[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 061234
SWODY1
SPC AC 061232

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0732 AM CDT THU APR 06 2006

VALID 061300Z - 071200Z

...THERE IS A HIGH RISK OF SVR TSTMS OVER NERN KS INTO SERN NEB AND
FAR NWRN MO LATER TODAY AND THIS EVENING...

...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK FROM
ERN NEB/WRN IA INTO WRN MO...ERN OK AND WRN AR...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK OVER
PORTIONS OF THE SRN/CENTRAL PLAINS EWD ACROSS THE MID MS RIVER
VALLEY...

...SIGNIFICANT SEVERE WEATHER OUTBREAK /INCLUDING NUMEROUS TORNADIC
SUPERCELLS/ IS EXPECTED TO EVOLVE ACROSS EASTERN PORTIONS OF THE
CENTRAL PLAINS STATES LATER TODAY AND THIS EVENING...

...SYNOPSIS...
POTENT MID/UPPER LEVEL LOW NOW OVER THE FOUR-CORNERS REGION WILL
RAPIDLY EJECT NEWD INTO THE CENTRAL PLAINS TODAY...WITH 210M HEIGHT
FALLS AT H5 SPREADING ACROSS ERN KS BY 00Z.  SIGNIFICANT MID TO
UPPER LEVEL JET MAX WILL ACCOMPANY THIS SYSTEM WITH H5 WINDS IN
EXCESS OF 100 KT /115+ KT AT H25/ SHIFTING ACROSS OK.  ASSOCIATED
SURFACE LOW NOW TAKING SHAPE OVER CENTRAL NEB WILL DEEPEN AS IT
BECOMES BETTER DEFINED NEAR THE N-CENTRAL KS/SERN NEB BORDER LATER
THIS AFTERNOON.  AS THIS OCCURS...VERY STRONG DRY LINE WILL MIX TO
NEAR THE I-35 CORRIDOR BY 18Z AND THEN SHIFT RAPIDLY EWD INTO WRN
MO/WRN AR THIS EVENING.  AHEAD OF THIS...MODEST LOW LEVEL MOISTURE
WILL REMAIN IN PLACE WITH AXIS OF AROUND 60F SURFACE DEW POINTS
EXTENDING INTO ERN KS AND FAR SERN NEB THIS AFTERNOON. IN
ADDITION...VERY STEEP LAPSE RATES /I.E. 8.5+ C/KM FROM H7-H5/ ARE
ALREADY OBSERVED ACROSS THE REGION AND WILL REMAIN IN PLACE TODAY.

...ERN SD/NEB INTO KS/MO/IA...
MORNING CONVECTION WITH THREAT OF ISOLATED LARGE HAIL WILL LIKELY
INCREASE WITHIN BROAD UPPER DIFFLUENCE ACROSS SD AND INTO PORTIONS
OF IA THIS MORNING.  IN ADDITION...WITH H85 FLOW REMAINING VEERED TO
SWLY OVER THE SRN PLAINS...LOW LEVEL WAA AND ASCENT AHEAD OF SUBTLE
DISTURBANCE EVIDENT ON WV IMAGERY MOVING INTO SWRN OK WILL LIKELY
INCREASE CLOUDS AND MOIST CONVECTION ACROSS CENTRAL OK AND INTO THE
OZARKS THIS MORNING.  THIS ACTIVITY WILL ALSO LIKELY REMAIN ELEVATED
ABOVE STRONGLY CAPPED BOUNDARY LAYER...THOUGH CLOUD LAYER SHEAR AND
STEEP LAPSE RATES COULD SUPPORT LARGE HAIL.

