853  
FXUS66 KHNX 142245  
AFDHNX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA  
245 PM PST THU DEC 14 2017  
   
SYNOPSIS
 
AN AREA OF HIGH PRESSURE OFF THE WEST COAST  
WILL DOMINATE THE WEATHER PATTERN ACROSS CENTRAL CALIFORNIA  
FOR SEVERAL MORE DAYS. A COLD FRONTAL PASSAGE EARLY SATURDAY  
MORNING COULD BRING A FEW SNOW SHOWERS TO THE SIERRA CREST.  
OTHERWISE, DRY WEATHER WILL PREVAIL OVER THE DISTRICT THROUGH  
AT LEAST TUESDAY NIGHT.  
 

 
   
DISCUSSION
 
SOME CHANGES IN THE OVERALL WEATHER PATTERN ARE  
FINALLY FORESEEN IN THE DAYS AHEAD, BUT IT'S NOT A FAVORABLE  
CHANGE FOR PRECIPITATION-STARVED CALIFORNIA. FOR ANOTHER 24  
TO 36 HOURS, OUR MUNDANE PATTERN WILL CONTINUE WITH A  
CONTINUATION OF VERY LOW HUMIDITIES AND RED FLAG CONDITIONS  
ABOVE 4,000 FEET WHILE A MURKY HAZE AND PATCHY LATE NIGHT AND  
MORNING FOG RESIDE IN THE SAN JOAQUIN VALLEY.  
 
THE RESILIENT MONSTER HIGH PRESSURE RIDGE THAT HAS BARRICADED THE  
GOLDEN STATE FROM PACIFIC STORMS THE PAST SEVERAL DAYS WILL BEGIN  
TO RETROGRADE FRIDAY AND ALLOW ENOUGH ROOM FOR A COLD FRONT TO  
DROP SOUTHWARD OUT OF WESTERN CANADA TOWARD THE END OF THIS WEEK.  
ALTHOUGH THIS FRONT WILL BE GREATLY LIMITED ON MOISTURE, IT COULD  
BRUSH THE HIGHER ELEVATIONS OF YOSEMITE NATIONAL PARK AND THE  
SIERRA CREST WITH A FEW SNOW SHOWERS LATE FRIDAY NIGHT OR FIRST  
THING SATURDAY MORNING. OTHERWISE, THE COLD FRONT WILL HERALD THE  
ARRIVAL OF A FRESHLY COLD AIR MASS OUT OF CANADA THIS WEEKEND.  
HIGH TEMPERATURES IN ITS WAKE WILL RUN A GOOD 5 TO AS MUCH AS 15  
DEGREES LOWER ACROSS THE CENTRAL CALIFORNIA INTERIOR, ESPECIALLY  
ABOVE THE VALLEY FLOOR. THE COLD FRONT WILL ALSO FINALLY BREAK THE  
INVERSION AND ALLOW FOR BETTER NIGHTLY HUMIDITY RECOVERIES OVER  
THE HIGHER TERRAIN THIS WEEKEND. ENOUGH ATMOSPHERIC MIXING SHOULD  
OCCUR TO DISPERSE PARTICULATE MATTER OUT OF THE SAN JOAQUIN  
VALLEY. IN THE POST FRONTAL ENVIRONMENT SATURDAY, NORTHERLY WINDS  
WILL BE GUSTY IN MERCED COUNTY AND OVER THE WESTERN HALF OF THE  
SAN JOAQUIN VALLEY WHERE BLOWING DUST IS POSSIBLE.  
 
A MODEST OFFSHORE FLOW WILL BECOME ESTABLISHED ACROSS THE GOLDEN  
STATE BY SUNDAY AND CONTINUE INTO EARLY NEXT WEEK AS THE EASTERN  
PACIFIC RIDGE BUILDS BACK OVER CENTRAL AND SOUTHERN CALIFORNIA.  
THE MODELS FORECAST A SOMEWHAT STRONGER UPPER LEVEL TROUGH TO  
MOVE INTO THE PACIFIC NORTHWEST TUESDAY NIGHT THEN TRACK AS AN  
INSIDE SLIDER INTO THE GREAT BASIN ON DAYS 6 AND 7. THE TRAJECTORY  
OF THESE TYPES OF TROUGHS USUALLY DO NOT BRING MUCH IF ANY  
PRECIPITATION INTO THE CENTRAL CALIFORNIA INTERIOR. HOWEVER, THE  
GFS DOES TRACK THIS SYSTEM A BIT FARTHER WEST, SO IF THIS WERE TO  
HAPPEN, SHOWERS COULD OCCUR OVER THE MOUNTAINS BY NEXT THURSDAY.  
A MORE IMPORTANT HIGHLIGHT WILL BE THE COLDER AIR MASS THAT THIS  
STORM SYSTEM WILL PROBABLY BRING INTO THE CWA DURING THE LATTER  
PART OF NEXT WEEK. MINIMUM TEMPERATURES FRIDAY MORNING, DECEMBER  
22ND COULD RANGE FROM THE UPPER TEENS TO MID 20S IN THE KERN  
COUNTY DESERT AND IN THE MID 20S TO AROUND 30 IN THE SAN JOAQUIN  
VALLEY. OTHERWISE, THE OVERALL PATTERN STILL LOOKS DRY FOR THE  
NEXT 7 DAYS.  
 

 
   
AVIATION
 
 
WIDESPREAD MVFR VISIBILITY IN HAZE AND MIST WILL PERSIST IN THE SAN  
JOAQUIN VALLEY, WITH AREAS OF IFR AND LOCAL LIFR/VLIFR IN FOG  
DEVELOPING AROUND 06Z UNTIL 18Z FRIDAY. OTHERWISE, VFR CONDITIONS  
WILL PREVAIL OVER THE CENTRAL CA INTERIOR DURING THE NEXT 24 HOURS.  
 

 
   
AIR QUALITY ISSUES
 
 
ON THURSDAY DECEMBER 14 2017... UNHEALTHY FOR SENSITIVE GROUPS IN  
FRESNO... KERN... KINGS AND TULARE COUNTIES. FIREPALCE/WOOD STOVE  
BURNING STATUS IS: NO BURNING UNLESS REGISTERED IN FRESNO...  
KERN... KINGS... MADERA... MERCED AND TULARE COUNTIES.  
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 LOW.  
 
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT  
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP FOR ADDITIONAL INFORMATION  
AN/OR TO PROVIDE FEEDBACK.  
 

 
   
HNX WATCHES/WARNINGS/ADVISORIES
 
 
RED FLAG WARNING UNTIL 8 PM PST FRIDAY CAZ295>297.  
 

 
 

 
 
PUBLIC...DURFEE  
AVN/FW...ANDERSEN  
SYNOPSIS...DURFEE  
 
WEATHER.GOV/HANFORD  
 
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