DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201300
SWODY1
SPC AC 201257

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0657 AM CST FRI DEC 20 2013

VALID 201300Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF S CNTRL TX NEWD
THROUGH THE ARKLATEX...

...SYNOPSIS...
AN AMPLIFIED...PROGRESSIVE SPLIT-FLOW PATTERN WILL PREVAIL OVER THE
LWR 48 THIS PERIOD...DOWNSTREAM FROM BROAD RIDGE IN THE E PACIFIC.
POTENT NRN BAJA CA UPR LOW WILL TRACK E ACROSS NW MEXICO TODAY
BEFORE TURNING SLIGHTLY N OF E INTO SE NM AND FAR W TX EARLY SAT AS
RIDGE HOLDS FIRM OVER THE WRN ATLANTIC/ERN GULF OF MEXICO. A
SHORTWAVE IMPULSE ROTATING AROUND THE BAJA LOW...MARKED BY VORT MAX
NOW APPROACHING THE BAJA SPUR...WILL SERVE TO FURTHER AMPLIFY THE
LARGER-SCALE LOW/TROUGH THROUGH THE PERIOD.

AT LWR LVLS...SHALLOW ARCTIC INTRUSION NOW IN PROGRESS OVER THE SRN
PLNS...IN CONJUNCTION WITH THE EWD ADVANCE OF THE BAJA SYSTEM...WILL
RESULT IN A STRONG S CNTRL TX-TO-LWR OH VLY FRONTAL ZONE BY THE END
OF THE PERIOD. THIS BAROCLINIC ZONE...AND INCREASINGLY WARM/MOIST
AIR SPREADING NWD TO ITS EAST...WILL SET THE STAGE FOR INCREASING
TSTM COVERAGE LATER TODAY AND...ESPECIALLY...TNGT/SAT OVER A BROAD
SWATH EXTENDING FROM PARTS OF NM AND TX NEWD INTO OH AND KY. SOME OF
THE STORMS COULD BECOME SVR EARLY SAT OVER PARTS TX AND THE
ARKLATEX.

...CNTRL TX/ARKLATEX LATER IN PERIOD...
SFC...VWP...AND SATELLITE OBSERVATIONS SUGGEST THAT SUBSTANTIAL
MOISTURE WILL CONTINUE TO STREAM N AND NNE ACROSS SRN AND ERN TX AND
THE LWR MS VLY THROUGH TNGT...IN STRENGTHENING LOW-LVL FLOW AHEAD OF
AFOREMENTIONED COLD FRONT. SFC DEWPOINTS IN THE MID 60S F SHOULD
BECOME ESTABLISHED FROM CNTRL TX E/NE INTO THE LWR MS VLY.

BEYOND LOW-LVL WAA AND FRONTAL UPLIFT...HOWEVER...FORCING FOR ASCENT
ACROSS THIS REGION WILL REMAIN WEAK THROUGH EARLY TNGT. COUPLED WITH
EXISTING WARM NOSE IN THE 850-700 LAYER AND ABUNDANT CLOUD
COVER...TSTM COVERAGE THROUGH THE DAY SHOULD REMAIN LIMITED.

LATER TNGT AND...ESPECIALLY...EARLY SAT...APPRECIABLE /ON THE ORDER
OF 60 M/ HEIGHT FALLS WILL BEGIN TO OVER SPREAD S CNTRL TX AS THE
BAJA SYSTEM APPROACHES THE REGION. COUPLED WITH AN ASSOCIATED
STRENGTHENING OF SSWLY 850 MB FLOW /SPEEDS INCREASING TO AOA 65 KTS/
AND PERSISTENT MOISTENING...SETUP SHOULD SUPPORT A FAIRLY WIDESPREAD
BLOSSOMING OF SHOWERS AND TSTMS ALONG AND N OF THE FRONT FROM WRN
AND S CNTRL TX NEWD THROUGH THE ARKLATEX INTO SE MO/SRN IL.

MOST OF THE ELEVATED ACTIVITY SHOULD REMAIN NON-SVR...ALTHOUGH
SUFFICIENT ELEVATED BUOYANCY MAY ARISE FOR MARGINALLY SVR HAIL IN S
CNTRL TX. OF GREATER SVR CONCERN...HOWEVER...WILL BE THE CONDITIONAL
RISK FOR SFC OR NEAR SFC-BASED STORMS ALONG THE IMMEDIATE FRONT...OR
PERHAPS JUST AHEAD OF IT...LATER TNGT AND EARLY SAT FROM S CNTRL TX
NE TO THE ARKLATEX.

GIVEN THE STRENGTH OF THE LLJ...700 MB FLOW INCREASING TO AOA 60
KTS...LIKELY PROGRESSION OF UPR TROUGH...AND SFC DEWPOINTS
APPROACHING 70F OVER WRN PARTS OF THE TX CSTL PLN...SETUP MAY YIELD
A CONDITIONAL RISK FOR SUPERCELL/LEWP CIRCULATIONS CAPABLE OF DMGG
WIND AND/OR TORNADOES. THIS THREAT WOULD BE GREATEST AFTER 09Z...AND
LIKELY WILL PERSIST/SPREAD FARTHER E/NE BEYOND 12Z SAT.

..CORFIDI/MOSIER.. 12/20/2013

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