209
FXUS66 KHNX 180952
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
252 AM PDT MON OCT 18 2021
SYNOPSIS
A COLD FRONT WILL PASS OVER THE AREA THIS MORNING
AND BRING LIGHT RAIN AND MOUNTAIN SNOW TO MUCH OF THE AREA.
LOCALLY STRONG AND GUSTY WINDS ARE LIKELY THROUGH THE KERN
COUNTY MOUNTAIN PASSES THROUGH THIS AFTERNOON. TEMPERATURES
WILL DROP WELL BELOW AVERAGE TODAY, THEN WARM TO NEAR NORMAL BY
THURSDAY. UNSETTLED CONDITIONS ARE EXPECTED TO RETURN BY THE
WEEKEND FOR MUCH OF CENTRAL CALIFORNIA.
DISCUSSION
LATEST RADAR IMAGERY SHOWS A BAND OF LIGHT TO
MODERATE PRECIPITATION THAT CONTINUES TO PASS OVER THE SIERRA
NEVADA AND CENTRAL VALLEY TONIGHT, INCLUDING AS FAR SOUTH AS KINGS
AND TULARE COUNTIES. PRECIPITATION WILL SHIFT SOUTHWARD TO KERN
COUNTY OVER THE NEXT SEVERAL HOURS, ALTHOUGH WILL MAINLY END BY
LATE THIS MORNING. SNOW LEVELS ARE AROUND 6,000 FEET AT THIS
TIME. LOW CLOUDS WILL LIKELY PERSIST OVER THE WEST AND NORTHWEST
FACING SLOPES IN THE SOUTHERN SIERRA NEVADA AND INTO THE KERN
COUNTY MOUNTAIN AREAS UNTIL THIS AFTERNOON. MUCH COOLER
TEMPERATURES ARE IN STORE TODAY, AS HIGHS IN MANY LOCATIONS WILL
LIKELY REACH AROUND 10 TO 15 DEGREES BELOW AVERAGE, INCLUDING
HIGHS MAINLY IN THE 60'S AT THE WARMEST LOCATIONS. THE
PROBABILITY THAT THE HIGHS IN THE CENTRAL VALLEY AND KERN COUNTY
DESERT WILL REMAIN BELOW 70 DEGREES TODAY IS 80 PERCENT OR
GREATER. WITH THE COOLER WEATHER WILL COME A PERIOD OF GUSTY
WINDS, INCLUDING THROUGH THIS EVENING TOWARDS EASTERN KERN COUNTY.
THE STRONGEST GUSTS ARE EXPECTED ALONG THE MOJAVE DESERT SLOPES
WITH GUSTS AROUND 55 MPH BY THIS AFTERNOON AND CONTINUING INTO
EARLY THIS EVENING.
CONTINUED COOL WEATHER WILL OCCUR ON TUESDAY, THOUGH A BIT WARMER,
AS WEAK UPPER-LEVEL HIGH PRESSURE RIDGING PASSES OVER THE REGION.
ANOTHER CHANCE FOR SHOWERS RETURNS ON WEDNESDAY AND THURSDAY FOR
MAINLY FRESNO COUNTY NORTHWARD AS THE SOUTHERN EDGE OF A LOW
PRESSURE SYSTEM THAT WILL MOST LIKELY BRING SIGNIFICANT IMPACTS
TO MAINLY NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST. IT SHOULD
BE NOTED THAT LOCATIONS IN MERCED AND MARIPOSA COUNTIES WOULD
MORE LIKELY RECEIVE ANY PRECIPITATION DURING THIS PERIOD AS THE
COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL STALL OVER THIS AREA
AND PUSH BACK NORTHWARD. THE ENSEMBLE AND DETERMINISTIC GUIDANCE
GENERALLY SHOWS AGREEMENT WITH THE LONGWAVE PATTERN, INCLUDING
WEAKENING INTENSITY OF THE SYSTEM AS IT MOVES FURTHER INLAND BY
WEDNESDAY. OTHERWISE, WEAK UPPER-LEVEL RIDGING WILL ALLOW WARMING
TEMPERATURES TO CONTINUE INTO THURSDAY, THOUGH LIKELY UP TO
SEASONAL VALUES.
RELATIVELY WARM WEATHER WILL CONTINUE INTO FRIDAY OR UNTIL THE
UPPER-LEVEL LOW MOVES SOUTHWARD AND BRINGS AN INCREASE IN
PRECIPITATION CHANCES TO MUCH OF CENTRAL CALIFORNIA BY THE
WEEKEND. UNSETTLED WEATHER IS EXPECTED TO CONTINUE INTO EARLY NEXT
WEEK AND COULD BRING MORE SIGNIFICANT AMOUNTS OF RAIN AND HIGH
ELEVATION SNOW. HOWEVER, ENSEMBLE GUIDANCE CONTINUES TO SHOW
NOTABLE DIFFERENCES IN TERMS OF INTENSITY AND TIMING FOR THIS
PERIOD. WHAT IS MORE CERTAIN IS THAT COOLER THAN NORMAL
TEMPERATURES WILL RETURN AFTER THE END OF THIS WEEK.
AVIATION
PRECIPITATION WILL SPREAD SOUTHWARD OVER CENTRAL CALIFORNIA UNTIL
18Z MONDAY. EXPECT AREAS OF MVFR IN MAINLY LIGHT SHOWERS, WITH
SOME LOCAL IFR AND MOUNTAIN OBSCURATIONS IN THE HIGHER TERRAIN,
MAINLY UNTIL 18Z MONDAY. LOCAL IFR CEILINGS WILL PERSIST UNTIL 00Z
TUESDAY OVER THE SOUTHERN SIERRA NEVADA AND TEHACHAPI MOUNTAINS.
GUSTS TO 45 KTS WILL OCCUR AT TIMES THROUGH THIS EVENING, OR 03Z
TUESDAY, ALONG THE MOJAVE DESERT SLOPES IN EASTERN KERN COUNTY.
VFR CONDITIONS WILL OTHERWISE PREVAIL ACROSS CENTRAL CALIFORNIA
THROUGH AT LEAST THE NEXT 24 HOURS.
AIR QUALITY ISSUES
ON MONDAY OCTOBER 18 2021... UNHEALTHY FOR SENSITIVE GROUPS IN
SEQUOIA NATIONAL PARK AND FOREST.
FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG
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
AN/OR TO PROVIDE FEEDBACK.
HNX WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY UNTIL 8 PM PDT THIS EVENING FOR CAZ338.
WINTER WEATHER ADVISORY UNTIL 5 AM PDT EARLY THIS MORNING FOR
CAZ323-326.
PUBLIC/FIRE WX......BSO
AVIATION/PIO/IDSS...JEB
WEATHER.GOV/HANFORD
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