Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 202222
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
222 PM PST SAT DEC 20 2014

.SYNOPSIS...HIGH PRESSURE WILL BEGIN TO BUILD OVER THE REGION
THIS EVENING BRINGING A RETURN TO DRY WEATHER THROUGH WEDNESDAY.
CHANCES FOR AREAS OF NIGHTTIME AND MORNING FOG WILL BE INCREASED
DUE TO THE HIGH PRESSURE RETURN.

&&

.DISCUSSION...IR IMAGERY INDICATING PLENTY OF MID/HIGH CLOUDS
FROM SHORTWAVE IMPULSES SPILLING OVER AN OFFSHORE RIDGE AND
DROPPING SOUTHEAST OVER CENTRAL CA. SCATTERED LIGHT SHOWERS HAVE
BEEN NOTED BY RADAR COMPOSITES MAINLY OVER THE SOUTHERN SIERRA
NEVADA. THE HIGH RESOLUTION MODELS ARE INDICATING THE
PRECIPITATION WILL TAPER OFF TONIGHT AS AN UPPER RIDGE BEGINS TO
AMPLIFY OFF THE COAST BETWEEN 130W AND 135W. THE 12Z WRF IS
INDICATING THAT THE RIDGE WILL NUDGE EASTWARD ON SUNDAY PUSHING
THE SPILLOVER MOISTURE TO THE NORTH AND EAST OF OUR AREA. ONE
POSSIBLE IMPACT THIS MIGHT HAVE IS THAT THERE MIGHT BE ENOUGH
CLEARING IN THE SAN JOAQUIN VALLEY OVERNIGHT FOR SOME PATCHY FOG
TO FORM. FOG WILL LIKELY BE MORE PREVALENT IN THE SAN JOAQUIN
VALLEY ON MONDAY AND TUESDAY AS THE RIDGE CONTINUES TO BUILD
INLAND AND HEIGHTS AND THICKNESSES RISE. A NOTICEABLE WARMING
TREND WILL TAKE PLACE OVER THE MOUNTAINS AN DESERTS ON MONDAY AS
WELL. WITH A COOL AND DRY NORTHERLY FLOW ALOFT OVER CENTRAL CA
DURING THIS TIME FRAME...THE FOG WILL LIKELY NOT HANG AROUND ALL
DAY...IT WILL EITHER LIFT INTO A STRATUS DECK OR BURN OFF
COMPLETELY BY EARLY AFTERNOON EACH DAY. RH PROGS ARE INDICATING
THAT SKIES SHOULD BE MAINLY CLEAR OVER THE HIGHER ELEVATIONS ON
MONDAY AND TUESDAY WITH A NOTICABLE LOWERING OF DAYTIME HUMIDITY
TAKING PLACE BY MONDAY.

THE MODELS CONTINUE TO BE IN POOR AGREEMENT WITH THEIR HANDLING A
AN UPPER TROUGH THAT IS PROGGED TO PUSH THROUGH CENTRAL CA ON
CHRISTMAS EVE. THE MODELS DO AGREE THAT THE RIDGE WILL BREAK DOWN
ON WEDNESDAY WHICH TEMPORARILY ELIMINATE FOG CHANCES IN THE
VALLEY THROUGH AT LEAST CHRISTMAS DAY AS THE PATTERN BECOMES MORE
UNSETTLED. HE OPERATIONAL GFS HAS BEEN INDICATING THAT THIS SYSTEM
WILL TRACK TO THE NORTH OF OUR AREA...BUT BRING COOLER
TEMPERATURES ALONG WITH A PERIOD OF BREEZY TO LOCALLY WINDY
CONDITIONS OVER THE WIND PRONE AREAS ON CHRISTMAS DAY. THE 12Z
ECMWF IS NOT AS DEEP WITH THIS SYSTEM AS IT/S PREVIOUS RUNS AND IS
TRENDING MORE TOWARD THE GFS. IT STILL INDICATES SOME DEEP
MOISTURE WILL CLIP CENTRAL CA. THE RELATIVE MEASURE OF
PREDICTABILITY (RMOP) FOR CHRISTMAS EVE AND CHRISTMAS DAY IS VERY
LOW IS THERE IS POOR ENSEMBLE MEMBER AGREEMENT FOR THIS PERIOD.
HAVE DECIDED TO COMPROMISE BETWEEN THE GFS AND ECWMF FOR NOW AND
MENTION A SLIGHT CHANCE OF PRECIPITATION MAINLY NORTH OF FRESNO
COUNTY ON WEDNESDAY NIGHT CONTINUING INTO CHRISTMAS MORNING AND
WAIT UNTIL THE MODELS SHOW BETTER AGREEMENT. THE RIDGE IS THEN
PROGGED TO RE-AMPLIFY OFF THE COAST ON FRIDAY AND SATURDAY
PROVIDING OUR AREA WITH A COOL AND DRY NORTHERLY FLOW. THE GFS HAS
BEEN A LITTLE MORE ROBUST WITH THE OFFSHORE RIDGING AND MEX
GUIDANCE IS SUGGESTING WE WILL FINALLY SEE SOME MORNING FROST IN
THE SAN JOAQUIN VALLEY BY THE END OF NEXT WEEK. THE ECMWF IS NOT
AS PRONOUNCED WITH THE COOLING TREND SO AM NOT MENTIONING FROST AT
THIS TIME...BUT THIS IS DEFINITELY SOMETHING LATER SHIFTS WILL
NEED TO LOOK AT AS THE TIME APPROACHES.

&&

.AVIATION...MVFR WITH PATCHES OF MOUNTAIN OBSCURING IFR CEILINGS
AND VISIBILITIES EXPECTED ACROSS THE FOOTHILLS AND HIGHER
ELEVATIONS OF THE SIERRA...ALONG WITH THE NORTH FACING SLOPES OF
THE TEHACHAPI RANGE. ACROSS THE LOWER ELEVATIONS OF THE SAN
JOAQUIN VALLEY AND KERN DESERTS...VFR WITH OCCASIONAL MVFR
CONDITIONS CAN BE EXPECTED DURING THE NEXT 24 HOURS.

&&

.AIR QUALITY ISSUES...NONE.

&&

.CERTAINTY...

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

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 12-20       70:2005     35:1908     53:1969     24:1897
KFAT 12-21       71:1955     34:1998     54:1964     23:1897
KFAT 12-22       70:1964     35:1998     57:1955     19:1990

KBFL 12-20       76:1944     35:1908     54:1964     26:1928
KBFL 12-21       78:1919     36:1998     59:1977     23:1905
KBFL 12-22       76:2005     34:1998     56:1977     20:1990
&&

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

&&

$$

PUBLIC...DS
AVN/FW...MOLINA
SYNOPSIS...ANDERSEN

WEATHER.GOV/HANFORD


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