DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 111937
SWODY1
SPC AC 111935

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0135 PM CST MON FEB 11 2013

VALID 112000Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE FL PANHANDLE
TO SWRN GA...

...FL PANHANDLE...SRN GA...
BROKEN BAND OF TSTMS ALONG A SEWD-MOVING COLD FRONT WILL POSE A RISK
FOR ISOLATED DAMAGING WINDS NEXT FEW HOURS AS ACTIVITY CROSSES A
SMALL POCKET OF STRONGER HEATING /SURFACE TEMPERATURES IN THE UPPER
70S/ JUXTAPOSED WITH A MODIFIED MARITIME TROPICAL AIR MASS /SURFACE
DEW POINTS IN THE MID 60S/. THE UNDERCUTTING NATURE OF THE BOUNDARY
ALONG WITH RELATIVELY MODEST LOW-LEVEL SWLYS AHEAD OF IT WILL REMAIN
LIMITING FACTORS. WHILE DECREASING BUOYANCY WITH ERN EXTENT SUGGESTS
ACTIVITY SHOULD DIMINISH AROUND SUNSET.

...CNTRL/SERN TX TO THE CNTRL GULF COAST...
NO APPRECIABLE CHANGE TO THE MARGINAL SEVERE HAIL RISK...SEE
DISCUSSION BELOW REGARDING THE THREAT TODAY. THIS RISK WILL PROBABLY
LINGER THROUGH THE PERIOD AS LOW-LEVEL ISENTROPIC ASCENT PERSISTS N
OF THE QUASI-STATIONARY FRONT IN THE NWRN GULF.

...WRN TX...
WILL MAINTAIN A VERY MARGINAL RISK FOR SEVERE HAIL TONIGHT...SEE
DISCUSSION BELOW REGARDING DETAILS. BUOYANCY APPEARS LIKELY TO
REMAIN QUITE LIMITED WHICH MAY ULTIMATELY MITIGATE ANYTHING BEYOND
SMALL HAIL.

..GRAMS.. 02/11/2013

.PREV DISCUSSION... /ISSUED 1029 AM CST MON FEB 11 2013/

...SYNOPSIS...

A DEEP-LAYER CYCLONE OVER THE UPPER GREAT LAKES WILL GRADUALLY
EVOLVE INTO AN OPEN WAVE WHILE TRANSLATING ENEWD INTO NEW ENGLAND.
THIS SYSTEM WILL PRECEDE A POSITIVELY TILTED SHORT-WAVE TROUGH WHICH
WILL ADVANCE FROM THE GREAT BASIN AND LOWER CO VALLEY INTO THE
CNTRL/SRN ROCKIES LATE TONIGHT/EARLY TUESDAY. BETWEEN THESE
FEATURES...A BELT OF HIGH MOMENTUM...MID AND UPPER-TROPOSPHERIC FLOW
WILL EXIST FROM THE SRN PLAINS THROUGH THE OH VALLEY TO THE
MID-ATLANTIC STATES AND SWD TO THE GULF COAST. MORNING WATER VAPOR
IMAGERY SHOWS A WEAK LOW-LATITUDE IMPULSE EMBEDDED WITHIN THIS AIR
STREAM OVER CNTRL TX WHICH WILL TRACK ENEWD ACROSS THE GULF COAST
STATES TODAY.

IN THE LOW LEVELS...A COLD FRONT INITIALLY FROM THE UPPER OH VALLEY
SWD INTO THE SRN APPALACHIANS AND THEN WSWWD TO ALONG THE CNTRL GULF
COAST WILL ADVANCE EWD TO OFF THE ATLANTIC COAST. THE WRN EXTENSION
OF THIS BOUNDARY WILL EVENTUALLY STALL AND SLOWLY SHIFT NORTH OVER
DEEP SOUTH TX AND THE FAR NWRN G.O.M. IN RESPONSE TO THE APPROACH OF
THE SRN ROCKIES SHORT-WAVE TROUGH.

...NERN GULF COAST TODAY...

12Z OBSERVED SOUNDINGS AND SATELLITE-DERIVED PW IMAGERY INDICATE THE
PRESENCE OF A SEASONALLY MOIST PRE-FRONTAL AIR MASS...CHARACTERIZED
BY PW VALUES OF 1.2-1.4 INCHES. AND WHILE MIDLEVEL LAPSE RATES WILL
REMAIN WEAK...POCKETS OF STRONGER HEATING OVER THE FL PNHDL MAY
YIELD MLCAPE VALUES APPROACHING 500-1000 J/KG. THIS GRADUAL
DESTABILIZATION COUPLED WITH LOW-LEVEL UPLIFT ALONG PRE-EXISTING
COLD POOLS...AND THE INFLUENCE OF THE UPSTREAM IMPULSE MOVING ACROSS
THE GULF COAST STATES SHOULD SUSTAIN ONGOING STORMS OVER FAR SERN
AL...THE FL PNHDL INTO SWRN GA. THE LOW-LEVEL WIND FIELD WILL
SLOWLY RELAX TODAY WITH THE NEWD MIGRATION OF THE LLJ.
HOWEVER...RELATIVELY STRONG /50-60 KT/ DEEP-LAYER SHEAR WILL
PERSIST...POTENTIALLY PROMOTING EMBEDDED BOWING STRUCTURES CAPABLE
OF LOCALLY DAMAGING WINDS.

...CNTRL/SERN TX TO THE CNTRL GULF COAST TODAY...

A BROKEN BAND OF SHOWERS AND TSTMS ARE IN PROGRESS AS OF MID-MORNING
FROM THE TX HILL COUNTRY EWD ACROSS SRN LA. THIS ACTIVITY IS
ELEVATED TO THE NORTH OF THE SURFACE COLD FRONT... LIKELY BEING
FORCED BY LOW-LEVEL ISENTROPIC ASCENT AND DCVA ATTENDANT TO
CNTRL/SERN TX VORTICITY MAXIMUM. 12Z SOUNDINGS SHOWED THE PRESENCE
OF A MOIST...LOW-LEVEL ENVIRONMENT BENEATH A PLUME OF STEEP MIDLEVEL
LAPSE RATES /NAMELY OVER TX/ WHICH WHERE YIELDING MUCAPE VALUES
APPROACHING 1000-1500 J/KG. GIVEN THE PRESENCE OF RELATIVELY STRONG
CLOUD-BEARING SHEAR...THE POTENTIAL WILL EXIST FOR A FEW
ORGANIZED/ROTATING UPDRAFTS CAPABLE OF MARGINALLY SEVERE HAIL.

...WRN TX LATE TONIGHT/EARLY TUE...

THE DEVELOPMENT OF A NOCTURNAL LOW-LEVEL WIND MAXIMUM WILL HASTEN
THE NWWD FLUX OF AN INCREASINGLY MOIST AIR MASS ABOVE A STABLE
NEAR-SURFACE LAYER AND BENEATH AN EML...CONTRIBUTING TO A
DESTABILIZING ENVIRONMENT OVERNIGHT. WHEN COMBINED WITH
STRENGTHENING DEEP-LAYER FORCING FOR ASCENT AHEAD OF SRN ROCKIES
SHORT-WAVE TROUGH...EXPECT AN INCREASE IN ELEVATED TSTMS THROUGH
12/12Z. SOME SEVERE HAIL MAY ACCOMPANY THE STRONGEST STORMS GIVEN
THE STRONG CLOUD-BEARING SHEAR...STEEP MIDLEVEL LAPSE RATES...AND
COLD THERMODYNAMIC PROFILES.

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