[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 181639
SWODY1
SPC AC 181638

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1138 AM CDT TUE JUL 18 2006

VALID 181630Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FROM
CENTRAL MO ACROSS THE OH VALLEY INTO NEW ENGLAND....

...OH VALLEY TO NEW ENGLAND TODAY...
A MID LEVEL TROUGH EXTENDING FROM NRN IL TO THE SAINT LAWRENCE
VALLEY...ALONG WITH AN ASSOCIATED SURFACE COLD FRONT AND PRE-FRONTAL
TROUGH...WILL MOVE EWD OVER THE OH VALLEY AND NEW ENGLAND BY
TONIGHT.  STRONG SURFACE HEATING NEAR AND E OF THE PRE-FRONTAL
TROUGH...BOUNDARY LAYER DEWPOINTS IN THE UPPER 60S TO LOWER
70S...AND STEEP LOW-MID LEVEL LAPSE RATES WILL RESULT IN MLCAPE
VALUES OF 1500-2500 J/KG.  EXPECT THUNDERSTORM DEVELOPMENT TO OCCUR
FROM MIDDAY INTO EARLY AFTERNOON AS SURFACE HEATING/MIXING REMOVES
CONVECTIVE INHIBITION FROM CENTRAL PA NEWD ACROSS SRN NEW ENGLAND
INTO SRN/ERN MAINE.  ROUGHLY 40 KT WSWLY FLOW IN THE 700-500 MB
LAYER WILL COMBINE WITH THE STEEP LOW-LEVEL LAPSE RATES AND LARGE
DCAPE VALUES /GREATER THAN 1000 J/KG/ TO SUPPORT A THREAT FOR
DAMAGING WINDS WITH THE STRONGER CELLS/BOWING SEGMENTS.  LARGE HAIL
WILL ALSO BE POSSIBLE GIVEN THE STEEP MID LEVEL LAPSE RATES LARGE
MLCAPE. 

...MO/IL THIS AFTERNOON/EVENING...
THE SURFACE COLD FRONT EXTENDS WWD INTO IL/MO/KS...WITH A WEAK
SURFACE LOW JUST N OF STL.  BOUNDARY LAYER DEWPOINTS REMAIN IN THE
MID 70S ALONG AND S OF THE FRONT...THOUGH EARLY STORMS ACROSS SRN IL
HAVE TEMPORARILY DELAYED SURFACE HEATING.  STILL...CLEARING OF THE
CLOUDS WILL ALLOW AFTERNOON TEMPERATURES TO WARM INTO THE 90S FROM
CENTRAL MO TO CENTRAL IL...WHICH WILL RESULT IN MLCAPE VALUES OF
2500-4000 J/KG.  THOUGH LOW-LEVEL SHEAR IS RELATIVELY WEAK OVER THIS
AREA...30 KT NWLY MID LEVEL FLOW COULD RESULT IN SUFFICIENT DEEP
LAYER SHEAR FOR ORGANIZED MULTICELL CLUSTERS OR STORMS WITH SOME
SUPERCELL STRUCTURES.  THE STRONG INSTABILITY WILL SUPPORT A THREAT
FOR DAMAGING OUTFLOW WINDS AND LARGE HAIL LATER THIS
AFTERNOON/EVENING.

...NRN PLAINS...
WATER VAPOR IMAGERY FEATURES MID LEVEL SPEED MAXIMA MOVING EASTWARD
FROM ERN MT INTO THE DAKOTAS AT MIDDAY. IN THE WAKE OF ONGOING
ELEVATED TSTMS ACROSS SRN ND/NRN SD...STRONG INSOLATION/HEATING WILL
LEAD TO A MODESTLY UNSTABLE/WEAKLY CAPPED BOUNDARY LAYER THIS
AFTERNOON.  ISOLATED STRONG STORMS CAPABLE OF STRONG WIND GUSTS/SOME
HAIL WILL LIKELY DEVELOP ALONG THE LEE TROUGH/ADVANCING COLD FRONT
THIS AFTERNOON/EARLY EVENING.

LATER TONIGHT...NUMERICAL MODEL GUIDANCE GENERALLY SUPPORTS THE
DEVELOPMENT OF A 40 KT LOW LEVEL JET/WARM ADVECTION REGIME OVERNIGHT
ACROSS THE ERN DAKOTAS/WRN MN. STEEP LAPSE RATES ABOVE A CAPPED
BOUNDARY LAYER WILL BE FAVORABLE FOR AT LEAST ISOLATED ELEVATED
CONVECTION TO DEVELOP AFTER 03-06Z. GIVEN SUFFICIENT CLOUD BEARING
SHEAR AND PRESENCE OF STEEP LAPSE RATES/ELEVATED CAPE...THE
STRONGEST STORMS MAY BE CAPABLE OF SEVERE HAIL OVERNIGHT.

...GULF COAST REGION...
NUMEROUS THUNDERSTORMS CONTINUE AT MIDDAY ALONG THE TX UPPER COASTAL
PLAIN IN ASSOCIATION WITH A WESTWARD MOVING WEAK SHEAR AXIS ALOFT. 
GIVEN DIURNAL HEATING...STORMS SHOULD DEVELOP INLAND THROUGH THE
AFTERNOON...NAMELY FROM THE MIDDLE TX COAST/SOUTHEAST TX INTO THE
CENTRAL GULF COAST STATES AND FL PENINSULA. ALTHOUGH THE DEEP LAYER
SHEAR IS WEAK...STRONG INSTABILITY AND HOT TEMPERATURES WILL SUPPORT
THE POTENTIAL FOR SHORT-LIVED MICROBURSTS CAPABLE OF STRONG WIND
GUSTS.

...FOUR CORNERS REGION...
MID/HIGH LEVEL MOISTURE REMAINS BENEATH UNDER UPPER RIDGE...WITH
NUMEROUS DIURNAL THUNDERSTORMS LIKELY THIS AFTERNOON. AMBIENT
VERTICAL SHEAR WILL BE WEAK...LIMITING SEVERE STORM
ORGANIZATION/LONGEVITY. NEVERTHELESS...A RELATIVELY DRY AND DEEPLY
MIXED BOUNDARY LAYER WILL SUPPORT A FEW STRONG WINDS GUSTS/PERHAPS
HAIL.

..THOMPSON/GUYER.. 07/18/2006