EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 910 PM PST WED JAN 23 2002
.SYNOPSIS...GUSTY WINDS WILL CONTINUE THROUGH AND BELOW MOUNTAIN
CANYONS AND PASSES TONIGHT AND THURSDAY...THEN GRADUALLY WEAKEN
THURSDAY NIGHT AND FRIDAY. EXPECT CLEAR...COLD NIGHTS AND SUNNY MILD
DAYS THROUGH FRIDAY. LOW PRESSURE WILL BRING COOLER WEATHER AND A
CHANCE OF SHOWERS SUNDAY.
.DISCUSSION...WEATHER CONCERNS TONIGHT INVOLVE THE WIND AND THE COLD.
THE WINDS PICKED UP THIS AFTERNOON IN THE MOUNTAIN PASSES NEAR THE
INLAND EMPIRE AND IN ORANGE COUNTY. WINDS HAVE TEMPORARILY DIMINISHED
IN A FEW SPOTS THIS EVENING...BUT WILL INCREASE OVERNIGHT AND REMAIN
STRONG IN THE WIND PRONE AREAS THROUGH THURSDAY MORNING. ACARS
SOUNDINGS INDICATED 30 KTS OF WIND AT 1000 FEET OVER ORANGE
COUNTY...INCREASING IN SPEED AS THEY FUNNEL THROUGH THE MOUNTAIN
PASSES.
WEAK COLD AIR ADVECTION WILL CONTINUE AT 850 MB THROUGH ABOUT 09Z. 850
MB WINDS FROM 25 TO 35 MPH CONTINUE THROUGH 18Z THURSDAY. AT THE
SURFACE...OFFSHORE PRESSURE GRADIENTS STRENGTHEN OVERNIGHT AS A 1040 MB
SURFACE HIGH BUILDS INTO CENTRAL NEVADA. AT 05Z...THE GRADIENTS WERE
STRONGLY OFFSHORE TO THE NORTHEAST (SAN-DRA 6.5MB) AND WERE TRENDING
STRONGLY OFFSHORE AS WELL...MOSTLY IN ORANGE AND SAN BERNARDINO
COUNTIES. THE WINDS WILL START TO PICK UP IN THE EAST-WEST PASSES OF
SAN DIEGO AND RIVERSIDE COUNTY TONIGHT AS THE FLOW SHIFT FROM THE
NORTHEAST TO THE EAST. CURRENT WARNINGS AND ADVISORIES LOOK GOOD.
AS FOR TEMPS...WITH A CLEAR SKIES AND A VERY DRY AIRMASS (PRECIPITABLE
WATER WAS ONLY 0.15 INCHES ON THE 12Z NKX SOUNDING) TEMPERATURES IN
WIND PROTECTED AREAS WILL FALL INTO THE UPPER 20S AND LOWER 30S WEST OF
THE MTNS. AREAS THAT REMAIN WINDY TONIGHT WILL ONLY SEE OVERNIGHT LOWS
IN THE 40S.
THURSDAY NIGHT AND FRIDAY THE SURFACE HIGH SLOWLY WEAKENS AND MOST THE
WIND SUPPORT WILL SHIFT SOUTH OVER RIVERSIDE AND SAN DIEGO COUNTY WHERE
GRADIENTS WILL STILL BE STRONG ENOUGH PRODUCE GUSTY WINDS IN THE
EAST-WEST PASSES OF THESE COUNTIES. WIND PROTECTED AREAS WILL ONCE
AGAIN SEE A VERY COOL NIGHT...BUT TEMPS WILL WARM NICELY DURING THE DAY
FRIDAY.
OVER THE WEEKEND THE UPPER RIDGE BREAKS DOWN AS A TROF APPROACHES FROM
THE NORTHERN PACIFIC. IT WILL SHIFT THE GRADIENTS BACK ONSHORE SATURDAY
AND LOW LEVEL MARINE LAYER MOISTURE WILL START TO RETURN TO THE COASTAL
AREAS. THE 00Z AVN RUN DIGS A SHORTWAVE AROUND THE BASE OF THIS TROF
INTO SOCAL SUNDAY FOR INCREASING CLOUDS AND A CHANCE OF SHOWERS.
.SAN...HIGH WIND WARNINGS AND WIND ADVISORIES...SEE LAXNPWSAN.
