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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