[SWODY1] SWODY1

Tue Apr 18 12:56:34 UTC 2006

ACUS01 KWNS 181253
SWODY1
SPC AC 181251

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT TUE APR 18 2006

VALID 181300Z - 191200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF MO...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR MO VLY...S AND SE
INTO AR AND THE TN VLY...

...SYNOPSIS...
AN OMEGA BLOCK WILL EVOLVE OVER THE AREA FROM THE RCKYS TO THE WRN
ATLANTIC THIS PERIOD AS POTENT SHORTWAVE TROUGH NOW OVER THE NRN HI
PLNS MOVES E AND CLOSES OFF OVER SD.  CYCLONICALLY CURVED 70-80 KT
MID LEVEL JET ROUNDING BASE OF TROUGH WILL SHIFT E/NE ACROSS THE
CNTRL PLNS/UPR MS VLY AS A WEAKER...MORE WLY...BAND OF FLOW
OVERSPREADS THE SRN PLNS...AR AND THE LWR MS VLY.

AT THE SURFACE...STRONG COLD FRONT NOW OVER WRN KS/NEB SHOULD
CONTINUE RAPIDLY ESE TODAY...REACHING A DSM/SZL/FYV/MLC LINE BY 00Z
WEDNESDAY.  AT THE SAME TIME...EXPECT THAT BACK-DOOR TYPE FRONT NOW
SETTLING S/SW ACROSS THE OZARKS AND TN VLY WILL BECOME STATIONARY
LATER THIS MORNING.  SURFACE HEATING AND CONTINUED ELY MOTION OF NRN
PLNS TROUGH SHOULD ALLOW BOUNDARY TO MOVE OR MIX NEWD INTO E CNTRL
MO/WRN KY AND MIDDLE TN BY LATE AFTERNOON/EARLY EVENING.  FARTHER
SE...RIDGING OFF THE S ATLANTIC CST EXPECTED TO DRIVE SRN PORTION OF
SAME FRONT FARTHER SW ACROSS PARTS OF AL/GA AND FL.

...LWR MO VLY INTO MID MS VLY/LWR TN VLY AND OZARKS...
CURRENT DATA SHOW LIGHT ELY SURFACE WINDS CONTINUING TO ADVECT
RELATIVELY DRY/COOL AIR FROM GRT LKS RIDGE INTO MO.  BUT PROFILER
AND VWP WINDS SHOW THAT THE FLOW IS SHALLOW /LESS THAN 1 KM DEEP/. 
THUS...WITH DAYTIME HEATING...WEAK FRONT NOW STALLED OVER NRN AR
SHOULD REDEVELOP NEWD...AND ALLOW SLIGHTLY ELEVATED MOIST LAYER TO
MIX TO THE SURFACE.  COMBINATION OF LOW LEVEL MOISTURE INFLOW /WITH
DEWPOINTS RANGING FROM THE UPR 50S IN NW MO TO PERHAPS THE MID 60S
IN S CNTRL AND SERN PARTS OF THE STATE/...SURFACE HEATING AND STEEP
MID LEVEL LAPSE RATES SHOULD BOOST AFTERNOON SBCAPE TO AOA 2500 J/KG
FROM THE SZL/COU AREA S/SE INTO NRN AR AND FAR W KY AND W TN.

STOUT EML CAP LIKELY WILL PROHIBIT SURFACE-BASED STORM DEVELOPMENT
IN WARM SECTOR THROUGH MOST OF THE DAY.  STORMS WILL...HOWEVER...
LIKELY DEVELOP SEWD FROM ERN NEB/FAR WRN IA BY EARLY AFTERNOON AS
FORCED ASCENT NEAR POINT OF OCCLUSION BETWEEN EWD-MOVING COLD FRONT
AND STATIONARY/WARM FRONT BREACHES CAP.  THIS ACTIVITY SHOULD BUILD
S/SE INTO NW MO BY MID AFTERNOON AND PRODUCE SEVERE HAIL.  FARTHER
E/SE...HEATING AND PERSISTENT WARM ADVECTION MAY INITIATE ADDITIONAL
STORMS BY LATE IN THE DAY SEWD ALONG WARM/STATIONARY FRONT INTO
CNTRL/ERN MO.

A RELATIVE WEAKNESS IN THE 700-500 MB FLOW WILL EXIST OVER CNTRL MO
TODAY...BETWEEN STRONGER BELTS OF FLOW AIMED TOWARD THE UPR MS VLY
AND TN.  BUT EVEN WITH MODEST /30 KT/ FLOW IN THAT LAYER...IT
APPEARS THAT DEEP SPEED AND DIRECTIONAL SHEAR SHOULD NEVERTHELESS BE
ADEQUATE FOR SUSTAINED SUPERCELLS.  GIVEN DEGREE OF EXPECTED
INSTABILITY...QUALITY OF MOISTURE RETURN AND LIKELIHOOD FOR STRONG
HEATING...POTENTIAL WILL THEREFORE EXIST FOR VERY LARGE HAIL AND
TORNADOES.  THE GREATEST RISK SHOULD FOCUS FROM POINT OF OCCLUSION
IN CNTRL MO SEWD ALONG WARM/STATIONARY FRONT.  SOMEWHAT LATER
TONIGHT...MORE ISOLATED SUPERCELLS MAY DEVELOP SWD ALONG COLD FRONT
INTO NRN/WRN AR.

W/E BREADTH OF WARM SECTOR AND CONTINUED LOW LEVEL WARM ADVECTION/
MOISTURE INFLOW SUGGEST THAT STORMS WILL CONTINUE TO MOVE/DEVELOP
ESE ACROSS THE MID MS/LWR OH AND LWR TN VLYS THROUGH EARLY
WEDNESDAY.  THE ACTIVITY IN WRN KY AND IN WRN/MIDDLE TN SHOULD
REMAIN SURFACE-BASED AND QUASI-DISCRETE.  THESE LIKELY WILL POSE A
THREAT FOR HAIL AND POSSIBLY AN ISOLATED TORNADO.  FARTHER N...A
BAND OR TWO OF ELEVATED STORMS COULD PRODUCE MARGINALLY SEVERE HAIL
EWD INTO IL/IND AND CNTRL KY.

...SW GA/AL INTO MIDDLE TN TODAY...
STRONG SURFACE HEATING WILL OCCUR AHEAD OF SHALLOW FRONT
BACK-DOORING WSW INTO AL TODAY.  COUPLED WITH RICH MOISTURE
AVAILABILITY...FAIRLY STEEP MID LEVEL LAPSE RATES AND 30-40 KT NWLY
MID LEVEL FLOW...SETUP COULD SUPPORT DEVELOPMENT OF SCATTERED STRONG
TO SEVERE STORMS WITH WIND/HAIL INTO EARLY EVENING.

...ERN TN/ERN KY/WRN NC EARLY WEDNESDAY...
ELEVATED STORMS WITH MARGINALLY SEVERE HAIL MAY AFFECT THE
CUMBERLAND PLATEAU AND PARTS OF THE SRN APPALACHIANS AFTER 06-09Z
WEDNESDAY AS WLY LLJ/ELEVATED MOISTURE INFLOW STRENGTHEN OVER
REGION.

..CORFIDI/JEWELL.. 04/18/2006