Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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000
FXUS66 KHNX 182245
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
245 PM PST THU DEC 18 2014

.SYNOPSIS...
YET ANOTHER WEATHER DISTURBANCE WILL ARRIVE ON FRIDAY AND FRIDAY NIGHT
FOR MAINLY THE NORTHERN AREAS. BY SUNDAY, A LARGE RIDGE OF HIGH PRESSURE
WILL BEGIN TO BUILD OVER THE REGION BRINGING DRY WEATHER THROUGH WEDNESDAY.
CHANCES FOR AREAS OF NIGHTTIME AND MORNING FOG WILL BE INCREASED EARLY NEXT
WEEK DUE TO THE HIGH PRESSURE.


&&

.DISCUSSION...
HIGH CLOUDS WERE MOVING OVER INTERIOR CENTRAL CALIFORNIA THIS
AFTERNOON. THESE CLOUDS ARE AHEAD OF AN APPROACHING STORM SYSTEM
THAT IS FORECAST TO REACH CENTRAL CALIFORNIA FRIDAY MORNING...
REACHING MERCED AND MARIPOSA COUNTIES BY 18Z /1000 PST/.

FOR THE REST OF TODAY AND THIS EVENING...AN UPPER-LEVEL SHORT-WAVE
RIDGE WILL BE OVER THE REGION...WITH THE 500-MB 5700-METER HEIGHT
LINE PUSHING NORTH OF THE WFO HANFORD WARNING/FORECAST AREA BY 06Z
FRIDAY /2200 PST TONIGHT/. THIS WILL STRENGTHEN THE INVERSION AND
INCREASE THE POTENTIAL FOR TULE FOG DEVELOPMENT.

BY 12Z /0400 PST/ FRIDAY MORNING...THE APPROACHING TROUGH IS
FORECAST TO MOVE ONSHORE OVER THE PACIFIC NORTHWEST...PUSHING THE
RIDGE INLAND. THE MODELS ARE IN GOOD AGREEMENT WITH THE TROUGH AXIS
MOVING THROUGH CENTRAL CALIFORNIA BETWEEN 18-24Z /1000-1600 PST/
FRIDAY. THE 500-MB 5700-METER HEIGHT LINE IS FORECAST TO DROP TO
OVER BAKERSFIELD BY 18Z FRIDAY...AND INTO NORTHERN BAJA CALIFORNIA
BY 00Z SATURDAY /1600 PST FRIDAY/...ALTHOUGH 500-MB HEIGHTS OVER
CENTRAL CALIFORNIA REMAIN ABOVE 5640 METERS.

THE TROUGH IS FORECAST TO BE A RELATIVELY FAST MOVER...PUSHING INTO
THE GREAT BASIN FRIDAY EVENING. THE MAIN ENERGY OF THIS STORM WILL
BE OVER THE NORTHERN HALF OF THE STATE...AND EXPECT A FEW HUNDREDTHS
OF AN INCH OF RAINFALL NORTH OF FRESNO COUNTY...AND ONLY LIGHT
PRECIPITATION OVER FRESNO COUNTY. WITH A WEST-NORTHWEST FLOW
ALOFT...THERE MAY BE SOME RAINSHADOWNG OVER THE WEST SIDE OF THE SAN
JOAQUIN VALLEY. IN THE SOUTHERN SIERRA NEVADA...THE SNOW LEVEL WILL
BE AROUND 6000 FEET...AND NEW SNOW ACCUMULATIONS OF 2-3 INCHES OVER
THE HIGH COUNTRY OF YOSEMITE NATIONAL PARK WILL BE POSSIBLE.

