118
FXUS66 KHNX 070037
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
537 PM PDT MON OCT 6 2025
UPDATE
AIR QUALITY AND AVIATION UPDATED
KEY MESSAGES
1. SEASONABLE TEMPERATURES WITH DRY CONDITIONS ARE EXPECTED
THROUGH MUCH OF THE UPCOMING WEEK. THERE IS A 30 TO 40 PERCENT
PROBABILITY TO EXCEED 90 DEGREES TUESDAY IN THE SAN JOAQUIN
VALLEY.
2. A LOW PRESSURE SYSTEM WILL BRING CHANCES FOR PRECIPITATION
TO THE AREA FRIDAY AND SATURDAY. THERE IS A 40 TO 50 PERCENT
PROBABILITY FOR MEASURABLE RAINFALL IN THE DESERT AND MOUNTAIN
AREAS, AND A 20 TO 30 PERCENT PROBABILITY FOR THE SAN JOAQUIN
VALLEY.
3. COLDER AIR WITH THE SYSTEM BRINGS A 30 TO 40 PERCENT
PROBABILITY FOR 1 INCH OR MORE OF SNOWFALL FRIDAY INTO SATURDAY
MAINLY FOR ELEVATIONS ABOVE 10000 FEET.
DISCUSSION
A BROAD, LONGWAVE TROUGH IS CURRENTLY MAKING ITS WAY ACROSS THE
INTERIOR US THIS MORNING, WITH A LOCALIZED LOW PRESSURE SYSTEM
ANTICIPATED TO BECOME CUTOFF FROM THE MAIN FLOW, AND SITTING
STATIONARY OFF THE CALIFORNIA COAST FOR MONDAY AND TUESDAY.
SOUTHWESTERLY WINDS ASSOCIATED WITH THE LOW WILL CAUSE A SLIGHT
WARMING TREND THROUGH MIDWEEK. AFTERNOON TEMPERATURES ARE
EXPECTED TO BE NEAR SEASON AVERAGES, BUT WITH A 30 TO 40 PERCENT
PROBABILITY TO EXCEED 90 DEGREES IN THE SAN JOAQUIN VALLEY ON
TUESDAY. A BREAKDOWN OF THE LOW PRESSURE SYSTEM ON WEDNESDAY
WILL RESULT IN MORE SEASONABLE CONDITIONS AS WEAKER FLOW SETS UP
ALOFT.
IN THE LATTER PORTION OF THE WEEK, THERE IS GOOD AGREEMENT FROM
ENSEMBLE CLUSTERS FOR A ROBUST LOW PRESSURE SYSTEM TO DROP
SOUTH FROM THE GULF OF ALASKA. STRONGER WINDS AROUND THE CENTER
OF THE LOW WILL START A COOLING TREND INTO THE WEEKEND, WITH
AFTERNOON HIGHS APPROACHING FIVE TO EIGHT DEGREES BELOW AVERAGE
FOR THIS TIME OF YEAR. ALSO WORTH MENTIONING, CURRENT HURRICANE
PRISCILLA IS EXPECTED FROM THE NATIONAL HURRICANE CENTER TO
SLIDE NORTH ALONG THE COAST OF BAJA CALIFORNIA THROUGH THE WEEK,
BECOMING A TROPICAL/POST-TROPICAL CYCLONE INTO THE WEEKEND.
WHILE SOME UNCERTAINTY IS PRESENT FOR THE LOCATION AND INTENSITY
OF THE SYSTEM, ENSEMBLE GUIDANCE SUGGESTS SOME TROPICAL
MOISTURE TO ENTRAIN OVER SOUTHERN CALIFORNIA. CLUSTERS SHOW THE
MAJORITY OF THE MOISTURE REMAINING TO THE SOUTH OF OUR CWA,
THOUGH THERE IS STILL A 40 TO 50 PERCENT PROBABILITY FOR
MEASUREABLE RAINFALL GREATER THAN 0.01 INCHES IN THE DESERT AND
MOUNTAIN AREAS OVER 24 HOURS ENDING 5 AM SATURDAY. HOWEVER,
PROBABILITIES ARE 20 TO 30 PERCENT FOR THE SAN JOAQUIN VALLEY.
THE RELATIVELY LOW CHANCES ARE PRIMARILY DUE TO THE
AFOREMENTIONED SYSTEM OFF THE PACIFIC COAST, WHICH FOR NOW IS
PROJECTED TO DEFLECT TROPICAL MOISTURE INTO THE DESERT
SOUTHWEST. COOLER MOISTURE WITH THIS LOW HAS A 30 TO 40 PERCENT
PROBABILITY TO RESULT IN AN INCH OF SNOWFALL IN THE CENTRAL
SIERRA, PRIMARILY ABOVE 10000 FEET.
AVIATION
VFR CONDITIONS ARE EXPECTED THROUGH 00Z WEDNESDAY.
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 MEDIUM.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.HTML FOR ADDITIONAL INFORMATION
AND/OR TO PROVIDE FEEDBACK.
HNX WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...MCCOY
AVIATION....JPK
WEATHER.GOV/HANFORD
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