SWODY1
SPC AC 301249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT THU AUG 30 2007
VALID 301300Z - 311200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
BROAD RIDGE CENTERED NEAR THE FOUR CORNERS WILL DOMINATE THE PATTERN
OVER MUCH OF THE LWR 48 THIS PERIOD...WITH THE WLYS ONCE AGAIN
REMAINING CONFINED TO SRN CANADA. LOW AMPLITUDE TROUGH THAT HAS
MOVED E ACROSS S CNTRL CANADA IN RECENT DAYS WILL CONTINUE E ACROSS
QUEBEC THROUGH FRIDAY. THE SYSTEM WILL UNDERGO SLIGHT AMPLIFICATION
AS IT REACHES THE ST LAWRENCE VLY TONIGHT IN RESPONSE TO A SERIES OF
IMPULSES DROPPING ESE ACROSS WRN ONTARIO.
IN THE WEST...WV IMAGERY SHOWS SEVERAL WEAK DISTURBANCES THAT LIKELY
WILL PLAY A ROLE IN GOVERNING DIURNAL TSTM DEVELOPMENT FROM CA/NV
NWD INTO THE PC NW/NRN RCKYS. DIFFUSE FEATURE NOW NEARING SFO
SHOULD EDGE SLOWLY NE INTO WRN NV...WHILE IMPULSE NOW IN CNTRL ORE
ACCELERATES NE TOWARD NRN ID.
AT LWR LVLS...WEAK COLD FRONT EXTENDING FROM THE NRN APPALACHIANS
ACROSS LWR TN VLY TO THE SRN PLNS ATTM SHOULD CONTINUE TO SLOWLY
WEAKEN AS SETTLES FARTHER S AND SE.
..NERN U.S....
STRONG HEATING WILL OCCUR OVER MUCH OF NRN NEW ENGLAND...ERN/SRN NY
AND NE PA TODAY AHEAD OF COLD FRONT SETTLING SE ACROSS REGION. AN
AXIS OF SLIGHTLY COOLER MID LVL AIR WILL ALSO PRECEDE THE FRONT.
NEVERTHELESS...EXPECT THAT DIURNAL DESTABILIZATION WILL REMAIN
MODEST...WITH AFTERNOON MLCAPE REMAINING AOB 1500 J/KG IN SRN
NY/PA...AND AOB 1000 J/KG IN ME.
30-40 KT WLY MID LVL FLOW WILL CONTRIBUTE TO MODERATE DEEP SHEAR IN
ME...BUT WILL WEAKEN SUBSTANTIALLY WITH SW EXTENT ALONG/AHEAD OF
COLD FRONT AS MAIN BELT OF WLYS REMAINS IN CANADA.
COMBINATION OF HEATING...WEAK CONVERGENCE ALONG FRONT AND/OR
TERRAIN-INDUCED CIRCULATIONS SHOULD SUPPORT DEVELOPMENT OF SCTD
AFTERNOON TSTMS FROM SW/CNTRL PA NEWD INTO CNTRL/NRN NEW ENGLAND.
POTENTIAL FOR DEVELOPMENT MAY ALSO BE ENHANCED BY UPR DIVERGENCE
ASSOCIATED WITH AMPLIFYING SYSTEM IN QUEBEC. WHILE THE AREAS OF
GREATEST SHEAR AND INSTABILITY WILL NOT BE VERY JUXTAPOSED...SETUP
COULD SUPPORT A FEW STRONG MULTICELL CLUSTERS AND LINE
SEGMENTS...WITH AN ATTENDANT THREAT FOR LOCALLY DAMAGING WIND FROM
NRN PA/NY INTO NRN/CNTRL NEW ENGLAND.
..ORE...
DEEP UNIDIRECTIONAL SW FLOW WILL PERSIST OVER NRN CA AND ORE THIS
PERIOD...SE OF BROAD GULF OF AK UPR LOW. SATELLITE AND MODEL FCSTS
SUGGEST THAT A RIBBON OF MID LVL MOISTURE WILL REMAIN/EVOLVE OVER
PARTS OF NRN CA AND WRN/CNTRL ORE TODAY AS AFOREMENTIONED UPR
SYSTEMS BECOME INCREASINGLY SHEARED. TSTMS LIKELY WILL FORM ALONG
THE MOIST AXIS AS SFC HEATING DESTABILIZES THE LWR LVLS DURING THE
AFTERNOON...ESPECIALLY INVOF TERRAIN-INDUCED CIRCULATIONS. COUPLED
WITH STRENGTHENING MID LVL GRADIENT FLOW...THIS SETUP COULD SUPPORT
DEVELOPMENT OF A FEW CLUSTERS OR SHORT LINES OF HIGH-BASED STORMS.
THESE COULD POSE A RISK FOR LOCALLY DAMAGING WIND/MARGINALLY SVR
HAIL AS THEY MOVE NEWD ATOP DEEPLY-MIXED LWR-ELEVATION BOUNDARY LYR.
.CORFIDI/CROSBIE.. 08/30/2007
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