DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 091930
SWODY1
SPC AC 091928

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT WED MAY 09 2012

VALID 092000Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN GA...SRN FL INTO THE
ERN CAROLINAS...

...SRN GA AND NRN FL THROUGH THE ERN CAROLINAS...

HAVE SHIFTED THE SLIGHT RISK AREA A LITTLE FARTHER EAST AND SOUTH.
PRE-FRONTAL MULTICELL BANDS OF STORMS ARE MOVING THROUGH THE WARM
SECTOR FROM CNTRL NC...ERN SC INTO SRN GA. A MODEST INCREASE IN MID
LEVEL WINDS HAS OCCURRED DURING THE PAST COUPLE OF HOURS...BUT THE
STRONGER FLOW ASSOCIATED WITH THE AMPLIFYING TROUGH WILL REMAIN POST
FRONTAL...AND SHEAR PROFILES WILL SUPPORT MULTICELL LINES AND
CLUSTERS. A THREAT FOR ISOLATED STRONG TO DAMAGING WIND GUSTS WILL
PERSIST INTO EARLY EVENING...ESPECIALLY AS ACTIVITY APPROACHES THE
COAST AND BEGINS TO INTERACT WITH THE SEA BREEZE CIRCULATIONS. THE
MARGINAL THERMODYNAMIC ENVIRONMENT WILL LIKELY PROVIDE A LIMITING
FACTOR FOR A MORE ROBUST/WIDESPREAD SEVERE EVENT.

...FAR WRN TX...SWRN NM INTO SERN AZ...

SCATTERED STORMS ARE DEVELOPING WITHING ZONE OF UPPER DIVERGENCE AND
DEEP ASCENT EAST AND NORTH OF CUTOFF UPPER LOW. ELY LOW LEVEL WINDS
VEERING TO SWLY AND INCREASING TO ABOVE 30 KT AT 500 MB IS RESULTING
IN SUFFICIENT VERTICAL SHEAR FOR UPDRAFT ROTATION OVER WRN TX...BUT
WITH WEAKER SHEAR WITH WWD EXTENT INTO SRN NM AND AZ. THE EARLY
DEVELOPMENT OF THUNDERSTORMS AND WIDESPREAD ANVIL CIRRUS ARE
LIMITING OVERALL DESTABILIZATION POTENTIAL SOMEWHAT...BUT STEEP MID
LEVEL LAPSE RATES AND MLCAPE FROM 500-1000 J/KG WILL SUPPORT A
THREAT OF ISOLATED LARGE HAIL AND LOCALLY STRONG TO DAMAGING WIND
GUSTS INTO THE EARLY EVENING. OVERALL THREAT DOES NOT APPEAR TO
WARRANT MORE THAN 5% SEVERE PROBABILITIES.

..DIAL.. 05/09/2012

.PREV DISCUSSION... /ISSUED 1108 AM CDT WED MAY 09 2012/

...SYNOPSIS...

AN AMPLIFIED...YET PROGRESSIVE LARGE-SCALE PATTERN WILL BE
MAINTAINED OVER THE CONUS THROUGH THE D1 PERIOD. POLAR BRANCH
TROUGH FROM HUDSON BAY TO MID MS VALLEY WILL INTENSIFY WHILE
ADVANCING EWD TOWARD THE ATLANTIC COAST...DOWNSTREAM FROM MIGRATORY
SYSTEM MOVING THROUGH WRN CANADA AND THE PACIFIC NW.
ELSEWHERE...SUBTROPICAL BRANCH UPPER LOW OVER THE GULF OF CA WILL
DRIFT EWD ACROSS NWRN MEXICO.

AT THE SURFACE...COLD FRONT FROM THE HUDSON VALLEY SSWWD ALONG THE
LEE OF THE CNTRL/SRN APPALACHIANS WILL ADVANCE EWD TO OFF THE
ATLANTIC COAST...WHILE SRN EXTENSION OF BOUNDARY SETTLES SWD INTO
THE FL PENINSULA.

