DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271245
SWODY1
SPC AC 271243

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 AM CDT THU SEP 27 2012

VALID 271300Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SRN AND CNTRL
HI PLNS...

...SYNOPSIS...
WEAK TO MODERATE TWO-STREAM ZONAL FLOW WILL PREVAIL OVER MUCH OF THE
LWR 48 TODAY...WITH THE STRONGEST BAND OF WINDS CONTINUING ALONG THE
SRN FRINGE OF BROAD/PERSISTENT CYCLONE OVER ONT/QUE.

AS THE LEAD IMPULSE IN THE CYCLONE LIFTS NE TOWARD
NEWFOUNDLAND...UPSTREAM VORT NOW OVER NE MB SHOULD AMPLIFY SE TO
JAMES BAY. THIS...IN TURN...WILL HELP ACCELERATE A SERIES OF
DISTURBANCES IN THE WEAKER SRN STREAM JET EWD ACROSS THE OH
VLY/CNTRL APPALACHIANS...AND NUDGE THE ASSOCIATED W-E SFC FRONT SWD.
BOTH THE FRONT AND THE DISTURBANCES MAY FOSTER A FEW STRONG STORMS
FROM PARTS OF THE OH VLY TO THE MID ATLANTIC CST LATER TODAY.
ELSEWHERE...THE WRN END OF THE SAME BOUNDARY MAY SERVE AS A FOCUS
FOR SCTD STRONG TO SVR STORMS AS THE FRONT REMAINS QSTNRY OVER PARTS
OF OK...TX...CO...AND NM BENEATH BELT OF ENHANCED SRN STREAM FLOW
ALOFT.

...S CNTRL HI PLNS THIS AFTN/EVE...
IN WAKE OF OVERNIGHT CONVECTIVE CLUSTERS...DAYTIME HEATING SHOULD
INDUCE REDEVELOPMENT OF MOIST...SELY...LOW-LVL UPSLOPE FLOW INVOF
STALLED FRONT FROM ERN CO SWD INTO E CNTRL NM. COUPLED WITH STEEP
MID-LVL LAPSE RATES AND 25-30 KT WLY 500 MB FLOW ASSOCIATED WITH SRN
STREAM JET...SETUP SHOULD PROVE FAVORABLE FOR THE DEVELOPMENT OF
SCTD STRONG TO SVR STORMS BY MID TO LATE AFTN.

LOW-LVL WINDS LIKELY WILL REMAIN WEAK. BUT A SIZABLE DIRECTIONAL
COMPONENT TO THE SHEAR WILL EXIST IN THE LWR LVLS...AND AMPLE DEEP
SHEAR WILL BE PRESENT FOR SUSTAINED UPDRAFTS. THUS...ISOLD
SUPERCELLS WITH LARGE HAIL AND LOCALLY DMGG WIND MAY
OCCUR...ESPECIALLY IN SE CO...FAR NE NM...AND THE WRN OK PANHANDLE.
THIS ACTIVITY MAY EVOLVE INTO ONE OR MORE ESE TO SE-MOVING CLUSTERS
BY EVE...WITH A CONTINUING THREAT FOR SVR HAIL AND WIND SEWD INTO
THE TX PANHANDLE.

...ERN OK/OZARKS THROUGH THE LWR OH/TN VLYS TO THE MID-ATLANTIC CST
THIS AFTN...
A RESIDUAL BAND OF ENHANCED WLY FLOW WILL PERSIST TODAY FROM OK/AR
E/ENE TO THE MID ATLANTIC CST...MORE OR LESS PARALLEL TO
AFOREMENTIONED SFC FRONT. THESE WINDS WILL...HOWEVER...BE DIMINISHED
RELATIVE TO YESTERDAY...ESPECIALLY OVER THE OH VLY AND CNTRL
APPALACHIANS. IN ADDITION...IT ALSO APPEARS THAT MID-LVL LAPSE RATES
ACROSS THIS CORRIDOR WILL BE SOMEWHAT WEAKER IN COMPARISON TO RECENT
DAYS.

NEVERTHELESS...A SERIES OF DISTURBANCES IN THE SRN STREAM...IN
CONJUNCTION WITH DAYTIME HEATING AND UPLIFT ALONG OUTFLOW
BOUNDARIES/FRONT...MAY SUPPORT INTENSIFICATION OF ONGOING STORMS
OVER THE OZARKS AND LWR OH/TN VLYS. OTHER STORMS MAY FORM OVER THE
HIGHER TERRAIN IN TN/WV/VA/MD...AND ALONG LEE TROUGH IN THE
CHESAPEAKE BAY REGION. THE MORNING RAOB DATA...AND PRE-FRONTAL CLOUD
COVER...SUGGEST THAT OVERALL SVR RISK IS TOO LOW/UNFOCUSED ATTM TO
WARRANT A CATEGORICAL UPGRADE TO SLIGHT RISK. HOWEVER...IT REMAINS A
POSSIBILITY THAT PARTS OF TN/ERN KY/WV/VA AND MD/DE ULTIMATELY MAY
REQUIRE AN UPGRADE IF DISTURBANCE NOW CROSSING IND PROVIDES
SUFFICIENT ASCENT TO FOCUS STORM DEVELOPMENT OVER THE REGION LATER
THIS AFTN.

..CORFIDI/GRAMS.. 09/27/2012

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.