SWODY3
SPC AC 180730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI APR 18 2008
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS SUGGEST CUTOFF UPPER LOW WILL CONTINUE EAST INTO THE MID
ATLANTIC AND CAROLINAS SUNDAY WITH THE GFS BEING FARTHER NORTH THAN
THE ECMWF AND NAM SOLUTIONS. ATTENDANT COLD FRONT WILL LIKELY MOVE
OFF THE CAROLINA COASTS EARLY IN THE PERIOD WITH AN OCCLUDED FRONT
EXTENDING NWWD INTO VA. FARTHER W A LARGE UPPER LOW WILL PERSIST
OVER THE WRN STATES. A STRONG UPPER JET IS FORECAST TO ROTATE
THROUGH BASE OF UPPER TROUGH AND NWD INTO THE NRN HIGH PLAINS SUNDAY
AFTERNOON. IN WAKE OF THIS IMPULSE...A STRONG COLD FRONT WILL SURGE
EWD THROUGH THE DAKOTAS AND NEB SUNDAY EVENING AND OVERNIGHT.
...NRN HIGH PLAINS...
BOUNDARY LAYER DEWPOINTS IN THE 60S WILL BEGIN RETURNING THROUGH THE
SRN PLAINS AS STRONG SLY LOW LEVEL FLOW BECOMES ESTABLISHED EAST OF
DEVELOPING LEE LOW. FARTHER NORTH DEWPOINTS IN THE 40S...POSSIBLY
MIXING DOWN INTO THE UPPER 30S WILL BE PROBABLE OVER THE DAKOTAS.
HOWEVER...AN AXIS OF 8+ C/KM 850-500 MB STEEP LAPSE RATES WILL
ADVECT INTO THE PRE-FRONTAL WARM SECTOR AND CONTRIBUTE TO MARGINAL
INSTABILITY AS THE BOUNDARY LAYER WARMS. THE ATMOSPHERE WILL LIKELY
REMAIN CAPPED MUCH OF THE DAY. THUNDERSTORMS ARE EXPECTED TO DEVELOP
WITHIN ZONE OF DEEP ASCENT ALONG THE COLD FRONT OVER THE NRN HIGH
PLAINS BY LATE AFTERNOON THEN SHIFT EWD THROUGH THE DAKOTAS
OVERNIGHT. BULK SHEAR OF 40+ KT ASSOCIATED WITH EJECTING VORT MAX
AND ATTENDANT UPPER JET WILL RESULT IN POTENTIAL FOR SOME ORGANIZED
STORM STRUCTURES. LIMITED LOW LEVEL MOISTURE WILL CONTRIBUTE TO
RELATIVELY HIGH STORM BASES. THIS ENVIRONMENT APPEARS SUPPORTIVE OF
ISOLATED DAMAGING WIND AND LARGE HAIL WITH THE STRONGER STORMS.
GIVEN LIMITED TIME FOR MOISTURE RETURN AND LIKELIHOOD OF MARGINAL
INSTABILITY...ONLY 5% SEVERE PROBABILITIES APPEAR WARRANTED AT THIS
TIME...BUT WILL CONTINUE TO MONITOR FOR POSSIBLE SLIGHT RISK IN
LATER OUTLOOKS.
...MID ATLANTIC THROUGH ERN NC...
SCATTERED THUNDERSTORMS WILL LIKELY ONCE AGAIN DEVELOP IN VICINITY
OF THE UPPER LOW WHERE COLD AIR ALOFT...STEEP MID LEVEL LAPSE RATES
AND MARGINAL INSTABILITY WILL EXIST. SOME THUNDERSTORMS COULD BECOME
CAPABLE OF PRODUCING HAIL...ESPECIALLY IF SURFACE HEATING DEVELOPS
BENEATH THE THERMAL TROUGH. HOWEVER...UNCERTAINTY REGARDING EXTENT
OF CLOUDS AND TRACK OF UPPER LOW PRECLUDES INTRODUCING PROBABILITIES
AT THIS TIME.
..DIAL.. 04/18/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment