000
FXUS66 KHNX 271722
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
922 AM PST MON DEC 27 2010
.SYNOPSIS...
HIGH PRESSURE CONTINUES TO DOMINATE THE AREA PRODUCING PARTLY
CLOUDY SKIES WITH PATCHY LATE NIGHT AND EARLY MORNING FOG IN THE
SAN JOAQUIN VALLEY THROUGH TUESDAY. ANOTHER LOW PRESSURE SYSTEM
WILL IMPACT THE REGION TUESDAY NIGHT INTO WEDNESDAY NIGHT BRINGING
YET ANOTHER CHANCE FOR RAIN AND MOUNTAIN SNOW. DRY CONDITIONS WILL
RETURN FOR THURSDAY INTO FRIDAY DUE TO ANOTHER RIDGE OF HIGH
PRESSURE.
&&
.DISCUSSION...
WITH THE RISING SUN...VISIBLE SATELLITE LOOPS REVEAL A STRIP OF
FOG ON THE EAST SIDE OF THE VALLEY FROM AROUND MADERA TO THE
VISALIA AND HANFORD VICINITIES AS WELL AS SOME LOW/MID CLOUDINESS
FARTHER SOUTH AND PATCHES OF HIGHER CLOUDS TRACKING SOUTHEAST ACROSS
THE REGION. THE FOG AND MOST OF THE LOW CLOUDS WILL BREAK UP THIS
MORNING AND THE CENTRAL CALIFORNIA INTERIOR WILL HAVE ANOTHER
SEASONABLY MILD DAY WITH TEMPERATURES TOPPING OUT A TAD ABOVE CLIMO.
EXPECT SOME SIMILAR VALLEY FOG OVERNIGHT TONIGHT...WITH WIDESPREAD
DEVELOPMENT SOMEWHAT INHIBITED BY CLOUDS OVERHEAD. THE NEXT STORM
SYSTEM IS ON TRACK TO BRING A RETURN OF WET...SNOWY...AND WINDY
WEATHER TUESDAY THROUGH WEDNESDAY...THIS TIME ADDING FREEZING
TEMPERATURES IN THE VALLEY TO THE MIX...AS COLDER AIR IS USHERED
INTO THE REGION BEHIND THE STORM. NO UPDATE IS PLANNED FOR THE
FORECAST THIS MORNING.
&&
.PREV DISCUSSION... /ISSUED 220 AM PST MON DEC 27 2010/
DISCUSSION...A WEAK SHORTWAVE TROUGH IS MOVING ACROSS THE REGION
THIS MORNING AND THE ASSOCIATED CLOUD COVER IS REALLY INHIBITING
FOG FORMATION IN THE SAN JOAQUIN VALLEY. IT APPEARS THAT ANY FOG
THAT DOES FORM WILL BE PATCHY AT BEST. FOR TODAY HIGH PRESSURE
WILL CONTINUE TO EDGE IN FROM THE WEST HOWEVER THE AREA WILL NOT
SEE A VERY DRAMATIC RISE IN HEIGHTS AS THE CORE OF THE RIDGE STAYS
WELL TO THE WEST. THE WEATHER WILL BE DRY TODAY AND FOR MUCH OF
TUESDAY HOWEVER BY LATE TUESDAY AND ESPECIALLY TUESDAY NIGHT AND
WEDNESDAY THE NEXT WINTER STORM WILL MOVE INTO AND ACROSS THE
AREA. I HAVE UPPED POPS TO NEARLY 100% IN ALL AREAS TUESDAY NIGHT
AND WEDNESDAY. THE MAIN IMPACTS FROM THIS SYSTEM ARE AS FOLLOWS:
1. LOWER ELEVATION RAIN...ANY ADDITIONAL RAIN WILL LIKELY RUNOFF
DUE TO SATURATED SOILS. PONDING BASINS ARE NEARLY FULL AND MOST
LOW SPOTS ALREADY HAVE STANDING WATER. QPF AMOUNTS RANGE FROM
AROUND 1.50 INCHES IN FRESNO TO AROUND 0.75 INCHES IN BAKERSFIELD.
AMOUNTS WILL BE HIGHER IN FOOTHILL AND ALL UPSLOPE MOUNTAIN
LOCATIONS BELOW THE SNOW LINE. ADDITIONAL FLOODING IS LIKELY.
