000
FXUS66 KHNX 262100
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
200 PM PDT WED MAY 26 2010
.SYNOPSIS...
WINTRY WEATHER CONDITIONS ARE EXPECTED IN THE SOUTHERN SIERRA NEVADA
FROM TONIGHT THROUGH FRIDAY MORNING. RAIN IS LIKELY IN PORTIONS OF
THE SAN JOAQUIN VALLEY ON THURSDAY AS AN AREA OF LOW PRESSURE HEADS
INTO CENTRAL CALIFORNIA. TEMPERATURES WILL REMAIN BELOW NORMAL
THROUGH THE END OF THE WORK WEEK...HOWEVER A STRONG WARM UP IS
EXPECTED EARLY INTO MID NEXT WEEK.
&&
.DISCUSSION...
KHNX 88D SHOWING SOME SHOWERS HAVE BROKEN OUT IN MERCED COUNTY
AND OVER THE SOUTHERN SIERRA NEVADA. MESOWEST OBSERVATIONS ARE
INDICATING THE SNOW LEVEL IS RUNNING ABOVE 9000 FEET...BUT SNOW
LEVELS WILL LOWER AS COLDER AIR FILTERS INTO OUR AREA THIS
EVENING. VISIBLE SAT PICS SHOWING INCREASED CLOUDS FROM FRESNO
COUNTY NORTHWARD...BUT SOUTH OF FRESNO COUNTY SKIES ARE MOSTLY
SUNNY AT THIS TIME. WV INDICATING THE LARGE UPPER LOW OFF THE PAC
NW COAST IS NOW BEGINNING TO DROP SOUTHEAST TOWARD NORCAL. 12Z
WRF/GFS INDICATING SHORTWAVE ENERGY ROTATING AROUND THIS UPPER LOW
WILL MOVE INTO OUR AREA TONIGHT SPREADING INCREASED CLOUDS AND
SHOWERS INTO OUR AREA ALONG WITH COOLER AIR. THE SHOWER ACTIVITY
WILL BE MOST NOTICEABLE FROM FRESNO COUNTY NORTHWARD WHERE
PRECIPITATION WILL BECOME LIKELY BY THURSDAY AFTERNOON AS THE
UPPER LOW BEGINS TO PUSH EASTWARD ACROSS NORCAL. TEMPERATURES ON
THURSDAY WILL CONTINUE THEIR DOWNWARD TREND AS THE LOW TO OUR
NORTH PROVIDES OUR AREA WITH UNSEASONABLY COOL AIR FOR LATE MAY.
HOWEVER...THE MAIN UPPER COLD POOL WITH THIS SYSTEM WILL REMAIN
NORTH OF OUR AREA...AND THE 12Z MODELS KEEP THE CAPE AND INSTABILITY
THAT WOULD BE SUFFICIENT FOR THUNDERSTORM DEVELOPMENT WELL TO THE
NORTH OF OUR CWFA. HAVE THEREFORE REMOVED MENTION OF THUNDERSTORMS
FOR THE NORTHERN HALF OF OUR AREA FOR THURSDAY. SNOW ACCUMULATIONS
WITH THIS SYSTEM WILL BE MOST SIGNIFICANT AROUND YOSEMITE PARK
WHERE UP TO 8 INCHES OF NEW SNOW WILL BE POSSIBLE NEAR THE RIDGE
TOPS BY FRIDAY MORNING. ALTHOUGH SNOW LEVELS ARE FAIRLY HIGH AT
THIS TIME...SNOW LEVELS WILL LOWER TO AROUND 5000 FEET BY THURSDAY
NIGHT WITH CAA TAKING PLACE. SINCE THIS STORM IS OUT OF SEASON
WILL LET THE WINTER STORM WARNING RIDE FOR THE SOUTHERN SIERRA
NEVADA FROM KINGS CANYON NORTHWARD THROUGH THURSDAY NIGHT. SOUTH
OF KINGS CANYON ONLY SCATTERED SHOWERS ARE EXPECTED...BUT SOME
RIDGE TOPS MAY PICK UP A FEW INCHES OF FRESH SNOWFALL BY THURSDAY
NIGHT. A SPECIAL WEATHER STATEMENT WAS ISSUED TO HIGHLIGHT THE
SNOWFALL POTENTIAL FOR THE SOUTHERN SIERRAS IN TULARE COUNTY.
MODELS ARE INDICATING THE UPPER TROUGH PUSHING EAST INTO THE GREAT
BASIN ON FRIDAY WITH BACKLASH MOISTURE PROVIDING FOR SOME RESIDUAL
SHOWERS OVER THE SOUTHERN SIERRA NEVADA. MEANWHILE...DRYER AIR
WILL ALLOW FOR SKIES TO CLEAR OUT OVER THE SAN JOAQUIN VALLEY ON
FRIDAY. THE 12Z NAM AND GFS INDICATE A DRY UPPER RIDGE BUILDING
INTO CA ON SATURDAY CORRESPONDING TO THE LONG WAVE PATTERN CHANGE
THAT HAS BEEN ADVERTISED TO TAKE PLACE OVER THE WEEKEND FOR SOME
TIME.
THE 12Z RUNS OF THE GFS AND ECMWF ARE SHOWING A BROAD UPPER RIDGE
OVER CA FROM SUNDAY THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. THIS
WILL KEEP OUR AREA DRY FOR THE EXTENDED PERIOD AND PROVIDE OUR
AREA WITH MUCH WARMER TEMPERATURES AS HEIGHTS AND THICKNESSES RISE
IN A DRY ATMOSPHERE. IN FACT...BY THE FIRST OF JUNE TEMPERATURES
ARE EXPECTED TO BE ABOVE SEASONAL NORMALS WHICH MEANS THAT
PORTIONS OF THE CENTRAL AND SOUTH SAN JOAQUIN VALLEY WILL HAVE
AFTERNOON HIGHS IN THE 90S.
&&
.AVIATION...
IN THE SOUTHERN SIERRA...AREAS OF IFR/MTN OBSCURATIONS IN CLOUDS
AND WIDELY SCT SHOWERS THRU 12Z THURS...THEN WIDESPREAD IFR/MTN
OBSCURATION IN CLOUDS/PRECIP THRU 00Z FRI. IN THE KERN COUNTY
MOUNTAINS AND DESERTS...PATCHES OF MVFR CLOUDS OVER
MTNS...OTHERWISE VFR THRU 00Z FRI. FOR THE SAN JOAQUIN
VALLEY...VFR THRU 00Z FRI EXCEPT AFTER 15Z THURS LOCAL MVFR IN
AREAS OF LIGHT RAIN FROM FRESNO NORTH.
&&
.AIR QUALITY ISSUES...NONE.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 AM PDT FRIDAY ABOVE 5000 FEET FOR
THE CAZ096.
&&
$$
PUBLIC...DS
AVN/FW...BINGHAM
SYNOPSIS...TLM