Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 042125
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
225 PM PDT MON MAY 4 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL CONTINUE TO WEAKEN THIS EVENING
AS A SYSTEM CROSSES SOUTHERN CALIFORNIA. A LOW PRESSURE CENTER WILL
PUSH INTO THE PACIFIC NORTHWEST ON TUESDAY THEN DROP SOUTHWARD LATER
IN THE WEEK BRINGING COOLER TEMPERATURES AND UNSETTLED CONDITIONS TO
THE AREA LATER IN THE WEEK.

&&

.DISCUSSION...
CONVECTION DEVELOPED BY MIDDAY OVER MONO COUNTY...INDICATING THAT
THE AIRMASS OVER CENTRAL CALIFORNIA IS MORE UNSTABLE TODAY THAN THE
PAST FEW DAYS. BY 2030Z /1330 PDT/...ISOLATED THUNDERSTORMS HAD
DEVELOPED OVER THE SIERRA NEVADA IN FRESNO AND TULARE COUNTIES. A
WEAK UPPER-LEVEL LOW WAS TRAVERSING SOUTHERN CALIFORNIA THIS
AFTERNOON AND WAS WRAPPING MOISTURE INTO THE SOUTHERN SIERRA NEVADA
TO SUPPORT THE CONVECTION. THE LOW IS FORECAST TO MOVE INTO WESTERN
ARIZONA BY 06Z TUESDAY /2300 PDT TONIGHT/...BUT COULD SUPPORT
NOCTURNAL CONVECTION OVER THE SIERRA CREST THROUGH MIDNIGHT.

AN UPPER-LEVEL LOW WEST OF VANCOUVER ISLAND THIS AFTERNOON IS
FORECAST TO DROP INTO WESTERN WASHINGTON STATE BY TUESDAY AFTERNOON
AND INTO CENTRAL OREGON WEDNESDAY. THIS LOW WILL ROTATE A SERIES OF
SHORT-WAVES THROUGH CALIFORNIA. THIS WILL KEEP A RISK OF MOUNTAIN
THUNDERSTORMS THROUGH THE MIDDLE OF THE WEEK.

THERE IS SOME UNCERTAINTY FOR THE LATTER PART OF THE WEEK. THE
MODELS HAVE SHOWN SOME DIFFERENCES IN THE TIMING AND TRAJECTORY OF
THE LOW AS IT DROPS INTO CALIFORNIA...NOT ONLY BETWEEN MODELS BUT
ALSO BETWEEN MODEL RUNS. THE 12Z MODELS DROP THE LOW INTO NORTHERN
CALIFORNIA BY 12Z /0500 PDT/ THURSDAY AND OVER THE NORTHERN SAN
JOAQUIN VALLEY BY 00Z FRIDAY /1700 PDT THURSDAY/. THIS BRINGS THE
TROUGH ACROSS INTERIOR CENTRAL CALIFORNIA MAINLY THURSDAY AFTERNOON
AND EVENING FOR THE BAST CHANCE FOR THUNDERSTORMS ACROSS MUCH OF THE
WFO HANFORD WARNING/FORECAST AREA. A COLD AIRMASS IS FORECAST TO BE
ASSOCIATED WITH THIS SYSTEM...WITH TEMPERATURES COOLING TO SEVERAL
DEGREES BELOW NORMAL AND THE SNOW LEVEL FALLING TO AROUND 6000
FEET.

THE LOW IS NOW FORECAST TO DOGLEG EAST THURSDAY NIGHT AND BE OVER
SOUTHERN NEVADA BY FRIDAY AFTERNOON. THIS WOULD REDUCE THE
THUNDERSTORM THREAT TO THE SAN JOAQUIN VALLEY...AND HAVE SCALED BACK
POPS ACCORDINGLY. SATURDAY WILL SEE DECREASING CHANCE OF
THUNDERSTORMS OVER THE HIGH COUNTRY OF THE SOUTHERN SIERRA NEVADA
AND THE FIRST PART OF NEXT WEEK LOOKS DRY.

ANOTHER UPPER-LEVEL TROUGH IS FORECAST TO APPROACH THE CALIFORNIA
COAST NEXT MONDAY...BUT THERE ARE SIGNIFICANT DIFFERENCES BETWEEN
THE GFS AND ECMWF SO HAVE KEPT THE DRY FORECAST FOR NOW.

&&

.AVIATION...
SCATTERED THUNDERSTORMS WILL BE POSSIBLE OVER THE SOUTHERN SIERRA
NEVADA THRU 05Z TUESDAY. OTHERWISE VFR CONDITIONS WILL PREVAIL
ACROSS THE CENTRAL CALIFORNIA INTERIOR FOR 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 MEDIUM.

THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.

&&

.CLIMATE...
             RECORDS
SITE DATE    HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR

KFAT 05-04      100:2004     58:1930     64:2013     39:1950
KFAT 05-05       99:1990     57:1921     65:1989     36:1975
KFAT 05-06      100:1987     58:1921     69:1992     41:1975

KBFL 05-04      101:2004     59:1930     70:1982     39:1893
KBFL 05-05      100:1990     61:1932     69:1909     42:1930
KBFL 05-06      104:1987     55:1921     71:1989     42:1988

&&

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

&&

$$

PUBLIC...SANGER
AVN...ANDERSEN
FW...BEAN
SYNOPSIS...ANDERSEN

WEATHER.GOV/HANFORD


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