Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 270514
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1014 PM PDT FRI JUN 26 2015

.SYNOPSIS...
HOT WEATHER WILL CONTINUE FOR THE NEXT WEEK...BUT A BRIEF REPRIEVE
FROM TRIPLE DIGITS IN THE CENTRAL SACRAMENTO VALLEY THIS WEEKEND.
MOUNTAIN THUNDERSTORM ACTIVITY THIS WEEKEND THROUGH NEXT WEEK.
THUNDERSTORMS WILL INITIALLY HAVE LIMITED RAINFALL CREATING AN
INCREASED FIRE THREAT.

&&

.DISCUSSION...
ALL OF THE LIGHTNING PRODUCING THUNDERSTORMS HAVE BEEN OVER
SHASTA COUNTY THIS AFTERNOON AND EVENING...WITH AROUND 20 CLOUD TO
GROUND STRIKES OBSERVED MAINLY JUST EAST OF BURNEY. IR SAT IS
SHOWING ALTO CUMULUS OVER THE NRN/CENT SAC VALLEY GENERALLY NORTH
OF SACRAMENTO AND ISOLATED SHOWERS/THUNDERSTORMS WILL BE POSSIBLE
OVER SHASTA AND TEHAMA COUNTIES OVER THE NEXT FEW HOURS. HOT DAY
HAS BEEN REPLACED BY MODERATE DELTA BREEZE SRN SAC VALLEY WITH
TEMPS COOLER TEMPS...STILL HOT NRN SAC VALLEY WITH 90`S REDDING
RED BLUFF. RECORD HEAT OCURRED OVER THE NRN VALLEY WITH RED BLUFF
HITTING 108. REDDING WAS JUST TWO DEGREES OFF AT 111 AND DOWNTOWN
SACRAMENTO MISSED BY 1 DEGREE WITH 105 AS THE HIGH.

.PREVIOUS DISCUSSION... A LARGE AREA OF HIGH PRESSURE OVER THE
GREAT BASIN AND SURGES OF MONSOON MOISTURE ROTATING AROUND THIS
RIDGE WILL BE THE DOMINANT WEATHER PATTERN THIS WEEKEND. THE
THUNDERSTORMS ARE EXPECTED TO BE MAINLY OVER THE SIERRA MOUNTAINS
TODAY THROUGH SATURDAY...CONTAINING LITTLE IF ANY
RAINFALL...LIGHTNING AND GUSTY WINDS. THESE STORMS COMBINED WITH
PRIMED FUELS FROM RECENT HOT/DRY CONDITIONS ARE SETTING THE STAGE
FOR POTENTIAL FIRE ISSUES. THEREFORE THE RED FLAG WARNING FOR
LIGHTNING AND DRY FUELS WILL REMAIN IN PLACE THIS AFTERNOON
THROUGH SATURDAY. STILL SEE POTENTIAL FOR STORMS TO MOISTEN ENOUGH
TO PRODUCE DECENT RAINFALL BY SUNDAY...BUT MAY NOT BE MOIST ENOUGH
TO OFF SET LIGHTNING. THEREFORE CONTINUED TO FIRE WEATHER WATCH
FOR SUNDAY. ALSO...MODELS ARE STILL HINTING AT THE POTENTIAL FOR
SOME OVERNIGHT SHOWERS AND THUNDERSTORMS SATURDAY NIGHT INTO
SUNDAY FOR THE NORTHERN VALLEY. WITH VERY DRY LOW LEVELS MAY JUST
SEE SOME SPRINKLES.

