Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 021031
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
331 AM PDT THU JUL 2 2015

.SYNOPSIS...
HOT WEATHER CONTINUES OVER THE NORTHERN SACRAMENTO VALLEY TODAY ALTHOUGH
A FEW DEGREES OF COOLING ARE LIKELY. MOUNTAIN THUNDERSTORMS ARE
POSSIBLE EACH AFTERNOON AND EVENING THROUGH THE WEEKEND WITH THE
POSSIBILITY OF A STRAY SHOWER OR TWO IN THE VALLEY THIS MORNING
AND TONIGHT. COOLER TEMPERATURES OVER THE WEEKEND AND NEXT WEEK
BUT REMAINING ABOVE NORMAL. DECREASING CHANCES OF MOUNTAIN
THUNDERSTORMS NEXT WEEK AS UPPER RIDGE SHIFTS EASTWARD.

&&

.DISCUSSION...
HIGH PRESSURE ALOFT WILL REMAIN STRETCHED ACROSS THE SOUTHWEST U.S
FROM FOUR CORNERS TO NORCAL THROUGH THE SHORT TERM PERIOD. THE
OVERALL PATTERN WILL NOT CHANGE MUCH DAY TO DAY WITH MOUNTAIN
THUNDERSTORMS POSSIBLE EACH DAY AND POSSIBLY DURING SOME NIGHT
TIME PERIODS AS WELL. A SHORTWAVE TROUGH ROTATING AROUND THE
SOUTHWEST PORTION OF THE HIGH IS BRINGING ONE OF THESE NIGHTTIME
THUNDERSTORM PERIODS THIS MORNING WITH ISOLATED THUNDERSTORMS
BEING GENERATED OVER THE SAN JOAQUIN VALLEY THIS MORNING.
SHORTWAVE MODELS INDICATE THESE THUNDERSTORMS WILL ROTATE WEST OF
THE FORECAST AREA LATER THIS MORNING. SOUTHEAST TO EAST FLOW ALOFT
WILL BRING MOISTURE AND INSTABILITY INTO THE AREA TODAY FOR A
THREAT OF THUNDERSTORMS OVER THE MOUNTAIN AREAS THIS AFTERNOON.
MEANWHILE...CLOUD COVER AND A SLIGHT AIRMASS COOLING WILL BRING A
FEW TO SEVERAL DEGREES OF COOLING TODAY ALTHOUGH HIGHS WILL REMAIN
WELL ABOVE NORMAL. MODELS PUSH A SURGE OF MOISTURE INTO NORCAL
TONIGHT WITH TPW VALUES FORECAST TO TOP 1.5 INCHES. HAVE PUT IN
SLIGHT CHANCE OF LIGHT SHOWERS ACROSS MOST OF THE CWA FOR THE
TONIGHT PERIOD BUT WITH LACK OF HEATING AND DYNAMICS...DO NOT
EXPECT MUCH IN THE WAY OF PRECIPITATION AND MORE LIKELY WILL SEE
ISOLATED SPRINKLES.

MOUNTAIN THUNDERSTORMS REMAIN IN THE FORECAST FRIDAY AND SATURDAY
AFTERNOONS WITH STABILITY PROGS SHOWING MODERATE INSTABILITY OVER
THE MOUNTAIN AREAS WHILE VALLEY LOCATIONS REMAIN UNDER PARTLY
CLOUDY SKIES. DAYTIME TEMPERATURES CONTINUE TO COOL BOTH DAYS AS
THE UPPER RIDGE IS WEAKENED BY A SYSTEM PASSAGE TO THE NORTH. A
MODERATE DELTA BREEZE WILL KEEP THE DELTA INFLUENCED HIGH
TEMPERATURES CLOSE TO NORMAL ON INDEPENDENCE DAY WHILE ELSEWHERE
HIGHS ARE FORECAST TO COME IN AROUND 5 TO 10 DEGREES ABOVE NORMAL.

CONDITIONS STABILIZE A BIT ON SUNDAY AS A LOW OFF THE COAST EDGES
A BIT CLOSER TO THE COAST BRINGING SLIGHTLY MORE ONSHORE FLOW.
AFTERNOON MOUNTAIN THUNDERSTORMS WILL STILL BE POSSIBLE BUT LIKELY
NOT AS WIDESPREAD. MOST LOCATIONS WILL SEE A SLIGHT COOLING AS
WELL.

&&
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)

OUR CWA WILL BE BETWEEN A LOW OVER THE EASTERN PACIFIC OCEAN AND
A RIDGE OVER THE GREAT BASIN THROUGH EARLY NEXT WEEK. 12Z GFS IS
NOW TRENDING TOWARDS THE EC SHOWING THE UPPER LOW MOVING INLAND
MIDWEEK. SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS ALONG SIERRA
CREST FOR MONDAY AND TUESDAY...THEN DRY ACROSS OUR CWA WEDNESDAY
AND THURSDAY.

HIGH TEMPERATURES WILL TREND DOWN SLIGHTLY THROUGH THE EXTENDED
FORECAST PERIOD AS UPPER HIGH WEAKENS AND ONSHORE FLOW INCREASES.
MAX TEMPERATURES MONDAY & TUESDAY EXPECTED MAINLY IN THE 90S FOR
THE CENTRAL VALLEY, 80S FOR THE DELTA AND FOOTHILLS, AND 70S FOR
THE MOUNTAINS...WHICH WILL BE NEAR AVERAGE. SLIGHT COOLING ON
WEDNESDAY AND THURSDAY WILL PUT TEMPERATURES A FEW DEGREES BELOW
AVERAGE. JBB

&&

.AVIATION...

PREDOMINANTLY VFR CONDITIONS TODAY, HOWEVER, PERIODS OF MVFR
POSSIBLE IN THUNDERSTORMS. CURRENT RADAR SHOWS SHOWER AND
THUNDERSTORM ACTIVITY IMPACTING PARTS OF TUOLUMNE, STANISLAUS, AND
SAN JOAQUIN COUNTIES INCLUDING NEAR THE VICINITY OF KSCK AND KMOD
TAF SITES WHICH IS EXPECTED TO CONTINUE THROUGH 15Z. THUNDESTORMS
WITH PERIODS OF MVFR ALSO POSSIBLE ALONG THE WESTERN SIERRA SLOPES
TODAY.

ONSHORE WINDS FOR TAF SITES WILL BE LIGHT THIS MORNING AND THEN
STRENGTHEN THIS AFTERNOON/EARLY EVENING AFTER 20Z WITH WINDS 10-20
KTS FOR TAF SITES. DELTA WINDS WILL RANGE 15-25 KTS.  JBB
&&

.STO WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING UNTIL 7 PM PDT THIS EVENING FOR MOUNTAINS
SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY-NORTHERN
SACRAMENTO VALLEY-SHASTA LAKE AREA / NORTHERN SHASTA COUNTY.

&&

$$


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