[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 121710
SWODY1
SPC AC 121708

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1108 AM CST SUN MAR 12 2006

VALID 121630Z - 131200Z

...THERE IS A HIGH RISK OF SVR TSTMS ACROSS EASTERN KANSAS...MUCH OF
MISSOURI...SOUTHEAST IOWA...AND WEST CENTRAL AND NORTHWESTERN
ILLINOIS...

...THERE IS A MDT RISK OF SVR TSTMS ACROSS EASTERN OKLAHOMA...FAR
NORTHEAST TEXAS..ARKANSAS..MISSOURI...SOUTHEAST NEBRASKA...SOUTHERN
IOWA...ILLINOIS...INDIANA...AND WESTERN KENTUCKY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN PORTIONS OF THE
CENTRAL AND SRN PLAINS EWD ACROSS THE MID MS AND OH VALLEYS...

...SYNOPSIS...
LARGE UPPER TROUGH OVER THE WRN U.S. WILL SHIFT ENEWD ACROSS THE
PLAINS STATES TOWARD THE MIDDLE AND UPPER MS VALLEY THIS
PERIOD...ACCOMPANIED BY VERY STRONG DEEP-LAYER WIND FIELD /H5 JET
100 TO 120 KT/.

AT THE SURFACE...WELL-DEVELOPED LOW IS FORECAST TO SHIFT ENEWD OUT
OF ERN CO...WHILE WARM FRONT NOW EXTENDING W-E ACROSS SRN KS/SRN MO
MOVES NWD WITH TIME.  THIS BOUNDARY WILL CONTINUE TO SERVE AS A
FOCUS FOR CONVECTIVE DEVELOPMENT...WITH DRYLINE ALSO FORECAST TO ACT
AS A CONVECTIVE FOCUS LATER THIS AFTERNOON AS IT MIXES EWD ACROSS
CENTRAL AND INTO ERN OK/SERN KS.

...CENTRAL AND SRN PLAINS EWD ACROSS THE MID MS AND OH VALLEYS...
VERY STEEP LAPSE RATES -- 8 TO 8.5 C/KM IN THE 850 TO 500 LAYER
ACCORDING TO MORNING RAOBS -- WILL CONTINUE TO SPREAD ENEWD ACROSS A
MOIST WARM SECTOR /SURFACE DEWPOINTS IN THE LOW TO MID 60S/ THIS
PERIOD.  LOW-LEVEL JET ADVECTING WARM/MOIST AIR ISENTROPICALLY NWD
INTO NRN KS/NRN MO COMBINED WITH VERY STRONG DEEP-LAYER WIND
PROFILES HAS YIELDED A CLUSTER OF ELEVATED SUPERCELLS...WHICH HAVE
PRODUCED SIGNIFICANT SEVERE WEATHER.  SUPERCELLS/SEVERE THREAT
SHOULD PERSIST/SHIFT SLOWLY EWD ALONG AND N OF RETREATING WARM FRONT
AS UPPER TROUGH AND ASSOCIATED JET STREAK MOVES EWD INTO THE PLAINS.


MEANWHILE...DRYLINE NOW LYING ACROSS WRN OK/WRN N TX WILL ALSO SERVE
AS A FOCUS FOR SEVERE CONVECTIVE DEVELOPMENT LATER THIS
AFTERNOON...AS IT MIXES EWD ACROSS N TX/OK/SERN KS INTO
DESTABILIZING AIRMASS /1500 TO 3000 J/KG MEAN-LAYER CAPE/.  THOUGH
WARM SECTOR AIRMASS REMAINS CAPPED ATTM...DAYTIME HEATING OF MOIST
BOUNDARY LAYER COMBINED WITH INCREASING LARGE-SCALE ASCENT SHOULD
WEAKEN CAP SUFFICIENTLY TO ALLOW STORM DEVELOPMENT TO OCCUR BY
20-21Z.  

AS STRONG MID-LEVEL SWLYS SHIFT EWD ACROSS THE WARM SECTOR ABOVE 35
TO 50 KT SLY/SSWLY LOW-LEVEL JET...VERY FAVORABLE WIND SHEAR WITH
HEIGHT WILL SUPPORT INTENSE SUPERCELLS -- PARTICULARLY GIVEN DEGREE
OF INSTABILITY.  ATTM...AREA OF MAXIMUM SEVERE THREAT APPEARS TO
EXIST FROM ERN KS ENEWD ACROSS CENTRAL AND NRN MO INTO SERN IA/W
CENTRAL AND NWRN IL.  WITH SURFACE LOW FORECAST TO SHIFT ENEWD WITH
TIME ACROSS THIS REGION...BACKING LOW-LEVEL FLOW IN THE WARM SECTOR
-- AND ELY WINDS N OF WARM FRONT -- WILL YIELD VERY FAVORABLE
LOW-LEVEL SHEAR SUPPORTIVE OF VIOLENT/LONG-TRACK TORNADOES ALONG A
BROAD AXIS ON EITHER SIDE OF WARM FRONT.  ALONG WITH
TORNADOES...VERY LARGE HAIL AND STRONG/DAMAGING WINDS CAN ALSO BE
EXPECTED.

THOUGH LOW-LEVEL FLOW SHOULD REMAIN MORE SLY -- AND MID-LEVEL FLOW
LESS INTENSE -- FURTHER S ACROSS ERN OK AND INTO N TX...SHEAR
PROFILES WILL REMAIN MORE THAN ADEQUATE FOR SUPERCELL STORMS.  GIVEN
DEGREE OF SHEAR AND INSTABILITY...A FEW STRONG/DAMAGING TORNADOES
ARE ANTICIPATED...ALONG WITH VERY LARGE HAIL AND LOCALLY DAMAGING
WIND GUSTS.

THIS EVENING/OVERNIGHT...70 KT LOW-LEVEL JET IS FORECAST TO DEVELOP
ACROSS THE MID MS VALLEY.  EXPECT STORMS TO INCREASE IN
COVERAGE...EVOLVING INTO ONE OR MORE SEVERE STORM CLUSTERS.  ALONG
WITH LARGE HAIL...DAMAGING WINDS AND ISOLATED TORNADOES WILL BE
POSSIBLE ALONG AND N OF WARM FRONT AS FAR E AS SRN LOWER MI/NRN OH.

FURTHER S...DRYLINE WILL CONTINUE SHIFTING EWD ACROSS MO/ERN OK/NERN
TX THIS EVENING/OVERNIGHT.  COLD FRONT SHOULD OVERTAKE THE DRYLINE
OVERNIGHT ACROSS MO...WHERE SQUALL LINE SHOULD EVOLVE. ALONG WITH
LARGE HAIL AND ISOLATED TORNADOES...A MORE WIDESPREAD THREAT FOR
VERY STRONG/DAMAGING WINDS APPEARS LIKELY.  A MORE BROKEN LINE OF
STORMS SHOULD CONTINUE EWD OVERNIGHT FROM ERN OK AND NERN TX ACROSS
AR/NRN LA AND TO THE MS VALLEY BY THE END OF THE PERIOD.  LARGE HAIL
AND LOCALLY DAMAGING WINDS ALONG WITH AN ISOLATED TORNADO THREAT
SHOULD PERSIST THROUGH THE END OF THE PERIOD.

..GOSS.. 03/12/2006