AREA FORECAST DISCUSSION
FXUS66 KHNX 202136
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
236 PM PDT FRI MAR 20 2009
.DISCUSSION...A WINTERLIKE STORM WILL BRING A DRAMATIC END TO
OUR SPELL OF MILD AND PLEASANT WEATHER THIS WEEKEND. THE STORM
IS CURRENTLY SITUATED OVER THE GULF OF ALASKA AND IT WILL TRACK
STEADILY SOUTHEASTWARD DURING THE NEXT 48 HRS. HIGH CLOUDS WELL
IN ADVANCE OF THIS STORM WILL BEGIN TO SHOW UP OVER THE NORTHERN
HALF OF OUR CWA LATER TONIGHT. AS THE STORM APPROACHES CA ON
SATURDAY...CLOUDS WILL CONTINUE TO INCREASE AND A STRENGTHENING
ONSHORE FLOW WILL GENERATE PRECIP OVER THE HIGHER ELEVATIONS OF
THE SIERRA NORTH OF KINGS CANYON SATURDAY AFTERNOON.
AS THE STORM TRACKS CLOSER...PRECIP WILL SPREAD OVER MUCH OF THE
REST OF OUR CWA SATURDAY NIGHT. COPIOUS MOISTURE COUPLED WITH
STRONG JET DYNAMICS AND COLD ADVECTION WILL PRODUCE HEAVY PRECIP
OVER THE HIGHER TERRAIN SATURDAY NIGHT THROUGH MIDDAY SUNDAY.
DURING THIS TIME...SNOW ACCUMULATIONS OF UP TO 3 FEET ARE LIKELY
OVER THE HIGHEST ELEVATIONS OF THE SIERRA. COLD AIR ACCOMPANYING
THIS STORM WILL BRING SNOW LEVELS DOWN TO 2K-3K FEET BY SUNDAY
WITH A SMALL ACCUMULATION OF SNOW POSSIBLE IN THE FOOTHILLS. IN
THE TEHACHAPI MOUNTAINS...UP TO A FOOT OF SNOW IS POSSIBLE ABOVE
6000 FEET AND THERE WILL BE ENOUGH SNOW TO CAUSE POTENTIAL TRAVEL
WOES ALONG INTERSTATE 5 OVER THE GRAPEVINE AND THROUGH TEHACHAPI
PASS SUNDAY. BY LATE IN THE DAY SUNDAY...SOME OF THE HIGHER RIDGES
IN THE KERN COUNTY DESERT MIGHT EVEN GET A LIGHT DUSTING OF SNOW.
AS THE COLDEST CORE OF THE STORM PASSES OVER THE CENTRAL CA
INTERIOR SUNDAY AFTERNOON...PRECIPITATION WILL BECOME SHOWERY.
HOWEVER...THE ATMOSPHERE WILL BECOME VERY UNSTABLE AND BRING A
THREAT OF SCATTERED THUNDERSTORMS WITH HAIL IN THE SJ VLY AND
ADJACENT FOOTHILLS. BY THEN...OUR CWA WILL BE IN THE LEFT FRONT
QUADRANT OF THE UPPER LEVEL JET WHERE A COUPLE OF THUNDERSTORMS
COULD MATURE TO SEVERE LEVELS.
ADDITIONALLY...POST FRONTAL WINDS WILL BE QUITE STRONG OVER THE
KERN COUNTY MOUNTAINS AND DESERT. IN THESE AREAS...WEST WINDS OF
25 TO 45 MPH ARE LIKELY THROUGH AND BELOW THE PASSES SUNDAY AFTN
AND EVENING WITH GUSTS AS HIGH AS 80 MPH.
PRECIP WILL DIMINISH IN MOST AREAS BY SUNDAY NIGHT AS THE STORM
SYSTEM MOVES INTO THE GREAT BASIN. AS WINDS ABATE AND SKIES
CLEAR IN THE SJ VLY SUNDAY NIGHT...IT WILL BECOME COLD ENOUGH FOR
PATCHY FROST BY DAYBREAK MONDAY. HOWEVER...UPSLOPE CLOUDS OUGHT
TO MITIGATE THE FROST THREAT ALONG THE EAST SIDE AND SOUTH END OF
THE SJ VLY AND ADJACENT FOOTHILLS MONDAY MORNING. OTHERWISE...
MONDAY WILL REMAIN MUCH COOLER THAN NORMAL AS A NORTHWESTERLY
FLOW ALOFT PREVAILS IN THE WAKE OF OUR WEEKEND STORM.
A NICE WARMING TREND IS SLATED FOR THE REMAINDER OF NEXT WEEK
AS AN EPAC RIDGE BUILDS INTO CA. BY NEXT FRIDAY...TEMPS WILL BOUNCE
BACK TO EARLY MAY LEVELS. THE 12Z GFS SEEMS TO BE AN OUTLIER TO
THIS SCENARIO AND PUTS A HALT TO THE WARMUP DURING THE MIDDLE OF
NEXT WEEK BY BRINGING AN INSIDE SLIDER TROUGH INTO THE GREAT
BASIN. UNLESS THE OTHER MODELS TREND SIMILARLY...THE GFS WILL
CONTINUE TO BE RULED OUT OF THE EXTENDED FORECAST.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA
INTERIOR THROUGH 00Z SUNDAY. WINDS OVER THE SIERRA CREST WILL
INCREASE TO 40-45 KTS SATURDAY AFTERNOON AHEAD OF AN APPROACHING
LATE-SEASON WINTER STORM.
&&
.AIR QUALITY ISSUES...
NONE
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 5 PM SATURDAY TO 5 PM PDT SUNDAY FOR
CAZ096-097.
WINTER STORM WARNING FROM 2 AM TO 11 PM PDT SUNDAY FOR CAZ095.
HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR
CAZ098-099.
&&
PUBLIC...DURFEE
AVN/FW...SANGER