SWODY2
SPC AC 061726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT THU SEP 06 2007
VALID 071200Z - 081200Z
..NO SVR TSTM AREAS FORECAST...
..GREAT LAKES AND MIDWEST...
UPPER TROUGH...CURRENTLY LOCATED OVER UT/WY/CO...IS EXPECTED TO
BECOME ABSORBED WITHIN POLAR WESTERLIES AS THIS MID/UPPER LEVEL FLOW
REGIME SINKS SWD INTO THE NRN LOWER 48 STATES ON FRIDAY. THIS UPPER
TROUGH WILL ACCELERATE NEWD FROM THE UPPER MS VALLEY ACROSS THE
GREAT LAKES FRIDAY AFTERNOON AND REACH QUEBEC LATE FRIDAY NIGHT.
ATTENDANT SURFACE LOW IS EXPECTED TO DEEPEN AS IT ALSO TRACKS
QUICKLY NEWD ACROSS THE UPPER GREAT LAKES THROUGH ONTARIO TO NRN
QUEBEC BY 12Z SATURDAY. NRN EXTENT OF TRAILING COLD FRONT WILL MOVE
EWD ACROSS THE GREAT LAKES REGION WHILE SRN EXTENT SETTLES SEWD INTO
THE MIDWEST AND SRN PLAINS.
TSTMS...POTENTIALLY IN THE FORM OF A LINEAR MCS...SHOULD BE ONGOING
ACROSS PARTS OF THE UPPER MS VALLEY AT 12Z FRIDAY. STRONG FORCING
ATTENDANT WITH THE ACCELERATING UPPER TROUGH AND ALONG THE GREAT
LAKES PORTION OF THE COLD FRONT COMBINED WITH STRONG DEEP LAYER WIND
FIELDS SUGGEST THE POTENTIAL FOR AT LEAST ISOLATED DAMAGING WIND
GUSTS FROM PARTS OF IL INTO THE CENTRAL GREAT LAKES REGION.
HOWEVER...WEAK PRE-FRONTAL THERMODYNAMICS ASSOCIATED WITH WEAK
LAPSES RATES AND EXTENSIVE CLOUD COVER SPREADING NEWD AHEAD OF THE
COLD FRONT WILL LIKELY RESULT IN WEAK INSTABILITY. THUS...THIS
OUTLOOK WILL MAINTAIN LOW SEVERE PROBABILITIES FROM THE MID MS
VALLEY INTO THE CENTRAL GREAT LAKES REGION ON FRIDAY.
..NRN HIGH PLAINS...
SHORT WAVE TROUGH...CURRENTLY APPROACHING THE NRN BRITISH COLUMBIA
COAST PER WATER VAPOR IMAGERY...IS EXPECTED TO DIG SE TOWARD THE NRN
ROCKIES FRIDAY AFTERNOON...AND THEN TRACK EWD REACHING THE NRN HIGH
PLAINS BY 12Z SATURDAY. IN THE LOW LEVELS...LEE CYCLOGENESIS IS
EXPECTED ACROSS CENTRAL/SRN MT FRIDAY AFTERNOON IN RESPONSE TO
HEIGHT FALLS WITH THE APPROACHING TROUGH ALOFT. MODELS CONTINUE TO
INDICATE PRESSURE FALLS AHEAD OF THE SYSTEM INDUCING SELY LOW-LEVEL
FLOW AND ADVECTING UPPER 40S SURFACE DEW POINTS BACK INTO CENTRAL
MT. THIS COMBINED WITH STEEP MID LEVEL LAPSE RATES WILL CONTRIBUTE
TO AT LEAST WEAK BUOYANCY AND THE POTENTIAL FOR HIGH BASED TSTMS
OVER THE MOUNTAINS FRIDAY AFTERNOON AS STRONGER LARGE SCALE ASCENT
SPREADS SEWD. ALTHOUGH STRONG WLY MID LEVEL WINDS/DEEP LAYER SHEAR
WOULD BE SUFFICIENT FOR ORGANIZED SEVERE TSTMS...THE LACK OF MORE
SUBSTANTIAL MOISTURE BEING ADVECTED NWWD WILL MAINTAIN LOW SEVERE
PROBABILITIES ACROSS THIS REGION. A FEW OF THE STRONGER CORES WILL
HAVE THE POTENTIAL TO PRODUCE ISOLATED DAMAGING WINDS AND/OR HAIL.
.PETERS.. 09/06/2007
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