MOEDE
AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 330 AM CST THU JAN 24 2002
COLD AIR OF -5 TO -7C AT BASE OF INVERSION AT 870 MB PER ACARS DATA
ENOUGH TO GENERATE RAIN SHOWERS OVER SOUTHERN LAKE MICHIGAN...MOVING
175/22 PER LOT WSR-88D...POISED TO MAKE LANDFALL ON COOK COUNTY
SHORE. CLOUD TOPS TO AROUND 4K FT SO INTENSITY LIMITED BY SMALL
VERTICAL EXTEND. LAKE EFFECT SHOWERS TO SHIFT TO LAKE COUNTY IND
THIS MORNING AS LOW LEVEL WINDS BACK SOME AS SURFACE LOW IN SOUTHERN
IND CONTINUES UP THE OH VALLEY THIS MORNING...WITH SPRINKLES OUT OF
PORTER COUNTY BY MID MORNING. LAST OF SHRA IN E CENTRAL IL AT RIGHT
ENTRANCE OF UPPER JET SHOWERS TO MOVE OUT OF FAR SOUTHEASTERN
COUNTIES OF FA EARLY THIS MORNING AS JET CORE CONTINUES TO E WHILE
JET AXIS CONTINUES TO SAG S AS THE NORTHERN PORTION OF THE UPPER
TROUGH MOVES THROUGH THE UPPER MIDWEST. BACK EDGE OF LOW CLOUDS SE
MN AND E IA CURRENTLY ONLY MAKING VERY SLOW PROGRESS TO THE E.
SHOULD PICK UP SOME AS GRADIENT INCREASES WITH SURFACE RIDGE
BUILDING ACROSS THE MID MS VALLEY SO SHOULD SEE CLEARING INTO NW FA
MIDDAY AND SE COUNTIES LATER AFTERNOON. WNW UPPER FLOW ACROSS REGION
TONIGHT GRADUALLY BECOMES WSW BY SUN MORNING. JET AXIS TO N OF AREA
KEEPS MOST CLOUDS AT BAY WHILE BACKING FLOW ALLOWS WARM UP FROM
ALREADY ABOVE NORMAL TEMPS. FLOW BACKS FURTHER SUN AND MON AS TROUGH
DEEPENS OVER THE W...WITH NEXT THREAT OF RAIN MON NIGHT AHEAD OF
SYSTEM IN PLAINS AS MOISTURE FROM THE WESTERN GULF STREAMS NORTHWARD
OUT OF THE SOUTHERN PLAINS AND ACROSS THE MID MS VALLEY AND INTO THE
MIDWEST.
.CHI...NONE
TRS
AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 220 AM PST THU JAN 24 2002
.SYNOPSIS...A STRONG COLD FRONT WILL BRING RAIN...WINDY
CONDITIONS...AND MOUNTAIN SNOW TO WESTERN WASHINGTON THROUGH TONIGHT.
A VERY COOL UPPER LEVEL TROUGH WILL BRING A SHOWERY AIR MASS TO THE
AREA FRIDAY THROUGH MONDAY. AN UPPER LEVEL RIDGE APPROACHING THE
REGION TUESDAY AND WEDNESDAY WILL BRING COOL DRIER WEATHER.
.DISCUSSION...AVN/MESOETA ARE QUITE SIMILAR IN HANDLING THE SHORT
TERM TIMING OF THE OFSHR CDFNT. SATELLITE IMAGERY SHOWS CLOUD TOPS
COOLING AND THUS SYSTEM FINALLY INTENSIFYING AS IT APPROACHES THE
PACNW. IMAGERY ALSO SHOWS A MOISTURE PLUME ARND 35N/145W BEING
ENTRAINED INTO THE SW FLOW AHEAD OF THE CDFNT...WHICH SUPPORTS THE
HIGH PCPN AMTS BEING ADVERTISED.
