[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 190102
SWODY1
SPC AC 190101

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0801 PM CDT TUE APR 18 2006

VALID 190100Z - 191200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL/SRN MO
THRU EXTREME SRN IL...WRN KY AND WRN TN...AND
NE AR...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK
AREA...FROM THE MID MS VLY INTO THE ERN GULF STATES...AND ACROSS
PARTS OF THE SRN PLAINS...

...LOWER MO VALLEY INTO PARTS OF LOWER OH/TN VALLEYS...
MID/UPPER LEVEL TROUGH IS EXPECTED TO INTENSIFY FAIRLY RAPIDLY /UP
TO 80 METERS/12 HOUR HEIGHT FALLS WITHIN CENTER OF CIRCULATION/ 
OVERNIGHT AS IT EVOLVES INTO A DEEP CLOSED LOW OVER CENTRAL SD BY
12Z WEDNESDAY.

EARLY EVENING SURFACE ANALYSIS SHOWED A COLD FRONT ADVANCING EWD
THROUGH WRN MO AND ERN OK...WITH OCCLUSION POINT OF THE COLD FRONT/
WARM FRONT OVER NWRN MO.  THE WARM FRONT STRETCHED SEWD TO SERN MO
AND THEN INTO MIDDLE TN...WHERE IT BECOMES QUASI-STATIONARY
EXTENDING S/SEWD INTO NWRN-SRN FL.  MEANWHILE... AN OCCLUDED FRONT
EXTENDED NNWWD FROM NWRN MO ACROSS WRN IA TO THE OCCLUDED SURFACE
LOW OVER SOUTH CENTRAL ND.

SUPERCELLS DEVELOPED DURING THE LATE AFTERNOON AT THE OCCLUSION
POINT OVER NWRN MO.  ALTHOUGH HEIGHT FALLS SHOULD NOT BE TOO STRONG
S OF MID-LEVEL JET AXIS...FORCING WITH PROGRESSIVE COLD FRONT AND
MODERATELY UNSTABLE AIR MASS WILL SUPPORT ADDITIONAL STORMS ACROSS
MO/AR INTO LOWER OH/TN VALLEYS AS OCCLUSION POINT TRACKS TOWARD THE
SSE REACHING WRN KY BY 12Z.  STRONG DEEP LAYER SHEAR FAVORS
ADDITIONAL SUPERCELLS...WITH THREAT FOR TORNADOES GREATEST IN
VICINITY OF OCCLUDED POINT AND ALONG WARM FRONT WHERE LOW-LEVEL
SHEAR WILL BE ENHANCED BY BACKED LOW-LEVEL WINDS. 
STRENGTHENING/VEERING LLJ FROM AR INTO LOWER OH VALLEY SHOULD ALSO
SUPPORT LARGER HODOGRAPHS FOR CONTINUED TORNADO POTENTIAL REACHING
WRN KY/WRN TN LATER TONIGHT/EARLY WEDNESDAY MORNING.  THIS LATTER
SEVERE THREAT IS EXPECTED TO BE ALONG THE SRN PERIPHERY OF AN EWD
MOVING MCS SPREADING INTO THE LOWER OH AND TN VALLEYS...WHERE
AVAILABLE INSTABILITY WILL REMAIN THE GREATEST.  LARGE HAIL/DAMAGING
WINDS WILL CONTINUE TO BE A THREAT AS WELL GIVEN FAVORABLE
THERMODYNAMICS...WITH HAIL BEING THE PRIMARY THREATS NE OF WARM
FRONT INTO MUCH OF IL TO SRN IND WHERE ACTIVITY WILL BE ELEVATED.

...TX...
ONGOING CLUSTER OF STRONG/SEVERE STORMS ACROSS CENTRAL TX TO THE NW
AND N OF SAT-AUS IS BEING AIDED BY LARGE SCALE ASCENT WITH WEAK
MID-LEVEL IMPULSE MOVING NEWD ACROSS REGION.  GIVEN THAT STORM
INITIATION WAS ALSO TIED TO STRONG SURFACE HEATING WITHIN DEEPLY
MIXED ENVIRONMENT...LOSS OF INSOLATION SHOULD ALLOW FOR EVENTUAL
DECREASE IN NEW ACTIVITY LATER THIS EVENING.  UNTIL THEN...LARGE
HAIL AND DAMAGING WINDS WILL REMAIN POSSIBLE.

...UPPER MS VALLEY...
STRONG HEIGHT FALLS AHEAD OF THIS UPPER FEATURE WILL DEVELOP/ SPREAD
ACROSS THE UPPER MS VALLEY AND IA TO NRN IL.  THIS COMBINED WITH
STRONG LOW-LEVEL WAA SHOULD MAINTAIN PRIMARILY ELEVATED
THUNDERSTORMS ALONG/E OF OCCLUDED FRONT...WHERE WEAK INSTABILITY AND
EFFECTIVE DEEP LAYER SHEAR SHOULD SUPPORT GENERALLY MARGINALLY
SEVERE HAIL.  HIGHER INSTABILITY VALUES...BUT STILL ELEVATED...SWD
INTO IA/IL MAY ALLOW FOR LOCALLY LARGER HAIL WITH THE STRONGEST
ACTIVITY.

...ERN AL/WRN-SWRN GA TO NRN FL...
ALTHOUGH DEEP LAYER SHEAR REMAINS SUPPORTIVE OF ORGANIZED STORMS...A
CONTINUED DIMINISHING TREND IN SEVERE STORM POTENTIAL IS EXPECTED
WITH THE LOSS OF DAYTIME HEATING STABILIZING THE AIR MASS.  UNTIL
ABOUT 03Z...A FEW STRONGER STORMS WILL BE CAPABLE OF PRODUCING
ISOLATED HAIL/STRONG WIND GUSTS.

..PETERS.. 04/19/2006