DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071250
SWODY1
SPC AC 071248

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0748 AM CDT SUN APR 07 2013

VALID 071300Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF KS AND NRN
OK INTO CNTRL MO THIS AFTERNOON INTO TONIGHT...

...SYNOPSIS...

AN INITIALLY QUASI-ZONAL PATTERN WILL UNDERGO AMPLIFICATION DURING
THE D1 PERIOD IN RESPONSE TO THE EQUATORWARD PROGRESSION OF MID AND
UPPER-LEVEL JET STREAKS FROM THE NERN PACIFIC INTO THE LOWER CO
RIVER VALLEY. THIS WILL RESULT IN THE FORMATION OF A SUBSTANTIAL
TROUGH FROM THE NRN INTERMOUNTAIN REGION INTO GREAT BASIN WHERE
12-HR HEIGHT FALLS AT 500 MB WILL EXCEED 100-150 M. FARTHER E...A
SERIES OF WEAK VORTICITY MAXIMA WILL PROGRESS THROUGH THE CNTRL
CONUS...AIDING IN THE DEVELOPMENT OF STRONG TO SEVERE TSTMS LATER
TODAY INTO TONIGHT.

IN THE LOW LEVELS...A SURFACE CYCLONE OVER THE UPPER GREAT LAKES
WILL DEVELOP NEWD INTO THE CANADIAN MARITIMES WHILE A TRAILING COLD
FRONT SETTLES SEWD THROUGH THE LOWER GREAT LAKES. THE WRN EXTENSION
OF THIS FRONT WILL REMAIN QUASI-STATIONARY OR RETREAT SLOWLY NWD
OVER THE MIDWEST INTO NRN PLAINS IN RESPONSE TO UPSTREAM CYCLONE
DEVELOPMENT IN THE NRN HIGH PLAINS. FARTHER S...A WEAK
FRONT/MOISTURE DISCONTINUITY CURRENTLY FROM CNTRL MO TO ALONG THE
KS-OK BORDER WILL SLOWLY MOVE NWD IN RESPONSE TO THE NRN HIGH PLAINS
CYCLOGENESIS. A DRYLINE WILL STRENGTHEN TODAY FROM WRN KS SWD
THROUGH A DEEPENING THERMAL LOW OVER NWRN TX INTO W-CNTRL TX.

...CNTRL/SRN PLAINS INTO THE OZARKS THIS AFTERNOON INTO TONIGHT...

A BIFURCATED LLJ PRESENT E OF THE ROCKIES WILL TEMPORARILY WEAKEN
THIS MORNING BEFORE CONSOLIDATING ACROSS LOWER ELEVATIONS OF THE
CNTRL/SRN PLAINS THIS AFTERNOON INTO EVENING. THIS FEATURE WILL
HASTEN THE NWD FLUX OF A MODIFIED CP AIR MASS THROUGH THE
REGION...AND BENEATH A PRONOUNCED EML AS SAMPLED BY 12Z REGIONAL
SOUNDINGS. THE CO-LOCATION OF THE STEEP LAPSE RATES AND INCREASING
BOUNDARY LAYER MOISTURE IS EXPECTED TO YIELD A MODERATELY UNSTABLE
WARM SECTOR BY MID TO LATE AFTERNOON WITH MLCAPE APPROACHING
1000-2000 J/KG.

THE EARLY PASSAGE OF A LEAD VORTICITY MAXIMUM THROUGH KS THIS
MORNING CASTS SOME UNCERTAINTY ON SPECIFIC TIMING OF STORM
DEVELOPMENT LATER TODAY. HOWEVER...MODEL GUIDANCE...AND TO A LESSER
EXTENT...WV IMAGERY SUGGEST THE PRESENCE OF WEAKER UPSTREAM IMPULSES
WHICH WILL AFFECT THE REGION DURING THE PEAK OF THE DIURNAL HEATING
CYCLE. FORCING FOR ASCENT ATTENDANT TO THESE FEATURES WILL COMBINE
WITH LOW-LEVEL CONVERGENCE ALONG THE EXISTING SURFACE BOUNDARIES TO
FOSTER WIDELY SCATTERED TSTMS...INCLUDING SUPERCELLS...BY MID
AFTERNOON ACROSS PORTIONS OF KS WITH AN ATTENDANT RISK FOR LARGE
HAIL AND PERHAPS A TORNADO OR TWO.

THE STRENGTHENING LLJ SHOULD SUPPORT UPSCALE GROWTH OF STORMS INTO
MULTIPLE CLUSTERS WITH A LARGE HAIL AND DAMAGING WIND THREAT
SPREADING EWD INTO WRN AND CNTRL PARTS OF MO LATE THIS AFTERNOON
INTO TONIGHT. FARTHER S...A CONDITIONAL RISK FOR SEVERE WEATHER
WILL EXIST ALONG THE DRYLINE OVER WRN OK AND NWRN TX THIS AFTERNOON
AND EVENING. HOWEVER...GIVEN A PROGRESSIVELY STRONGER CAP AND
WEAKER FORCING FOR ASCENT WITH SWD EXTENT...UNCERTAINTY IN STORM
INITIATION AND SUSTENANCE REMAINS QUITE HIGH.

..MEAD/ROGERS.. 04/07/2013

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