SWODY1
SPC AC 151249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT FRI AUG 15 2008
VALID 151300Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS INTO EARLY TONIGHT FOR THE SRN
HIGH PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS TODAY FOR THE MID ATLANTIC INTO
PARTS OF SRN NEW ENGLAND...
...SRN HIGH PLAINS THROUGH EARLY TONIGHT...
A CLOSED MID LEVEL LOW NOW OVER N CENTRAL WY WILL DRIFT SSWWD TOWARD
THE CO/WY/UT BORDER REGION THROUGH EARLY SATURDAY...AROUND THE ERN
PERIPHERY OF A BLOCKING RIDGE SITUATED FROM NV NWD TO THE INTERIOR
PAC NW. AT THE SURFACE...A SERIES OF FRONTAL SURGES ASSOCIATED WITH
THE MID LEVEL LOW AND MULTIPLE THUNDERSTORM OUTFLOWS ACROSS THE
CENTRAL/SRN HIGH PLAINS HAVE CONTRIBUTED TO AN EFFECTIVE BOUNDARY
LOCATION FROM N CENTRAL AND W CENTRAL TX INTO ERN NM. THE RECENT
THUNDERSTORM CLUSTERS HAVE ALSO REDUCED MID LEVEL LAPSE RATES ACROSS
MUCH OF THE CENTRAL/SRN PLAINS REGION. HOWEVER...UPSLOPE FLOW OF
BOUNDARY LAYER DEWPOINTS IN THE LOW 60S TO THE N OF THE
FRONT/OUTFLOW BOUNDARY AND DAYTIME HEATING ON THE SRN/WRN FRINGES OF
THE COLD POOL SHOULD RESULT IN MODERATE INSTABILITY THIS AFTERNOON
OVER W TX AND ERN NM.
EXPECT THUNDERSTORM CLUSTERS TO FORM DURING THE DAY AND MOVE SEWD
ALONG THE IMMEDIATE COOL SIDE OF THE FRONT/OUTFLOW. VERTICAL SHEAR
SHOULD BE SUFFICIENT FOR ORGANIZED MULTICELL CLUSTERS AND SUPERCELLS
CAPABLE OF PRODUCING DAMAGING WINDS AND LARGE HAIL. PROXIMITY OF
THE MID LEVEL LOW AND SEVERAL EMBEDDED SHORTWAVE TROUGHS...AS WELL
AS RELATIVELY WEAK CONVECTIVE INHIBITION WITH SURFACE TEMPERATURES
IN THE 80S...SUGGEST THAT CONVECTION WILL FORM BY EARLY AFTERNOON
AND PERSIST INTO TONIGHT...THOUGH THE SEVERE THREAT WILL DIMINISH
TONIGHT AS INSTABILITY WANES.
...MID ATLANTIC TO SRN NEW ENGLAND TODAY...
A DIFFUSE BAROCLINIC ZONE WILL MOVE ONLY SLOWLY EWD TODAY IN ADVANCE
OF A MID LEVEL TROUGH PROGRESSING EWD FROM THE LOWER GREAT LAKES
REGION. THOUGH MID LEVEL LAPSE RATES ARE NOT STEEP...BOUNDARY LAYER
DEWPOINTS WELL INTO THE 60S...DAYTIME HEATING IN CLOUD BREAKS...AND
RELATIVELY COOL 500 MB TEMPERATURES OF -12 TO -15 C WILL ALL
CONTRIBUTE OF MLCAPE VALUES APPROACHING 750-1000 J/KG TODAY.
EFFECTIVE BULK SHEAR WILL BE SUFFICIENT FOR ORGANIZED MULTICELL
CLUSTERS...AND PERHAPS SOME SUPERCELL STRUCTURES. THE PRIMARY
THREATS WILL BE HAIL AOB 1 INCH IN DIAMETER AND ISOLATED DAMAGING
OUTFLOW GUSTS THROUGH THE AFTERNOON.
FARTHER W ACROSS NY/PA...LOW-LEVEL MOISTURE WILL BE MORE LIMITED
COMPARED TO THE I-95 CORRIDOR. STILL...THE CORE OF THE COOLEST MID
LEVEL TEMPERATURES COULD SUPPORT AT LEAST ISOLATED/MARGINALLY SEVERE
HAIL WITH SCATTERED DIURNAL CONVECTION.
..THOMPSON/CROSBIE.. 08/15/2008
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