794  
FXUS66 KHNX 241051  
AFDHNX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA  
351 AM PDT SAT JUN 24 2017  
   
SYNOPSIS
 
SLIGHTLY LOWER TEMPERATURES THIS WEEKEND BUT STILL  
WELL ABOVE NORMAL. A FEW AFTERNOON AND EVENING THUNDERSTORMS  
REMAIN POSSIBLE OVER THE SOUTHERN SIERRA NEVADA THROUGH SUNDAY.  
DRY CONDITIONS AND MORE NOTICEABLE COOLING WILL OCCUR EARLY NEXT  
WEEK.  
 

 
   
DISCUSSION
 
HIGH PRESSURE OVER THE REGION CONTINUES TO DOMINATE  
BUT IS WEAKENING A LITTLE. THIS WILL ALLOW TEMPERATURES TO COOL  
SLIGHTLY THIS WEEKEND, EXCEPT FOR THE DESERT WHERE LITTLE CHANGE  
IS EXPECTED. DESPITE THIS, MOST OF THE SAN JOAQUIN VALLEY AND  
LOWER FOOTHILLS WILL STILL SEE TRIPLE DIGIT HIGHS. THE ONSHORE  
SURFACE FLOW HAS PICKED UP A LITTLE AND THE FORT ORD PROFILER  
SHOWS THE MARINE LAYER DEPTH APPROACHING 2000 FEET. THIS SHOULD  
HELP COOL AREAS AROUND MERCED COUNTY AND WESTERN FRESNO COUNTY A  
BIT MORE WITH HIGHS IN THE UPPER 90S. DUE TO THE PREVAILING 100+  
DEGREES HIGHS FORECAST, A HEAT ADVISORY IS IN EFFECT THROUGH THE  
WEEKEND FOR THE SJ VALLEY, FOOTHILLS, AND KERN COUNTY MOUNTAINS.  
AS MENTIONED EARLIER, THE KERN COUNTY DESERT WILL CONTINUE TO SEE  
TEMPERATURES CLIMBING TO 106-113. THUS, AN EXCESSIVE HEAT WARNING  
REMAINS IN EFFECT THERE THROUGH THE WEEKEND.  
 
A MORE WIDESPREAD AND SIGNIFICANT COOLDOWN IS EXPECT EARLY NEXT  
WEEK AS AN EPAC UPPER TROUGH MOVES IN OVER NORTHERN CALIFORNIA.  
THIS WILL DROP TEMPERATURES DOWN ABOUT 10 DEGREES FROM SUNDAY TO  
TUESDAY. HIGHS IN THE SJ VALLEY WILL BE BACK TO MORE SEASONABLE  
LEVELS FOR LATE JUNE, THE LOWER TO MID 90S. ALSO, STRONGER ONSHORE  
SURFACE FLOW WILL SPREAD MORE MARINE AIR INTO THE SJ VALLEY. MORE  
COMFORTABLE NIGHT TIME TEMPERATURES WILL OCCUR WITH SOME PARTS OF  
MERCED COUNTY AND WESTERN FRESNO COUNTY DROPPING INTO THE UPPER  
50S OVERNIGHT. LITTLE CHANGE IS EXPECTED THROUGH THE REST OF THE  
WEEK WITH A GENERAL ZONAL FLOW ALOFT.  
 
SATELLITE IMAGERY SHOWS SOME MID/HIGH LEVEL CLOUDS SPREADING IN  
FROM THE SOUTH AS A WEAK DISTURBANCE ROUNDS THE UPPER RIDGE. A FEW  
AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE OVER THE SIERRA  
NEVADA THIS WEEKEND WITH TODAY SEEING A LITTLE BETTER CHANCE THAN  
SUNDAY. ANY STORMS THAT DEVELOP TODAY WOULD GENERALLY MOVE FROM  
SOUTH TO NORTH, BUT A LITTLE SOUTHEAST COMPONENT COULD PUSH SOME  
TOWARDS THE FOOTHILLS. STEERING FLOW ON SUNDAY IS WESTERLY, SO  
ANY STORMS WOULD BE CONFINED ALONG THE SIERRA CREST.  
 
PEOPLE SHOULD CONTINUE TO TAKE EXTRA PRECAUTIONS THIS WEEKEND  
WITH WIDESPREAD TRIPLE DIGIT HEAT EXPECTED. TRY TO AVOID OUTDOOR  
ACTIVITIES DURING THE HEAT OF THE DAY. PREFERABLY, WEAR LIGHT  
COLORED, LOOSE FITTING CLOTHING. TAKE BREAKS, SEEK OUT SHADE, AND  
REMEMBER TO STAY HYDRATED. CHILDREN AND THE ELDERLY ARE THE MOST  
SUSCEPTIBLE TO THE HEAT. ALSO, DON'T FORGET TO PROVIDE WATER AND  
SHELTER FOR PETS AND LIVESTOCK.  
 
SNOW MELT CONTINUES FROM THE HIGH SIERRA WITH RIVERS AND STREAMS  
RUNNING VERY HIGH AND FAST. A FLOOD WARNING IS IN EFFECT ALONG  
PART OF THE KINGS RIVER DUE TO INCREASED RELEASES FROM PINE FLAT  
DAM. ALSO, A FLOOD ADVISORY IS IN EFFECT ALONG THE SAN JOAQUIN  
RIVER BELOW FRIANT DAM DUE TO HIGH WATER RELEASES. REMEMBER TOO,  
THE RIVERS MAY LOOK INVITING DURING THE HEAT, BUT THE COLD AND  
FAST MOVING WATERS ARE EXTREMELY DANGEROUS.  
 

 
   
AVIATION
 
 
ISOLATED THUNDERSTORMS ARE POSSIBLE OVER THE HIGHER ELEVATIONS  
OF THE SOUTHERN SIERRA NEVADA FROM 21Z SATURDAY TO 04Z SUNDAY.  
OTHERWISE, VFR CONDITIONS WILL PREVAIL ACROSS THE CENTRAL CA  
INTERIOR DURING THE NEXT 24 HOURS.  
 

 
   
AIR QUALITY ISSUES
 
 
ON SATURDAY JUNE 24 2017...UNHEALTHY FOR SENSITIVE GROUPS IN  
FRESNO...KERN 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 HIGH.  
 
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
 
 
HEAT ADVISORY FROM NOON TODAY TO 9 PM PDT SUNDAY CAZ089>095.  
 
EXCESSIVE HEAT WARNING UNTIL 9 PM PDT SUNDAY CAZ098-099.  
 

 
 

 
 
PUBLIC...DCH  
AVN/FW...KL/DCH  
SYNOPSIS...DCH  
 
WEATHER.GOV/HANFORD  
 
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