THE WIDESPREAD TRIPLE DIGIT HEAT TODAY WILL RETREAT SOME OVER THE
WEEKEND AS HIGH LEVEL CLOUDS INCREASE AND THE DELTA BREEZE KICKS
IN. WINDS WILL INCREASE LATE THIS AFTERNOON AND CONTINUE THROUGH
THE EVENING. THIS WILL USHER IN SOME COOLER AIR WITH OVERNIGHT
LOWS SOME 3-10 DEGREES COOLER THAN LAST NIGHT. MOST DRAMATIC
COOLING WILL BE AREAS CLOSEST TO THE DELTA. THIS TREND WILL
CONTINUE THROUGH THE WEEKEND FOR MUCH OF THE SACRAMENTO AND SAN
JOAQUIN VALLEY WITH READINGS BACK IN THE 90S. THE NORTHERN VALLEY
WILL SEE SOME COOLING AS WELL...BUT WILL REMAIN CLOSER TO 100.


.EXTENDED DISCUSSION (TUESDAY THROUGH FRIDAY)

UPPER HIGH EXTENDING FROM THE FOUR CORNERS OVER NORCAL WILL BE THE
DOMINANT SYNOPTIC FEATURE THROUGH THE EXTENDED FORECAST PERIOD.
S-SE FLOW ALOFT AROUND THE PERIPHERY OF THE HIGH WILL ALLOW FOR
POTENTIAL ADVECTION OF SOME MONSOONAL MOISTURE INTO THE AREA.
THIS COMBINED WITH DIFFERENTIAL HEATING INSTABILITY OVER THE
MOUNTAINS WILL BRING A THREAT OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. WELL ABOVE NORMAL TEMPERATURES EXPECTED NEXT WEEK
WITH TRIPLE DIGIT HIGHS IN THE CENTRAL VALLEY. AFTERNOON MERCURY
READINGS FORECAST AT OR ABOVE 110 TUESDAY THROUGH THURSDAY IN
PORTIONS OF THE NORTHERN SACRAMENTO VALLEY. GUIDANCE SHOWING A
FEW DEGREES OF COOLING FRIDAY AS THE UPPER HIGH WEAKENS AND FLOW
THROUGH DELTA INCREASES. HIGHS IN THE FOOTHILLS AND MOUNTAINS WILL
RANGE FROM UPPER 80S TO AROUND 100.

PCH

&&

.AVIATION...

SLY FLOW ALF AS UPR LOW NR 35N 127W MOVS N THRU SAT. VFR CONDS
OVR INTR NORCAL NXT 24 HRS EXC ISOLD MVFR POSS IN ST VCNTY OF
DELTA BTWN 12Z-18Z SAT. SCT AFTN INTO EVE TSTMS POSS OVR MTNS WITH
ASSOCD STG GSTY SFC WNDS. LCL SWLY SFC WND GSTS UP TO 35 KTS POSS
THRU DELTA TNGT INTO SAT.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL MIDNIGHT PDT SATURDAY NIGHT FOR BURNEY
BASIN AND NORTHEAST PLATEAU IN SHASTA COUNTY INCLUDING NORTHWEST
LASSEN NF NORTH OF LASSEN NP-NORTHERN SIERRA INCLUDING LASSEN NP
AND PLUMAS AND LASSEN NF/S WEST OF THE SIERRA CREST (WEST OF
EVANS PEAK-GRIZZLY PEAK-BECKWORTH PEAK)-NORTHERN SIERRA
INCLUDING THE TAHOE AND ELDORADO NF/S WEST OF THE SIERRA CREST-
STANISLAUS NF WEST OF THE SIERRA CREST.

FIRE WEATHER WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING FOR BURNEY BASIN AND NORTHEAST PLATEAU IN SHASTA COUNTY
INCLUDING NORTHWEST LASSEN NF NORTH OF LASSEN NP-NORTHERN SIERRA
INCLUDING LASSEN NP AND PLUMAS AND LASSEN NF/S WEST OF THE
SIERRA CREST (WEST OF EVANS PEAK-GRIZZLY PEAK-BECKWORTH PEAK)-
NORTHERN SIERRA INCLUDING THE TAHOE AND ELDORADO NF/S WEST OF
THE SIERRA CREST-STANISLAUS NF WEST OF THE SIERRA CREST.

&&

$$


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