SPC AC 041241
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT SUN APR 04 2010
VALID 041300Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FOR
MUCH OF MO/IL/AR...AND PARTS OF NE OK/SE KS...
...SYNOPSIS...
A BROAD SWATH OF WSWLY FLOW ALOFT WILL BE MAINTAINED FROM THE
ROCKIES TO THE GREAT LAKES...DOWNSTREAM FROM A STRONG MIDLEVEL
TROUGH THAT WILL PROGRESS INLAND OVER THE PAC COAST LATER TODAY INTO
TONIGHT. WITHIN THIS FLOW BELT...AND EMBEDDED SPEED MAX NEAR AND
JUST N OF THE FOUR CORNERS THIS MORNING WILL TRANSLATE QUICKLY ENEWD
TO THE MID MS VALLEY THIS EVENING. IN ADVANCE OF THIS SPEED
MAX...LOW-LEVEL MOISTURE IS SPREADING QUICKLY NWD ACROSS LA/TX
TOWARD OK/AR/MO IN CONJUNCTION WITH A 35-55 KT LLJ. REGIONAL 12Z
SOUNDINGS SUGGEST THAT THE MOISTURE WILL SPREAD QUICKLY NEWD AND MIX
DOWNWARD WITH DAYTIME HEATING...BENEATH A PLUME OF MIDLEVEL LAPSE
RATES IN EXCESS OF 7 C/KM. AFTERNOON TEMPERATURES AOA 80 F AND
BOUNDARY LAYER DEWPOINTS IN THE MID 60S WILL SUPPORT A BROAD SWATH
OF MLCAPE IN EXCESS OF 1500 J/KG ACROSS OK/TX/AR...WITH SOMEWHAT
LESSER MOISTURE/INSTABILITY EXPECTED FARTHER N INTO MO/IL.
...NRN MO/NW IL THIS AFTERNOON/EVENING...
DESPITE THE LESSER MOISTURE COMPARED TO AREAS FARTHER S...THE
ARRIVAL OF THE FOUR CORNERS SPEED MAX THIS AFTERNOON AND A SURFACE
FRONT WILL HELP FOCUS THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON
FROM THE I-70 CORRIDOR IN MO NEWD INTO NW IL AND EXTREME SE IA. THE
MAGNITUDE AND ORIENTATION OF FORECAST WIND PROFILES/HODOGRAPHS
APPEAR FAVORABLE FOR A BAND OF STORMS ALONG THE FRONT...WITH
EMBEDDED SUPERCELLS. LARGE HAIL AND DAMAGING WINDS SHOULD BE THE
MORE COMMON THREATS...THOUGH AN INCREASE IN LOW-LEVEL SHEAR AND
MOISTURE DURING THE EVENING WILL ALSO BE SUPPORTIVE OF A FEW
TORNADOES.
...KS/OK THIS AFTERNOON INTO TONIGHT...
THUNDERSTORM DEVELOPMENT IS LESS CERTAIN ALONG THE TRAILING BOUNDARY
INTO SE KS AND NRN OK WHERE LOW-LEVEL ASCENT WILL BE WEAKER...THOUGH
ISOLATED THUNDERSTORMS CANNOT BE RULED OUT THIS EVENING. A SOMEWHAT
HIGHER CONFIDENCE SCENARIO WILL BE FOR SLIGHTLY ELEVATED CONVECTION
TO DEVELOP OVERNIGHT ALONG AND N OF THE BOUNDARY ACROSS NRN OK/SRN
KS AS THE LLJ STRENGTHENS FROM WRN OK INTO SW/CENTRAL KS. LARGE
HAIL WILL BE THE PRIMARY THREAT WITH THIS CONVECTION.
...AR AREA THIS AFTERNOON/EVENING...
DESPITE NO SHARP FOCUS...AT LEAST ISOLATED STORMS WILL PROBABLY FORM
THIS AFTERNOON ALONG THE LLJ/MOIST AXIS INTO AR...WHERE CONVECTIVE
INHIBITION WILL BE WEAKER THAN AREAS TO THE WEST. LOW-LEVEL AND
DEEP-LAYER VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS...WITH
DISCRETE STORMS PROBABLE GIVEN A LACK OF STRONG/LINEAR FORCING FOR
ASCENT. LIKEWISE...ISOLATED LARGE HAIL/DAMAGING WINDS...AND PERHAPS
A TORNADO OR TWO...WILL BE POSSIBLE WITH ANY STORMS THAT FORM DURING
THE AFTERNOON/EVENING.
..THOMPSON/ROGERS.. 04/04/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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