SWODY2
SPC AC 141729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT MON JUL 14 2008
VALID 151200Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS NRN NEB TO WRN UPPER PENINSULA
OF MI...
...SYNOPSIS...
NRN STREAM PATTERN ALOFT IS FCST TO DEAMPLIFY AND BECOME NEARLY
ZONAL BY END OF PERIOD. S OF THAT FLOW BELT...AND DESPITE
SUBSTANTIAL HEIGHT RISES OVER MUCH OF E-CENTRAL/NERN CONUS...DIFFUSE
TROUGH WILL LINGER OVER CENTRAL/SRN APPALACHIANS REGION AND
FL...PERHAPS CONTAINING ONE OR TWO WEAK/EMBEDDED 500 MB LOWS INVOF
SRN FL AND/OR ERN TN/WRN NC REGIONS. FARTHER W...INTERACTION OF
SEVERAL LOW-AMPLITUDE VORTICITY LOBES SHOULD RESULT IN POSITIVELY
TILTED MID-UPPER TROUGH FROM CANADIAN ROCKIES SWWD ACROSS WA AND
OFFSHORE ORE BY ABOUT 16/00Z. WEAK MID/UPPER PERTURBATION -- NOW
EVIDENT IN MOISTURE CHANNEL IMAGERY OVER SERN ID/WRN WY/NRN UT AREA
-- MAY MOVE EWD ACROSS N-CENTRAL ROCKIES TO VICINITY BLACK HILLS BY
MID-PERIOD. THIS FEATURE IS INCONSISTENTLY PROGGED/RESOLVED BY
MODELS...AND CONFIDENCE IS LOW IN ITS TIMING/STRENGTH TUESDAY
AFTERNOON WHEN ITS INFLUENCE ON CONVECTIVE POTENTIAL WOULD BE MOST
CRUCIAL.
SFC COLD FRONT -- INITIALLY ANALYZED FROM NEW ENGLAND SWWD ACROSS
CAROLINAS TO SRN AL -- IS EXPECTED TO BECOME QUASISTATIONARY INVOF
COASTAL CAROLINAS AND NRN FL MUCH OF THIS PERIOD BENEATH WEAKENING
AND NEARLY PARALLEL MID/UPPER WINDS. AREA OF LOW PRESSURE -- NOW
ANALYZED FROM SRN GA ESEWD OVER ATLANTIC WATERS OFFSHORE NRN FL --
SHOULD LINK WITH FRONTAL ZONE INVOF NRN FL...CONTRIBUTING TO GEN
TSTM POTENTIAL IN THAT REGION. WRN SEGMENT OF FRONTAL ZONE -- NOW
ANALYZED FROM SRN AL ACROSS CENTRAL TX TO E-CENTRAL NM -- WILL LIFT
NWD ACROSS SRN PLAINS WITH GRADUAL FRONTOLYSIS FCST...BUT STILL
SUPPORTING GEN THUNDER POTENTIAL. ANOTHER COLD FRONT -- NOW
ANALYZED FROM NWRN ONT/SRN MB SWWD ACROSS NRN/WRN ND AND E-CENTRAL
MT -- SHOULD MOVE EWD OVER NRN MN AND LS REGION...BUT STALL AND
BECOME NEARLY ZONALLY ALIGNED ACROSS SD BY 16/00Z...EXTENDING WWD
INTO WEAK LEE-SIDE LOW OVER NERN WY/SERN MT AREA. SEPARATE SFC LOW
MAY FORM OVER NEB PANHANDLE REGION...ALONG PREFRONTAL TROUGH THAT
SHOULD EXTEND NEWD ACROSS N-CENTRAL NEB TOWARD S-CENTRAL/SERN SD.
...CENTRAL NRN PLAINS...UPPER MIDWEST...
SCATTERED TSTMS IN SHOULD DEVELOP DURING AFTERNOON/EVENING FROM SRN
LS/UPPER MI REGION SWWD ACROSS CENTRAL/SRN MN TO NRN NEB/SRN
SD...PERHAPS SWWD OVER WRN NEB. DAMAGING GUSTS AND LARGE HAIL ARE
POSSIBLE. MOST FAVORABLE AREAS FOR DEVELOPMENT WILL BE INVOF
FRONTAL ZONE AND PREFRONTAL TROUGH...WHERE BOUNDARY LAYER
CONVERGENCE AND INSOLATION-WEAKENED SBCINH WILL OVERLAP. FAVORABLE
ENVIRONMENTAL CHARACTERISTICS SHOULD JUXTAPOSE BETWEEN CENTRAL/NERN
NEB AND UPPER MS VALLEY...HENCE UNCONDITIONAL PROBABILITIES
SUPPORTING CATEGORICAL OUTLOOK. THESE FACTORS INCLUDE VERY DIFLUENT
MID/UPPER LEVEL FLOW...REGIONALLY MAXIMIZED BUOYANCY AND SFC
MOISTURE...STG SFC HEATING...AND SOMEWHAT ENLARGED LOW LEVEL
HODOGRAPHS. SFC DEW POINTS MID-UPPER 60S SHOULD BE COMMON GIVEN
ANTICIPATED EVAPOTRANSPIRATIONAL EFFECTS...CONTRIBUTING TO MLCAPES
COMMONLY IN 2500-4000 J/KG RANGE IN MID-LATE AFTERNOON PRECONVECTIVE
AIR MASS.
LIMITING FACTORS OVER REGION OF GREATEST BUOYANCY WILL INCLUDE LACK
OF MORE ROBUST MID/UPPER LEVEL FLOW...RESULTING IN EFFECTIVE SHEAR
MAGNITUDES GENERALLY AOB 30 KT. MULTICELLULAR CLUSTERS THEREFORE
SHOULD DOMINATE CONVECTIVE MODE W OF MS RIVER. FARTHER NE TOWARD
UPPER MI...DEEP-LAYER WINDS AND VERTICAL SHEAR WILL INCREASE...BUT
INSTABILITY WILL BE LESS. LS LAKE BREEZE MAY SERVE AS ADDITIONAL
CONVECTIVE FOCUS...AND ISOLATED SUPERCELL CANNOT BE RULED OUT GIVEN
40-50 KT EFFECTIVE SHEARS EXPECTED. FARTHER SW ACROSS CENTRAL/NRN
HIGH PLAINS...DEEPENING/DRYING BOUNDARY LAYER MAY SUPPORT POTENTIAL
FOR SVR HAIL/GUSTS FROM MOST INTENSE TSTMS...BUT ORGANIZATION OF
THREAT IS QUESTIONABLE GIVEN WEAK AMBIENT LOW-MIDLEVEL WINDS.
INCREASINGLY MOIST LLJ IS FCST TO STRENGTHEN AFTER
16/00Z...SUPPORTING MAINTENANCE OF CONVECTIVE POTENTIAL NOCTURNALLY
ACROSS PORTIONS N-CENTRAL PLAINS CORRIDOR BETWEEN S-CENTRAL
SD...N-CENTRAL NEB AND SRN MN. ADDITIONAL OR CONTINUED WIND/HAIL
POTENTIAL WILL EXIST WITH ANY SUCH ACTIVITY.
..EDWARDS.. 07/14/2008
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