SWODY1
SPC AC 230504
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1204 AM CDT FRI SEP 23 2011
VALID 231200Z - 241200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT THE UPPER MIDWEST CLOSED LOW WILL BECOME
CUT-OFF FROM THE STRONGER WESTERLIES DURING THIS PERIOD. THE CENTER
OF THE LARGE CYCLONIC CIRCULATION ENCOMPASSING MUCH OF THE CENTRAL
AND EASTERN U.S. IS EXPECTED TO SHIFT INTO NORTHERN ILLINOIS BEFORE
BEGINNING TO RETROGRADE LATE FRIDAY NIGHT INTO SATURDAY. UPSTREAM
...MID/UPPER RIDGING LIKELY WILL PERSIST ACROSS EASTERN PORTIONS OF
THE INTERMOUNTAIN WEST AND ROCKIES...WHILE A TROUGH CONTINUES TO
SLOWLY LIFT NORTHWARD NEAR THE SOUTHERN AND CENTRAL CALIFORNIA
COAST...AHEAD OF A LARGER AND MUCH MORE SIGNIFICANT TROUGH SHIFTING
EASTWARD WITHIN THE WESTERLIES...ACROSS THE EASTERN PACIFIC.
THE EVOLVING PATTERN DOES NOT APPEAR ANY MORE CONDUCIVE TO
SIGNIFICANT DESTABILIZATION THAN THE PAST FEW DAYS...BUT POTENTIAL
FOR CONVECTION AND SCATTERED THUNDERSTORM ACTIVITY WILL CONTINUE
AHEAD OF A COLD FRONT ASSOCIATED WITH UPPER LOW AND TROUGH IN THE
EAST. A FEW THUNDERSTORMS MAY ALSO ACCOMPANY THE CALIFORNIA
IMPULSE.
...WRN SLOPES OF THE CNTRL APPALACHIANS INTO LWR GREAT LAKES...
STRENGTHENING SOUTHWESTERLY MID/UPPER FLOW...COUPLED WITH FORCING
AND LOW-LEVEL SHEAR ASSOCIATED WITH A WEAK FRONTAL WAVE PROGGED TO
LIFT NORTHWARD ACROSS THE REGION...MAY ENHANCE CONVECTIVE POTENTIAL
TODAY. WITH THE MID-LEVEL COLD CORE REMAINING GENERALLY UPSTREAM OF
THE WARM SECTOR...LAPSE RATES ARE NOT EXPECTED TO STEEPEN
SUBSTANTIALLY. HOWEVER...GUIDANCE IS SUGGESTIVE THAT BREAKS IN
CLOUD COVER COULD ALLOW FOR ENOUGH BOUNDARY LAYER WARMING TO SUPPORT
MIXED LAYER CAPE UP TO AROUND 500 J/KG. IF THIS OCCURS...ORGANIZED
CONVECTIVE DEVELOPMENT DOES NOT APPEAR OUT OF THE
QUESTION...INCLUDING A LOW RISK FOR STRONG/SEVERE STORMS.
...LEE OF THE CENTRAL APPALACHIANS...
MODELS SUGGEST THAT SOUTHERLY LOW-LEVEL FLOW WILL BECOME MODERATELY
STRONG /30-40+ KTS AT 850 MB/ TODAY IN A BELT NEAR THE MID ATLANTIC
COAST...ON THE WESTERN PERIPHERY OF RIDGING OVER THE WESTERN
ATLANTIC. GIVEN AT LEAST WEAK CONDITIONAL INSTABILITY WITHIN A
PLUME OF HIGH MOISTURE CONTENT AIR /CHARACTERIZED BY PRECIPITABLE
WATER IN EXCESS OF 2 INCHES AND 70F+ SURFACE DEW
POINTS/...ENLARGING...CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS APPEAR
SUPPORTIVE OF LOW POTENTIAL FOR STORMS CAPABLE OF PRODUCING DAMAGING
WINDS...PERHAPS ISOLATED TORNADOES. HOWEVER...MUCH WILL DEPEND ON
THE EXTENT OF THE BOUNDARY LAYER DESTABILIZATION...WHICH REMAINS
UNCLEAR DUE TO THE POTENTIAL FOR CONSIDERABLE CLOUD COVER AND
ASSOCIATED AREAS OF PRECIPITATION.
..KERR.. 09/23/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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:
Post a Comment