Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 292253
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
353 PM PDT MON JUN 29 2015

.SYNOPSIS...
VERY HOT WEATHER ACROSS MUCH OF THE REGION FOR THE REMAINDER OF
THE WEEK. SOME SIERRA THUNDERSTORMS THROUGHOUT THE WEEK.
THUNDERSTORMS MAY MOVE INTO PORTIONS OF THE VALLEY ON THURSDAY
AND FRIDAY.

&&

.DISCUSSION...
HEAT, THUNDERSTORM, AND FIRE CONCERNS THIS WEEK FOR INTERIOR
NORTHERN CALIFORNIA. HIGH PRESSURE OVER THE GREAT BASIN WILL
STRENGTHEN INTO NORCAL TUESDAY THROUGH THURSDAY WITH MUCH OF THE
VALLEY EXPERIENCING TRIPLE DIGIT HEAT. MONSOONAL MOISTURE WILL
CONTINUE TO SPREAD INTO OUR REGION MAINLY OVER THE MOUNTAINS.

HEAT: HOTTEST DAYS THIS WEEK WILL BE TUESDAY-THURSDAY. VALLEY
HIGHS WILL PEAK BETWEEN 100-115 DEGREES DURING THIS WINDOW.
OVERNIGHT LOWS WILL BE WARMEST IN THE NORTHERN SACRAMENTO VALLEY
RANGING 75 TO 80. BECAUSE THIS HEAT CONTINUES FOR SEVERAL DAYS,
WE HAVE ISSUED AN EXCESSIVE HEAT WATCH FOR THE CENTRAL AND
NORTHERN SACRAMENTO VALLEY AND ADJACENT FOOTHILLS NORTH OF
INTERSTATE 80 WHICH IS IN EFFECT WEDNESDAY AFTERNOON INTO FRIDAY
MORNING. ALTHOUGH HOT TEMPERATURES BEGIN TUESDAY, THE CUMULATIVE
EFFECTS OF PROLONGED HEAT WILL PEAK WEDNESDAY INTO FRIDAY MORNING. FOR
AREAS SOUTH OF INTERSTATE 80 (INCLUDING THE SACRAMENTO METRO
REGION), THE HEAT WILL BE MORE OF A TUESDAY-WEDNESDAY EVENT SINCE
THE DELTA BREEZE WILL BRING SOME COOLING ON THURSDAY.

THUNDERSTORMS: MONSOONAL MOISTURE WILL PRIMARILY IMPACT THE SIERRA
WITH THUNDERSTORM POTENTIAL THIS WEEK. HOWEVER, MODELS ARE NOW
SHOWING THAT THUNDERSTORM/SHOWERS COULD MOVE INTO THE VALLEY
STARTING THURSDAY. HAVE INCREASED THE CHANCES OF PRECIPITATION FOR
PORTIONS OF THE VALLEY THURSDAY AND THURSDAY NIGHT IN THE SHORT
TERM FORECAST.

FIRE CONCERNS: VERY HOT WEATHER COMBINED WITH LIGHTNING POTENTIAL
AND VERY DRY FUELS HAS ELEVATED CONCERNS FOR FIRE STARTS AND FIRE
SPREAD. ANY FIREWORKS USED THIS WEEK WILL ALSO CONTRIBUTE TO
CONCERNS FOR FIRE STARTS.
JBB

&&
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)

MONSOONAL MOISTURE WILL CONTINUE TO BE DRAWN UP INTO THE REGION
BETWEEN HIGH PRESSURE CENTERED OVER THE GREAT BASIN AND LOW
PRESSURE OFF THE COAST. MID AND HIGH LEVEL CLOUDS WILL REDUCE DAY
TIME HEATING TO AN EXTENT, AS WELL AS SOME ONSHORE FLOW.
TEMPERATURES WILL STILL BE FAIRLY HOT OVER THE NORTHERN SACRAMENTO
VALLEY, THOUGHMOST SHOWER AND THUNDERSTORM ACTIIVTY IS EXPECTED
TO BE OVER THE MOUNTAINS. THE 18Z GFS IS HINTING AT SOME VALLEY
PRECIPITATION FOR FRIDAY MORNING...BUT INSTABILITY FOR CONVECTION
APPEARS TO BE FAIRLY WEAK SO WILL KEEP THE VALLEY FORECAST DRY FOR
NOW.

SOME POTENTIAL FOR MOUNTAIN SHOWERS WILL CONTINUE INTO THE
WEEKEND, BUT WILL SHIFT EASTWARD AND WEAKEN EACH DAY. FURTHER
COOLING IS EXPECTED FOR THE WEEKEND WITH MORE ONSHORE FLOW AND
AN INCREASING DELTA BREEZE, THOUGH HIGHS WILL REMAIN A LITTLE
ABOVE NORMAL LEVELS FOR THE SOUTHERN SACRAMENTO VALLEY/DELTA,
ABOUT 5-10 DEGREES ABOVE NORMAL FOR THE NORTHERN SACRAMENTO. EK

&&

.AVIATION...

GENERAL VFR CONDITIONS EXPECTED OVER THE NEXT 24 HOURS...ALTHOUGH
LOCAL MVFR/IFR IS POSSIBLE OVER THE NORTHERN SIERRA SOUTH OF KTVL
THROUGH 06Z THIS EVEING. LCL SW WIND GUSTS TO 25 KT THROUGH 15Z
TUESDAY. EK
&&

.STO WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WATCH FROM WEDNESDAY AFTERNOON THROUGH FRIDAY
MORNING FOR CENTRAL SACRAMENTO VALLEY-NORTHEAST
FOOTHILLS/SACRAMENTO VALLEY-NORTHERN SACRAMENTO VALLEY.

&&

$$



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