EXPECT THE SYSTEM TO PROGRESS SLOWLY BUT NOT STALL...AS IT IS BEING
PUSHED ALONG BY THE BIG DVLPG UPR TROF OVER THE GULF OF AK. ALTHOUGH
THE STRONG 140KT JET OFSHR IS ALMOST PARALLEL TO THE FRONTAL
BOUNDARY...THE UPSTREAM 130-140KT JET COMING AROUND THE W SIDE OF THE
UPR TROF WL KEEP THE FRONT MOVING SLOWLY EWD...LIMITING THE REGION TO
ABT 24HR OF HEAVY PCPN. BOTH AVN/MESOETA BRING 850MB COLD ADVECTION
INTO THE OLYMPICS AND START WEAKENING THE SWLY 850MB FLOW AFTER 00Z
THIS AFTN. MDLS ALSO SHOW THE LAST VORT MAX MOVG UP THE
FNT...CROSSING THE N CST 06Z-09Z. HPC QPF FCST REFLECTS THIS AND IS
ACCEPTED. FNT WILL STILL BE PUMPING MSTR INTO S HALF OF THE CASCADES
UNTIL ARND 12Z FRI MORNING.
MAIN PROBLEMS REMAIN HEAVY SNOW IN THE MTNS AND POTENTIAL RIVER
FLOODING. FRZG LVL LOOKS LIKE ITS AT THE MAX RIGHT NOW...NR 4300 FT
BASED ON ACARS SNDGS...AND SHOULDN'T GET ANY HIGHER...THUS XPCT SNOW
LVLS TO BE NR 3500 FT OR LOWER REMAINDER OF THIS EVENT. WINTER STORM
WARNING LOOKS GOOD WITH LATEST QPF FCST SHOWING ENOUGH WATER FOR 1-2
FT OF SNOW NXT 24 HRS. WL DO MINOR FRESHENING OF WINTER STORM
WARNING. AVALANCHE OBS AT SNOQUALMIE AND STEVENS ALREADY SHOW NR AN
INCH OF WATER THROUGH MIDNIGHT. FLOOD WATCH ALREADY UP FOR MOST OF SW
WA AND PGTSND RGN. WITH LOW SNOW LEVELS AND SHORTER PERIOD OF HVY
PCPN...IT IS NOT A LIKELY THAT THIS WILL BE A MAJOR FLOOD EVENT. BUT
LATEST RIVER GUIDANCE SHOWS POTENTIAL FOR A FEW RIVERS TO REACH FLOOD
STAGE. WL ALSO DO MINOR UPDATE TO FLOOD WATCH.
LONGER RANGE...THE COLD GULF OF AK UPPER TROUGH IS STILL FCST TO
SHIFT DOWN OVR THE PACNW FRI-MON...WITH AN UPPER LVL RDG BEGINNING TO
MOVE INTO THE AREA TUE-WED. THE VARIOUS LONG RANGE MDLS AGREE ON THIS
TIMING. SHOWERY REGIME PERSISTS THE ENTIRE WEEKEND. ABT 3 IMPULSES
MOVE ACRS THE AREA FRI NIGHT THRU SUN NIGHT WITH THE 4TH STRONGEST
ONE ON MON. MOST IMPORTANT FEATURE IS THAT AMS BECOMES JUST COOL
ENOUGH BY SATURDAY FOR POSSIBLE SNOW SHOWERS OVER THE LOWLANDS. WITH
FZL LVL NEAR 1500 FT...BEST CHANCE WOULD BE ON HIGHER HILLS ABV 500
FT. BIGGEST PROB IN MDLS IS TRACK OF 4TH WAVE ON MON. LATEST AVN HAS
IT MOVG S OFSHR...BUT IT STILL COULD COME IN RIGHT OVR W WA. FCSTS ON
TRACK AND WL CONT MENTION OF RAIN/SNOW. UPR RDG PROGRESSES ENOUGH FOR
NLY FLOW OVR W WA SFC/ALF BY TUE...SO WL DRY OUT TUE/WED. KAM
UIL +++ SEA 999 OLM +++
.SEW...GALE WARNING ALL WATERS.
WINTER STORM WARNING CASCADES AND OLYMPICS.
.KATX...VCP21/CSR21...OPERATIONAL.
