SWODY1
SPC AC 151259
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0659 AM CST WED FEB 15 2012
VALID 151300Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
OVER PORTIONS OF SERN TX...LA AND SWRN/SRN MS...
...SYNOPSIS...
DOWNSTREAM FROM A MIDLEVEL IMPULSE PROGRESSING SWD INTO THE LOWER CO
VALLEY...A VIGOROUS SHORT-WAVE TROUGH OVER THE CNTRL/SRN HIGH PLAINS
WILL WEAKEN/DE-AMPLIFY WHILE LIFTING NEWD INTO AN INCREASINGLY
CONFLUENT FLOW REGIME OVER THE MID-MS VALLEY. THIS SYSTEM WILL BE
ATTENDED BY A 70-80 KT MIDLEVEL JET STREAK AND A CORRIDOR OF MODEST
HEIGHT FALLS. HOWEVER...IT APPEARS THAT THIS FORCING FOR ASCENT
WILL REMAIN DISPLACED TO THE N OF THE SURFACE WARM SECTOR WITH
SLIGHT HEIGHT RISES FORECAST TODAY AND TONIGHT ACROSS THE GULF COAST
REGION.
AT THE SURFACE...LEE CYCLONE OVER FAR NERN NM WILL DEVELOP GENERALLY
EWD ACROSS OK TODAY BEFORE ACCELERATING NEWD INTO IND BY 16/12Z IN
TANDEM WITH THE WEAKENING MIDLEVEL SYSTEM. A TRAILING COLD FRONT
ANALYZED OVER WRN TX WILL ACCORDINGLY ADVANCE EWD ACROSS THE SRN
PLAINS...REACHING THE LOWER MS VALLEY BY THU MORNING. A COUPLE OF
WARM FRONTS WERE EVIDENT AS OF 12Z...ONE EXTENDING FROM THE
INTERSECTION WITH THE PACIFIC FRONT OVER NWRN TX AND THEN ARCING
SEWD THROUGH SERN TX INTO THE SHELF WATERS OF THE NWRN GULF OF
MEXICO. THE OTHER --DELINEATING MORE OF AN MT AIR MASS FROM THAT OF
CP IN ORIGIN-- EXTENDED FROM DEEP S TX ENEWD ALONG THE LOWER/MIDDLE
TX COAST. EXPECT BOTH OF THESE BOUNDARIES TO GRADUALLY LIFT NWD IN
ADVANCE OF EWD-PROGRESSING COLD FRONT.
...SRN PLAINS INTO LOWER MS VALLEY THIS AFTERNOON INTO TONIGHT...
MOISTURE AND WARM ADVECTIONS OCCURRING ALONG A BROAD 30-40 KT LLJ
AXIS FROM CNTRL/ERN TX INTO THE OZARK PLATEAU HAVE GIVEN RISE TO
WIDELY SCATTERED TSTMS THIS MORNING WITHIN AN ENVIRONMENT OF
MIDLEVEL LAPSE RATES OF 7-7.5 C/KM AND MUCAPE VALUES OF UP TO 500
J/KG. EXPECT THESE STORMS TO SHIFT EWD ACROSS THE OZARK PLATEAU
REGION THIS MORNING WITH SOME SMALL HAIL POSSIBLE. IN THE WAKE OF
THIS INITIAL ACTIVITY...LATEST CONSENSUS OF CONVECTION-ALLOWING AND
MESOSCALE MODEL GUIDANCE SUGGESTS THAT MORE ROBUST SURFACE-BASED
TSTM DEVELOPMENT WILL OCCUR BY EARLY AFTERNOON AHEAD OF THE PACIFIC
FRONT INVOF SRN-MOST WARM FRONT LIFTING NWD THROUGH ERN PARTS OF THE
HILL COUNTRY AND MIDDLE TX COAST.
12Z OBSERVED BRO/CRP SOUNDINGS INDICATE A MOIST BOUNDARY LAYER /I.E.
100-MB MEAN-MIXING RATIOS OF 13.5-15.5 G PER KG/ BENEATH AN EML
CHARACTERIZED BY A CAPPING INVERSION BASED AROUND 850 MB AND
MIDLEVEL LAPSE RATES OF 7.5 C/KM. THE PRESENCE OF A SUBTROPICAL
CIRRUS SHIELD WILL SLOW DAYTIME HEATING WITH CONVERGENCE ALONG THE
WARM FRONT LIKELY BEING THE PRIMARY FOCUS FOR CAP REMOVAL AND
SUBSEQUENT TSTM DEVELOPMENT. CURRENT OBSERVATIONS AND FORECAST
HODOGRAPHS DEPICT A VERTICALLY VEERING WIND PROFILE WITH MODEST LOW-
AND DEEP-LAYER SHEAR WHICH WILL BE SUPPORTIVE OF ROTATING STORMS
CAPABLE OF A TORNADO OR TWO...DAMAGING WINDS AND PERHAPS SOME
HAIL.
EXPECT ISOLATED TO WIDELY SCATTERED SEVERE TSTMS TO MOVE/DEVELOP EWD
INTO PORTIONS OF CNTRL/SRN LA/SWRN MS LATER THIS AFTERNOON INTO
TONIGHT...ALONG AND S OF WARM FRONT SLOWLY LIFTING NWD. DAMAGING
WINDS AND PERHAPS A TORNADO OR TWO WILL REMAIN THE PRIMARY HAZARDS
IN ASSOCIATION WITH ANY MORE PERSISTENT ROTATING STORMS.
...N CNTRL OK INTO THE OZARK PLATEAU THIS AFTERNOON...
THE RE-DEVELOPMENT OF ISOLATED TO WIDELY SCATTERED TSTMS APPEARS
POSSIBLE THIS AFTERNOON AHEAD OF THE SURFACE LOW AND WEAKENING
MIDLEVEL SYSTEM. HERE...STEEPENING LOW-LEVEL LAPSE RATES WILL ALIGN
WITH 500-MB TEMPERATURES AOB -20C...YIELDING A THERMODYNAMIC
ENVIRONMENT SUPPORTIVE OF SOME HAIL WITH THE STRONGEST STORMS.
..MEAD/COHEN.. 02/15/2012
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