SWODY2
SPC AC 170550
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT TUE MAR 17 2009
VALID 181200Z - 191200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A LOW-AMPLITUDE MID-LEVEL TROUGH EXTENDING FROM HUDSON BAY SWWD INTO
THE N CENTRAL CONUS INITIALLY WILL AMPLIFY SLIGHTLY AS IT CONTINUES
EWD ACROSS ERN CANADA AND THE GREAT LAKES/MIDWEST.
AS THIS OCCURS...A COLD FRONT WILL MOVE EWD INTO/ACROSS NEW
ENGLAND...WHILE THE TRAILING PORTION OF THE BOUNDARY PROGRESSES MORE
SLOWLY SEWD ACROSS THE MIDWEST/OH VALLEY/SRN PLAINS. THIS FRONT
SHOULD BE THE PRIMARY FOCUS FOR CONVECTION THIS PERIOD...WHILE
RELATIVELY QUIESCENT WEATHER AFFECTS MOST OF THE REST OF THE CONUS.
...MID MS/OH VALLEYS INTO THE OZARKS REGION...
AN ENE-WSW COLD FRONT WILL CONTINUE MOVING SLOWLY SEWD ACROSS THE
MIDWEST/OH VALLEY/S CENTRAL U.S. THIS PERIOD. A CLOSED GULF WILL
HINDER TROPICAL MOISTURE RETURN...BUT 50S DEWPOINTS AHEAD OF THE
FRONT AND COOL MID-LEVEL TEMPERATURES SHOULD PROVIDE MODEST
INSTABILITY /500 TO 1000 J/KG SURFACE-BASED CAPE/. THUS...EXPECT
SHOWERS AND THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON INVOF THE
FRONT...FROM THE LOWER GREAT LAKES REGION WSWWD INTO ERN OK.
ALONG WITH RELATIVELY WEAK INSTABILITY...DEEP-LAYER SHEAR WILL ALSO
REMAIN MARGINAL FOR SEVERE STORMS...WITH WEAK SWLY LOW-LEVEL FLOW
FORECAST TO VEER SLIGHTLY AND INCREASE SLOWLY WITH HEIGHT -- TO 30
TO 40 KT FROM THE W AT MID LEVELS. RESULTING 0-6 KM SHEAR NEAR 30
KT MAY SUPPORT A FEW WEAKLY-ORGANIZED STORMS. A FEW OF THE
STRONGEST CELLS COULD PRODUCE MARGINAL HAIL...AND WITH A DRY/FAIRLY
DEEP MIXED LAYER EXPECTED...A LOCALLY-STRONGER GUST OR TWO WILL ALSO
BE POSSIBLE. HOWEVER...WITH THE COMBINED KINEMATIC AND
THERMODYNAMIC ENVIRONMENTS FORECAST TO REMAIN ONLY
MARGINALLY-SUPPORTIVE OF SEVERE STORMS...A LIMITED/LOW-END SEVERE
THREAT APPEARS TO REMAIN THE MOST LIKELY OUTCOME. THUS -- WILL
MAINTAIN 5% SEVERE PROBABILITY THIS FORECAST.
...S FL...
MOIST BOUNDARY LAYER AND WEAK LAPSE RATES WILL YIELD MINIMAL
INSTABILITY ACROSS FL...WHICH SHOULD SUPPORT DIURNAL DEVELOPMENT OF
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS AS A WEAK UPPER
DISTURBANCE CROSSES THIS REGION DURING THE DAY.
..GOSS.. 03/17/2009
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