[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 021255
SWODY1
SPC AC 021253

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT SUN JUL 02 2006

VALID 021300Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY FROM THE UPPER OH VALLEY
INTO NEW ENGLAND...AND INTO TONIGHT FROM THE CENTRAL HIGH PLAINS TO
PORTIONS MN/IA....

...UPPER OH VALLEY TO NEW ENGLAND TODAY...
A MID LEVEL SHORTWAVE TROUGH OVER SW QUEBEC WILL MOVE EWD OVER NEW
ENGLAND TODAY...WHILE ANOTHER UPSTREAM WAVE OVER SRN ONTARIO FOLLOWS
A SIMILAR TRAJECTORY IN THE BROAD CYCLONIC FLOW REGIME FROM NRN MN
TO MAINE.  A SURFACE CYCLONE WILL ACCOMPANY THE MID LEVEL WAVE
ACROSS NRN MAINE...WHILE A WEAK SURFACE TROUGH TRAILS SWWD ACROSS
NY/PA INTO THE NRN OH VALLEY STATES.

ONGOING ELEVATED STORMS OVER NY/VT/NH WILL SPREAD EWD TODAY.  SOME
OF THIS CONVECTION MAY INTENSIFY ACROSS PA/NY/SRN NEW ENGLAND BY
MIDDAY AS THE LOW LEVELS DESTABILIZE...WHILE THE PRIMARY THREAT FOR
SEVERE STORMS ACROSS MAINE WILL BE IN THE WAKE OF THIS EARLY
CONVECTION.  MODEST WARM SECTOR INSTABILITY IS EXPECTED TODAY WITH
SURFACE DEWPOINTS IN THE LOW-MID 60S AND TEMPERATURES GENERALLY IN
THE 80S...WHILE VERTICAL SHEAR WILL BE STRONGER ACROSS NRN NEW
ENGLAND IN ASSOCIATION WITH THE MAIN BELT OF MID LEVEL WESTERLIES. 
BOTH BOWING SEGMENTS AND SUPERCELLS WILL BE CAPABLE OF PRODUCING
DAMAGING WINDS...MARGINALLY SEVERE HAIL...AND PERHAPS A TORNADO.

...CENTRAL HIGH PLAINS TO MS VALLEY THIS AFTERNOON/TONIGHT...
A DIFFUSE FRONTAL ZONE EXTENDS FROM ERN CO/NW KS TO SRN IA AND NRN
IL/SRN LOWER MI.  THIS BOUNDARY HAS BEEN REINFORCED SOME BY
OVERNIGHT RAINFALL...AND DIFFERENTIAL HEATING MAY HELP MAINTAIN ITS
IDENTITY ALONG THE SRN FRINGE OF THE MID LEVEL WESTERLIES.  MODERATE
INSTABILITY AGAIN CAN BE EXPECTED ALONG THE IMMEDIATE B0UNDARY WHERE
SURFACE HEATING AND A BELT OF MID 60 DEWPOINTS CONTRIBUTE TO MLCAPE
VALUES NEAR 1500 J/KG. MEANWHILE...VERTICAL SHEAR SHOULD BE
MARGINAL FOR SUPERCELLS...WITH MULTICELL CLUSTERS THE MORE PROBABLE
STORM MODE.  ISOLATED LARGE HAIL AND DAMAGING OUTFLOW GUSTS WILL BE
POSSIBLE WITH THE STRONGEST STORMS THIS AFTERNOON.

THE SURFACE BOUNDARY SHOULD BEGIN TO LIFT NWD TONIGHT AS A SWLY LLJ
DEVELOPS FROM THE CENTRAL PLAINS TO THE MID/UPPER MS VALLEY... IN
RESPONSE TO ANOTHER MID LEVEL TROUGH DIGGING SEWD TOWARD WRN ONTARIO
AND THE MN ARROWHEAD AREA.  WAA ON THE NOSE OF THE LLJ AND ASCENT
ALONG A DEVELOPING SURFACE COLD FRONT SHOULD SUPPORT ELEVATED
THUNDERSTORMS TONIGHT AS THE LOW LEVELS GRADUALLY
MOISTEN/DESTABILIZE.  LARGE HAIL WILL BE THE MAIN SEVERE
THREAT...THOUGH ISOLATED DAMAGING WINDS MAY ALSO OCCUR SINCE THE
SURFACE-BASED INVERSION LAYER SHOULD BE FAIRLY SHALLOW OVERNIGHT.

...INTERIOR ORE LATE THIS AFTERNOON...
A WEAK MID LEVEL TROUGH /APPARENT IN WATER VAPOR IMAGERY NEAR 40 N
AND 127 W/ WILL MOVE NEWD OVER EXTREME NW CA AND ORE BY LATE TODAY. 
THIS APPROACHING WAVE WILL PROVIDE WEAK LARGE SCALE ASCENT OVER
ORE...WHILE STRONG SURFACE HEATING AND OBSERVED BOUNDARY LAYER
DEWPOINTS IN THE MID-UPPER 40S F CONTRIBUTE TO LATE AFTERNOON MLCAPE
VALUES OF 500-1000 J/KG.  EXPECT A FEW THUNDERSTORMS TO DEVELOP NEAR
AND E OF THE CASCADES THIS AFTERNOON AND PERSIST INTO EARLY TONIGHT
WITH THE POTENTIAL FOR MARGINALLY SEVERE HAIL/WINDS.

..THOMPSON/GUYER.. 07/02/2006