Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 261113
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
413 AM PDT SUN JUL 26 2015

.SYNOPSIS...
DRY WEATHER CONTINUES ACROSS THE AREA EXCEPT FOR A SLIGHT CHANCE
OF SHOWERS OVER NORTHERN SHASTA COUNTY LATE TODAY AND TONIGHT.
TEMPERATURES BELOW OR NEAR NORMAL THROUGH MONDAY THEN CLIMBING TO
WELL ABOVE NORMAL TUESDAY THROUGH THE WEEK WITH TRIPLE DIGIT HEAT
RETURNING TO THE VALLEY.

&&

.DISCUSSION...
QUIET MORNING UNDER LIGHT SOUTHWEST FLOW ALOFT. THE MARINE LAYER
CONTINUES TO DEEPEN AS AN UPPER LEVEL TROUGH DIGS INTO THE EASTERN
PACIFIC. FORT ORD PROFILER SHOWING MARINE LAYER AT ABOUT 1600 FEET
THIS MORNING AND SOME COASTAL STRATUS SEEMS TO BE MAKING IT INTO
THE WESTERN DELTA SO FAR THIS MORNING. OTHERWISE...FAIR SKIES
PREVAIL OVER NORTHERN CALIFORNIA. TEMPERATURES THIS MORNING
RUNNING SIMILAR TO 24 HOURS AGO AND SHOULD SEE DAYTIME HIGHS
SIMILAR TO YESTERDAY AS WELL. THERE MAY BE A SLIGHT COOLING
ESPECIALLY NORTHERN PORTIONS OF THE CWA AS THE UPPER TROUGH
APPROACHES. THIS TROUGH MAY GENERATE ENOUGH INSTABILITY FOR A FEW
SHOWERS LATE THIS AFTERNOON OVER FAR NORTHWEST SHASTA COUNTY.
SMOKE WILL LIKELY IMPACT SOME AREAS EAST OF THE LOWELL FIRE AS
SOUTHWEST FLOW AHEAD OF THE OFFSHORE TROUGH BECOMES ESTABLISHED
TODAY. OTHERWISE FAIR SKIES WILL CONTINUE FOR MOST AREAS. UPPER
TROUGH PASSAGE THROUGH THE PACIFIC NORTHWEST WILL BRING A THREAT
OF SHOWERS ACROSS THE NORTHERN PORTIONS OF SHASTA COUNTY THIS
EVENING BUT THIS WILL BE ABOUT THE EXTENT OF ITS IMPACT IN THE
SHORT TERM. AS THE TROUGH SHIFTS EAST OF THE STATE MONDAY MORNING
HIGH PRESSURE ALOFT BEGINS TO MOVE INLAND OVER THE WEST COAST.
THIS WILL BRING THE BEGINNING OF A WARMING AND DRYING TREND
EXPECTED TO LAST THROUGH MID WEEK. SURFACE HIGH PRESSURE PUSHING
IN BEHIND THE TROUGH AND INTO THE PACIFIC NORTHWEST WILL PRODUCE A
MODERATE NORTHERLY SURFACE GRADIENT ACROSS NORTHERN CALIFORNIA BY
EARLY MONDAY. THIS DRY NORTHERLY FLOW WILL BRING MUCH LOWER
HUMIDITY BY MONDAY AFTERNOON FOR INCREASED FIRE DANGER. BUILDING
HIGH PRESSURE WILL BRING A WARM UP TO RIGHT AROUND NORMAL ON
MONDAY AFTERNOON WITH MORE WARMING TUESDAY AND WEDNESDAY AS UPPER
RIDGING BUILDS OVER THE WEST COAST. HIGH TEMPERATURES ON TUESDAY
WILL BE SEVERAL DEGREES ABOVE NORMAL WITH A LITTLE MORE WARMING
STILL IN STORE FOR WEDNESDAY. HIGHS IN THE VALLEY WILL LIKELY TOP
100 MOST LOCATIONS ON TUESDAY AND 105 MOST VALLEY BOTTOM LOCATIONS
ON WEDNESDAY.

&&
.EXTENDED DISCUSSION (THURSDAY THROUGH SUNDAY)

HIGH PRESSURE WILL MAINTAIN ABOVE NORMAL TEMPERATURES IN THE
EXTENDED PERIOD, ALTHOUGH, THERE WILL BE A GRADUAL COOLING TREND
FROM THURSDAY INTO THE WEEKEND.

HIGH PRESSURE CELL OVER THE GREAT BASIN AND EXTENDING INTO NORCAL
WILL STILL BE FAIRLY STRONG ON THURSDAY...DAYTIME HIGHS MEASURE
AROUND 5 TO 11 DEGREES ABOVE NORMAL. WIDESPREAD TRIPLE DIGIT HEAT
FORECAST IN THE VALLEY WITH PEAK HIGHS RANGING 100-110 (WARMEST
IN THE REDDING/RED BLUFF VICINITY). THE HIGH WEAKENS INTO THE
WEEKEND AS A TROUGH DIGS SOUTHWARD OVER THE EASTERN PACIFIC OCEAN.
BY SUNDAY, DAYTIME HIGHS WILL ONLY BE ABOUT 1-5 DEGREES ABOVE
NORMAL.

THE OTHER INTERESTING FACTOR WITH THIS HIGH IS THAT MOISTURE
WRAPPING AROUND THE HIGH COULD BRING THUNDERSTORMS AND/OR SHOWERS
TO OUR REGION, MAINLY LIMITED TO THE MOUNTAINS. MODELS ARE
INDICATING THAT BEST CHANCES FOR MOUNTAIN SHOWER ACTIVITY WILL BE
FRI-SUN.  JBB

&&

.AVIATION...

VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS.
THOUGH HAZY, SMOKY CONDITIONS ARE EXPECTED NEAR WILDFIRES,
ESPECIALLY THE LOWELL FIRE NEAR ALTA, CA. IFR STRATUS RETURNS TO
THE WESTERN DELTA EARLY THIS MORNING. VALLEY WINDS SHOULD REMAIN
BELOW 15 KT THROUGH SUNDAY. NEAR THE DELTA...SOUTHWEST WINDS 15-25
KT WILL CONTINUE.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
DENSE SMOKE ADVISORY UNTIL 11 AM PDT THIS MORNING FOR MOTHERLODE.

&&

$$


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