Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 050938
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
238 AM PDT THU MAY 5 2016

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL BRING UNSETTLED WEATHER THROUGH THE
WEEKEND. THIS SYSTEM WILL BRING THE THREAT OF SHOWERS AND
THUNDERSTORMS TO MUCH OF THE REGION ALONG WITH COOLER TEMPERATURES.

&&

.DISCUSSION...LOTS OF MID AND HIGH LEVEL MOISTURE CONTINUES TO
MOVE RAPIDLY NORTHWARD INTO THE FORECAST AREA IN RESPONSE TO THE
LARGE AND ESSENTIALLY STATIONARY LOW PRESSURE SYSTEM PARKED ABOUT
300 MILES WEST OF POINT CONCEPTION. AFTER A DAY OF VERY LIMITED
CONVECTION OVER THE FORECAST AREA AND ALL ORGANIZED PRECIPITATION
LIMITED TO NORTHERN CALIFORNIA, TODAY HOLDS THE PROMISE OF A MORE
SHOWERY SCENARIO.

THE ABOVE MENTIONED PARENT LOW PRESSURE SYSTEM IS ONLY VERY SLOWLY
MOVING TOWARD THE COAST AS A LARGE SCALE BLOCKING "OMEGA BLOCK"
HAS SET UP OVER THE CONTINENTAL U.S. THIS BLOCKING PATTERN IS VERY
STABLE AND IT IS KEEPING THE LOW FROM MAKING MUCH EASTWARD
PROGRESS. WHAT IS NEEDED FOR THE CENTRAL CALIFORNIA INTERIOR TO
GET THE PRECIPITATION STARTED IS THE LOW TO MOVE CLOSER AND BRING
INCREASED DYNAMICS DUE TO RISING AIR AND INSTABILITY FROM COOLING
TEMPERATURES ALOFT. FORECAST MODELS PROJECT THIS WILL BE THE CASE
THIS AFTERNOON AS THE LOW REACHES A POSITION NEAR POINT CONCEPTION
LATE THIS AFTERNOON AND EVENING. BY FRIDAY AFTERNOON THE LATEST
MODELS ONLY MOVE THE CENTER OF THE FIRST CIRCULATION TO A POSITION
NEAR BARSTOW AND PROJECT WIDESPREAD SHOWER AND THUNDERSTORM
ACTIVITY OVER MUCH OF THE AREA.

WITH THE UPSTREAM BLOCKING PATTERN IN PLACE, THE LOW BECOMES
NEARLY STATIONARY ON SATURDAY SOUTH OF LAS VEGAS AND THE
INGREDIENTS FOR YET MORE SHOWERS, THUNDERSTORMS AND HIGH MOUNTAIN
SNOW SHOWERS REMAIN WITH "WRAP AROUND" NORTHEAST FLOW INTO CENTRAL
CALIFORNIA. BY SUNDAY, FAIRLY GOOD AGREEMENT EXISTS BETWEEN
OPERATIONAL RUNS OF THE GFS AND EUROPEAN MODELS IN FINALLY MOVING
THE LOW WELL TO THE EAST AND LIMITING THE PRECIPITATION THREAT TO
THE SIERRA. OF COURSE THIS SCENARIO IS BASED ON THE BLOCKING
PATTERN TO THE EAST EASING UP.

FOR NEXT WEEK, MODELS ARE IN GOOD AGREEMENT IN FINALLY MOVING THE
LOW INTO THE CENTRAL U.S. AND BUILDING A HIGH AMPLITUDE RIDGE INTO
THE WEST COAST. THIS WILL ALLOW FOR A DRYING TREND WITH MUCH
WARMER TO HOT TEMPERATURES BY MID WEEK.

&&

.AVIATION...INCREASING AREAS OF MVFR AND LOCAL MOUNTAIN OBSCURING
IFR OVER THE SOUTHERN SIERRA NEVADA THRU 18Z THU. THEN MAINLY IFR
OVER THE SOUTHERN SIERRA NEVADA AFTER 18Z THU. INCREASING AREAS OF
MVFR OVER THE TEHACHAPI MOUNTAIN AFTER 18Z THU. ISOLATED
THUNDERSTORMS POSSIBLE THROUGHOUT THE CENTRAL CA INTERIOR AFTER 18Z
THU. OTHERWISE...VFR CONDITIONS WILL PREVAIL DURING THE NEXT 24
HOURS.

&&

.AIR QUALITY ISSUES...
NONE.

&&

.CERTAINTY...

THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH.

CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP FOR ADDITIONAL INFORMATION
AN/OR TO PROVIDE FEEDBACK.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

PUBLIC...DUDLEY
AVN/FW...MV
SYNOPSIS...DUDLEY

WEATHER.GOV/HANFORD



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