Saturday, August 9, 2008

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 090711
SWODY3
SPC AC 090709

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0209 AM CDT SAT AUG 09 2008

VALID 111200Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE DAKOTAS INTO NEB...

...SYNOPSIS...

UPPER LOW OVER NY/PA WILL GRADUALLY EVOLVE INTO AN OPEN WAVE WHILE
SHIFTING ENEWD ACROSS NEW ENGLAND DURING THE DAY THREE PERIOD.
MEANWHILE...UPPER LOW OVER SRN ALBERTA WILL MOVE EWD INTO SRN
SASKATCHEWAN WITH AN ASSOCIATED SHORT WAVE TROUGH WEAKENING WHILE
TRANSLATING EWD ACROSS ERN MT INTO THE DAKOTAS. IN THE LOW
LEVELS...A SURFACE LOW OVER THE HUDSON VALLEY WILL SLOWLY DEVELOP
EWD ACROSS CNTRL NEW ENGLAND IN CONCERT WITH PARENT UPPER SYSTEM.
FARTHER W...A COLD FRONT WILL PUSH EWD FROM ERN PARTS OF MT/WY
ACROSS THE DAKOTAS AND WRN NEB.

...DAKOTAS/NEB...

WHILE BOUNDARY LAYER MOISTURE WILL BE SOMEWHAT MARGINAL /DEWPOINTS
IN THE 50S/ IN PRE-FRONTAL WARM SECTOR...DAYTIME HEATING COMBINED
WITH AN EML PLUME PRECEDING MIDLEVEL TROUGH WILL RESULT IN A
MODERATELY UNSTABLE AIR MASS BY AFTERNOON. INCREASED FORCING FOR
ASCENT ASSOCIATED WITH SHORT WAVE TROUGH AND FRONTAL CONVERGENCE
WILL CONTRIBUTE TO DIURNAL TSTM DEVELOPMENT OVER THE WRN DAKOTAS AND
THE NEB PNHDL. MID AND HIGH-LEVEL WIND FIELDS WILL GRADUALLY
STRENGTHEN THROUGH THE AFTERNOON AND EVENING HOURS WITH DEEP-LAYER
VERTICAL SHEAR BECOMING MARGINALLY SUFFICIENT FOR TSTM
ORGANIZATION/UPDRAFT ROTATION. LARGE HAIL AND DAMAGING WINDS WILL
BE THE PRIMARY SEVERE WEATHER THREATS.

STORMS MAY TEND TO GROW UPSCALE INTO CLUSTERS OR MULTIPLE MCS/S
MONDAY NIGHT OVER THE CNTRL/ERN DAKOTAS AND CNTRL NEB WITH A
CONTINUED THREAT OF GUSTY WINDS AND SOME HAIL.

...NEW ENGLAND...

DEEP-LAYER LOW WILL LARGELY BE EQUIVALENT BAROTROPIC IN NATURE WHILE
PROGRESSING ENEWD ACROSS REGION MONDAY INTO MONDAY NIGHT.
NONETHELESS...SYSTEM WILL MAINTAIN A RESERVOIR OF RELATIVELY COOL
MIDLEVEL TEMPERATURES /-16 TO -18 C AT 500 MB/ WHICH WILL CONTRIBUTE
TO THE DEVELOPMENT OF STEEP LAPSE RATES AND POCKETS OF WEAK
CONVECTIVE INSTABILITY. AS SUCH...THE POTENTIAL WILL EXIST FOR SOME
HAIL WITH ANY MORE INTENSE STORMS THAT DEVELOP MONDAY AFTERNOON.

..MEAD.. 08/09/2008

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