED TO WIDELY SCATTERED TSTMS WILL BE POSSIBLE WITHIN LOW-LEVEL
BAROCLINIC ZONE ACROSS THIS REGION...SUPPORTED BY WEAK FRONTAL
ASCENT...DIURNAL HEATING...AND SFC DEW POINTS UPPER 60S/LOW 70S F.
50-80 KT UPPER-LEVEL WINDS BENEATH SRN FRINGE OF SUBTROPICAL JET
BRANCH MAY AID IN STORM ORGANIZATION...ESPECIALLY INVOF E COAST
WHERE SLY AND ELY FLOW COMPONENTS MAY AID IN SHEAR THROUGH
CLOUD-BEARING LAYER. HOWEVER...SVR POTENTIAL APPEARS TOO
MRGL/CONDITIONAL FOR AOA 5-PERCENT PROBABILITIES ATTM.
..EDWARDS.. 11/23/2009
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