440
FXUS66 KHNX 201655
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
955 AM PDT MON APR 20 2026
KEY MESSAGES...
1. WINTER STORM WARNING IN EFFECT FOR THE SIERRA NEVADA ABOVE
7,000 FT.
2. AN ELEVATED RISK FOR FIRE STARTS IN EASTERN TULARE AND KERN
COUNTIES.
3. AN APPROACHING CUT-OFF LOW BRINGS PERIODS OF HEAVY RAINFALL
AND MOUNTAIN SNOW BY EARLY TUESDAY, WITH FAVORABLE CONDITIONS
FOR CONVECTIVE WEATHER AFTERWARDS.
DISCUSSION...
A WINTER STORM WARNING IS IN EFFECT FOR THE SIERRA NEVADA ABOVE
7,000 FT, WITH ACCUMULATIONS OF 3 TO 5 INCHES ABOVE THIS LEVEL,
INCREASING TO 12 TO 18 INCHES AT THE HIGHEST LEVELS. WINDS
COULD GUST AS HIGH AS 75 MPH ALONG THE SIERRA CREST.
CURRENT SATELLITE IMAGERY SHOWS THE STORM SYSTEM THAT WILL
IMPACT CENTRAL CALIFORNIA THIS WEEK JUST OFF THE COAST OF THE
WESTERN CONUS. IN THE MEANTIME, THE LINGERING INFLUENCE OF THE
RIDGE OVER THE AREA WILL KEEP TEMPERATURES A BIT ABOVE NORMAL
TODAY, WITH HIGHS IN THE LOW- TO MID-80S ACROSS THE VALLEY,
CREATING A MINOR HEAT RISK, PARTICULARLY FOR VULNERABLE
POPULATIONS. AS THE TROUGH MOVES INTO THE AREA, EXPECT BELOW-
AVERAGE TEMPERATURES TUESDAY AND WEDNESDAY, WITH VALLEY HIGHS IN
THE 60S TO LOW 70S TUESDAY, SLOWLY REBOUNDING TO CLIMATOLOGICAL
NORMALS LATER IN THE WEEK.
LOOKING TO THE MORE ACTIVE WEATHER, THE SYSTEM IS EXPECTED TO
ARRIVE MONDAY EVENING AND CONTINUE THROUGH WEDNESDAY AFTERNOON.
THE MAJORITY OF THE PRECIPITATION IS EXPECTED LATE TUESDAY
MORNING THROUGH THE AFTERNOON AS A LARGE RAIN BAND MOVES THROUGH
THE REGION DURING THAT TIME PERIOD, AND THE MOST IMPACTED AREAS
ARE EXPECTED TO BE THE SIERRA NEVADA AND ITS FOOTHILLS. CURRENT
PROBABILITIES FOR A HALF-INCH OF RAINFALL ARE 40-50% NEAR
FRESNO, INCREASING TO 65-75% TOWARD MERCED. THERE IS ALSO A
MARGINAL RISK (AT LEAST 5%) FOR EXCESSIVE RAINFALL IN THAT AREA,
ALONG WITH THE SAN JOAQUIN VALLEY FROM VISALIA TO LOS BANOS AS
THE CROW FLIES.
WITH REGARDS TO WIND, ON TUESDAY, THERE IS A 50-70% CHANCE OF
64 MPH GUSTS OR HIGHER ALONG THE MOJAVE DESERT SLOPES,
INCREASING TO 60-95% ALONG THE SIERRA CREST.
AS THE MAIN RAIN BAND MOVES THROUGH THE REGION TUESDAY
AFTERNOON, THE CHANCES FOR THUNDERSTORMS INCREASES INTO THE 30 TO
45% RANGE IN THE VALLEY FROM PORTERVILLE NORTH. THE SOUTHERN
HALF OF THE VALLEY CAN EXPECT A 15-30% CHANCE OF THUNDERSTORMS.
THIS IS DUE TO THE INCREASED DYNAMICS BEHIND THE INITIAL WAVE
COMBINED WITH THE NEWLY FALLEN MOISTURE AND AFTERNOON HEATING.
AS OF TODAY, THE STORM PREDICTION CENTER HAS PUT THIS AREA UNDER
A GENERAL RISK FOR THUNDERSTORMS. SEVERE THUNDERSTORMS ARE NOT
EXPECTED. HOWEVER, ANY CELL THAT FORMS STILL COMES WITH THE RISK
FOR SMALL HAIL, FREQUENT LIGHTNING, GUSTY WINDS, AND LOCALIZED
FLOODING.
AFTER THIS SYSTEM MOVES EAST AND THE PRECIPITATION MOVES ON,
A WEAK TROUGH MAY STILL HANG AROUND ALOFT, WITH CURRENT
ENSEMBLE MODELS CONTINUING TO AGREE WITH THAT FORECAST. A
SECOND, ALBEIT WEAKER, CUT-OFF LOW MAY DEVELOP LATER THIS WEEK
AND PRODUCE SOME PRECIPITATION BY THE WEEKEND, PARTICULARLY IN
THE SIERRA NEVADAS.
AVIATION
VFR CONDITIONS EXPECTED ACROSS THE AREA FOR THE NEXT 24 HOURS,
WITH MVFR IN AND NEAR THUNDERSTORMS.
AIR QUALITY ISSUES
POCKETS OF MINOR AIR QUALITY ISSUES MAY AFFECT VULNERABLE
POPULATIONS TODAY.
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
WINTER STORM WARNING FROM LATE TONIGHT THROUGH WEDNESDAY
AFTERNOON FOR CAZ323-326>328-330.
PUBLIC...AC
AVIATION....AC
WEATHER.GOV/HANFORD
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