SPC AC 220656
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CST TUE DEC 22 2015
VALID 231200Z - 241200Z
...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF THE MID-SOUTH
AND TN VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENH FROM PARTS
OF THE LOWER GREAT LAKES REGION TO THE CNTRL GULF COAST...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT FROM PARTS
OF THE LOWER GREAT LAKES REGION TO THE CNTRL GULF COAST...
...SUMMARY...
THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL EXTEND FROM THE CENTRAL
GULF COAST TO THE LOWER GREAT LAKES REGION ON WEDNESDAY INTO
WEDNESDAY NIGHT. THE GREATEST POTENTIAL FOR SEVERE THUNDERSTORMS IS
FORECAST FROM PORTIONS OF THE MID-SOUTH REGION TO THE TENNESSEE
VALLEY...WHERE TORNADOES...SOME POSSIBLY SIGNIFICANT...ALONG WITH
DAMAGING WINDS AND HAIL WILL BE POSSIBLE.
...SYNOPSIS...
WITHIN A BELT OF BROADLY CYCLONIC MID-LEVEL FLOW COVERING MUCH OF
THE WRN TWO-THIRDS OF THE CONUS...A SHORTWAVE TROUGH IS FORECAST TO
QUICKLY PROGRESS FROM THE SRN GREAT PLAINS TO THE GREAT LAKES
REGION. AS THIS OCCURS...A SFC CYCLONE WILL DEVELOP NEWD FROM THE
CNTRL GREAT PLAINS TO LAKE SUPERIOR...WITH A STRONG LLJ IN THE WARM
SECTOR ATTENDANT TO THE SFC CYCLONE. THIS WILL ENCOURAGE INLAND
FLUXES OF GULF-MODIFIED MOISTURE...WITH A BROAD CORRIDOR OF 60S SFC
DEWPOINTS BECOMING ESTABLISHED ACROSS THE SERN QUARTER OF THE CONUS
EXTENDING AS FAR N AS THE OHIO VALLEY. THE WRN EXTENT OF THE RICHER
MOISTURE WILL BE MARKED BY A BOUNDARY EXTENDING SWWD FROM THE
AFOREMENTIONED SFC LOW TO S TX.
...CNTRL GULF COAST TO THE OHIO VALLEY...
AS THE BROAD WARM/MOIST SECTOR BECOMES ESTABLISHED FROM PORTIONS OF
THE GREAT LAKES REGION TO THE CNTRL GULF COAST AND COINCIDES WITH
AMPLE DEEP SHEAR...A LONG-DURATION/SPATIALLY EXTENSIVE SVR RISK WILL
EXIST THROUGH THE D2/WED PERIOD. MULTIPLE CORRIDORS OF STRONG TO SVR
TSTMS WILL BE LIKELY ACROSS THE WARM SECTOR...FOCUSED IN A VARIETY
OF REGIMES. DCVA PRECEDING THE SHORTWAVE TROUGH AND RELATED
DESTABILIZATION WILL ENHANCE TSTM ACTIVITY FROM PARTS OF THE MID-MS
VALLEY TO PORTIONS OF THE LOWER GREAT LAKES AND OHIO VALLEY
REGION...WHERE BUOYANCY WILL BE RELATIVELY MARGINAL.
MEANWHILE...AMPLE LOW-LEVEL MOISTURE CHARACTERIZED BY LOWER/MIDDLE
70S SFC DEWPOINTS CURRENTLY RESIDES OFF THE GULF COAST. GIVEN
ANTICIPATED NWD TRANSPORT OF THE RICH MOISTURE...AT LEAST ISOLATED
SVR TSTMS WILL BE POSSIBLE SWD TO THE GULF COAST THROUGH THE PERIOD.
THE OVERLAP OF STRONGER DEEP ASCENT PERIPHERAL TO THE SHORTWAVE
TROUGH...AND MLCAPE OF 500-1250 J/KG AIDED BY SFC DEWPOINTS AROUND
63-66F...IS FORECAST TO EXIST FROM PARTS OF THE LOWER MS VALLEY TO
THE TN VALLEY AND VICINITY DURING PEAK HEATING. WITH AT LEAST
POCKETS OF INSOLATION SUPPORTING STEEPENING LOW-LEVEL LAPSE RATES
ACROSS THIS AREA...AND AN INFLUX OF MODESTLY STEEP MID-LEVEL LAPSE
RATES...DIURNAL SUPERCELL DEVELOPMENT WILL BE MORE LIKELY IN THIS
REGION. THIS WILL BE AIDED BY 50-60 KT OF DEEP SHEAR ORIENTED WITH
AT LEAST SOME ORTHOGONAL COMPONENT TO THE SFC BOUNDARY. WITH 60-70
KT OF H7 FLOW ABOVE 45-55 KT OF H85 FLOW...LOW-LEVEL SHEAR WILL BE
ADEQUATE FOR TORNADOES...SOME POTENTIALLY SIGNIFICANT. DMGG WIND
GUSTS AND HAIL MAY ALSO ACCOMPANY THIS ACTIVITY. SVR-TSTM POTENTIAL
WILL BE MORE ISOLATED FARTHER S TOWARD THE GULF COAST AS DEEP ASCENT
WILL BE MORE LACKING...THOUGH STRONGER INSTABILITY WILL BE AIDED BY
RICHER LOW-LEVEL MOISTURE IN PROXIMITY TO THE COAST.
THE SVR TSTM POTENTIAL -- INCLUDING RISK FOR TORNADOES AND DMGG
WINDS -- WILL SPREAD EWD/ENEWD ACROSS THE RISK AREAS THROUGH WED
NIGHT. SVR TSTM POTENTIAL MAY LAST WELL INTO THE OVERNIGHT HOURS
FROM THE TN VALLEY SWD...WHERE NOCTURNAL GAINS IN MLCINH WILL BE
LIMITED BY THE RETURNING LOW-LEVEL MOISTURE.
..COHEN.. 12/22/2015
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
| 
)
