[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 190539
SWODY1
SPC AC 190537

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1237 AM CDT FRI MAY 19 2006

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS OZARKS REGION TO TN VALLEY....

...SYNOPSIS...
VERY STABLE LARGE SCALE PATTERN WILL FEATURE SYNOPTIC RIDGE OVER WRN
NORTH AMERICA AND TROUGH IN ERN PORTIONS CONUS/CANADA. SHORTWAVE
TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER NRN SASK --
SHOULD AMPLIFY AND DIG SEWD WHILE LEAVING MEAN RIDGE POSITION. AS
THIS OCCURS...PRONOUNCED MIDDLE-UPPER LEVEL LOW PRESENTLY OVER LE
REGION IS FCST TO MOVE EWD THEN NNEWD ACROSS NY AND SRN QUE.  WEAK
PERTURBATION OVER NRN HIGH PLAINS IS FCST TO MOVE SEWD ACROSS
CENTRAL PLAINS AND OZARKS.  ASSOCIATED FRONTAL-WAVE LOW -- NOW
WEAKLY EVIDENT OVER ND -- IS EXPECTED TO STRENGTHEN SOMEWHAT AS IT
PROPAGATES SEWD ALONG CURRENTLY QUASISTATIONARY BAROCLINIC ZONE. 
THIS LOW SHOULD CROSS OZARKS REGION DURING LATE AFTERNOON/EARLY
EVENING.

...OZARKS REGION TO TN VALLEY...
WEAKENING CINH AND LIFT NEAR FRONT WILL SUPPORT TSTM DEVELOPMENT
DURING AFTERNOON...SHIFTING SEWD AND PERHAPS EXPANDING IN COVERAGE
THROUGH LATE EVENING BEFORE DIMINISHING.  DAMAGING GUSTS AND LARGE
HAIL ARE ANTICIPATED.  TORNADO POTENTIAL IS MORE MRGL...UNCERTAIN
AND STRONGLY CONDITIONAL ON MESOSCALE TO STORM SCALE PROCESSES.

ETA INITIALIZED TOO HIGH ON SFC MOISTURE IN THIS AREA AND
UPSTREAM...AND ITS PROGGED DEW POINT AND CAPE VALUES APPEAR TOO
LARGE. HOWEVER...WITH EVAPOTRANSPIRATIVE SUPPORT...SFC DEW POINTS
MAINLY FROM UPPER 50S TO MID 60S F ARE POSSIBLE ACROSS THIS
AREA...PER WRF SOUNDINGS.  LOW-MIDLEVEL LAPSE RATES SHOULD BE
STEEPEST OVER MO/AR AT 8-9 DEG C/KM...WEAKENING WITH SEWD EXTENT
ALONG FRONTAL ZONE.  THIS COMBINED WITH DIABATIC HEATING WILL
SUPPORT AFTERNOON MLCAPES NEAR 3000 J/KG...ALSO DIMINISHING WITH
SEWD EXTENT...BUT SUPPORTING SEVERE POTENTIAL THROUGH NEAR-FRONTAL
CORRIDOR FROM OZARKS SEWD ACROSS WRN/MID TN GIVEN FAVORABLE VERTICAL
SHEAR PROFILES EXPECTED. SFC WINDS SHOULD RANGE FROM SWLY IN WARM
SECTOR TO LIGHT/VARIABLE IN FRONTAL ZONE...AND PERHAPS SLY-SELY JUST
SE OF SFC LOW. THIS WILL SUPPORT LARGE VARIATION IN LOW LEVEL SHEAR
PROFILES...WITH 0-3 KM SRH 100-400 J/KG WHERE THERE IS SFC-BASED
BUOYANCY...AND EFFECTIVE BULK VALUES 35-55 KT OVER MUCH OF OUTLOOK
AREA.  SOME SUPERCELLS AND BOW ECHOES ARE POSSIBLE.

...ERN NJ TO SRN/CENTRAL NEW ENGLAND AREA...
AIR MASS MAY HEAT/RECOVER SUFFICIENTLY AFTER MORNING CLOUDS/PRECIP
TO PERMIT ADDITIONAL TSTMS DURING AFTERNOON...SOME OF WHICH MAY
PRODUCE HAIL.  AS MID/UPPER LEVEL LOW APCHS...MIDLEVEL
ASCENT/COOLING SHOULD CONTRIBUTE TO STEEPENED LAPSE RATES.  CINH
SHOULD BE SMALL...REQUIRING ONLY WEAK SFC HEATING TO CONVECT IN FCST
SOUNDINGS WITH MLCAPES UP TO ABOUT 500 J/KG.  UNCERTAINTIES ABOUT
SPEED/STRENGTH OF DIURNAL DESTABILIZATION PRECLUDE CATEGORICAL
OUTLOOK ATTM.  STRONG-SVR TSTM POTENTIAL SHOULD DIMINISH MARKEDLY
WITH LOSS OF AFTERNOON INSOLATION.

...NWRN CONUS...
WIDELY SCATTERED AFTERNOON TSTMS AGAIN ARE EXPECTED TO
FORM...INITIALLY OVER HEATED HIGHER TERRAIN WITH
DEVELOPMENT/PROPAGATION INTO VALLEYS AND BASINS.  STRONGEST SFC
HEATING/MIXING AND AT LEAST MRGLLY FAVORABLE SFC MOISTURE IS
EXPECTED OVER THIS AREA...AIDED BY EVAPOTRANSPIRATION OF SOME 
PRECIP THAT FELL ON THURSDAY.  LOW-MIDLEVEL LAPSE RATES APCHG DRY
ADIABATIC WILL FURTHER CONTRIBUTE TO MLCAPES GENERALLY 300-800 J/KG.

..EDWARDS.. 05/19/2006