PRIMARY SEVERE THREAT IS STILL EXPECTED TO ERUPT ALONG THE DRY LINE
ALONG LEADING EDGE OF STRONG ASCENT FROM CENTRAL NEB INTO N-CENTRAL
OK...POSSIBLY AS EARLY AS 18Z...AND EVOLVE INTO AN OUTBREAK OF
SEVERE THUNDERSTORMS THROUGH 02-03Z ACROSS MUCH OF ERN KS AND
PORTIONS OF SERN NEB/WRN MO.  WARM SECTOR IS FORECAST TO BECOME
MODERATELY UNSTABLE WITH MLCAPE TO 2000 J/KG INTO THE CENTRAL
PLAINS.  VERY STRONG SHEAR REMAINS SUPPORTIVE OF SUPERCELLS...WITH A
VARIETY OF STORM MOTIONS.  CELLS INTO ERN NEB WILL TEND TO DEVELOP
NWD AND ROTATE NWWD TOWARDS CENTRAL NEB...WHILE DEVELOPMENT SOUTH OF
THE SURFACE LOW WILL TEND TO SHIFT RAPIDLY ENEWD ACROSS ERN KS AND
INTO WRN MO WHERE AIR MASS WILL LIKELY DESTABILIZE IN WAKE OF ANY
EARLY DAY ACTIVITY.  SOUNDINGS CONTINUE TO SUPPORT VERY LARGE AND
DAMAGING HAIL WITH SOME HAIL STONES EXCEEDING 3-4 INCHES IN
DIAMETER.  SUPERCELLS ARE ALSO EXPECTED TO BECOME
TORNADIC...ESPECIALLY INTO NERN KS/FAR SERN NEB/NWRN MO WHERE STRONG
PRESSURE FALLS AND BACKED SURFACE WINDS WILL ENHANCE LOW LEVEL
HELICITIES AND LCLS REMAIN MORE FAVORABLE ESE OF THE LOW CENTER. 
CONVECTIVE MODE/STORM-SCALE EVOLUTION STILL HARD TO DETERMINE
ATTM...AS SOME OF THE ACTIVITY MAY EVOLVE INTO LEWP/BOW
ECHOES...ESPECIALLY INTO THE EVENING.  REGARDLESS...SUPERCELL
STRUCTURES ARE EXPECTED TO REMAIN WIDESPREAD WITH ATTENDANT THREAT
OF TORNADOES...SOME OF WHICH COULD BE QUITE STRONG GIVEN MAGNITUDE
OF SHEAR AND STRONG SURFACE PRESSURE FALLS.  STORMS ARE EXPECTED TO
EVENTUALLY OUTRUN INSTABILITY NEAR THE LOWER MO/MID-MS RIVER VALLEYS
AND BECOME INCREASINGLY ELEVATED NORTH OF THE WARM FRONT LATER THIS
EVENING/OVERNIGHT...THOUGH LARGE HAIL POTENTIAL MAY SPREAD ACROSS
THE MID MS RIVER VALLEY AND INTO THE OH RIVER VALLEY LATE TONIGHT.

...ERN OK/WRN AR INTO FAR NERN TX...
SIGNIFICANT MID/UPPER LEVEL SHEAR WILL DEVELOP ACROSS THE DRY LINE
INTO ERN OK/NERN TX LATER TODAY...WHERE MLCAPES SHOULD APPROACH 2500
J/KG ALONG WRN EDGE OF MID LEVEL CLOUD SHIELD NOW EXTENDING NE-SW
ACROSS CENTRAL OK.  CAPPING WILL BE MORE PROBLEMATIC SOUTH OF UPPER
JET AND WITHIN WEAKER ASCENT THAN COMPARED TO AREAS FARTHER NORTH. 
HOWEVER...FORECAST SOUNDINGS CONTINUE TO INDICATE DANGEROUS
COMBINATION OF LONG HODOGRAPHS AND MODERATE INSTABILITY.  STORMS MAY
REMAIN MORE ISOLATED ACROSS THIS REGION...THOUGH PARAMETERS REMAIN
QUITE FAVORABLE FOR LONG-LIVED SUPERCELLS... INCLUDING STRONG AND
DAMAGING TORNADOES...WITH STORMS THAT DO DEVELOP.  THIS ACTIVITY
WILL LIKELY BECOME ELEVATED DURING THE MID/LATE EVENING INTO CENTRAL
AR AND SPREAD ISOLATED DAMAGING WIND/LARGE HAIL THREAT TOWARDS THE
LOWER OH RIVER VALLEY LATER TONIGHT.

..EVANS/CROSBIE.. 04/06/2006