Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 072230
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PDT TUE JUL 7 2015

.SYNOPSIS...
THUNDERSTORMS TODAY THROUGH THURSDAY...HEAVY RAIN IN MOUNTAINS.
ISOLATED THUNDERSTORMS POSSIBLE VALLEY LATE TONIGHT AND WEDNESDAY
MORNING.

&&

.DISCUSSION (TODAY THROUGH FRIDAY)...
FORECAST WAS IN REALLY GOOD SHAPE SO NOT TOO MANY CHANGES TO GOING
FORECAST. RADAR ALREADY LIGHTNING UP PRETTY WELL WITH CONVECTION
AGAIN REMAINING MOSTLY ON EAST SIDE OF CREST WITH A SOUTH TO
SOUTHEAST FLOW ALOFT PROVIDING UPSLOPE FLOW EAST SIDE OF SIERRA AS
WELL AS UPWARD MOTION FROM UPPER LOW MOVING INTO CALIFORNIA.

THE UPPER LOW WILL PUSH INTO CENTRAL CALIFORNIA TONIGHT AND IS
OFTEN THE CASE WITH UPPER LOWS IT WILL HAVE SOME ELEVATED
INSTABILITY WITH IT AS WELL AS SOME LIFT. 12Z RUN OF NAM WAS
SHOWING A BAND OF INSTABILITY MOVING INTO SACRAMENTO AREA AROUND
2 AM AND LINGERING THROUGH THE EARLY MORNING OF ELEVATED CAPE UP
TO AROUND 800 MB. THIS IS PROBABLY OVERDONE AS GFS HAS NEARLY
NOTHING...BUT WORTH AT LEAST A 20 PERCENT CHANCE OF THUNDERSTORMS
INTO VALLEY FOR THIS FEATURE AS THIS IS NOT UNCOMMON WITH UPPER
LOWS. OVERALL THOUGH DON`T EXPECT THESE T-STORMS TO BE HIGH IMPACT
WITH MOST IMPACT THIS EVENING FROM THUNDERSTORMS THAT SNEAK OVER
THE CREST.

WEDNESDAY AFTERNOON AND NIGHT...UPPER LOW MOVES FURTHER EAST.
ANOMALY DATA SHOWING SOME PRETTY HEFTY 30 YEAR RETURN VALUES OF
PRECIPITABLE WATER IN FAR NORTHER CALIFORNIA AND EXPECT SOME
PRETTY HEAVY RAIN NORTH AND WEST OF SHASTA COUNTY IN NORTHERN
MOUNTAINS. LOOKS LIKE MAIN IMPACTS WILL REMAIN OUT OF OUR
FORECAST AREA.

THURSDAY EASTERLY FLOW ALOFT WILL CONTINUE TO BRING A RISK OF
THUNDERSTORMS TO MOUNTAINS AND ALSO TO NORTHERN SACRAMENTO VALLEY
IN REDDING AND RED BLUFF AREAS. THUNDERSTORMS THAT DO OCCUR WILL
HAVE HEAVY RAIN ONCE AGAIN BUT NOT WIDE ENOUGH COVERAGE TO ISSUE
ANY HIGHLIGHTS AT THIS TIME.

&&
.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)

BROAD UPPER LEVEL TROUGHING WITH RELATIVELY DRY SOUTHWEST FLOW
EXPECTED FOR THE WEEKEND INTO NEXT WEEK. SOME LINGERING SHOWERS
ARE POSSIBLE OVER THE MOUNTAINS EARLY SATURDAY, WITH SOME
AFTERNOON THUNDERSTORMS POSSIBLE NEAR THE CREST. TEMPERATURES FOR
THE WEEKEND ARE EXPECTED TO BE BELOW NORMAL, THEN GRADUALLY TREND
UPWARD EARLY NEXT WEEK. MODELS ARE IN FAIRLY GOOD
AGREEMENT...THOUGH THE EUROPEAN MODEL CONTINUES TO BE A LITTLE
SLOWER IN WEAKENING OF THE TROUGH. CURRENT FORECAST NOW HAS
WARMING TO NEAR NORMAL LEVELS BY MONDAY...MAYBE SLIGHTLY ABOVE
NORMAL BY TUESDAY. EK


&&

.AVIATION...

GENERAL VFR CONDITIONS CONTINUE. ONSHORE FLOW CONTINUES WITH SW
WIND GUSTS 20-30 KT NEAR THE DELTA. TAF SITES WINDS WILL GENERALLY
BE LIGHT EXCEPT THROUGH 04Z WITH WINDS 10-20 KTS FOR KSAC, KSMF,
KMHR, KSAC. SHOWERS AND THUNDERSTORMS ARE DEVELOPING NEAR THE
SIERRA CREST AND WILL SPREAD DOWN THE WESTERN SLOPES INTO THE
FOOTHILLS OVERNIGHT INTO WEDNESDAY WITH IFR CONDITIONS IN STRONGER
STORMS. A FEW STORMS COULD POTENTIALLY REACH INTO THE EASTERN
SACRAMENTO METRO AREA AFTER 06Z. LOCAL MVFR CONDITIONS POSSIBLE
DUE TO STRATUS FROM THE DELTA REGION INTO THE SOUTHERN SACRAMENTO
VALLEY THROUGH 16Z TOMORROW.

&&

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

$$


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