FXUS66 KOTX 302329
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
325 PM PST MON NOV 30 2009
.SYNOPSIS...
A WEAK PACIFIC FRONT WILL MOVE THROUGH THE AREA TONIGHT BRINGING
LIGHT PRECIPITATION TO THE CASCADES AND PANHANDLE MOUNTAINS. DRY
CONDITIONS WILL PREVAIL FOR THE REST OF THE WEEK UNTIL ANOTHER
POTENTIAL WEAK WEATHER SYSTEM MOVES INTO THE REGION BY THURSDAY
NIGHT OR FRIDAY. TEMPERATURES WILL REMAIN AROUND SEASONAL
NORMALS THROUGH THIS WEEK...WITH A SHARP COOL DOWN POSSIBLE BY
NEXT WEEKEND.
&&
.DISCUSSION...
TONIGHT AND FRIDAY...SATELLITE INDICATES A WEAK UPPER LEVEL COLD
FRONT IS SLUMPING INTO THE FORECAST AREA FROM THE NORTH THIS
AFTERNOON. DYNAMIC SUPPORT WITH THIS FRONT IS RATHER SPARSE AND
WEAK...HOWEVER THE FRONTAL SURFACE IS MODERATELY STRONG WITH A
WEAK BUT WELL DIRECTED PRECIPITABLE WATER FETCH TO PROVIDE FUEL
FOR PLENTY OF CLOUDS. PRECIPITATION WITH THIS SYSTEM WILL LIKELY
BE LIMITED TO THE MOUNTAINS OF THE IDAHO PANHANDLE...CASCADE
CREST...AND THE HIGHER TERRAIN NORTH OF THE BASIN. THERE IS A
CHANCE OF A STRAY SNOW SHOWER OVER THE PALOUSE AND CAMAS PRAIRIE
AREAS AS MID LEVEL FLOW BECOMES SLIGHTLY MORE NORTHERLY AFTER THE
FRONTAL PASSAGE AND THUS MORE OROGRAPHICALLY FAVORABLE IN THESE
LOCATIONS. OTHERWISE A STRONG DRYING TREND IS EXPECTED IN THE WAKE
OF THE FRONT TONIGHT AS DRY CONTINENTAL ORIGIN CANADIAN AIR BEGINS
TO SQUEEZE THROUGH THE OKANOGAN VALLEY AND FILL THE BASIN. THIS
AIR MASS EXCHANGE WILL LIKELY SCRUB THE DEEP BASIN WHERE STRATUS
AND FOG HAS PERSISTED WELL INTO THIS AFTERNOON. THE SURFACE HIGH
PRESSURE DRIVING THIS AIR MASS WILL CROWD A MODERATE NORTHERLY
GRADIENT INTO THE FORECAST AREA OVERNIGHT AND THROUGH TUESDAY.
THIS WILL ALLOW NORTH WINDS TO DOMINATE FOR THE NEXT 24 HOURS.
WHILE THE DRIER AIR MASS WILL PROMOTE COOLER OVERNIGHT LOW
TEMPERATURES THAN RECENT DAYS...MORE SUN ON TUESDAY WILL ALLOW
EFFICIENT WARMING OF THIS DRY AIR SO TUESDAY'S HIGHS WILL STILL BE
ABLE TO CREST RIGHT AROUND NORMAL FOR THIS TIME OF YEAR. /FUGAZZI
TUESDAY NIGHT TO THURSDAY...BENIGN AND COOLER WEATHER IS EXPECTED
AS A RIDGE BUILDS OFF THE COAST AND BRINGS A DRY NORTHERLY FLOW.
