DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 021236
SWODY1
SPC AC 021233

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0733 AM CDT WED OCT 02 2013

VALID 021300Z - 031200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

THE LARGE-SCALE PATTERN WILL UNDERGO AMPLIFICATION THIS PERIOD IN
RESPONSE TO THE SEWD PROGRESSION OF MID AND UPPER-LEVEL JET STREAKS
FROM THE NERN PACIFIC INTO THE BASE OF AN EVOLVING TROUGH OVER THE
GREAT BASIN. DOWNSTREAM FROM THESE DEVELOPMENTS...A WEAK SHORT-WAVE
TROUGH WILL TRANSLATE NEWD THROUGH THE CNTRL PLAINS WHILE ANOTHER
SYSTEM SHEARS OUT ACROSS THE LOWER MS VALLEY INTO OH VALLEY.

IN THE LOW LEVELS...A COLD FRONT PROGRESSING EWD/SEWD ACROSS THE NRN
PLAINS AND UPPER MS VALLEY WILL MERGE WITH A WARM FRONT LIFTING NWD
THROUGH THE MID MO VALLEY AND MIDWEST. LEE CYCLOGENESIS IS FORECAST
ALONG THE WRN EXTENSION OF THESE BOUNDARIES OVER THE CNTRL HIGH
PLAINS WITH A DRYLINE BECOMING WELL ESTABLISHED BY AFTERNOON FROM
NEAR THE CO-KS BORDER INTO WRN TX.

...NRN/CNTRL PLAINS THIS AFTERNOON AND EVENING...

12Z REGIONAL SOUNDINGS INDICATE THE PRESENCE OF A SEASONABLY MOIST
AIR MASS FROM KS SWD WHERE PW VALUES EXCEEDED AN INCH AND LOWEST
100-MB MEAN-MIXING RATIOS RANGED FROM 11-15+ G/KG. THE PRESENCE OF
A SLY LLJ /25-35 KT AT 850 MB/ WILL ENHANCE THE NWD FLUX OF THIS
MOISTURE BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES...
CONTRIBUTING TO AFTERNOON MLCAPE VALUES APPROACHING 1000-2500 J/KG.

MORNING WATER VAPOR IMAGERY SUGGESTS THAT FORCING FOR ASCENT/DCVA
ASSOCIATED WITH THE CNTRL PLAINS VORTICITY MAXIMUM WILL ADVANCE NEWD
THROUGH THE MID MO VALLEY RELATIVELY EARLY IN THE DAY...LIKELY
FOSTERING INITIAL STORM DEVELOPMENT BY EARLY TO MID AFTERNOON ALONG
THE SURFACE COLD FRONT ACROSS SERN SD/SWRN MN/NWRN IA. CONTINUED
BOUNDARY LAYER HEATING AND PERSISTENT LOW-LEVEL CONVERGENCE SHOULD
SUPPORT SUBSEQUENT STORM DEVELOPMENT SWWD ALONG THE FRONT INTO SWRN
NEB BY MID TO LATE AFTERNOON.

THE PRESENCE OF THE STEEP LAPSE RATES AND MODERATE INSTABILITY WILL
PROMOTE VIGOROUS UP/DOWNDRAFTS WITH A RISK FOR ISOLATED OCCURRENCES
OF SEVERE HAIL AND LOCALLY DAMAGING WIND GUSTS INTO THIS EVENING.
ORGANIZED SEVERE WEATHER POTENTIAL WILL BE LIMITED BY THE GENERALLY
WEAK VERTICAL SHEAR WHICH WILL FAVOR PULSE AND SOME MULTICELL STORM
STRUCTURES.

..MEAD/MOSIER.. 10/02/2013

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