DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 102003
SWODY1
SPC AC 102000

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT FRI MAY 10 2013

VALID 102000Z - 111200Z

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

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE UPPER OH VALLEY...

...TX...
OUTLOOK ADJUSTMENTS MADE IN ACCORDANCE WITH CONVECTIVE COMPLEX
EXITING THE UPPER TX COAST. PRIMARY SEVERE THREAT INTO THIS EVENING
IS STILL EXPECTED ACROSS PORTIONS OF THE RIO GRANDE
VALLEY/WEST-CENTRAL TX AND EVENTUALLY PORTIONS OF SOUTH-CENTRAL
TX/HILL COUNTRY...AS STORMS/SUPERCELLS CONTINUE TO INCREASE AND
PROPAGATE EASTWARD ACROSS THE RIO GRANDE OUT OF MEXICO. SEE SEVERE
TSTM WATCH 156 AND ASSOCIATED MESOSCALE DISCUSSIONS.

...UPPER OH VALLEY...
LITTLE CHANGE TO PRIOR OUTLOOK REASONING...ALTHOUGH SPATIAL
ADJUSTMENTS TO SLIGHT RISK WERE MADE /REMOVED/ IN THE WAKE OF UPPER
OH VALLEY QUASI-LINEAR COMPLEX. DAMAGING WINDS/SOME SEVERE HAIL WILL
BE POSSIBLE INTO THIS EVENING.

..GUYER.. 05/10/2013

.PREV DISCUSSION... /ISSUED 1129 AM CDT FRI MAY 10 2013/

...TX...
BOTH VISIBLE SATL IMAGERY AND SFC ANALYSIS REVEAL A PLETHORA OF
CONVECTIVELY INDUCED MESOSCALE BOUNDARIES ACROSS TX TODAY.
MEANWHILE...A BAND OF RELATIVELY STRONGER WLY MID LEVEL FLOW OF
40-50KT PERSISTS OVER THE SRN HALF OF TX ON THE SRN/ERN FLANK OF A
POSITIVELY TILTED LARGE SCALE TROUGH WITH AN AXIS FROM THE CNTRL
PLAINS TO NRN BAJA. PERTURBATIONS WITHIN THIS MID/UPPER LEVEL STREAM
WILL AGAIN COMBINE WITH AREAS OF STRONGER DIURNAL DESTABILIZATION TO
SUPPORT SCATTERED STRONG TO SEVERE TSTMS THROUGH THE AFTERNOON AND
INTO THIS EVENING. AFTER A NUMBER OF OUTFLOW SURGES...GREATEST
SFC-BASED INSTABILITY NOW RESIDES ACROSS FAR SOUTH TX WHERE STRONG
CAPPING WILL LIKELY PERSIST DUE TO PRONOUNCED EML PLUME. FROM
TRANS-PECOS REGION ACROSS THE HILL COUNTRY...AREAS OF STRONGER
HEATING AND MODEST LARGE SCALE ASCENT WILL CONTRIBUTE TO AN INCREASE
IN CONVECTION AMIDST MORE THAN SUFFICIENT DEEP LAYER SHEAR FOR
UPDRAFT ROTATION/PERSISTENCE. LARGE HAIL SHOULD BE THE GREATEST
HAZARD FROM THIS ACTIVITY. HOWEVER...LOW PROBABILITY TORNADO THREAT
MAY ALSO EVOLVE WITH ANY DISCRETE CELLS INTERACTING WITH RESIDUAL
BOUNDARIES WHERE BACKED LOW LEVEL FLOW WILL ENHANCE HODOGRAPH
CURVATURE.

...UPPER OH VALLEY...
WARM/MOIST CONVEYOR BELT WILL INTENSIFY FROM THE SPINE OF THE
APPALACHIANS WWD ACROSS THE UPPER OH VALLEY AS FRONTAL WAVE/LOW
TRACKS EAST ACROSS THE ERN GREAT LAKES THROUGH THIS EVENING. WEAK
LAPSE RATES ALOFT WILL RESULT IN ONLY MARGINAL INSTABILITY WITHIN
THE WARM SECTOR WITH AFTERNOON SBCAPE PERHAPS PEAKING AROUND 1000
J/KG. THE LIMITED INSTABILITY SHOULD BE SOMEWHAT OFFSET BY MAGNITUDE
OF FORCING/ASCENT AND AREAS OF STRONGER SURFACE HEATING FROM NRN WV
ACROSS SERN OH AND INTO PA. HERE EXPECT A GRADUAL UPTICK IN
CONVECTIVE VIGOR AMIDST SUFFICIENT DEEP-LAYER SHEAR FOR SOME
STORM-SCALE ORGANIZATION/PERSISTENCE. MARGINALLY SEVERE HAIL AND
LOCALLY STRONGER WIND GUSTS APPEAR POSSIBLE WITH LOOSELY ORGANIZED
LINES/CLUSTERS OF STORMS MOVING ACROSS THE REGION THROUGH EARLY
EVENING.

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