Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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000
FXUS66 KHNX 212305
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
305 PM PST SUN DEC 21 2014

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD INTO CENTRAL
CALIFORNIA DURING THE NEXT FEW DAYS. SPOTTY LIGHT PRECIPITATION IS
STILL POSSIBLE THROUGH TONIGHT IN THE KERN COUNTY MOUNTAINS.
MEANWHILE...MUCH OF THE SAN JOAQUIN VALLEY WILL BE PLAGUED WITH LOW
CLOUDS THROUGH TUESDAY ALONG WITH PATCHY DENSE FOG AND DRIZZLE EACH
NIGHT AND MORNING.

&&

.DISCUSSION...
AS THE FOG DISSIPATES THIS AFTERNOON FROM MERCED TO FRESNO...FOG
AND LOW CLOUDS ARE NOW PILING UP AGAINST THE TEHACHAPI/GRAPEVINE/
RANGE AS THE FLOW MOVES THE MOISTURE SOUTHWARD. THE NORTHWEST
FLOW ALOFT IS EXPECTED TO WEAKEN TONIGHT AS THE BUILDING HIGH
PRESSURE RIDGE MOVES FURTHER ONSHORE. THIS WEAKENING OF THE WIND
FLOW ALOFT WILL ALLOW THE MOISTURE PILED UP AT THE SOUTH END THE
VALLEY TO FLOW BACK ACROSS THE SAN JOAQUIN VALLEY FOR ANOTHER
NIGHT OF CLOUDS AND DENSE FOG.

WHILE SHORT RANGE MESO-SCALE MODELS SHOW A CHANGE IS VISIBILITIES
AS FOG AND HAZE DECREASES...THE MODELS SHOW ALMOST NO CHANGE IN
THE SURFACE RELATIVE HUMIDITIES ACROSS THE SAN JOAQUIN VALLEY IN
THE NEXT 24 HOURS. THIS LACK OF CHANGE TRANSLATES IN A VERY HIGH
POTENTIAL FOR FOG DEVELOPMENT OVER THE LOWER ELEVATIONS OF THE
CENTRAL CALIFORNIA INTERIOR. THEREFORE...WILL GO AHEAD A ISSUE
ANOTHER DENSE FOG ADVISORY TONIGHT FROM NEAR MIDNIGHT TO AROUND
1000 AM PST MONDAY MORNING.

BY MONDAY...MODELS SHOW A HIGH DEGREE OF CONFIDENCE IN A SOLUTION
THAT STRENGTHENS THE RIDGE WITH ITS AXIS JUST OFF THE PACIFIC
COAST. THIS PATTERN WILL KEEP THE REGION DRY WITH PERSISTENT
CLOUDS AND FOG OVER THE SAN JOAQUIN VALLEY. THE STAGNANT PATTERN
MAY SEE SOME CHANGE BY MIDWEEK AS MODELS ATTEMPT TO MOVE AN INSIDE
SLIDER THROUGH NORTHERN CALIFORNIA/GREAT BASIN TOWARD WEDNESDAY.
WHILE CONFIDENCE IS LOW WITH THE MIDWEEK TROUGH...WILL KEEP A
SLIGHT CHANCE OF POSSIBLE PRECIP OVER THE SIERRA NEVADA AND AREAS
NORTH OF FRESNO COUNTY. TIMING ISSUES ARE THE MAIN CONCERN WITH
THE MIDWEEK SYSTEM THAT IS EXPECTED TO EXIT OUT OF CALIFORNIA ON
THURSDAY. AFTERWARD...THE RIDGE REBUILDS UNTIL NEXT WEEKEND. BY
NEXT SUNDAY...UNCERTAINTY IS TOO HIGH TO DEVIATE MUCH FROM CLIMO.
THEREFORE...WILL OPT FOR NEAR CLIMO ON DAY SEVEN.

&&

.AVIATION...
IN THE SAN JOAQUIN VALLEY...WIDESPREAD MVFR AND AREAS OF IFR IN
MIST/HAZE AND LOW CLOUDS WITH LIFR CONDITIONS BECOMING PREVALENT IN
FOG BETWEEN 06Z MON AND 12Z MON. IN THE TEHACHAPI MOUNTAINS....AREAS
OF IFR AND LOCAL LIFR IN UPSLOPE LOW CLOUDS ALONG THE VALLEY FACING
SLOPES. OTHERWISE VFR WILL PREVAIL OVER THE CENTRAL CA INTERIOR FOR
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 12-21       71:1955     34:1998     54:1964     23:1897
KFAT 12-22       70:1964     35:1998     57:1955     19:1990
KFAT 12-23       68:1964     37:1928     60:1964     18:1990

KBFL 12-21       78:1919     36:1998     59:1977     23:1905
KBFL 12-22       76:2005     34:1998     56:1977     20:1990
KBFL 12-23       73:1964     36:1928     63:1955     14:1905
&&

.HNX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY FROM MIDNIGHT UNTIL 10 AM PST MONDAY MORNING
FOR ZONES CAZ089>092.

&&

$$

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

WEATHER.GOV/HANFORD



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