FXUS66 KSTO 020601
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
900 PM PST TUE DEC 1 2009
.DISCUSSION...
UPPER LEVEL RIDGE OF HIGH PRESSURE OVER EASTERN PACIFIC AND WEST
COAST CONTINUING FAIR SKIES OVER THE REGION THIS EVENING. SHORTWAVE
DROPPING DOWN EASTERN SIDE OF RIDGE HAS GENERATED SOME HIGH
CLOUDINESS OVER THE FORECAST AREA BUT THIS CLOUDINESS NOT LIKELY TO
BRING SIGNIFICANT IMPACT ON OVERNIGHT TEMPERATURES OR FOG
POSSIBILITIES. HIGH TEMPERATURES TODAY WERE SIMILAR TO MONDAYS AND
SIMILAR CHARACTERISTICS CARRYING INTO THIS EVENING WITH TEMPERATURES
RUNNING CLOSE TO 24 HOURS AGO. CURRENT FORECAST OVERNIGHT LOWS MAY
BE A BIT HIGH BUT NOT ENOUGH TO MAKE FORECAST CHANGES AND WILL LEAVE
AS IS FOR NOW. SURFACE PRESSURE GRADIENTS REMAIN LIGHT SO LITTLE IN
THE WAY OF WIND EXPECTED. AREAS OF LIGHT FOG FORMED EARLY THIS
MORNING IN THE SOUTHERN SACRAMENTO AND NORTHERN SAN JOAQUIN VALLEYS
AND WITH LITTLE CHANGE IN AIRMASS OR WIND CONDITIONS EXPECT MORE
LIGHT FOG AGAIN IN THESE AREAS TONIGHT. EVENING NAM WARMS AIRMASS A
BIT ON WEDNESDAY SO SHOULD SEE A LITTLE WARMING MOST AREAS. WILL
BUMP UP MAX TEMPS A BIT FOR WEDNESDAY TO REFLECT THIS WARMING TREND.
LITTLE CHANGE EXPECTED THURSDAY AS HIGH PRESSURE REMAINS IN CONTROL
OVER THE AREA.
UPPER RIDGING BEGINS TO BREAK DOWN ON FRIDAY AS UPPER LOW DROPS OUT
OF WESTERN CANADA AND INTO THE PACIFIC NORTHWEST. SHOULD SEE A
LITTLE COOLING AS COOLER AIR FILTERS INTO THE AREA BUT NOT MUCH.
EVENING GFS ENTRAINS SOME UPPER LEVEL MOISTURE FROM THE SUB TROPICS
INTO NORCAL ON FRIDAY BUT OTHERWISE FRIDAY SHOULD REMAIN A FAIR
WEATHER DAY.
.EXTENDED DISCUSSION (SATURDAY THROUGH WEDNESDAY)...WEATHER PATTERN
SHOWS MORE SIGNIFICANT CHANGES OVER THE WEEKEND INTO EARLY NEXT WEEK
EXTENDED MODELS STILL VARY SOME WITH THE STRENGTH AND TRACK OF THE
UPPER LOW AND THE SUBTROPICAL MOISTURE PLUME. ECMWF MODEL STILL
TRACKS THE LOW FARTHEST TO THE WEST WHILE THE GFS KEEPS THE LOW
FARTHEST TO THE EAST. THE LATEST GEM RUN COMES IN SOMEWHERE IN
BETWEEN. THE LOW IS EXPECTED TO RETROGRADE AND MOVE SOUTH INTO
NORTHERN CALIFORNIA OVER THE WEEKEND. THE TEMPERATURES WILL COOL
AROUND 10 TO 20 DEGREES BY SUNDAY COMPARED TO THE TEMPERATURES WE
HAVE BEEN SEEING THIS WEEK. THE COOLER AIR WITH THIS SYSTEM COULD
BRING SNOW LEVELS DOWN TO AROUND 3000 TO 4500 FEET BUT THE MODELS
VARY HOW MUCH COLD AIR WILL COME WITH THIS SYSTEM. THE SNOW COULD
IMPACT TRAVEL OVER THE MOUNTAINS...ESPECIALLY THE SIERRA THIS
WEEKEND. THE MODELS ARE NOW SHOWING THE SUBTROPICAL MOISTURE PLUME
NEAR THE CALIFORNIA COAST NEXT WEEK WHICH IS LATER THAN IN PREVIOUS
RUNS. SEVERAL SHORTWAVES ARE EXPECTED TO MOVE THROUGH THE AREA NEXT
WEEK. THE MOISTURE COMBINED WITH SOME OF THE ENERGY COULD BRING MORE
WIDESPREAD PRECIPITATION TO NORTHERN CALIFORNIA NEXT WEEK.
&&
.AVIATION...
UPR RDG CONTS OVR NORCAL WITH NW-N FLOW ALF. VFR CONDS OVR INTR
NORCAL EXC AREAS OF MVFR IN BR FM VCNTY KMYV SWD TIL ARND 18-20Z
WITH LCL IFR POSS IN FOG BTWN 10Z-17Z FM SACRAMENTO AREA SWD INTO
PTNS OF NRN SAN JOAQUIN VLY. ISOLD NE-E SFC WND GSTS 25-35 KTS OVR
SIERNEV FTHLS/W SLPS TIL ARND 18Z.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
