Wednesday, March 28, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 280556
SWODY1
SPC AC 280555

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT WED MAR 28 2012

VALID 281200Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF ERN KS AND SWRN
MO...

...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF KY...TN...WV INTO
NRN VA...

...SYNOPSIS...
AN UPPER TROUGH WILL MOVE ACROSS THE GREAT LAKES AND INTO NEW
ENGLAND BY 00Z...WITH ATTENDANT SURFACE LOW. A BROAD AREA OF STRONG
WLY FLOW WILL EXIST AROUND THE BASE OF THIS TROUGH WITH 60-70 KT
MIDLEVEL FLOW FROM THE OH VALLEY TO THE ATLANTIC. A COLD FRONT WILL
EXTEND FROM SRN NEW ENGLAND SWWD INTO THE DELMARVA AT 00Z...WITH LOW
TO MID 50S F DEWPOINTS TO THE S. THIS FRONT WILL SERVE AS A FOCUS
FOR SCATTERED THUNDERSTORMS BEGINNING EARLY IN THE DAY OVER NY AND
PA...EXPANDING SWWD INTO KY DURING THE AFTERNOON.

TO THE W...GENERALLY ZONAL FLOW WILL EXIST OVER THE CNTRL
PLAINS...WITH SLIGHT RIDGING ALOFT. THE WRN PORTION OF THE ERN U.S.
COLD FRONT WILL STALL ACROSS THE MO VALLEY WWD INTO NRN KS. THIS
PORTION OF THE BOUNDARY WILL ALSO SERVE AS A FOCUS FOR SEVERE
THUNDERSTORMS...WITH SUBSTANTIAL LOW LEVEL MOISTURE STREAMING NWD
WITH AT LEAST LOWER 60S F DEWPOINTS.

MEANWHILE...STRONG HEATING WILL OCCUR NEAR A DRYLINE WHICH WILL
EXTEND FROM WRN KS INTO W TX...WITH AREAS OF THUNDERSTORMS BY
AFTERNOON.

OVERNIGHT...AN UPPER LEVEL TROUGH WILL MOVE ACROSS THE NRN ROCKIES
WITH HEIGHT FALLS SPREADING INTO THE NRN PLAINS. LOW PRESSURE WILL
FORM OVER SD WITH AN AREA OF THUNDERSTORMS OVER THE ERN DAKOTAS
LATE.

...ERN KS...SWRN MO...FAR NERN OK AND NWRN AR...
SLY WINDS WILL BRING DEWPOINTS INTO THE LOWER 60S F NWD ACROSS OK
AND KS...BENEATH RELATIVELY COOL AIR ALOFT WITH -16 C AT 500 MB
ACROSS ERN KS. THIS WILL RESULT IN STRONG INSTABILITY BY MID
AFTERNOON ACROSS KS...OK...AND SWRN MO.

DAYTIME HEATING WILL QUICKLY ERODE CAPPING. FORCING WILL BE
SUBTLE...BUT SUFFICIENT FOR STORMS TO FORM BY EARLY TO MID AFTERNOON
ALONG THE SURFACE BOUNDARY THAT WILL LIE FROM NRN KS ESEWD INTO
CNTRL MO. SELY LOW LEVEL WINDS WILL VEER TO WLY ALOFT AND WITH
HODOGRAPHS SUFFICIENT FOR SUPERCELLS. THERMODYNAMICS WILL BE
FAVORABLE FOR PARTICULARLY LARGE HAIL. STORMS ARE THEN EXPECTED TO
TREK SEWD SLOWLY AT FIRST AND IN SUPERCELLULAR MODE...BUT MAY
EVENTUALLY MERGE OUTFLOWS AND ACCELERATE SEWD ALONG AND S OF THE
SURFACE BOUNDARY...WITH A DAMAGING WIND THREAT EXPANDING INTO WRN MO
AND NERN OK. EXACT PLACEMENT OF THIS TRACK OF THIS POTENTIAL
CORRIDOR OF SEVERE PRECLUDES HIGH PROBS AT THIS TIME.

...PA INTO SERN NY...NJ...
A LINE OF SHOWERS AND STORMS WILL BE ONGOING ALONG A COLD
FRONT...EXTENDING FROM CNTRL NY INTO WRN PA AROUND 15Z...AND WILL
RAPIDLY TRAVEL EWD TO SRN NEW ENGLAND/LONG ISLAND BY LATE AFTERNOON.
WIND FIELDS WILL BE STRONG...WITH UP TO 60 KT FLOW AROUND 700 MB.
INSTABILITY WILL BE THE LIMITING FACTOR TO A MORE SIGNIFICANT SEVERE
WEATHER DAY...AS WELL AS TIME OF DAY FOR WRN AREAS. HOWEVER...AT
LEAST ISOLATED SEVERE WIND GUSTS MAY OCCUR...ESPECIALLY BETWEEN
18-21Z FROM S-CNTRL AND ERN PA INTO MD DUE TO DOWNWARD MOMENTUM
TRANSFER.

...MUCH OF KY AND TN...WV INTO VA...
STORMS WILL EXPAND SWWD ALONG THE COLD FRONT DURING THE DAY...FROM
MD AND NRN VA WWD INTO KY. LOW LEVEL LAPSE RATES WILL STEEPEN BY
AFTERNOON HELPING THE WIND THREAT OVER MD/VA WHERE SHEAR WILL BE
FAVORABLE. FARTHER W OVER KY...INSTABILITY WILL BE STRONGER BUT
HODOGRAPHS WILL NOT BE PARTICULARLY LONG. STILL...ENOUGH SHEAR WILL
EXIST FOR MULTICELLS OR LINE SEGMENTS CAPABLE OF HAIL AND DAMAGING
WINDS. THIS ACTIVITY MAY ENTER INTO TN DURING THE EVENING WITH A
SOMEWHAT LESSER THREAT AFTER SUNSET.

...ERN DAKOTAS OVERNIGHT...
ALTHOUGH THE AREA WILL BE VOID OF STORMS FOR MOST OF THE
PERIOD...THUNDERSTORMS ARE EXPECTED TO FORM OVER THE ERN DAKOTAS
AFTER 06Z AS STRONG WARM ADVECTION AND ISENTROPIC LIFT COMMENCE WITH
A 50 KT SLY LOW LEVEL JET. STEEP LAPSE RATES ALOFT AND FAVORABLE
SHEAR IN THE CLOUD BEARING LAYER WILL CONDITIONALLY SUPPORT HAIL.

..JEWELL/COHEN.. 03/28/2012

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.

No comments: