DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 031614
SWODY1
SPC AC 031611

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1011 AM CST MON DEC 03 2012

VALID 031630Z - 041200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

THE LARGE-SCALE PATTERN WILL REMAIN PROGRESSIVE THROUGH THE D1
PERIOD WITH THE PRIMARY FEATURE OF INTEREST BEING A SHORTWAVE TROUGH
WHICH WILL TRANSLATE FROM THE NRN PLAINS INTO THE UPPER GREAT LAKES.
THIS SYSTEM WILL BE ATTENDED BY A 50-60 KT MIDLEVEL JET STREAK AND A
CORRIDOR OF 12-HR HEIGHT FALLS AT 500 MB OF 50-150 M. MEANWHILE...A
LOWER-LATITUDE LOBE OF MIDLEVEL VORTICITY OVER THE CNTRL/SRN HIGH
PLAINS WILL LIKEWISE PROGRESS EWD...REACHING THE OZARK PLATEAU AND
RED RIVER VALLEY BY 04/12Z.

IN THE LOW LEVELS...MID-MORNING SURFACE ANALYSIS SHOWED A COLD FRONT
STRETCHING FROM WRN MN SSWWD THROUGH ERN NEB...CNTRL KS...INTO THE
NRN TX PNHDL AND CNTRL NM. A PRE-FRONTAL TROUGH PRECEDED THE FRONT
FROM CNTRL KS SWD INTO WRN TX WHILE A WARM FRONT WAS OBSERVED FROM
NRN IA EWD THROUGH SRN PARTS OF WI AND LOWER MI. EXPECT THE WARM
FRONT TO CONTINUE TO DEVELOP NWD TODAY IN ADVANCE OF THE COLD FRONT
WHICH WILL ADVANCE EWD/SEWD...LIKELY EXTENDING FROM CNTRL WI THROUGH
W-CNTRL MO/E-CNTRL KS...CNTRL OK AND W-CNTRL TX BY 04/00Z. BY
04/12Z...THIS BOUNDARY WILL LIE FROM SERN LOWER MI THROUGH NRN
IND...CNTRL IL INTO THE OZARK PLATEAU.

...UPPER GREAT LAKES INTO OZARK PLATEAU...

THE MASS RESPONSE TO THE ABOVE-MENTIONED...PRIMARY SHORTWAVE TROUGH
WILL MAINTAIN A SWLY LLJ ACROSS THE REGION WHICH WILL HASTEN THE NWD
FLUX OF AN INCREASINGLY MOIST AIR MASS /I.E. PW VALUES OF .75-1.00
INCH/ INTO WI/LOWER MI. HOWEVER...BASED ON 12Z OBSERVED SOUNDINGS
AND FORECAST DATA...WEAK MIDLEVEL LAPSE RATES WILL LIMIT THE DEGREE
OF AIR MASS DESTABILIZATION WITH AFTERNOON MLCAPE VALUES ONLY
REACHING 500-800 J/KG.

LOW-LEVEL CONVERGENCE/UPLIFT ALONG THE COLD FRONT WILL COMBINE WITH
DCVA AHEAD OF THE SHORTWAVE TROUGH TO FOSTER THE DEVELOPMENT OF
SURFACE-BASED STORMS IN THE 03/21Z-04/00Z TIME FRAME FROM CNTRL OR
SRN WI INTO FAR ERN IA/WRN IL. WHILE DEEP-LAYER SHEAR WILL BE
MARGINALLY SUPPORTIVE OF STORM ORGANIZATION/UPDRAFT
ROTATION...FORECAST HODOGRAPHS DO EXHIBIT MODERATELY STRONG
LOW-LEVEL SHEAR WITH EFFECTIVE SRH VALUES OF 150-200 M2/S2. AS
SUCH...A LOW PROBABILITY RISK FOR A TORNADO AND/OR LOCALLY DAMAGING
WIND GUSTS WILL EXIST THROUGH THIS EVENING.

ADDITIONAL STORM FORMATION IS ANTICIPATED AFTER 04/00Z SWWD ALONG
THE COLD FRONT FROM CNTRL MO INTO ERN OK AS DEEP-LAYER ASCENT IS
ENHANCED BY THE LOWER-LATITUDE IMPULSE MENTIONED ABOVE. WHILE THE
BOUNDARY LAYER WILL BE MORE MOIST /I.E. DEWPOINTS OF AROUND 60 TO
THE LOWER 60S F/ THAN POINTS TO THE N...MIDLEVEL LAPSE RATES WILL
ALSO BE WEAK. MOREOVER...THE ONSET OF DIABATIC COOLING IN THE
BOUNDARY LAYER WILL LIMIT MLCAPE TO LESS THAN 500-1000 J/KG.
MODESTLY STRONG LOW-LEVEL SHEAR MAY OFFSET THE MARGINAL INSTABILITY
AND DEEP-LAYER SHEAR TO PROMOTE BRIEF PERIODS OF STORM ORGANIZATION
AND AN ASSOCIATED LOW-PROBABILITY RISK FOR LOCALLY DAMAGING WINDS.

..MEAD/GARNER.. 12/03/2012

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