SWODY2
SPC AC 071735
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1135 AM CST MON MAR 07 2011
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS FOR ERN PARTS OF THE SRN PLAINS
TO THE LOWER/MID MS VALLEY...
...SYNOPSIS...
PROGRESSIVE UPPER-LEVEL SHORTWAVE TROUGH DIGGING SEWD OVER THE SWRN
CONUS MONDAY MORNING WILL MOVE DOWNSTREAM ACROSS THE SRN PLAINS
DURING TUE AFTERNOON...ACCOMPANIED BY STRONG 70 KT MIDLEVEL
JET...AND THEN EJECT NEWD INTO THE MID MS VALLEY BY 09/12Z. AS THIS
OCCURS...SURFACE LOW IS FORECAST TO PROGRESS ACROSS OK THROUGH TUE
AFTERNOON...AND THEN MOVE NEWD ACROSS MO DURING THE OVERNIGHT HRS. A
MODIFIED CP AIRMASS WILL BE DRAWN NWD IN RESPONSE TO THE SURFACE
CYCLONE...BOUNDED BY A DRYLINE TRAILING SWD ACROSS TX...AND A
RETREATING WARM FRONT...WHICH IS FORECAST TO RAPIDLY LIFT NWD INTO
SRN AR BY 09/00Z.
...AR DURING THE MORNING AND AFTERNOON...
AS THE LOW-LEVEL CYCLONE ATTENDANT TO THE UPPER TROUGH EMERGES OVER
THE SRN PLAINS...40-50 KT SLY 850 MB JET WILL DEVELOP OVER THE LWR
MS VALLEY BY LATE MORNING. THIS WILL RESULT IN ROBUST LOW-LEVEL
WAA/MOISTURE ADVECTION ABOVE A STABLE BOUNDARY LAYER
AIRMASS...AIDING IN DESTABILIZATION AND MUCAPE VALUES NEAR 500 J/KG
ACROSS AR AS MIDLEVEL LAPSE RATES STEEPEN TO 7.0-7.5 C/KM. GIVEN
SWLY 500 MB FLOW INCREASING TO 60 KT COMBINED WITH DEEPENING FREE
CONVECTIVE LAYER...EFFECTIVE BULK SHEAR VALUES NEAR 40 KT APPEAR
PROBABLE...WHICH MAY SUPPORT MARGINALLY SVR HAIL ACROSS AR THROUGH
MID AFTERNOON.
...ERN OK/NERN TX EWD TO OZARKS/MID SOUTH...
FARTHER W...NARROW WEDGE OF MID TO UPR 50S DEWPOINTS ARE FORECAST TO
ADVECT NWD BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES OVER
CNTRL/ERN OK BY MID TO LATE AFTERNOON. MEANWHILE...A ZONE OF STEEP
LOW-LEVEL LAPSE RATES WILL DEVELOP NEWD ACROSS SWRN OK BEHIND THE
DRYLINE AND AHEAD OF A COLD FRONT OVER W-CNTRL AND N-CNTRL OK. THIS
SHOULD PROVE SUFFICIENT FOR THE DEVELOPMENT OF A CORRIDOR OF MLCAPE
VALUES FROM 500-1000 J/KG. STRONGEST LOW-LEVEL CONVERGENCE IS
EXPECTED FROM THE TRIPLE POINT N-NEWD ALONG THE COLD FRONT OVER
N-CNTRL/NERN OK...WHICH WILL AID IN THUNDERSTORM INITIATION DURING
THE AFTERNOON. DUE TO AN INCREASINGLY NARROW ZONE OF INSTABILITY
WITH NWD EXTENT...STORMS MAY STRUGGLE TO PERSIST N OF I-40.
HOWEVER...A STRONGLY SHEARED ENVIRONMENT JUXTAPOSED WITH STEEP
MIDLEVEL LAPSE RATES MAY FAVOR A FEW SVR STORMS PRODUCING LARGE HAIL
AND DAMAGING WIND GUSTS.