2. HEAVY MOUNTAIN SNOW...IT LOOKS LIKE ANOTHER 2-3+ FEET OF SNOW
WILL FALL ABOVE 5000 FEET AND WITH ARRIVAL OF MUCH COLDER AIR ON
WEDNESDAY FOR THE LAST 1/3RD OF THE PRECIPITATION EVENT,
ACCUMULATING SNOW WILL FALL DOWN TO 4000 FEET. THE KERN COUNTY
MOUNTAINS MAY SEE SOME SNOW ON THE HEAVILY TRAVELED GRAPEVINE AND
TEHACHAPI PASSES. A WINTER STORM WATCH HAS BEEN ISSUED FOR THE
MOUNTAINS.
3. POTENTIALLY STRONG TO LOCALLY DAMAGING WINDS IN THE MOUNTAINS
AND KERN COUNTY DESERT...FORECAST MODELS INCREASE GRADIENTS TO AS
MUCH AS 20+ MILLIBARS FROM SAN FRANCISCO TO LAS VEGAS ON WEDNESDAY
AFTERNOON AND EVENING AND THE NAM MODEL CRANKS OUT A 12 MILLIBAR
PRESSURE DIFFERENCE BETWEEN BAKERSFIELD AND CHINA LAKE DURING THIS
SAME TIME PERIOD! ADDITIONALLY 4500 FOOT LEVEL WINDS ARE PROGGED
TO EXCEED 55 MPH DURING THIS TIME FRAME AND WINDS AT THE 9000 FOOT
LEVEL ARE FORECAST TO EXCEED 70 MPH. THIS DOES NOT INCLUDE GUSTS.
WITH SATURATED SOILS AND WINDS OF THIS STRENGTH, TREES AND
POWER LINES WILL BE AT RISK.
4. BEHIND THIS SYSTEM MUCH COLDER AIR FROM CANADA WILL MOVE INTO
THE REGION THUS IN THE THURSDAY THROUGH SATURDAY TIME FRAME THE
THREAT OF A FREEZE IS REAL. TEMPERATURES IN THE SAN JOAQUIN VALLEY
WILL FALL BELOW FREEZING EVEN IN THE URBAN CENTERS AND THE
OUTLYING AREAS WILL SEE LOTS OF MID TO UPPER 20S THURSDAY AND
ESPECIALLY FRIDAY MORNING. IN THE DESERT AREAS WIDESPREAD LOW TO
MID 20S WILL BE PREVALENT. HIGHS WILL ONLY RECOVER INTO THE 40S AT
MANY LOWER ELEVATION LOCATIONS.
FOR THE UPCOMING WEEKEND, DISAGREEMENT CONTINUES BETWEEN THE GFS
AND ECMWF MODELS IN THE HANDLING AND TRACK OF THE INCOMING LOW.
THE GFS BRINGS THE LOW ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY AND SETS UP THE PATTERN FOR A KERN COUNTY DESERT POTENTIAL
SNOW EVENT. THE ECMWF MODEL ON THE OTHER HAND KEEPS THE LOW WELL
OFFSHORE AND DOESN'T BRING IT INLAND UNTIL LATE MONDAY AND WELL TO
THE SOUTH. FOR NOW THE SEEMINGLY MORE CONSISTENT GFS MODEL WILL BE
USED TO BASE THE WEATHER FOR SUNDAY. THIS COULD CHANGE HOWEVER
SINCE IT IS 6-7 DAYS IN THE FUTURE. THAT'S ALL FOR NOW.
&&
.AVIATION...
MVFR CEILINGS WITH LOCAL IFR IN THE SOUTHERN SIERRA FOOTHILLS AND
ALONG THE NORTH FACING SLOPES OF THE TEHACHAPI MOUNTAINS UNTIL 18Z
TUESDAY. IN THE SAN JOAQUIN VALLEY...AREAS OF MVFR CONDITIONS IN
MIST/FOG CAN BE EXPECTED WITH LOCAL IFR/LIFR IN FOG MAINLY AN AREA
FROM KMAE TO KVIS THROUGH 19Z. IMPROVEMENT TO MVFR WILL OCCUR IN THE
SAN JOAQUIN VALLEY BY 20Z MONDAY AND CONTINUE UNTIL 08Z TUESDAY WHEN
MORE WIDESPREAD AREAS OF FOG REDEVELOP RESULTING IN IFR AND LOCAL
LIFR CONDITIONS THROUGH 18Z TUESDAY. VFR CONDITIONS WILL PREVAIL
ACROSS THE REMAINDER OF THE CENTRAL CALIFORNIA INTERIOR THROUGH 18Z
TUESDAY.
&&
.AIR QUALITY ISSUES...
NONE
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
AFTERNOON CAZ096-097.
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
EVENING ABOVE 4000 FEET FOR THE CAZ095.
&&
$$
PUBLIC...JEB
AVN/FW...MV
SYNOPSIS...WP
WEATHER.GOV/HANFORD
