000
FXUS66 KMTR 201751
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
945 AM PST THU NOV 20 2008
.DISCUSSION...SKIES ACROSS THE DISTRICT ARE PARTLY TO MOSTLY CLOUDY.
THERE HAS BEEN A FEW LIGHT RAIN SHOWERS IN THE NORTH BAY...WITH QPF
TOPPING OFF AT ONLY A COUPLE HUNDREDS. SATL IMAGERY IS INDC A
WEAKENING COLD FRONT MOVING MOVING ACROSS THE PACIFIC NW AND
NORTHWEST CALIFORNIA. WATER VAPOR IMAGERY ALSO INDC A SHORTWAVE NR
30/128 MOVING ENE. AMSU IMAGERY AS WELL AS LONG RANGE LIGHTNING
DATA INDC THAT THIS FEATURE IS MAINLY MID AND HIGH LEVEL CLOUDS.
MODELS ARE INDC THAT A COUPLE OF SHORTWAVES WILL MOVE ACROSS THE
PACIFIC NORTHWEST THE NEXT COUPLE OF DAYS. THESE SYSTEMS WILL
REMAIN TO THE NORTH OF THE DISTRICT WITH ANY RAIN STAYING TO THE
NORTH. WEAK RIDGING LATE SATURDAY AND SUNDAY WILL CONTINUE THE DRY
WEATHER. BOTH THE GFS AND THE ECMWF SHEAR OFF A CUTOFF LOW MONDAY
WELL WEST OF THE COAST. HOWEVER...AFTER MONDAY THERE CONTINUES TO
BE LARGE DIFFERENCES BETWEEN THE MODELS...AS WELL AS LARGE RUN TO
RUN DIFFERENCES FOR EACH MODEL. FOR NOW...WILL WAIT TO SEE THE 12Z
ECMWF BEFORE CONSIDERING MAKING ANY CHANGES TO THE EXTENDED.
FORECAST LOOKS GOOD...NO UPDATES.
&&
.AVIATION...AS OF 9:45 AM PST THURSDAY...WEAK FRONTAL BOUNDARY IS
OVER THE NORTH BAY AND SF BAY APPROACH AT THIS HOUR. LIGHT RAIN HAS
BEEN REPORTED AS FAR SOUTH AS UKIAH AND BRIEFLY AT KSTS...CANT RULE
OUT A FEW MORE SPRINKLES BUT NOTHING MORE THAN THAT. TAIL END OF
FRONT WILL BE SLOW TO CLEAR FOR SF APPROACH AND SEVERAL MORE HOURS
OF NUISANCE CEILINGS EXPECTED AT LEAST THROUGH 21Z AND POSSIBLY AS
LATE AS 23Z. LIGHT S/SE FLOW TO TURN W/NW BEYOND THAT. THE EVENING
PERIOD SHOULD BE CLEAR WITH VAPS...THEN POSSIBLE PATCHY LOW CIGS
OVERNIGHT ESPECIALLY FOR KSTS. LIGHT OFFSHORE FLOW AND DRYING
BOUNDARY LAYER EXPECTED FOR MOST OF FRIDAY.
TERMINAL AERODROME FORECAST (TAFS) FORMAT CHANGE...
AS OF 0000Z (NOVEMBER 5 2008) THE NWS IN AGREEMENT WITH THE FAA HAS
CHANGED THE TAF FORMAT TO CONFORM TO INTERNATIONAL STANDARDS OUTLINED
IN ICAO ANNEX 3. THE CHANGE INCLUDES THE INITIATING OF 30-HOUR TAFS
FOR HIGH IMPACT U.S. AIRPORTS. TO ACCOMMODATE THE EXTENDED TAF
PERIOD...THE FORMAT OF ALL TAFS HAVE CHANGED. THE CHANGE INVOLVES
IDENTIFYING THE DATA ASSOCIATED WITH EACH TIME GROUP.
KSFO AND KOAK ARE NOW 30-HOUR TAFS.
FOR ADDITIONAL INFORMATION REGARDING THE CHANGE PLEASE VISIT THE
AVIATION WEATHER CENTERS WEBSITE:
HTTP://AVIATIONWEATHER.NOAA.GOV/NOTICE/TAF30.PHP
&&
.MTR WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC FORECAST: MHS
AVIATION/MARINE: RWW
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
