DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 090526
SWODY2
SPC AC 090525

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1225 AM CDT WED MAY 09 2012

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS S TX...

...SYNOPSIS...
HIGH-AMPLITUDE UPPER-AIR PATTERN FCST ACROSS MOST OF CONUS THIS
PERIOD. POSITIVELY TILTED TROUGH THAT NOW EXTENDS FROM UPPER GREAT
LAKES TO CENTRAL PLAINS IS FCST TO BECOME NEARLY NEUTRALLY TILTED BY
START OF PERIOD...OVER ERN CONUS. ANCHORING/EMBEDDED UPPER LOW IS
PROGGED TO DEVELOP OVER SERN ONT/NRN NY REGION...AROUND
10/12Z-10/18Z TIME FRAME. THIS LOW IS EXPECTED TO PIVOT SEWD ACROSS
NY/NEW ENGLAND THROUGH REMAINDER PERIOD...AS TRAILING TROUGH MOVES
EWD TO MID-ATLC COAST. ASSOCIATED SFC COLD FRONT WILL BE OFFSHORE
MOST OF ATLC COAST BY 10/12Z...AND IS EXPECTED TO MOVE SEWD THROUGH
FL PENINSULA BY ABOUT 11/12Z.

SRN-STREAM CYCLONE -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
NRN BAJA -- IS EXPECTED TO TURN EWD ACROSS NWRN MEX DAY-1...REACHING
TX BIG BEND REGION BY 11/00Z. THIS SYSTEM WILL WEAKEN THROUGHOUT
PERIOD...AS IT TURNS ENEWD ACROSS PORTIONS SW TX. TRACK GUIDANCE
FOR THIS SYSTEM DIVERGES CONSIDERABLY AFTER 11/00Z...SPECTRAL
DEVIATING NEWD ACROSS W TX WHILE MOST OTHER PROGS PROCEED EWD WITH
REMNANT LOW OVER S-CENTRAL/SW TX.

AT SFC...WRN LIMB OF ATLC COAST FRONTAL ZONE WILL BECOME
QUASISTATIONARY OVER CENTRAL/WRN GULF...WHILE RETURNING NWD ACROSS
PART OF DEEP S AND PERHAPS S-CENTRAL AHEAD OF EJECTING/WEAKENING
UPPER PERTURBATION. FAVORABLE SFC MOISTURE WILL BE PRESENT ON BOTH
SIDES OF FRONT...GIVEN SUBSTANTIAL ELY FLOW COMPONENT EXPECTED TO
ITS IMMEDIATE N.

MEANWHILE...POSITIVELY TILTED NRN-STREAM SHORTWAVE TROUGH IS FCST TO
MOVE ACROSS NRN ROCKIES AND NRN HIGH PLAINS THIS PERIOD...WHILE
GRADUALLY DEAMPLIFYING. FOREGOING COLD FRONT SHOULD MOVE EWD ACROSS
NRN PLAINS AND SEWD OVER CENTRAL HIGH PLAINS...REACHING WRN
MN...CENTRAL NEB AND ERN CO BY 11/12Z. TSTM DEVELOPMENT MAY BE
FOCUSED ALONG/BEHIND SFC COLD FRONT FROM LATE AFTERNOON/EARLY
EVENING ONWARD...HOWEVER MOISTURE APPEARS TOO SCANT FOR SVR RISK
ATTM.

...S-CENTRAL TX...RIO GRANDE VALLEY...
ARC OF CONVECTION MAY BE ONGOING EARLY IN PERIOD OVER PARTS OF SW
AND FAR W TX...N THROUGH ENE OF MID-UPPER VORTEX...IN CONVEYOR OF
STRONGEST ELEVATED WAA/ASCENT. ISOLATED HAIL IS POSSIBLE...ALTHOUGH
PRIMARY SVR THREAT WILL BE WITH LATER ACTIVITY FARTHER SE. SERN
FRINGE OF THIS ARC MAY BE TIMED INTO HIGHER TERRAIN OF NRN COAHUILA
WITH AFTERNOON HEATING...AIDING IN PROCESS DESCRIBED BELOW.

SCATTERED TSTMS SHOULD FORM OVER SERRANIAS DEL BURRO RANGE OF NRN
COAHUILA...AND PERHAPS FARTHER E INVOF FRONT...DURING
AFTERNOON...WHEN STG DIABATIC HEATING MINIMIZES CINH. ACTIVITY WILL
MOVE EWD TO SEWD INTO ENVIRONMENT OF INCREASINGLY LARGE
BOUNDARY-LAYER THETAE...WITH SFC DEW POINTS MID-60S TO LOW-70S F
SUPPORTING MLCAPE 1500-2500 J/KG. MAIN UNCERTAINTY ATTM INVOLVES
SPECIFIC LOCATION OF SFC BAROCLINIC ZONE...WHOSE BACKED SFC FLOW
SHOULD ACT AS
1. ENHANCING MECHANISM FOR UPSLOPE FLOW AND TSTM DEVELOPMENT OVER
HIGHER TERRAIN OF MEX...
2. CORRIDOR OF RELATIVELY MAXIMIZED LOW-LEVEL LIFT AND
STORM-RELATIVE INFLOW FOR ANY ACTIVITY THAT CAN MOVE ALONG
BOUNDARY...AND
3. SOURCE OF ENHANCED LOW-LEVEL VORTICITY AND SRH...IN SUPPORT OF
SUPERCELL POTENTIAL WHILE CONVECTION STILL IS AT LEAST SOMEWHAT
DISCRETE.

LOW-LEVEL VERTICAL SHEAR WILL BE ENHANCED INVOF FRONT...WHILE DEEP
SHEAR AND LARGE-SCALE ASCENT ALOFT ARE MAXIMIZED BENEATH NRN FRINGE
OF CYCLONICALLY CURVED...SUBTROPICAL...UPPER-LEVEL SPEED MAX. FCST
SOUNDINGS SUGGEST CAPPING NEAR 700-MB LEVEL WILL STRENGTHEN WITH SWD
EXTENT FROM LRD-CRP LINE TOWARD LOWER VALLEY/MFE-BRO AREA...WHICH
APPEARS REASONABLE GIVEN ANTECEDENT SWLYS OFF OF MEX PLATEAU.
HOWEVER...ANY MCS THAT EVOLVES FROM AFTERNOON CONVECTION MAY PROVIDE
SUFFICIENT FORWARD-PROPAGATIONAL FORCED ASCENT TO TAP INTO RICHLY
MOIST BOUNDARY LAYER AND POTENTIALLY AFFECT THIS REGION.

..EDWARDS.. 05/09/2012

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