Severe Thunderstorm Warning 148, NWS Mobile, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
310 PM CDT SAT AUG 18 2001

SHORT TERM...PERSISTENCE SEEMS TO BE A FAIR FORECAST...WITH SCT
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH MONDAY.  ONE IN A SERIES
OF UPPER LEVEL SHORTWAVES MOVING THROUGH THE BASE OF THE BROAD 500
MB TROF TO THE WEST GENERATING AN AREA OF SHOWERS AND THUNDERSTORMS
FROM NORTHERN LA TO CENTRAL MS AT THIS TIME...MOVING EAST.  AHEAD OF
IT...SCT SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER OUR REGION
CLOSER TO THE COAST.

THIS IS SOMEWHAT LIKE WHAT WE HAVE SEEN PAST 2 DAYS...EXCEPT WE ARE
SLIGHTLY DRIER ALOFT TODAY.  ISOLATED SEVERE STORMS ARE POSSIBLE
THROUGH 03Z.  DIURNALLY DRIVEN BY DAYTIME HEATING...AND CURRENT POP
REGIME HAS THIS HANDLED.  SOME ISOLATED STORMS INLAND COULD PERSIST
OVERNIGHT CLOSER TO THE MAIN UPPER SUPPORT.  A FEW STORMS INLAND
TOMORROW AFTERNOON COULD AGAIN GET HEFTY...AND SPC HAS THE AREA JUST
NORTH OF OUR FORECAST ZONES OUTLOOKED FOR SLIGHT RISK SEVERE.

THE ETA AND AVN ARE IN SOME DISAGREEMENT ON BRINGING DOWN A
WEAKENING COLD FRONT IN THE MON-TUE TIMEFRAME AS THE UPPER SYSTEM
TRANSITIONS ACROSS.  ETA STALLS IT WELL INLAND BY 60 HOURS WHILE THE
AVN BRINGS IT TO THE MOB-PNS AREA BY 12Z TUE.  OF COURSE THE AVN IS
MORE PRONOUNCED IN THE BOUNDARY LAYER DRYING WHILE THE ETA DRIES OUT
THE MID/UPPER MOISTURE HOLDING ON TO MOISTURE BELOW 850 MB.  FOR
NOW...WE WILL STALL THE SURFACE FRONT OVER OUR NORTHERN ZONES BY TUE
MORNING...BUT WILL DROP POPS BACK TO LOW END CATEGORIES SCATTERED
CATEGORIES TUE AND WED AS WE SHOULD SEE SOME DRYING ALOFT TO DROP
COVERAGES.  WE DO THIS BECAUSE THE MAIN UPPER SYSTEM MOVES EAST AND
NOT MUCH EXPECTED TO DRIVE THE BOUNDARY WELL OFFSHORE.

EXTENDED RANGE...STILL SOME QUESTION AS TO THE FATE OF CHANTAL
CURRENTLY MOVING ACROSS THE CARRIBEAN.  WHILE NOT A BIG CONCERN FOR
OUR REGION RIGHT NOW...IT IS A STORM IN THE CARRIBEAN ALBEIT IT
POORLY PUT TOGETHER RIGHT NOW.  NHC/NCEP FORECASTS KEEP CHANTAL WELL
SOUTH AND WEST OF OUR REGION THROUGH THE 7 DAY PERIOD...BUT THEY DO
STRENGTHEN IT TO A MINIMAL HURRICANE...AND SOME OF THE MODELS HAVE
SHOWN A NORTHWARD TREND AFTER 72 HOURS.  IF IT STAYS ORGANIZED AND
GETS INTO THE GULF IT WILL OF COURSE BEAR WATCHING.  FOR NOW WE WILL
JUST BRING THE FORECAST BACK TO THE SCT SHOWER/THUNDERSTORM MENTION
THU THROUGH SAT.  THATS MORE TO DO WITH SOME RETURN MOISTURE AND A
TREND BACK TOWARD CLIMO.  THERE ARE MANY VARIABLES AT PLAY IN THE
EXTENDED FORECAST...STAY TUNED.

/05

PRELIM CCF NUMBERS...
MOB TE 074/092 073/092 072 053623
PNS TE 076/091 076/091 073 053623
DTS TE 079/089 079/089 XXX 053623
GZH EE 072/092 071/093 XXX 053622
2R0 TE 071/093 067/093 XXX 053622
61A TE 071/093 068/093 XXX 053622

.MOB...
AL...NONE.
FL...NONE.
MS...NONE.