DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 280505
SWODY2
SPC AC 280503

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CDT SAT SEP 28 2013

VALID 291200Z - 301200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
ANOTHER POWERFUL UPPER TROUGH AND SURFACE LOW WILL AFFECT THE
PACIFIC NW ON SUNDAY...BRINGING STRONG WINDS AND HEAVY RAIN TO MUCH
OF WRN WA AND OREGON. TO THE E...A FRONT WILL STALL FROM ERN TX NEWD
ACROSS THE LOWER MS VALLEY AND INTO THE LOWER OH VALLEY. THIS
DIFFUSE FRONTAL ZONE WILL BE A FOCUS FOR SCATTERED
THUNDERSTORMS...THE STRONGEST OF WHICH MAY BE NEAR A WEAK SURFACE
LOW NEAR THE ARKLATEX.

...WRN WA AND OREGON...
MODEL CONSENSUS IS FOR THE STRONGEST ASCENT ASSOCIATED WITH THE
SHORTWAVE TROUGH AND COLD FRONT TO ARRIVE BETWEEN 00-06Z ACROSS WRN
WA...AND INTO NWRN OREGON. VERY STRONG/VEERING SHEAR PROFILES WITH
HEIGHT WILL EXIST IMMEDIATELY AHEAD OF THE FRONT...WITH RAPID
COOLING ALOFT COINCIDENT WITH FRONTAL PASSAGE. AS SUCH...IT MIGHT BE
DIFFICULT FOR MODELS TO RESOLVE THE TRUE INSTABILITY GRADIENT ALONG
THE FRONT. LOW TOPPED...NARROW LINES SEGMENTS OR A SQUALL LINE IS
EXPECTED TO COME ASHORE DURING THE EVENING...ENHANCING DAMAGING WIND
POTENTIAL. MODELS INDICATE MEAN WINDS IN EXCESS OF 55 KT JUST IN THE
LOWEST 1 KM. A FEW AREAS OF ROTATION MAY ALSO BE PRESENT IN THESE
LINES.

...ERN TX INTO AR...
RAIN AND STORMS WILL BE ONGOING ALONG A COLD FRONT/OUTFLOW COMPOSITE
BOUNDARY FROM CNTRL AND NRN TX ACROSS THE ARKLATEX AND EXTENDING
NEWD INTO SRN IL AND IND. THESE STORMS WILL BE CAPABLE MAINLY OF
HEAVY RAIN. SHEAR PROFILES AND MEAN WINDS WILL BE WEAK...AS WILL
LAPSE RATE PROFILES DUE TO LACK OF HEATING AND WARM AIR ALOFT.
MODELS INDICATE THE BEST CONVERGENCE WILL BE NEAR THE
ARKLATEX...ALSO COINCIDENT WITH A VERY MOIST AIRMASS. PRECIPITATION
LOADING COULD RESULT IN LOCALLY STRONG OUTFLOW WINDS...BUT SEVERE IS
NOT EXPECTED.

..JEWELL.. 09/28/2013

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