FARTHER S ALONG THE DRYLINE OVER SERN OK/NERN TX...FORCING FOR
ASCENT WILL BE WEAKER...WHICH MAY DELAY INITIATION UNTIL LATE
AFTERNOON. THE POTENTIAL FOR AN INITIALLY DISCRETE CONVECTIVE
MODE...COMBINED WITH INCREASING DOWNSTREAM DESTABILIZATION...WILL
FAVOR LONGER-LIVED STORMS...LIKELY SUPERCELLS GIVEN STRONG DEEP
LAYER SHEAR /0-6 KM BULK SHEAR AOA 60 KT/ SPREADING ACROSS THE
DRYLINE. THIS ACTIVITY SHOULD MOVE QUICKLY E-NEWD INTO AN EXPANDING
WARM SECTOR OVER NRN LA AND SRN AR...AND WILL POSE A THREAT FOR
LARGE HAIL/DAMAGING WINDS AND TORNADOES.
THE FORECAST POSITION OF THE WARM FRONT IS NOT CERTAIN ATTM DUE TO
THE POTENTIAL FOR PERSISTENT CONVECTION AND SUBSEQUENT COLD POOL
REINFORCEMENT. HOWEVER...ADDITIONAL STORM DEVELOPMENT WILL BE
POSSIBLE ALONG THE BOUNDARY OVER AR GIVEN A FAVORABLE ORIENTATION OF
THE LLJ ACROSS THE FRONT...AIDING IN MESOSCALE ASCENT. LOW-LEVEL
VERTICAL WIND SHEAR WILL BE QUITE STRONG /EFFECTIVE SRH VALUES IN
EXCESS OF 300 M2 S-2/ OVER SRN AR/NRN LA...AND WILL FAVOR A FEW
TORNADIC STORMS /POSSIBLY PRODUCING STRONG TORNADOES/ ASSOCIATED
WITH EITHER THE ACTIVITY MOVING OUT OF SERN OK/NERN TX...OR NEW
DEVELOPMENT INVOF THE WARM FRONT. OVERNIGHT...THE UPPER TROUGH AND
SURFACE COLD FRONT WILL PROGRESS ACROSS AR AND SRN MO. INCREASING
LINEAR FORCING FOR ASCENT WILL FAVOR A TRANSITION TO A QUASI-LINEAR
CONVECTIVE MODE...POSING A CONTINUED THREAT FOR DAMAGING WINDS AND
TORNADOES.
...E TX AND LOWER MS VALLEY...
FARTHER S OVER ERN TX...THUNDERSTORM INITIATION IS SOMEWHAT IN
QUESTION GIVEN A PERSISTENT CAP NOTED IN MODEL FORECAST SOUNDINGS.
HOWEVER...IF A FEW STORMS MANAGE TO DEVELOP...THE POTENTIAL WILL
EXIST FOR DAMAGING WINDS AND LARGE HAIL. OVER LA/MS...STRONG UPPER
DIVERGENCE/LARGE-SCALE ASCENT IS FORECAST TO DEVELOP FROM SRN LA
ACROSS SWRN MS. THUNDERSTORMS ARE EXPECTED TO FORM WITHIN THIS
REGIME BY LATE AFTERNOON THROUGH THE NIGHT...FOCUSED ALONG AND AHEAD
OF A SW-NE ORIENTED LOW-LEVEL CONVERGENCE ZONE...AS WELL AS ALONG
THE SRN EXTENSION OF THE WARM FRONT. A VERY MOIST BOUNDARY LAYER
/SURFACE DEWPOINTS IN THE MID 60S/ AND MODERATELY STEEP MIDLEVEL
LAPSE RATES WILL SUPPORT MLCAPE VALUES AROUND 1000 J/KG. IN
ADDITION...STRONG VERTICAL WIND SHEAR PROFILES WILL BE IN
PLACE...WITH EFFECTIVE SRH NEAR 400 M2 S-2 /PARTICULARLY NEAR THE
WARM FRONT/. THE STRONGLY SHEARED AND MOIST ENVIRONMENT WILL FAVOR
SUPERCELLS POSING A THREAT FOR TORNADOES /POSSIBLY SIGNIFICANT/ AND
DAMAGING WINDS.
..GARNER/EDWARDS.. 03/07/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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