Monday, June 2, 2008

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 020717
SWODY3
SPC AC 020715

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0215 AM CDT MON JUN 02 2008

VALID 041200Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CNTRL
PLAINS INTO UPPER MIDWEST...

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE MID ATLANTIC
COAST/SWRN NEW ENGLAND WWD INTO THE UPPER OH VALLEY...

...SYNOPSIS...

PRIMARY FEATURE OF INTEREST DURING THE DAY THREE PERIOD WILL BE
EVOLVING...LARGE-SCALE TROUGH WHICH IS FORECAST TO UNDERGO
CONSIDERABLE INTENSIFICATION AS UPSTREAM JET STEAK DIGS SEWD THROUGH
THE GREAT BASIN INTO THE SRN ROCKIES. IN THE E...LARGER-SCALE
TROUGH OVER QUEBEC WILL SHIFT EWD INTO THE CANADIAN MARITIMES WITH
TRAILING SHORT WAVE TROUGH TRANSLATING EWD THROUGH THE LOWER GREAT
LAKES AND NERN STATES.

IN THE LOW LEVELS...LEE CYCLONE OVER SERN CO/WRN KS WILL DEEPEN
WHILE DEVELOPING SLOWLY NEWD ACROSS KS. ATTENDANT WARM FRONT IS
FORECAST TO LIFT NWD THROUGH THE LOWER INTO MID MO VALLEY WITH ERN
EXTENSION OF THIS BOUNDARY STRETCHING EWD ACROSS THE OH VALLEY AND
THEN NEWD TO SECONDARY LOW PRESSURE MOVING THROUGH NEW ENGLAND. A
DRYLINE WILL SHARPEN FROM THE KS LOW SWD THROUGH WRN OK INTO NWRN
TX.

...CNTRL/SRN PLAINS INTO UPPER MIDWEST...

THE CO-LOCATION OF RICH BOUNDARY LAYER MOISTURE AND STEEP MIDLEVEL
LAPSE RATES IS EXPECTED TO CONTRIBUTE TO STRONG INSTABILITY INVOF
WARM FRONT WEDNESDAY...WITH A MODERATELY UNSTABLE AIR MASS EXTENDING
SWD ALONG DRYLINE. THESE LAPSE RATES WILL BE ASSOCIATED WITH A
CONSIDERABLE EML/CAP WHICH WILL OVERSPREAD THE CNTRL/SRN PLAINS IN
ADVANCE OF EVOLVING UPPER TROUGH.

THE GREATEST LIKELIHOOD FOR DIURNAL STORM INITIATION APPEARS TO BE
ALONG WARM FRONT...PERHAPS IN ASSOCIATION WITH A LEAD IMPULSE
EJECTING NEWD FROM PRIMARY TROUGH. VERTICAL SHEAR /BOTH DEEP LAYER
AND IN THE LOW-LEVELS/ WILL BE MORE THAN SUFFICIENT FOR SUPERCELLS
CAPABLE OF VERY LARGE HAIL...DAMAGING WINDS AND TORNADOES. STORMS
ARE EXPECTED TO SPREAD NEWD THROUGH THE MID MO VALLEY INTO PORTIONS
OF THE UPPER MIDWEST WEDNESDAY NIGHT ALONG NOSE OF STRENGTHENING
LLJ. MANY OF THESE STORMS WILL LIKELY BE SLIGHTLY ELEVATED WITH THE
PRIMARY THREAT BEING LARGE HAIL.

OTHER DIURNAL STORMS ARE POSSIBLE IN UPSLOPE FLOW REGIME NW OF
SURFACE LOW INTO NERN CO. MODERATELY STRONG INSTABILITY AND
VERTICAL SHEAR WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE
HAIL...DAMAGING WINDS AND PERHAPS A COUPLE OF TORNADOES.

FINALLY...DIURNAL STORM INITIATION SWD ALONG THE DRYLINE IS MUCH
MORE UNCERTAIN GIVEN THE STRONG CAP AND APPARENT ABSENCE OF ANY
LARGE-SCALE FORCING MECHANISMS. SHOULD A STORM
DEVELOP...ENVIRONMENT WOULD SUPPORT SUPERCELL STRUCTURES.
HOWEVER...GIVEN THE LOW CONFIDENCE IN INITIATION...ONLY LOW
PROBABILITIES WILL BE INCLUDED.

...NEW ENGLAND/MID ATLANTIC COAST WWD INTO THE OH VALLEY...

AN AXIS OF MODERATE INSTABILITY IS FORECAST TO DEVELOP WEDNESDAY IN
ADVANCE OF SURFACE LOW AND TRAILING COLD FRONT. FRONTAL CONVERGENCE
COMBINED WITH THE LARGER-SCALE FORCING ASSOCIATED WITH SHORT WAVE
TROUGH MOVING ACROSS THE REGION SHOULD PROMOTE SCATTERED TSTM
DEVELOPMENT ALONG THE FRONT. DESPITE THE VEERING LOW-LEVEL FLOW
WITH TIME...DEEP-LAYER VERTICAL SHEAR WILL BE SUFFICIENT FOR
EMBEDDED BOWING STRUCTURES CAPABLE OF DAMAGING WINDS...HAIL AND
PERHAPS A TORNADO OR TWO.

ISOLATED TO SCATTERED STRONG/SEVERE STORMS MAY DEVELOP FURTHER W
INTO THE OH VALLEY ALONG LOW-LEVEL BAROCLINIC ZONE. CURRENTLY...IT
APPEARS THAT THE OVERALL SEVERE WEATHER THREAT MAY BE LIMITED BY
COMPARABLY WEAKER VERTICAL SHEAR AND LARGE-SCALE HEIGHT RISES ACROSS
THE REGION.

..MEAD.. 06/02/2008

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