Weather Service Report


291 
FXUS66 KMTR 251754
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
954 AM PST THU DEC 25 2014

...MUCH COOLER WEATHER ON CHRISTMAS DAY AND ON INTO THE WEEKEND...

.SYNOPSIS...SUNNY SKIES AND COOL TEMPERATURES WILL PREVAIL
ACROSS THE DISTRICT TODAY. DRY WEATHER IS EXPECTED TO PERSIST INTO
AT LEAST THE BEGINNING OF NEXT WEEK. MOST LOCATIONS WILL SEE THEIR
COLDEST TEMPERATURES SO FAR THIS SEASON OVER THE NEXT TWO
NIGHTS...WITH OVERNIGHT LOWS FORECAST TO BE AT OR SLIGHTLY BELOW
FREEZING IN THE INLAND VALLEYS ALONG WITH SOME LATE NIGHT AND
MORNING FROST.

&&

.DISCUSSION...AS OF 9:19 AM PST CHRISTMAS DAY...ALTHOUGH THE SKIES
ARE SUNNY WE ARE HAVING A COOL START TO THE DAY. MORNING
TEMPERATURES ARE RUNNING 5 TO 10 DEGREES COOLER THAN YESTERDAY AT
THIS HOUR WITH SOME LOCATIONS SUCH AS NAPA AIRPORT RUNNING 12
DEGREES COOLER THAN AT THIS HOUR YESTERDAY. THE COLD AIRMASS
RESPONSIBLE FOR THESE COLD TEMPERATURES IS EXPECTED TO STICK
AROUND FOR A FEW DAYS AS A RIDGE OF HIGH PRESSURE SETTLES IN OVER
THE FORECAST AREA. THIS COLD AIRMASS COMBINED WITH THE RIDGE OF
HIGH PRESSURE WILL RESULT IN SOME OF THE COLDEST OVERNIGHT
TEMPERATURES OBSERVED IN OUR FORECAST AREA SO FAR THIS SEASON.

THE 0000Z ECMWF ALONG WITH THE 1200Z GFS40 AND NAM12 HAVE
INITIALIZED WELL WITH THE CURRENT SYNOPTIC PATTERN AND REMAIN IN
GOOD AGREEMENT THROUGH THE NEXT 84 HOURS. THE FORECAST MODELS ARE
INDICATING THAT THE RIDGE OF HIGH PRESSURE WILL STICK AROUND
THROUGH AT LEAST SATURDAY. AT THE SURFACE LIGHT OFFSHORE WINDS
WILL PREVAIL THROUGH AT LEAST SATURDAY NIGHT LIMITING THE OCEANS
INFLUENCE ON OUR TEMPERATURES AND REINFORCING THE COLD AIRMASS
THAT IS ALREADY IN PLACE. AS PREVIOUSLY STATED THIS COLD AIRMASS
WILL PROMOTE SOME OF THE COLDEST OVERNIGHT TEMPERATURES THAT OUR
FORECAST AREA HAS SEEN SO FAR THIS SEASON. THE COLDEST NIGHT IS
EXPECTED TO BE FRIDAY NIGHT WITH TEMPERATURES AT MANY INLAND
LOCATIONS REACHING FREEZING TO SLIGHTLY BELOW. 

BY MONDAY THE FORECAST MODELS BEGIN TO SLIDE AN ARCTIC AIRMASS
INTO THE GREAT BASIN AREA. THE PARENT UPPER LEVEL LOW WILL SLIDE
INTO NORTHERN CALIFORNIA MONDAY NIGHT INTO TUESDAY. INITIALLY
MODERATE OFFSHORE WINDS WILL ACCOMPANY THIS STORM SYSTEM AS IT
ARRIVES TO THE COAST. THIS STORM SYSTEM AND ASSOCIATED COLD
AIRMASS WILL BE OUR NEXT SHOT AT COLD OVERNIGHT TEMPERATURES AND A
POTENTIAL FOR SNOW FALL ON OUR RIDGES DEPENDING ON THE TIMING OF
ANY PRECIPITATION.  

&&

.AVIATION...AS OF 10 AM PST CHRISTMAS DAY... WIDESPREAD VFR CONDS
WITH A DRY AIR MASS OVER THE REGION TODAY. LARGE DEW POINT
DEPRESSION AT ALL LEVELS SHOULD KEEP SKC CONDS THROUGH THE
HOLIDAY. NORTH TO NORTHWEST WINDS BECOMING GUSTY AFTER 18Z.

VICINITY OF KSFO...VFR. NORTHWEST WINDS TO 10 KT INCREASING TO 15
KT GUSTING TO 20 KT AFTER 18-19Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS... VFR. OCCASIONALLY GUSTY THROUGH THE
DAYLIGHT HOURS.

&&

.MARINE...AS OF 09:44 AM PST THURSDAY...NORTH WINDS WILL REMAIN
MODERATE TO STRONG OVER THE COASTAL WATERS TODAY AS HIGH PRESSURE
BUILDS ALOFT. WINDS WILL GRADUALLY DECREASE THROUGH TODAY AND INTO
THE WEEKEND. NORTHWEST SWELL WILL GRADUALLY DIMINISH INTO THE
WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 4 PM
             SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR


&&

$$

PUBLIC FORECAST: LARRY
AVIATION: DRP
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA



Return to Home page


Western Regional Climate Center, wrcc@dri.edu