Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 311712
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1012 AM PDT FRI JUL 31 2015

.SYNOPSIS...
A SLOW COOLING TREND INTO NEXT WEEK. DAYTIME HIGHS NEAR NORMAL
BY SUNDAY AND AT OR BELOW NORMAL MUCH OF NEXT WEEK. SCATTERED
MOUNTAIN THUNDERSTORMS THROUGH MONDAY AS MONSOON MOISTURE IS
PULLED NORTHWARD...ELSEWHERE CONTINUED DRY.

&&

.DISCUSSION...
A NICELY DEFINED VORTMAX VISIBLE ON SATELLITE IS MOVING NORTHWARD THROUGH
THE AREA THIS MORNING. THIS ALONG WITH MONSOONAL MOISTURE IS
BRINGING SOME LOCAL PRECIPITATION. DID A QUICK UPDATE TO ADD
SPRINKLES INTO THE EASTERN SACRAMENTO VALLEY AND ISOLATED
THUNDERSTORMS INTO THE MOTHERLODE FOOTHILLS AND SOUTHEAST SAN
JOAQUIN VALLEY THIS MORNING. SO FAR HAVE SEEN A FEW ISOLATED
THUNDERSTORMS IN THE SIERRA BRINGING SOME BRIEF PERIODS OF RAIN
AND SOME LIGHTNING STRIKES. SOME LIGHT SPRINKLES HAVE BEEN
REPORTED IN ROSEVILLE AND EL DORADO SPRINGS. HAVE ADJUSTED
CLOUD COVER UP A LITTLE TEMEPRATURES DOWN SLIGHTLY. EXPECT
ADDITIONAL SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS THIS
AFTERNOON. EK

.PREVIOUS DISCUSSION...
HIGH PRESSURE RIDGE OVER THE WESTERN U.S. WITH UPPER LEVEL
SOUTHEAST FLOW OVER THE STATE. THIS RIDGE OF HIGH PRESSURE HAS
BROUGHT ANOMALOUSLY HOT TEMPERATURES TO THE FORECAST AREA OVER
THE LAST SEVERAL DAYS WITH ANOTHER DAY OF ABOVE NORMAL
TEMPERATURES EXPECTED TODAY MOST AREAS. CLOSER TO NORMAL DAYTIME
HIGHS CAN BE EXPECTED IN THE DELTA...SOUTHERN SACRAMENTO AND
NORTHERN SAN JOAQUIN VALLEYS TODAY THANKS TO A DELTA BREEZE WHICH
CONTINUES TO INCREASE AS THE WESTERN U.S. RIDGE BEGINS TO WEAKEN.
SOUTHEAST FLOW ALOFT WILL BRING INCREASED MONSOON MOISTURE INTO
THE REGION TODAY WITH TPW VALUES FORECAST TO TOP AN INCH MOST OF
THE CWA BY THIS AFTERNOON. A SHORTWAVE DISTURBANCE NOW BRINGING
SHOWERS TO SOUTHERN TUOLUMNE COUNTY WILL LIKELY CONTINUE TO THE
NORTHWEST THIS MORNING BRINGING LIGHT SHOWERS TO THE NORTHERN
SIERRA PORTION OF THE CWA OVER THE NEXT FEW HOURS. ISOLATED
MOUNTAIN THUNDERSTORMS ARE A GOOD BET THIS AFTERNOON WITH PLENTY
OF MOISTURE...SUFFICIENT INSTABILITY AND OROGRAPHIC LIFT. HIGH PW
CONTENT SHOULD MEAN THAT ANY THUNDERSTORM ACTIVITY WILL CONTAIN
RAINFALL WITH HEAVY RAINFALL POSSIBLE WITH SOME THUNDERSTORMS.
OVERALL AIRMASS COOLS A BIT MORE ON SATURDAY AS THE UPPER RIDGE
SHIFTS EASTWARD A BIT IN RESPONSE TO AN UPPER LOW OFF THE CENTRAL
CA COAST SHIFTING COASTWARD. A CONTINUED STRONG DELTA BREEZE WILL
KEEP DAYTIME TEMPERATURES IN DELTA INFLUENCED AREAS AT OR BELOW
NORMAL. MOISTURE...INSTABILITY AND OROGRAPHIC LIFT WILL BRING
ANOTHER DAY OF ISOLATED THUNDERSTORMS OVER THE MOUNTAINS SATURDAY.
UPPER RIDGE AXIS SHIFTS FARTHER INLAND ON SUNDAY WITH AN INCREASE
IN ONSHORE FLOW BRINGING STILL COOLER TEMPERATURES. DAYTIME HIGHS
ON SUNDAY SHOULD COME IN CLOSE TO OR EVEN BELOW NORMAL MOST AREAS.
MOUNTAIN THUNDERSTORMS WILL CONTINUE TO REDEVELOP IN THE AFTERNOON
BUT AREA OF EMPHASIS WILL LIKELY SHIFT TO THE NORTHERN MOUNTAINS
UNDER A MORE SOUTHERLY FLOW ALOFT. UPPER TROUGH DEVELOPMENT IN THE
EASTERN PACIFIC WITH SOUTHWEST FLOW ALOFT OVER THE NORTH STATE
SHOULD SHIFT ANY AFTERNOON THUNDERSTORM DEVELOPMENT TO THE SIERRA
CASCADE CREST ON MONDAY. INCREASED ONSHORE FLOW AND COOLER AIRMASS
WILL BRING DOWN HIGH TEMPERATURES TO BELOW NORMAL FOR THIS TIME OF
YEAR WITH THESE BELOW NORMAL TEMPERATURES LASTING THROUGH MUCH OF
THE COMING WEEK.

&&
.EXTENDED DISCUSSION (TUESDAY THROUGH FRIDAY)

MAINLY DRY FORECAST EXPECTED FOR THE EXTENDED PERIOD. UPPER LEVEL
LOW WILL SPIN OFF THE BRITISH COLUMBIA COAST FOR MUCH OF THE WEEK
WITH ASSOCIATED TROUGH JUST OFF THE WEST COAST AND HIGH PRESSURE
ANCHORED OVER THE PLAINS. SEVERAL SHORTWAVES WILL RIPPLE EAST IN
THE FLOW BUT MOISTURE WILL BE LIMITED. THERE`S A SMALL CHANCE A
FEW SHOWERS COULD ACCOMPANY EACH WAVE BUT BEST CHANCES LOOK TO BE
ACROSS OREGON AND FAR NORTHERN CA. FOR NOW HAVE KEPT WITH DRY
FORECAST. TROUGH WILL SLOWLY BEGIN TO MOVE ONSHORE BY END OF NEXT
WEEK. TEMPERATURES WILL BE WITHIN A FEW DEGREES OF NORMAL FOR THE
WEEK AS AIRMASS COOLS AND ONSHORE FLOW STRENGTHENS. CEO
&&

.AVIATION...

VFR CONDITIONS NEXT 24 HOURS FOR TAF SITES. POSSIBLE LOCAL VSBY
RESTRICTIONS NEAR CURRENT FIRES DUE TO SMOKE. WINDS GENERALLY LESS
THAN 10-15 KTS FOR TAF SITES. WIND GUSTS OF 25-30 KTS POSSIBLE
INVOF DELTA.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$


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