SWODY1
SPC AC 161607
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1107 AM CDT SAT AUG 16 2008
VALID 161630Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CENTRAL AND
SOUTHERN NEW ENGLAND...
...NEW ENGLAND...
AN UPPER TROUGH CONTINUES TO TRACK SLOWLY EASTWARD ACROSS THE
NORTHEAST UNITED STATES TODAY...PROVIDING RATHER COOL MID LEVEL
TEMPERATURES /-15 TO -17C AT 500MB/ AND STEEPENING LAPSE RATES TO
THE REGION. MODEL GUIDANCE IS CONSISTENT IN MOVING TROUGH AXIS
ACROSS NEW ENGLAND THIS AFTERNOON...WHERE POCKETS OF STRONG DAYTIME
HEATING WILL YIELD AFTERNOON MLCAPE VALUES AROUND 1000 J/KG.
THERMODYNAMIC PARAMETERS IN THIS REGION APPEAR FAVORABLE FOR HAIL IN
STRONGER CELLS. HOWEVER...PRIMARY FORECAST CONCERN INVOLVES THE
LACK OF LOW LEVEL FORCING MECHANISMS AND UNCERTAINTIES REGARDING
AREAL COVERAGE OF STRONGER THUNDERSTORMS THIS AFTERNOON AND EVENING.
NEVERTHELESS...HAVE OPTED TO UPGRADE PORTIONS OF AREA TO SLIGHT
GIVEN CONDITIONAL THREAT OF HAIL. STORMS SHOULD WEAKEN QUICKLY
AFTER SUNSET.
...MI/WI...
A LOW-AMPLITUDE SHORTWAVE TROUGH WILL PROGRESS SEWD FROM WRN
ONTARIO TO UPPER MI THIS AFTERNOON AND EVENING. THIS MID LEVEL
TROUGH WILL BE ACCOMPANIED BY A DIFFUSE SURFACE TROUGH. ALTHOUGH
BOUNDARY LAYER DEWPOINTS WILL BE LIMITED TO THE 50S AND MID LEVEL
LAPSE RATES WILL BE RATHER MODEST /ROUGHLY 6.5 C/KM/...DAYTIME
HEATING INTO THE 80S WILL SUPPORT THE DEVELOPMENT OF MUCAPE VALUES
OF 500-1000 J/KG. WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO
DEVELOP AROUND MID AFTERNOON AND SPREAD SEWD WITH THE MID LEVEL
TROUGH. MARGINAL BULK SHEAR AND INSTABILITY COULD BE SUFFICIENT FOR
ISOLATED STORMS WITH HAIL AND GUSTY WINDS LATER THIS
AFTERNOON/EVENING.
...AZ/NM...
A MOIST AND MODERATELY UNSTABLE AIRMASS REMAINS IN PLACE TODAY OVER
AZ/NM...ON SOUTHWEST FLANK OF UPPER LOW ALONG THE UT/CO BORDER.
AREAS OF STRONG HEATING WILL OCCUR TODAY OVER THE MOUNTAINS OF AZ
AND WESTERN NM...WHERE DEWPOINTS IN THE 50S WILL RESULT IN AFTERNOON
MLCAPE VALUES OF 1000 J/KG. SCATTERED THUNDERSTORMS ARE LIKELY TO
DEVELOP OVER THIS REGION BY LATE AFTERNOON...SPREADING SLOWLY
SOUTHWARD DURING THE EVENING. MODELS SUGGEST THAT NORTHERLY
COMPONENT OF MID LEVEL FLOW WILL INCREASE SLIGHTLY BY 00Z AS UPPER
LOW DRIFTS SOUTHWARD. THIS MAY AID IN PROPAGATION OF STORMS INTO
LOWER DESERTS WHERE LOCALLY DAMAGING WINDS WOULD BE POSSIBLE.
..HART/JEWELL.. 08/16/2008
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