EASTERN WASHINGTON AND NORTH IDAHO AREA FORECAST DISCUSSION
NWS SPOKANE WASHINGTON
AFDGEG 830 PM PST WED JAN 23 2002
COMPLEX UPPER CYCLONE IN NORTHERN GULF OF ALASKA WITH DEEP TROUGH
EXTENDING SOUTHWEST THROUGH 155W IN COMBINATION WITH MOIST UPPER JET
FLATTENING THE EAST PACIFIC RIDGE. STILL NORTHWESTERLY FLOW ALOFT PER
00Z AIRCRAFT AND RADIOSONDE REPORTS WITH A WAVE CONTINUING ACROSS
EASTERN WA. SOUTHERN PORTION OF THE WAVE HAS SHIFTED FURTHER EAST
WITH NORTHERN PORTION CONTINUING TO SIT UNDER THE SOUTHERN EDGE OF
THE JET STREAM...WHILE A WARM FRONT LIES BENEATH. OTX 88D IS OUT OF
SERVICE...HOWEVER CALLS TO SPOTTERS INDICATED SNOW HAD ENDED A FEW
HOURS AGO ACROSS THE COE-PUW AREAS...WITH JUST A FEW SPOTTY FLURRIES
DOWN TOWARD LEWISTON. EARLY ZFP UPDATE HANDLED THE BREAK IN THE
ACTION. RADARS FURTHER WEST CONFIRM WIDESPREAD RAIN AND MOUNTAIN
SNOWS WITH SOME SLOSH OVER THE CASCADE CREST. SPOTTY LIGHT MIXED
PRECIPITATION HAS OCCURRED AT ELLENSBURG THIS EVENING OUT OF A 6500-
8000 FOOT CLOUD BASE. WESTERLY FLOW HAS INCREASED AT STAMPEDE
PASS...SO SIGNIFICANT DESCENT BELOW THE CLOUD DECK IS OCCURRING. A
CALL TO MAZAMA SPOTTER REVEALED NO SOLID OVERCAST AT THIS TIME. WILL
FINE-TUNE THE EASTERN CASCADE ZONE TO EMPHASIZE THE ACCUMULATIONS AS
EXPECTED TO BE NEAR THE CREST. WILL ALSO INDICATE THIS ON AN UPDATE
TO THE WSW. SPRINKLES AND FLURRIES SHOULD BE SPOTTY AT BEST ACROSS
THE WESTERN BASIN THROUGH THE OKANOGAN VALLEY OVERNIGHT.
WARM ADVECTION CONTINUES AT LOW TO MID LEVELS...AND EVENING SPOKANE
SOUNDING INDICATING SOUTHWEST WINDS NEAR 40 KNOTS 3000 FEET AMSL.
WHILE SUPPORTING A GOOD UPSLOPE ENVIRONMENT FOR THE NORTHEAST
MOUNTAINS THROUGH CENTRAL IDAHO PANHANDLE...IT PRESENTS A DILEMMA FOR
THE PALOUSE THROUGH GEG/COE. THERE IS UPPER DIVERGENCE ON THE SOUTH
EDGE OF THE JET STREAM...HOWEVER THERE DOESN'T APPEAR TO BE A STRONG
LIFTING MECHANISM OTHER THAN THE UPSLOPE TONIGHT. WILL LIKELY HAVE TO
REDUCE POPS GEG/COE AREAS FOR THE OVERNIGHT WITH SLIGHT ADJUSTMENT
UPWARD IN TEMPERATURES.
SFP ALSO REQUIRES SOME ADJUSTMENT TO INDICATE THE LESSER POPS TONIGHT
SOUTHERN SECTIONS. JR
...THE INFORMATION IN THIS PRODUCT CONCERNING WARNINGS AND FORECASTS
IS VALID ONLY AT THE TIME OF ISSUANCE. THE LATEST WARNING AND
FORECAST INFORMATION WILL BE FOUND IN THE APPROPRIATE PRODUCTS...
GEG 029/038/032/036/027/034 388843
COE 027/037/032/035/026/032 489843
PUW 030/040/036/039/033/036 358743
LWS 035/045/039/044/035/040 346633
CQV 028/036/034/036/030/033 888844
SPT 027/037/034/036/029/032 9++854
WWP 026/037/034/036/032/033 99++54
EAT 032/040/037/040/033/038 345333
MWH 034/042/039/041/035/038 234433
.OTX...WINTER STORM WARNING TONIGHT THROUGH THURSDAY NIGHT FOR ID ZNS
1 AND 4 AND WA ZNS 37 AND 42.