Monday, August 25, 2008

Latest from the SPC


MESOSCALE DISCUSSION 2153
NWS STORM PREDICTION CENTER NORMAN OK
1026 AM CDT MON AUG 25 2008

AREAS AFFECTED...AL/FL PANHANDLE/WRN GA

CONCERNING...TORNADO WATCH 863...

VALID 251526Z - 251630Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 863 CONTINUES.

COUNTIES WITHIN THE TLH...FFC...AND BHM /ALONG THE ERN AND NRN
PERIPHERIES OF WW 863/ MAY BE LOCALLY ADDED TO THIS WW AS THE
THREATS FOR DAMAGING WINDS AND ISOLATED TORNADOES ADVANCES SLOWLY TO
THE E AND NNE.

TRENDS WILL CONTINUE TO BE MONITORED FARTHER N ACROSS FAR NRN AL/
NWRN GA FOR AN INCREASED SEVERE WEATHER THREAT. IF A NEW WATCH
BECOMES WARRANTED FARTHER N...THEN WW 863 WILL LIKELY BE REPLACED
WITH A NEW WW.

REGIONAL RADARS INDICATED THE MOST PERSISTENT LOW LEVEL ROTATIONAL
COUPLETS IN THE NERN QUADRANT OF FAY /OVER NERN PART OF WW 863/
WHERE LOW LEVEL WINDS ARE MORE BACKED ENHANCING LOW LEVEL SHEAR.
CORRIDOR OF RICH LOW LEVEL MOISTURE EXTENDING NWD ALONG ERN
PERIPHERY OF T.D. FAY /CENTERED OVER EAST CENTRAL MS AT 15Z/ WILL
CONTINUE TO MAINTAIN MARGINAL INSTABILITY DESPITE EXISTENCE OF
CLOUDS AND WEAK LAPSE RATES. AREA VWP DATA SHOWED A 40 KT SLY LLJ
EXTENDING NWD THROUGH AL...WITH LOW LEVEL SHEAR /EFFECTIVE SRH
100-300 M2/S2/ ENHANCED IN THE VICINITY OF THIS JET. SHORT TERM
MODELS SUGGEST THAT FAY WILL TEND TO MOVE N THEN NNEWD TODAY...WITH
ATTENDANT LLJ TRANSLATING NWD ACROSS AL INTO NERN AL THIS AFTERNOON.
THIS WOULD SUGGEST THAT LOW LEVEL SHEAR SHOULD IN TURN INCREASE AND
MAY SUPPORT A SEVERE WEATHER THREAT SHIFTING E AND NNE OF WW 863.

..PETERS.. 08/25/2008

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