...MID ATLANTIC COAST TO FL THIS AFTERNOON AND EVENING...

VISIBLE SATELLITE IMAGERY SHOWS WIDESPREAD CLOUDS ACROSS PRE-FRONTAL
WARM SECTOR FROM SERN VA INTO THE CAROLINAS WITH THE POTENTIAL FOR
STRONGER DAYTIME HEATING AND RESULTANT AIR MASS DESTABILIZATION
ACROSS SRN GA INTO FL. LOW-LEVEL UPLIFT ALONG THE FRONT COMBINED
WITH A COUPLED UPPER-LEVEL JET STRUCTURE AND INCREASING HEIGHT FALLS
AHEAD OF MIDLEVEL TROUGH WILL RESULT IN AN UPSWING IN TSTM
DEVELOPMENT THIS AFTERNOON...ESPECIALLY WHERE GREATER INSTABILITY
CAN DEVELOP.

LATEST MODEL GUIDANCE AND CURRENT OBSERVATIONAL DATA SUGGEST THAT
THE STRONGEST MID AND HIGH-LEVEL FLOW /AND RESULTING VERTICAL SHEAR/
WILL REMAIN WITHIN POST-FRONTAL ENVIRONMENT FROM THE CNTRL
APPALACHIANS INTO THE LOWER GREAT LAKES. THE EXCEPTION MAY BE
ACROSS SRN GA INTO NRN FL LATER THIS AFTERNOON INTO EVENING AS THE
EXIT REGION OF THE SUBTROPICAL JET EDGES EWD. DAMAGING WINDS WILL
BE THE PRIMARY SEVERE WEATHER HAZARD WITH DEVELOPING MULTICELL
CLUSTERS/LINE SEGMENTS...THOUGH SOME HAIL IS POSSIBLE.

...SRN TX THIS AFTERNOON AND TONIGHT...

WEAK...BUT PERSISTENT WAA AND POST-FRONTAL UPSLOPE ALONG THE HIGH
TERRAIN OF NRN MEXICO ARE LIKELY TO FOSTER AN INCREASE IN TSTMS
LATER TODAY INTO TONIGHT. WLY MEAN FLOW WILL ALLOW TSTMS TO MOVE
INTO THE REGION /MAINLY TONIGHT/ WITHIN AN ENVIRONMENT FEATURING A
RESIDUAL EML AND MOIST LOW-LEVEL ENVIRONMENT AND RESULTING MODERATE
INSTABILITY. GIVEN THE COLLOCATION OF THE SUBTROPICAL JET
AXIS...SUFFICIENT CLOUD-BEARING SHEAR WILL EXIST TO SUPPORT
ORGANIZED/ROTATING UPDRAFTS WITH A RISK FOR SOME HAIL AND PERHAPS
LOCALLY STRONG WIND GUSTS.

...SERN AZ/SWRN NM/FAR WRN TX THIS AFTERNOON AND EVENING...

THE SLOW EWD ADVANCEMENT OF UPPER LOW AND ASSOCIATED MIDLEVEL COLD
POOL ATOP WRN EXTENSION OF LOW-LEVEL MOISTURE AXIS WITHIN
POST-FRONTAL ELY/ENELY FLOW REGIME WILL CONTRIBUTE TO AIR MASS
DESTABILIZATION TODAY. HEATING ALONG THE HIGH TERRAIN COUPLED WITH
UPPER-LEVEL DIVERGENCE IMMEDIATELY DOWNSTREAM FROM THE LOW WILL GIVE
RISE TO WIDELY SCATTERED TSTMS THIS AFTERNOON AND EVENING. SEVERE
HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS...AS WILL DAMAGING
WIND GUSTS OWING TO THE DEVELOPMENT OF A DEEPLY MIXED BOUNDARY LAYER
AND MODERATELY STRONG ELY FLOW BELOW 3 KM /PER 12Z TUCSON SOUNDING/.

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