Wednesday, November 16, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161302
SWODY1
SPC AC 161300

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 AM CST WED NOV 16 2011

VALID 161300Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR MS VLY/ERN GULF
CST INTO THE CAROLINAS/MID ATLANTIC...

...SYNOPSIS...
BROAD CYCLONIC FLOW OVER THE CONUS IN RECENT DAYS WILL AMPLIFY THIS
PERIOD AS JET STREAKS NOW OVER AB...MT...AND WY SWEEP RAPIDLY
SEWD...RESULTING IN A DEEP BUT PROGRESSIVE TROUGH OVER THE LWR OH
VLY BY 12Z THU. IN THE MEANTIME...UPR IMPULSE THAT CROSSED E TX
YESTERDAY WILL CONTINUE TO BECOME ABSORBED WITHIN STRONG AND FURTHER
STRENGTHENING SW FLOW OVER THE SERN STATES. THE MAIN PART OF THAT
DISTURBANCE IS OVER MS ATTM...AND SHOULD REACH PIEDMONT NC BY EARLY
EVE AS A HIGH LVL JET ENTRANCE REGION DEVELOPS OVER THE MID ATLANTIC
IN RESPONSE TO AMPLIFICATION OF LARGER SCALE TROUGH.

AT THE SFC...SEASONABLY RICH MOISTURE /WITH SFC DEWPOINTS IN THE MID
60S F AND PW AROUND 1.50 INCHES/...WILL CONTINUE TO STREAM NEWD
ACROSS GA AND THE CAROLINAS TO VICINITY OF STNRY FRONT OVER VA. SFC
WAVE NOW OVER NRN MS/AL SHOULD REDEVELOP ENE ALONG THE FRONT INTO
CNTRL VA LATER TODAY. ADDITIONAL WEAK WAVES LIKELY WILL DEVELOP
ALONG THE BOUNDARY UNTIL IT FINALLY CLEARS THE CAROLINA CST AS A
COLD FRONT LATER THU MORNING.

...LWR MS VLY/ERN GULF CST INTO CAROLINAS/MID-ATLANTIC...
BAND OF SCTD SUPERCELLS ALONG LOW LVL CONFLUENCE AXIS OVER SE LA/ERN
MS AND WRN AL LIKELY WILL PERSIST FOR AT LEAST A WHILE LONGER THIS
MORNING AS THE AXIS EDGES SLOWLY EWD IN RESPONSE TO EJECTING UPR
IMPULSE. COMBINATION OF RICH MOISTURE INFLOW AND STRONG LOW LVL
SHEAR MAY CONTINUE TO FOSTER LOW LVL ROTATION/ISOLD TORNADOES AS THE
FEATURES CROSSES AL /REF WWS 887 888/.

WITH TIME...MODEST DIURNAL HEATING MAY FOSTER REJUVENATION OF THE
CONFLUENCE AXIS STORMS. MORE LIKELY...HOWEVER...HEATING WILL
SUPPORT EVENTUAL ADDITIONAL DEVELOPMENT EAST OF THE CONFLUENCE AXIS
OVER PARTS OF GA AND THE CAROLINAS...S AND E OF SHALLOW
RAIN-REINFORCED BOUNDARY ALONG THE SRN SLOPES OF THE APPALACHIANS.
WEAKENING OF UPR IMPULSE IN CONFLUENT FLOW ALOFT SUGGESTS THAT LARGE
SCALE FORCING FOR ASCENT WILL BE WEAK. BUT COMBINATION OF EVEN WEAK
DESTABILIZATION /SBCAPE TO 1000 J PER KG/ WITH STRONG VEERING WIND
PROFILES /40 KT SW 850 MB FLOW BENEATH 60-70 KT WSW FLOW AT 500 MB/
LIKELY WILL SUPPORT SUSTAINED STORMS/SUPERCELLS. THESE MAY ORGANIZE
INTO BROKEN BANDS THAT WILL POSE A RISK FOR BOTH TORNADOES AND
NARROW SWATHS OF DMGG WIND...ESPECIALLY ACROSS APPALACHIAN
FOOTHILLS/PIEDMONT OF GA AND THE CAROLINAS/VA. ADDITIONAL CLUSTERS
OF STORMS MAY FORM TNGT THROUGH EARLY THU CLOSER TO THE CST AS LARGE
SCALE ASCENT INCREASES WITH THE DEVELOPMENT OF AFOREMENTIONED UPR
LVL JET ENTRANCE REGION.

FARTHER NW...OTHER TSTMS MAY PERSIST THROUGH THE PERIOD ALONG
MERGING COLD FRONTS OVER THE TN VLY...BUT THIS ACTIVITY SHOULD
REMAIN MARGINAL DUE TO WEAKER INSTABILITY.

..CORFIDI/ROGERS.. 11/16/2011

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