SWODY1
SPC AC 221259
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0659 AM CST SUN JAN 22 2012
VALID 221300Z - 231200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF AR...MS...AND AL
NWD THROUGH SE MO...WRN TN...AND WRN KY INTO SRN IL AND SRN IND...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM THE CNTRL GULF CST NEWD INTO PARTS OF OH...
...SYNOPSIS...
...A REGIONAL SEVERE WEATHER EVENT LIKELY TO OCCUR FROM THE LWR MS
VLY NEWD INTO PARTS OF THE MID MS...TN...AND LWR OH VLYS THIS EVE
THROUGH EARLY MON...
POTENT UPR TROUGH NOW OVER THE CNTRL/SRN RCKYS WILL MOVE E INTO ERN
KS/OK THIS EVE...BEFORE ASSUMING A NEGATIVE TILT AND ACCELERATING
ENE ACROSS THE MID MS...LWR OH...AND TN VLYS TNGT AND EARLY MON.
ASSOCIATED SFC LOW WILL TRACK E ACROSS KS TODAY...BEFORE TURNING NE
ACROSS NRN MO AND IA TNGT...AND INTO WI EARLY MON.
AHEAD OF THE LOW AND TROUGH...SATELLITE AND VWP DATA ATTM SHOW BROAD
50+ KT SSWLY LLJ EXPANDING NWD ACROSS ERN PARTS OF THE PLNS. THIS
JET WILL EXPAND FARTHER E ACROSS THE MID MS AND TN VLYS TODAY...WITH
STRONG MOISTURE ADVECTION OCCURRING ATOP SHALLOW SURFACE-BASED LAYER
OF COLD AIR OVER THE REGION.
STRONG TSTMS SHOULD FORM LATE THIS AFTN OR EARLY THIS EVE FROM IL
SSW INTO PARTS OF MO/AR AND LA...ALONG LEAD COLD FRONT TRAILING SWD
FROM THE LOW. GIVEN VERY STRONG WIND FIELD ASSOCIATED WITH THE UPR
TROUGH AND INCREASINGLY WARM/MOIST LOW LVL ENVIRONMENT ALONG/AHEAD
OF FRONT...THE STORMS WILL HAVE THE POTENTIAL TO PRODUCE STRONG
TORNADOES IN ADDITION TO DMGG WIND AND HAIL AS THEY MOVE/DEVELOP E
AND NE ACROSS THE TN AND LWR OH VLYS THROUGH 12Z MON.
...LWR MS VLY NWD AND EWD INTO THE TN AND LWR OH VLYS LATE TODAY
THROUGH EARLY MON...
SFC DEWPOINTS IN THE LOW TO MID 60S F SHOULD EXTEND NWD TO THE MO
BOOTHEEL BY LATE TODAY GIVEN STRONG/PERSISTENT LOW LVL WAA/MOISTURE
TRANSPORT. COUPLED WITH MODEST SFC HEATING...THIS SHOULD RESULT IN
AN AXIS OF MODERATE INSTABILITY THAT WILL REACH SSWWD ACROSS ERN/SRN
AR INTO MS/LA. TSTMS SHOULD FORM ALONG THE NW EDGE OF THIS
INSTABILITY AXIS LATE THIS AFTN...AND SHOULD QUICKLY EXPAND IN
COVERAGE BOTH NWD AND SWD AS LEAD SFC COLD FRONT OVERTAKES MOIST
AXIS AND CONTINUES EWD. WITH TIME...AN EXTENSIVE SQLN SHOULD EVOLVE
FROM THE LWR OH VLY SSW INTO AR/NW MS/LA.
70 TO 90 KT MID LVL JET OVERSPREADING REGION SHOULD SUPPORT AT LEAST
A FEW LONGER-LIVED SUPERCELLS. LOW LVL SRH SHOULD MAXIMIZE OVER
PARTS OF AR...SE MO...WRN TN AND NRN MS...ON SRN FRINGE OF
RETREATING SHALLOW COOL AIR LAYER. GIVEN COMPARATIVELY GREATER
SFC-BASED INSTABILITY IN THIS REGION...POTENTIAL WILL EXIST FOR
STRONG TORNADOES....ESPECIALLY THROUGH EARLY EVENING. TORNADOES
WILL ALSO BE POSSIBLE THROUGH EARLY MON E/SE INTO PARTS OF ERN MS
AND AL AS EXISTING STORMS AND STRENGTHENING WIND FIELD ENCOUNTER
MORE SLOWLY-RETREATING PART OF WEDGE AIR MASS IN THAT REGION.
FARTHER N...THE MORE SIGNIFICANT SVR THREAT SHOULD BE DMGG WINDS AS
THE DEVELOPING SQLN AND TURBULENT MIXING ENCOURAGE DOWNWARD
TRANSPORT OF STRONG LWR TROPOSPHERIC FLOW...EVEN IN REGIONS OF
NEAR-ZERO SFC-BASED CAPE. THIS THREAT MAY CONTINUE...AT LEAST ON A
SPORADIC BASIS...NWD AND EWD INTO PARTS OF OH AND TO THE WRN SLOPES
OF THE CNTRL/SRN APPALACHIANS EARLY MON.
IN THE MEAN TIME...A CONDITIONAL RISK WILL EXIST FOR A FEW STRONG
STORMS OVER PARTS OF AL AND WRN GA TODAY...WHERE SFC HEATING AND
ASCENT WITH WEAK LEAD UPR IMPULSE MAY SUPPORT SCTD STORM.
ENVIRONMENT MAY PROVE FAVORABLY MOIST...UNSTABLE...AND SUFFICIENTLY
SHEARED TO POSE A THREAT FOR AN ISOLD TORNADO.
..CORFIDI/SMITH.. 01/22/2012
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