MODELS SHOWS HEIGHT RISES INTO WEDNESDAY NIGHT. JUST A FEW MID TO
HIGH CLOUDS ARE EXPECTED...WITH POSSIBLE PATCHY NIGHT/EARLY AM FOG
IN SHELTERED NORTHERN/CASCADE VALLEYS...L-C VALLEY AND MOSES LAKE
AREA. THE NEXT SYSTEM NEARS THURSDAY. THE FLOW TURNS NW WITH SOME
INCREASE IN CLOUDS. THE LIGHT SNOW RISK HAS BEEN CUT BACK...AS THE
GFS TRENDED THE SYSTEM NORTH AND OTHER GUIDANCE IS SLOWER. BELOW
NORMAL TEMPS ARE SUPPORTED WEDNESDAY WITH SLIGHT MODERATION
THURSDAY. THIS IS A COOL DOWN FROM THE PREVIOUS FORECAST. /JCOTE
THURSDAY NIGHT THROUGH MONDAY...VISIBLE ON A GLOBAL COMPOSITE IR
SATELLITE IMAGE THE DECAYING REMNANTS OF WEST PACIFIC TYPHOON
NIDA...AN OLD TROPICAL SYSTEM LOCATED ABOVE AUSTRALIA NORTH OF THE
EQUATOR AT 20N AND 140E...CONTINUES TO STREAM MOISTURE AND ENERGY
UP INTO THE MID LATITUDES AND HAS DONE SO SINCE THANKSGIVING. THIS
HAS PROBABLY AIDED THE FORMATION OF IMPRESSIVE LARGE BAROCLINIC
BANDS OVER THE PACIFIC THAT DRIFT EAST WITH THE WESTERLIES AND
HAVE AN IMPACT...IN ONE WAY OR ANOTHER...ON THE SENSIBLE WEATHER
OVER EASTERN WASHINGTON AND NORTHERN IDAHO. OFTEN THE SPREAD IN
STANDARD DEVIATION OF MODEL SOLUTIONS...MODEL UNCERTAINTY...IS
ATTRIBUTED TO HAVING A DECAYING SYSTEM SUCH AS THIS TRANSFER
SIGNIFICANT ENERGY FROM THE TROPICS UP INTO THE SUBTROPICS. THE
BAROCLINIC BAND CURRENTLY INTERACTING WITH REMNANT MOISTURE
STREAMING FROM DECAYING TYPHOON NIDA RUNS EAST JUST ABOVE 30 DEG
NORTH BEFORE TAKING A TURN TO THE NORTH AND WRAPPING UP AND AROUND
THE GULF OF ALASKA AND BACK WESTWARD TO A COMMA SHAPE ENCOMPASSING
MOST IF NOT ALL OF THE ALEUTIAN ISLANDS. TO GO COUNTER TO THIS
IDEA OF MODEL UNCERTAINTY I DO SEE CONSISTENCY IN THE GFS TURNING
THE EARLIER MENTIONED LARGE COMMA CLOUD/BAROCLINIC BAND INTO A
VERY DEEP AND INTENSE LOW TO THE SOUTH OF THE ALEUTIANS...THE
PLACEMENT HERE RESULTS IN A HIGH AMPLITUDE BUT VERY NARROW RIDGE
OF HIGH PRESSURE EXTENDING UP OFF THE WEST COAST OF NORTH AMERICA
OVER THE WEEKEND AND BEYOND. THE RIDGE IS SO NARROW IN FACT THAT
THE EASTERN EDGE OF THE RIDGE IS POSITIONED TO STEER SHORTWAVES
THAT MIGRATE OVER IT DOWN INTO EASTERN WASHINGTON AND NORTHERN
IDAHO. AREAS TO THE EAST OF THE CONTINENTAL DIVIDE SUCH AS
NORTHWEST MONTANA...WILL BE BETTER POSITIONED TO BE INFLUENCED BY
THE NORTHERLY FLOW ON THIS RIDGE WITH THE IDEA THAT AS ONE TRAVELS
WEST INTO IDAHO AND WASHINGTON THE NARROW RIDGE WILL HAVE A
GREATER INFLUENCE. WITH THIS IN MIND POPS AND COLDER TEMPERATURES
WILL SHOW GREATER RESOLUTION AND FAVOR TO NORTHERN IDAHO AND
EXTREME NORTHEAST WASHINGTON. /PELATTI
&&
.AVIATION...
A COLD FRONT STRETCHING FROM KOMK TO CWJR AT 00Z WILL MOVE TO KDLS
TO KLWS BY 06S TONIGHT. AHEAD OF THE FRONT STUBBORN IFR AND LIFR
STRATUS WILL PERSIST IN THE COLUMBIA BASIN MAINLY IMPACTING KMWH AND
KGEG...WITH VFR CONDITIONS UNDER HEAVY MID LEVEL CLOUDS ELSEWHERE.
THE FRONT WILL ALSO PROMOTE SIOLATED TO SCATTERED MOUNTAIN SNOW
SHOWERS NORTH AND EAST OF THE COLUMBIA BASIN. AFTER THE FROPA DRY
AIR WILL SCRUB REMAINING STRATUS OUT OF THE BASIN WITH VFR
CONDITIONS THROUGH OUT THE REGION UNTIL THE END OF THE TAF PERIOD AT
00Z WEDNESAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 25 35 21 32 21 35 / 10 0 0 0 0 0
COEUR D'ALENE 27 38 23 33 21 37 / 20 0 0 0 0 10
PULLMAN 30 35 23 32 23 36 / 20 10 0 0 0 10
LEWISTON 36 45 25 38 24 41 / 10 10 0 0 0 0
COLVILLE 27 36 21 35 23 38 / 20 0 0 0 0 10
SANDPOINT 25 32 21 31 17 33 / 20 0 0 0 0 10
KELLOGG 28 33 21 30 20 34 / 40 10 0 0 0 10
MOSES LAKE 27 40 21 35 21 37 / 0 0 0 0 0 10
WENATCHEE 31 41 28 38 23 39 / 0 0 0 0 0 10
OMAK 26 38 23 37 25 38 / 10 0 0 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
