Wednesday, February 06, 2008

MESOSCALE DISCUSSION 0175


MESOSCALE DISCUSSION 0175
NWS STORM PREDICTION CENTER NORMAN OK
0241 AM CST WED FEB 06 2008

AREAS AFFECTED...PORTIONS SRN/ERN MS...WRN/CENTRAL/NRN
AL...MIDDLE-ERN TN.

CONCERNING...TORNADO WATCH 41...43...

VALID 060841Z - 061045Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 41...43...CONTINUES.

ADDITIONAL WW ISSUANCES ARE PROBABLE BEFORE THESE WOULD EXPIRE AT
11Z. TORNADO THREAT PERSISTS ACROSS WW AREAS AND SHOULD FOR AT LEAST
ANOTHER 2-3 HOURS...WITH GREATEST POTENTIAL FOR LONG-LIVED/DAMAGING
TORNADOES ACCOMPANYING DISCRETE SUPERCELLS DEVELOPING AHEAD OF
PRIMARY CONVECTIVE BAND. SHORTER-LIVED/WEAKER TORNADOES ALSO ARE
POSSIBLE WITH PRIMARY TSTM LINE...FROM WHICH DAMAGING GUSTS WILL BE
PRIMARY THREAT.

AREA E OF THESE WWS ACROSS ERN TN AND MOST OF NWRN GA MAY REMAIN
CONSIDERABLY MORE STABLE AND LESS FAVORABLE FOR SUPERCELL TORNADOES
THAN FARTHER W...BUT WITH DAMAGING WIND POSSIBLY ACCOMPANYING MAIN
TSTM BAND. AIR MASS RECOVERY ACROSS PORTIONS NERN/CENTRAL/SRN AL
MAY COMPEL ADDITIONAL/REPLACEMENT TORNADO WW ISSUANCE FOR THOSE
AREAS BEFORE PRESENT WW 41 EXPIRES.

MODIFIED RAOBS AND RUC SOUNDINGS INDICATE EFFECTIVE INFLOW PARCELS
REMAIN ROOTED NEAR GROUND FOR SFC THETAE VALUES CORRESPONDING TO
TEMPS AROUND 65 F AND DEW POINTS AOA ABOUT 63 F. SFC MESOANALYSIS
SHOWS THIS AIR MASS ALREADY COVERING LARGE PART OF AL...NARROWING
NWD OVER MID TN FROM CSV AREA WWD TO MAIN CONVECTIVE BAND. THIS
SUPPORTS MLCAPES RANGING FROM LESS THAN 200 J/KG OVER MID TN TO
5000-800 J/KG RANGE OVER SERN MS AND SWRN AL. KINEMATIC PROFILES
WILL REMAIN VERY STRONG...WITH ELONGATED HODOGRAPHS YIELDING 0-1 KM
SRH EXCEEDING 300 J/KG IN MANY AREAS...AND EFFECTIVE SHEAR 50-60 KT.

No comments: