DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 241226
SWODY1
SPC AC 241224

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0724 AM CDT WED APR 24 2013

VALID 241300Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A SMALL PART OF THE CNTRL
GULF CST REGION...

...SYNOPSIS...
BROAD CYCLONIC FLOW WILL AGAIN PREVAIL OVER MUCH OF THE LWR 48 THIS
PERIOD...ON SRN FRINGE OF MAIN UPR LOW/TROUGH CENTERED NEAR HUDSON
BAY. POSITIVE-TILT SHORTWAVE IMPULSE WITHIN THIS FLOW...NOW OVER
MO...SHOULD ACCELERATE E/NE TO THE UPR OH VLY THIS EVE...AND INTO
QUE EARLY THU...AS UPSTREAM DISTURBANCE NOW ENTERING ND ARCS E/SE
ACROSS THE UPR MS VLY TO NEAR LK MI. FARTHER S...WEAK SRN STREAM
TROUGH NOW OVER SE TX SHOULD CONTINUE RAPIDLY ENE INTO GA THIS EVE
WHILE UPR LOW OFF THE CST OF BAJA CA ADVANCES MORE SLOWLY ENE TOWARD
NRN BAJA.

AT LWR LVLS...STRONG COLD FRONT WITH MO TROUGH WILL PROGRESS
STEADILY E ACROSS THE UPR OH VLY AND CNTRL/NRN APPALACHIANS LATER
TODAY...AND MORE SLOWLY SE ACROSS THE TN VLY/GULF CST STATES. THIS
BOUNDARY WILL BE THE MAIN FOCUS FOR A FEW POCKETS OF STRONG TO
POSSIBLY SVR TSTMS TODAY. A WEAKER FRONT WILL MOVE SE OVER THE
MID-MO VLY IN ASSOCIATION WITH THE ND TROUGH.

...LA/MS TODAY...
A BAND OF STRONG TSTMS HAS FORMED IN RECENT HOURS ALONG PORTION OF
COLD FRONT CROSSING THE WRN GULF CST REGION. THIS ACTIVITY LIKELY IS
BEING SUPPORTED BY AREA OF ENHANCED WAA/LOW-LVL MOISTURE INFLOW /PW
AOA 2 INCHES/ AHEAD OF SRN STREAM DISTURBANCE. AREA VWP DATA SHOW
LOW TO MID-TROPOSPHERIC WIND PROFILES SUFFICIENT FOR AT LEAST SOME
DEGREE OF STORM ORGANIZATION/SUSTENANCE GIVEN 30 KT SLY LLJ VEERING
TO 50+ KT WSWLY FLOW AT 500 MB. WHILE WEAK LOW-LVL LAPSE RATES
SHOULD LIMIT DEGREE/COVERAGE OF SVR THREAT...SETUP COULD YIELD A FEW
INSTANCES OF LOCALLY DMGG WIND AND POSSIBLY A TORNADO OR TWO UNTIL
LATER THIS MORNING WHEN LOW-LVL FLOW VEERS WITH THE CONTINUED EWD
MOTION OF UPR DISTURBANCE.

...CNTRL APPALACHIANS THIS AFTN...
SCTD SHOWERS/TSTMS SHOULD PERSIST ALONG/NEAR COLD FRONT CROSSING THE
UPR OH VLY TODAY...WITH SOME INCREASE POSSIBLE AS THE BOUNDARY
REACHES THE WRN SLOPES OF THE APPALACHIANS IN SW PA...WRN MD...AND
NRN WV BY EARLY TO MID AFTN. THE FRONTAL CIRCULATION ACROSS THE
REGION MAY SOMEWHAT STRENGTHEN AT THAT TIME AS UPR VORT MORE CLOSELY
APPROACHES LOW-LVL BAROCLINIC ZONE. COUPLED WITH RELATIVELY STEEP
MID-LVL LAPSE RATES AND MODERATE SFC HEATING...SETUP MAY YIELD A FEW
LOW-TOPPED STORMS WITH EMBEDDED BOWING SEGMENTS/LOCALLY DMGG
WIND...DESPITE LIMITED MOISTURE /SFC DEWPOINTS MAINLY IN THE UPR 40S
F/. WEAK BUOYANCY DUE TO LINGERING INFLUENCE OF SFC LOW NEAR CAPE
COD SHOULD LIMIT SVR THREAT TO THE MOUNTAINS AND PERHAPS THE FAR WRN
PARTS OF THE PA/MD/ERN WV/NRN VA PIEDMONT.

...MID MO VLY THIS AFTN...
WDLY SCTD SHOWERS AND A FEW TSTMS MAY FORM NEAR WEAK COLD FRONT
CROSSING PARTS OF SD/MN/NEB/IA TODAY...IN NARROW ZONE OF LOW-LVL
PRE-FRONTAL HEATING BENEATH NOSE OF STEEP MID-LVL LAPSE RATE PLUME
EXTENDING ENE FROM THE HIGH PLNS. WHILE LOW-LVL MOISTURE WILL BE
SCANT /PW BLO .50 INCH/...COLD 500 MB TEMPS /AOB -30 C/ COULD YIELD
SMALL HAIL WITH THE STRONGEST UPDRAFTS.

..CORFIDI/GARNER.. 04/24/2013

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