Monday, October 8, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 081245
SWODY1
SPC AC 081242

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0742 AM CDT MON OCT 08 2007

VALID 081300Z - 091200Z

..NO SVR TSTM AREAS FORECAST...

..WI/UPPER MI AREA TODAY...
THE MID LEVEL LOW OVER THE WRN DAKOTAS THIS MORNING WILL CONTINUE TO
PROGRESS NEWD TODAY TO THE MN/ONTARIO BORDER REGION BY THIS
EVENING...AS A PRONOUNCED SHORTWAVE TROUGH ROTATES NEWD FROM KS/NEB.
A WEAK TRIPLE POINT LOW INITIALLY S OF DLH WILL DEVELOP ENEWD
ACROSS WRN UPPER MI TODAY...BEFORE THE ENTIRE SYSTEM OCCLUDES AND
BECOMES VERTICALLY STACKED TONIGHT INVOF THE MN/ONTARIO BORDER.
MEANWHILE...AN ASSOCIATED COLD FRONT WILL SURGE EWD ACROSS THE UPPER
GREAT LAKES AND SEWD ACROSS THE MID MS VALLEY AND SRN PLAINS. THIS
COLD FRONT WILL PROVIDE A PRIMARY FOCUS FOR THUNDERSTORM
DEVELOPMENT.

A NARROW CORRIDOR OF 65-70 F BOUNDARY LAYER DEWPOINTS IS PRESENT
AHEAD OF THE COLD FRONT IN WI AND S OF A STATIONARY BOUNDARY ACROSS
UPPER MI. SURFACE HEATING WILL RESULT IN SOME LOW-LEVEL
DESTABILIZATION IN THE WARM SECTOR IN ADVANCE OF THE TRIPLE POINT
LOW...BUT MLCAPE VALUES WILL BE LIMITED TO AOB 1000 J/KG BY POOR MID
LEVEL LAPSE RATES. AT THE SAME TIME...VERTICAL SHEAR WILL BECOME
SUFFICIENT FOR ORGANIZED SEVERE STORMS IN A SMALL AREA IMMEDIATELY
E/SE OF THE TRIPLE POINT LOW THIS AFTERNOON ACROSS E/NE WI AND
ADJACENT UPPER MI...WHERE ISOLATED STORMS MAY EXHIBIT SUPERCELL
STRUCTURE. STILL...THE THREAT FOR DAMAGING WINDS AND/OR HAIL WILL
BE LIMITED BY THE RATHER WEAK INSTABILITY AND THE TENDENCY FOR
CONVECTION TO BE UNDERCUT BY THE COLD FRONT.

..SRN NY/NE PA AREA TODAY...
THE BAROCLINIC ZONE ACROSS UPPER MI EXTENDS EWD INTO SW
ONTARIO...AND THEN SEWD ACROSS NY INTO SRN NEW ENGLAND. THE FRONT
SHOULD DRIFT NEWD TODAY AS THE BOUNDARY LAYER WARMS AND MOISTENS ON
WLY LOW-LEVEL FLOW ACROSS NY/PA...AND MAY PROVIDE A FOCUS FOR WIDELY
SCATTERED THUNDERSTORMS LATER TODAY. THE 12Z BUF AND ALB SOUNDINGS
REVEALED THE POTENTIAL FOR AFTERNOON MLCAPE VALUES OF AT LEAST
1000-1500 J/KG...BASED ON LOW-LEVEL MOISTURE VALUES WHICH ARE
SUBSTANTIALLY GREATER THAN SHOWN IN RECENT NAM AND RUC FORECAST
SOUNDINGS. THOUGH THE STRONGER DEEP LAYER WINDS/VERTICAL SHEAR WILL
REMAIN LARGELY N/NE OF THE SURFACE FRONT...THERE MAY BE A NARROW
CORRIDOR WITH SOME THREAT FOR STORMS WITH BOWING AND/OR SUPERCELL
STRUCTURES...AND AN ASSOCIATED THREAT FOR ISOLATED DAMAGING WINDS.

.THOMPSON/BOTHWELL.. 10/08/2007

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