AS THE TROUGH CONTINUES TO PUSH EASTWARD...REACHING THE FOUR-CORNERS
AREA BY 18Z SATURDAY...AN EAST-PACIFIC UPPER-LEVEL RIDGE IS FORECAST
TO BUILD INTO CALIFORNIA BEHIND THE SYSTEM. 500-M HEIGHTS OVER
INTERIOR CENTRAL CALIFORNIA ARE FORECAST TO RISE ABOVE 5700 METERS
BY 18Z SATURDAY...AND ABOVE 5820 METERS BY 06Z MONDAY /2200 PST
SUNDAY/. THIS WILL RESULT IN A DRY...STABLE WEATHER PATTERN OVER
CENTRAL CALIFORNIA FOR THE FIRST HALF OF NEXT WEEK...WITH A STRONG
PERSISTENT INVERSION OVER THE SAN JOAQUIN VALLEY.

NIGHT AND MORNING TULE FOG WILL FORM DAILY AND PLAT HAVOC WITH HIGH
TEMPERATURES /AS WELL AS PLAGUING SAN JOAQUIN VALLEY DRIVERS/. THE
CURRENT FORECAST ASSUMES THAT THE FOG WILL LIFT INTO AN AFTERNOON
AND EVENING STRATUS DECK...KEEPING HIGHS BELOW THE INVERSION IN THE
MID 50S EXCEPT ALONG THE WEST SIDE WHERE THE DRAINAGE WINDS WILL BE
ADIABATICALLY WARMED AND DRIED...RESULTING IN SOME EROSION OF THE
FAR WEST-SIDE FOG. ABOVE THE INVERSION...TEMPERATURES WILL WARM WELL
ABOVE NORMAL WITH MARIPOSA AND OAKHURST REACHING THE LOWER TO MID
60S UNLESS THE INVERSION IS HIGHER THAN CURRENTLY ANTICIPATED.

ANOTHER UPPER-LEVEL LOW WAS MOVING EAST OUT OF THE BERING SEA THIS
AFTERNOON. THIS LOW IS FORECAST TO TRACK EASTWARD SOUTH OF THE
ALEUTIAN ISLANDS OVER THE NEXT TWO DAYS...AND ENTER THE GULF OF
ALASKA SATURDAY AFTERNOON. THE LOW IS THEN FORECAST TO OPEN INTO AN
UPPER-LEVEL TROUGH THAT REACHES THE PACIFIC NORTHWEST COAST NEXT
WEDNESDAY...ALTHOUGH DIFFERENCES IN TIMING AND STRENGTH DEVELOP
BETWEEN THE GFS AND ECMWF.

BOTH MODELS DO TREAT THIS TROUGH AS AN INSIDE SLIDER...DROPPING INTO
THE GREAT BASIN CHRISTMAS DAY. IF THIS HOLDS...THE MAIN IMPACT OF
THE TROUGH WILL BE COLDER TEMPERATURES FOR CHRISTMAS WITH THE
MAIN PRECIPITATION CHANCES EAST OF THE SOUTHERN SIERRA NEVADA
CREST.

&&

.AVIATION...
IN THE SAN JOAQUIN VALLEY...LOCAL IFR CONDITIONS IN MIST/FOG
06Z-18Z FRIDAY. OTHERWISE...VFR CONDITIONS EXPECTED ELSEWHERE IN
THE NEXT 24 HOURS.

&&

.AIR QUALITY ISSUES...
NONE.

&&

.CERTAINTY...

THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH.

THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.

&&

.CLIMATE...
             RECORDS
SITE DATE    HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR

KFAT 12-18       71:1979     41:1963     52:2010     26:1965
KFAT 12-19       74:1981     36:1908     53:2005     25:1965
KFAT 12-20       70:2005     35:1908     53:1969     24:1897

KBFL 12-18       75:1979     35:1908     53:1938     23:1908
KBFL 12-19       80:1981     39:1965     55:2010     23:1924
KBFL 12-20       76:1944     35:1908     54:1964     26:1928

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

PUBLIC...SANGER
AVN/FW...MV
SYNOPSIS...ANDERSEN

WEATHER.GOV/HANFORD


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