Strong Wind in California, April 18 to 19, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
930 AM PDT MON APR 18 2005

.UPDATE...FOR THE CENTRAL CALIFORNIA INTERIOR...THE UPPER-LEVEL
TROUGH MOVING THROUGH CENTRAL CALIFORNIA GENERATED UPSLOPE
STRATOCUMULUS ALONG THE EAST SIDE AND OVER THE SOUTH END OF THE SAN
JOAQUIN VALLEY. OTHERWISE...SKIES ARE CLEAR ACROSS THE REGION EXCEPT
FOR SOME HIGH CLOUDS.

CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY TEMPERATURES AT 15Z WERE
DOWN AS MUCH AS 6 F FROM 24 HOURS EARLIER AS COLD AIR CONTINUES TO
MOVE INTO THE SAN JOAQUIN VALLEY WITH THE TROUGH. HAVE SEEN A FEW
GUSTS TO 25 MPH ON THE VALLEY FLOOR. HAVE ALSO SEEN A FEW LOCAL
GUSTS TO 40-50 MPH IN THE KERN COUNTY DESERTS...BUT THEY ARE NOT
WIDESPREAD AT THIS TIME. 12Z GFS AND NAM MOS GUIDANCE STILL
FORECAST WINDS TO PICK UP THIS AFTERNOON...WITH LOCALLY STRONG GUSTS
POSSIBLE BELOW THE PASSES. MODEL SURFACE PRESSURE GRADIENTS ARE
FORECAST TO PEAK AROUND 00Z TUESDAY...AND WILL BE ALERT FOR POSSIBLE
ADVISORIES WITH THE AFTERNOON PACKAGE.

SATELLITE LOOPS SHOW THE UPPER-LEVEL TROUGH OVER CALIFORNIA...WITH
DRY AIR OVER THE HANFORD WARNING/FORECAST AREA EVIDENT ON THE WATER-
VAPOR LOOP. THE 12Z MODELS ARE IN AGREEMENT WITH A CLOSED LOW
FORMING WITHIN THE TROUGH THIS AFTERNOON OVER SOUTHEASTERN OREGON...
A LOCATION WEST OF THAT FORECAST BY EARLIER RUNS. THE GFS/NAM/UKMET
NOW ELONGATE THE LOW ACROSS NEVADA TONIGHT...THEN SLOWLY DRIFT THE
LOWE EASTWARD ACROSS NEVADA TUESDAY AND TUESDAY NIGHT AS AN UPPER-
LEVEL RIDGE BUILDS OFF THE COAST.

THE NAM-40 /FORMERLY MESO-ETA/ HAS THE SOUTHERN SIERRA NEVADA UNDER
THE LEFT FRONT QUADRANT OF AN 85+ KT SPEED MAX CORE THIS EVENING...
WITH 850-700-MB LAYER HUMIDITIES OF 80-100 PERCENT AND 500-MB HEIGHTS
OF 5560-5600 METERS. PER COORDINATION WITH WFO/S SACRAMENTO AND
RENO...SLIGHT CHANCE POPS WERE ADDED ALONG THE CREST TONIGHT IN THE
MORNING FORECAST PACKAGE. THIS IS WELL SUPPORTED BY THE NAM-40.

NO UPDATES AT THIS TIME...PENDING CHANGES IN THE WINDS.

.FROM PREVIOUS DISCUSSION...

.SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...LEADING
SHORTWAVE HAS MOVED THROUGH THE AREA BRINGING SOME WINDS AND
COOLER AIR. WATER VAPOR SATELLITE IMAGERY SHOWS A SECONDARY IMPULSE
MOVING INTO THE TAHOE AREA...HOWEVER THE AIRMASS REMAINS RATHER DRY.
LOOKS LIKE A MUCH COOLER DAY OVER THE ENTIRE AREA WITH THE UPPER
LOW MOVING INTO THE GREAT BASIN BY TONIGHT. HAVE MADE SOME
GRID CHANGES BASED ON THE OBSERVED MESOWEST TEMPERATURES. FORECAST
MODELS CONTINUE TO SHOW GOOD RUN TO RUN CONSISTENCY IN PROGGING SOME
QPF OVER THE EAST SIERRA. IN COORDINATION WITH NWS RENO...WILL
INTRODUCE SLIGHT CHANCE POPS TONIGHT AND TUESDAY FOR THE SIERRA
CREST. MODELS KEEP A RATHER DEEP UPPER LOW NEAR ELKO AND NORTHEAST
NEVADA THROUGH WEDNESDAY MORNING AND THIS SHOULD KEEP NORTHERLY FLOW
OVER CENTRAL CALIFORNIA. COOL TEMPERATURES WILL PREVAIL IN THIS
PATTERN...HOWEVER THE THREAT OF ANY PRECIPITATION SHOULD STAY JUST
EAST OF THE SIERRA.

.LONG TERM...FOR WEDNESDAY NIGHT THROUGH SUNDAY...MEDIUM RANGE
MODELS IN MUCH BETTER AGREEMENT TODAY. AN UPPER LEVEL LOW IN THE
SOUTHERN GREAT BASIN WILL LIFT NORTH AND WEAKEN NEAR IDAHO
WEDNESDAY NIGHT. THIS WILL ALLOW A DRY AND WARMING TREND TO DEVELOP
THURSDAY AND FRIDAY AS AN UPPER LEVEL RIDGE BUILDS OVER CALIFORNIA.
NEXT WEEKEND LOOKS INTERESTING...AS MODELS TRENDING TOWARDS A
WET PATTERN CHANGE. MOST PROGS BRING AN A CLOSED UPPER LEVEL LOW
OFF THE CALIFORNIA SATURDAY...THEN MOVE THE LOW FURTHER EAST SUNDAY.
TIMING ONSET OF PRECIPITATION WILL BE DIFFICULT WITH A CLOSED
SYSTEM. BUT WILL INTRODUCE A SLIGHT THREAT FOR THE AREA SATURDAY
AFTERNOON WITH INCREASING SOUTHWEST FLOW BRINGING MOISTURE OFF THE
PACIFIC AND GFS SHOWS A VORTICITY MAX MOVING ONSHORE AROUND 00Z
SUNDAY. EXPECT HIGHER POTENTIAL PRECIPITATION SUNDAY WITH DEEPER
MOISTURE AND ADDITIONAL UPPER LEVEL ENERGY MOVING THROUGH THE LOW.

&&

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

&&

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