FXUS66 KMTR 300330
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
730 PM PST SUN NOV 29 2009

.DISCUSSION...AS OF 7:30 PM PST SUNDAY...CLEAR SKIES CONTINUE THIS
EVENING. TEMPERATURES TODAY REACHED THE MID 60S TO LOWER 70S IN
MANY AREAS WITH A FEW LOCATIONS IN THE NORTH BAY REACHING THE MID
70S. SANTA ROSA MATCHED THE RECORD HIGH 76 SET IN PREVIOUS YEARS
1976 AS WELL AS IN 1907. OVERALL TEMPERATURES DID MAKE A REMARKABLE
RECOVERY JUST ABOUT EVERYWHERE AFTER A CHILLY AND BREEZY START EARLY
THIS MORNING.

CLEAR SKIES AND LIGHT WINDS WILL ALLOW FOR ENHANCED RADIATIONAL
COOLING TONIGHT. THERE WERE LOCALIZED INCIDENCES OF FREEZING
TEMPERATURES FOR 2-3 HOURS THIS MORNING. FOR INSTANCE BRADLEY HAD A
LOW OF 26F AND PARKFIELD RECORDED A LOW OF 28F. THE AIRMASS REMAINS
FAIRLY DRY THIS EVENING BUT THERE IS A NOTABLE JUMP UP IN AIRMASS
DEWPOINT TEMPERATURES SINCE YESTERDAY. MOST DEWPOINTS ARE NOW IN THE
20S WITH A FEW LOW 30S ALSO NOTED CLOSE TO IMMEDIATE COAST. SLIGHTLY
WARMER TEMPERATURES TODAY AGAINST A BACKDROP OF MUCH LESS WIND
TONIGHT AND SLIGHTLY HIGHER DEWPOINTS AREA-WIDE PROBABLY MEANS THAT A
SIMILAR TEMPERATURE SCENARIO WILL UNFOLD MONDAY MORNING. AT THIS
POINT IT DOES NOT APPEAR TO WARRANT A FROST OR FREEZE STATEMENT.
HOWEVER A RECENT UPDATE WAS ISSUED FOR SLIGHTLY LOWER MIN
TEMPERATURES TONIGHT FOR MOST ZONES AND TO ACCOUNT FOR POSSIBLE
LOCALIZED FREEZING BY MORNING IN THE SOUTHERN SALINAS VALLEY.

CLEAR SKIES ARE FORECAST FOR THE NEXT FEW DAYS BUT AS THE AIRMASS
REGAINS HIGHER HUMIDITIES SOME COASTAL STRATUS DEVELOPMENT IS
POSSIBLE BUT NOT LIKELY UNTIL MID-WEEK AT THE EARLIEST. IN THE
INTERIM THE NEXT FOCUS WILL BE ON THE BEHAVIOR OF THE WESTERLIES
ATTEMPT TO UNDERCUT THE AMPLIFIED WEST COAST LONG WAVE RIDGE. THE
LATEST ECMWF IS FOCUSING WET WEATHER OVER THE AREA LATE NEXT WEEKEND
AND EARLY NEXT WEEK. THE GFS IS NOT ON BOARD WITH THIS SOLUTION. AS A
RESULT THERE IS A LARGE DEGREE OF UNCERTAINTY AS TO WHAT WILL HAPPEN
LATE IN THE EXTENDED PERIOD. A RECENT TREND IN 6-10 DAY 500 MB
HEIGHTS/ANOMALIES IS INDICATING THE LONG WAVE RIDGE OVER THE WEST
COAST MIGRATING SLIGHTLY NORTHWARD IN LATITUDE. THIS MAY BE ONE
POSSIBLE INDICATION OF A STRONGER WESTERLY JET STREAM GETTING READY
TO MOVE INTO CA LATE IN THE EXTENDED PERIOD. WHAT HAPPENS WITH SOME
OF THE OLD MOISTURE REMNANTS ASSOCIATED WITH NIDA IS ALSO UNCERTAIN.
AS THE DAY SHIFT POINTED OUT IN THE EARLIER DISCUSSION THE BEST
APPROACH AT THE MOMENT IS TO LEAVE "CHANCE" POPS IN THE EXTENDED AS
IS.

&&

.AVIATION...AS OF 9:15 AM PST SUNDAY...STRONG HIGH PRESSURE WITH
CLEAR SKIES NEXT 24 HOURS. STRONG NORTH WINDS WILL CONTINUE TO
DECREASE THROUGH MIDDAY AND INTO THE AFTERNOON.

VICINITY OF KSFO...VFR SKY NEXT 24 HOURS. LIGHT WINDS THRU THE
PERIOD UNDER 10 KTS.

KSFO BRIDGE APPROACH...SAME AS KSFO...SPEED SHEAR ALOFT WILL
DECREASE THROUGH THIS AFTERNOON.

MRY BAY AREA TERMINALS...VFR CONDITIONS. NORTHEAST TO EAST
WINDS 5-10 KT DURING THE MORNING BECOMING NORTH TO NORTHWEST IN THE
AFTERNOON.

&&

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

$$

PUBLIC FORECAST: CANEPA
AVIATION/MARINE: RWW

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO