Small Craft Advisory 80, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
835 PM PDT WED AUG 26 2009

.DISCUSSION...AS OF 8:35 PM PDT WEDNESDAY...MAINLY CLEAR SKIES OVER
LAND THIS EVENING WITH A COMPRESSED MARINE LAYER/STATUS OF 1000 FEET
ALONG THE COAST. SATELLITE IMAGERY SHOWS MINIMAL STRATUS INTRUSION AT
THIS HOUR AND WITH A RELATIVELY SHALLOW MARINE LAYER AND WEAKER
ONSHORE GRADIENTS STRATUS IS NOT EXPECTED TO PENETRATE AS FAR INLAND
OR AS EARLY AS IT HAS PREVIOUS NIGHTS.

THE MAIN STORY REMAINS THE WARMER THAN USUAL TEMPERATURES EXPECTED
THURSDAY AND FRIDAY AND MORE NOTABLY THE WARMER THAN USUAL
OVERNIGHT TEMPERATURES EXPECTED THURSDAY AND FRIDAY NIGHTS. THIS
AFTERNOON TEMPERATURES ROSE INTO THE 60S ALONG THE COAST AND INTO
THE 80S AND 90S INLAND. THURSDAYS HIGHS ARE FORECAST TO INCREASE
ANYWHERE FROM 5 TO 10 DEGREES OVER TODAY HIGHS AS 850 MB TEMPS AND
HEIGHTS INCREASE OVER THE REGION. THE MERCURY INLAND SHOULD REACH
INTO THE UPPER 80S AND 90S WITH SOME LOCATIONS REACHING INTO THE
TRIPLE DIGITS IN THE WARMEST INTERIOR VALLEYS. ALSO OF NOTE IS THE
MOISTURE THAT IS ADVECTING NORTHWARD FROM WEAKENING TROPICAL STORM
IGNACIO THAT IS SPINNING OFF THE COAST OF BAJA MEXICO. MOISTURE FROM
THIS SYSTEM IS EXPECTED TO INCREASE PRECIPITABLE WATER VALUES TO
OVER 1 INCH THURSDAY NIGHT HOWEVER THE MAIN PLUME OF MOISTURE IS
PROGGED TO STAY OUT OVER THE COASTAL WATERS AND MOVE INLAND OVER
THE MENDOCINO COAST KEEPING THE GREATEST CHANCE OF THUNDERSTORMS
WEST AND NORTH OF OUR CWA. MODELS AT THIS TIME APPEAR TO BE IN
GOOD AGREEMENT HOWEVER THE SITUATIONS WILL CONTINUE TO BE WATCHED
CLOSELY.

WHILE THE REMNANTS OF IGNACIO WORK THEIR WAY TOWARD THE COAST DURING
THE LATER PART OF THIS WEEK AND INTO THE WEEKEND A LARGE UPPER LEVEL
TROUGH IS PROGGED TO DROP DOWN FROM THE GULF OF ALASKA. THE LOW
WILL SWING INTO THE PACIFIC NORTHWEST AND SPINS OFF A CLOSED LOW THAT
IS EXPECTED TO MOVE SOUTH AND THEN EAST INTO NORTHERN NEVADA AND
UTAH. ANOTHER TROUGH IS POISED TO DROP DOWN ON THE HEELS OF THE
PREVIOUS TROUGH BY THE MIDDLE OF NEXT WEEK. OVERALL THE WEATHER
WILL REMAIN DRY WITH SEASONAL TO SLIGHTLY ABOVE SEASONAL TEMPERATURES
FOR THIS TIME OF YEAR.

&&

.AVIATION...AS OF 10:40 PM WEDNESDAY...A COMPRESSED MARINE LAYER
WILL KEEP THE STRATUS OUT OF THE SFO BAY AREA UNTIL LATE TONIGHT.
CEILINGS AND VISIBILITIES WILL BE LOWERED.

VICINITY OF KSFO...VFR CONDITIONS THROUGH THE AIRPORT EVENING
RUSH HOUR. BKN-OVC CEILINGS NOT EXPECTED UNTIL 10-12Z. BASES
BELOW 1000 FEET. EARLY CLEARING TIME OF 17Z IS EXPECTED.

KSFO BRIDGE APPROACH...VFR CONDITIONS THROUGH THE AIRPORT EVENING
RUSH HOUR. BKN-OVC CEILINGS NOT EXPECTED UNTIL AFTER 12Z. BASES
BELOW 1000 FEET. EARLY CLEARING TIME OF 17Z IS EXPECTED.

MONTEREY BAY TERMINALS...CEILINGS HAVE DROPPED BELOW 500 FEET
AND VISIBILITIES ARE DOWN AS LOW AS 1-3 MILES. CLEARING
EXPECTED AFTER 17Z.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

PUBLIC FORECAST: CW
AVIATION/MARINE: WJK/W PI

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO