SPC AC 280549
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CDT MON AUG 28 2006
VALID 291200Z - 301200Z
...NO SVR TSTM AREAS FORECAST...
MODELS CONTINUE TO INDICATE THAT A MORE AMPLIFIED AND LESS
PROGRESSIVE UPPER FLOW PATTERN WILL DEVELOP ACROSS NORTH AMERICA
LATER TODAY INTO TUESDAY. DISCREPANCIES EXIST...PERHAPS MOST
NOTABLY CONCERNING THE EVOLUTION OF CENTRAL U.S. TROUGH WITHIN THE
SOUTHERN BRANCH OF A SPLIT FLOW REGIME...DOWNSTREAM OF A SIGNIFICANT
NORTHERN BRANCH TROUGH EVOLVING ACROSS WESTERN CANADA AND THE
NORTHERN U.S. INTERMOUNTAIN REGION. THE IMPACT OF THESE FEATURES ON
LINGERING SUBTROPICAL RIDGE ACROSS THE SOUTHERN TIER STATES IS ALSO
UNCERTAIN...BUT MOST SUBSTANTIAL WEAKENING SEEMS LIKELY TO OCCUR
ACROSS THE SOUTHERN PLATEAU. NCEP SREF AND BULK OF MODEL DATA
SUGGEST RIDGING WILL BE SLOWEST TO WEAKEN OVER THE LOWER LATITUDE
WESTERN ATLANTIC. AND ERNESTO...TRACKING AROUND SOUTHWESTERN
PERIPHERY OF HIGH CENTER BEFORE LIFTING AHEAD OF WEAK SOUTHERN
BRANCH TROUGH...SEEMS MOST LIKELY TO MIGRATE ACROSS THE LOWER KEYS
INTO THE VICINITY OF THE SOUTHERN FLORIDA GULF COAST BY 12Z
WEDNESDAY.
...MID ATLANTIC STATES...
MODELS CONTINUE TO SUGGEST THAT A WEAK SURFACE LOW WILL DEVELOP TO
THE LEE OF THE CENTRAL APPALACHIANS...ALONG OR SOUTH OF SURFACE
FRONT ADVANCING SOUTHWARD INTO THE MID ATLANTIC REGION. THIS COULD
PROVIDE THE FOCUS FOR AT LEAST SCATTERED CONVECTIVE DEVELOPMENT
ACROSS PARTS OF EASTERN VIRGINIA...AND PERHAPS NORTHEASTERN NORTH
CAROLINA...INTO THE DELMARVA PENINSULA...WHERE BOUNDARY LAYER IS
EXPECTED TO BE QUITE MOIST WITH DEW POINTS AROUND 70F. WEAK
MID-LEVEL LAPSE RATES WILL PROBABLY LIMIT CAPE TO WEAK TO MODERATE
LEVELS AT OR ABOVE 1000 J/KG. HOWEVER...SHEAR PROFILES WILL BE
MARGINALLY FAVORABLE FOR UPDRAFT ROTATION... BENEATH 30+ KT WESTERLY
MID-LEVEL FLOW...IN CONFLUENT REGIME DOWNSTREAM OF SOUTHERN BRANCH
TROUGH. AND...INSTABILITY MAY BE SUFFICIENT FOR AN ISOLATED
SUPERCELL OR TWO...MAINLY DURING/ SHORTLY AFTER PEAK DAYTIME
HEATING. IF THIS OCCURS...POTENTIAL EXISTS FOR A TORNADO...IN
ADDITION TO DAMAGING WIND GUSTS...AND POSSIBLY SOME HAIL.
...FLORIDA...
UNCERTAINTIES CONCERNING TRACK/STRENGTH OF ERNESTO...AND ASSOCIATED
WIND FIELDS AND LOW-LEVEL SHEAR ARE STILL LARGE.
HOWEVER...POTENTIAL FOR AT LEAST ISOLATED TORNADOES WILL PROBABLY
INCREASE ACROSS THE FLORIDA KEYS INTO THE SOUTHERN PENINSULA LATE
TUESDAY/TUESDAY NIGHT...NORTH/NORTHEAST OF APPROACHING CIRCULATION
CENTER.
...NORTHWEST...
LACK OF MOISTURE IN WARM PRE-FRONTAL ENVIRONMENT IS EXPECTED TO
MINIMIZE CONVECTIVE POTENTIAL ASSOCIATED WITH VIGOROUS UPPER TROUGH
DIGGING INTO THE NORTHERN INTERMOUNTAIN REGION. OROGRAPHY MAY AID
DEVELOPMENT OF THUNDERSTORMS ACROSS THE MOUNTAINS OF NORTHERN
IDAHO/WESTERN MONTANA...SOME OF WHICH COULD DEVELOP EAST OF THE
HIGHER TERRAIN WITH POTENTIAL FOR ISOLATED MICROBURSTS IN DEEP MIXED
BOUNDARY LAYER.
...SOUTHWEST...
A NORTHWARD SURGE OF LOW-LEVEL MOISTURE THROUGH THE GULF OF
CALIFORNIA INTO THE LOWER COLORADO VALLEY AND SOUTHERN PLATEAU
APPEARS LIKELY TO OCCUR BY TUESDAY. FAIRLY STRONG DAYTIME HEATING
AND WEAKENING INHIBITION ARE EXPECTED TO CONTRIBUTE TO INCREASING
THUNDERSTORM ACTIVITY TUESDAY AFTERNOON. SHEAR WILL BE WEAK... BUT
DEEP MIXED BOUNDARY LAYER WITH CAPE AS LARGE AS 1000 J/KG WILL
PROBABLY BE SUFFICIENT FOR A FEW VIGOROUS STORMS...SOME OF WHICH MAY
BE ACCOMPANIED BY LOCALIZED DOWNBURSTS...POSSIBLY SOME SMALL HAIL.
..KERR.. 08/28/2006
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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