FXUS66 KOTX 071033
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
233 AM PST MON DEC 7 2009
.SYNOPSIS...
BITTERLY COLD TEMPERATURES WILL CONTINUE ACROSS THE INLAND NORTHWEST
TODAY AND TUESDAY. WARMER...BUT STILL DRY AND COLD CONDITIONS
WILL PERSIST THROUGH MUCH OF THE WORK WEEK...WITH THE NEXT CHANCE
OF ACCUMULATING SNOW ARRIVING IN TIME FOR NEXT WEEKEND.
&&
.DISCUSSION...
TODAY AND TONIGHT...A HIGHLY AMPLIFIED PATTERN WILL REMAIN OVER
THE PACIFIC NORTHWEST THROUGH THE SHORT TERM. HIGH PRESSURE IN THE
GULF OF ALASKA CONTINUES TO GET SQUEEZED BETWEEN AN UPPER LOW
MOVING ACROSS THE EASTERN PACIFIC AND A LOW PRESSURE SYSTEM
DROPPING SOUTH INTO CALIFORNIA. THIS PUTS THE REGION IN A
DRY...BUT VERY COLD NORTHERLY FLOW. THIS MORNING THE SURFACE
PRESSURE GRADIENT BETWEEN THE CONTINENTAL DIVIDE AND THE CASCADES
HAD WEAKENED A BIT...NOW DOWN BELOW 10MBS AND EXPECTED TO
CONTINUE TO WEAKEN TODAY. WINDS WILL REMAIN BREEZY THROUGH THE
MORNING HOURS BUT WILL SLOWLY DECREASE THIS AFTERNOON. MEANWHILE
COLD AIR ADVECTION CONTINUES INTO THE REGION. AT 00Z 85H
TEMPERATURES WERE -15C AND GUIDANCE HAS BEEN CONSISTENT COOLING
THESE TEMPS DOWN TO NEAR -19C THIS MORNING BEFORE REBOUNDING
TONIGHT AND TUESDAY SLIGHTLY.
FOR TODAY...FRIGID TEMPERATURES AND CONTINUED BREEZY WINDS WILL
KEEP THE POTENTIAL FOR DANGEROUS WIND CHILLS THIS MORNING. AT THIS
TIME IT APPEARS AS IF ONLY A FEW OF THE COOLER AND WINDIER
LOCATIONS WILL JUST FLIRT WITH THE -20F MARK...BUT IT WILL STILL
BE VERY COLD. OTHERWISE DRY AND COOL TODAY WITH MAXIMUM
TEMPERATURES FROM THE LOW TEENS TO LOWER 20S WHICH IS 15 TO 20
DEGREES BELOW NORMAL.
FOR TONIGHT DECREASING WINDS AND MAINLY CLEAR SKIES WILL RESULT IN
ANOTHER NIGHT OF VERY COLD TEMPERATURES. MINIMUM TEMPERATURES WILL
RANGE FROM THE LOWER SINGLE DIGITS IN THE COLUMBIA BASIN TO BELOW
ZERO ACROSS THE REMAINDER OF THE FORECAST AREA. THESE WILL MOST
LIKELY BE THE COLDEST TEMPERATURES OF THE WEEK. BRRR. /TOBIN
TUESDAY THROUGH FRIDAY...DRY NORTHERLY FLOW WILL PERSIST ACROSS
THE INLAND NORTHWEST AS THE LONGWAVE PATTERN MAKES VERY LITTLE
CHANGE WITH A BLOCKING HIGH OVER THE EASTERN PACIFIC AND TROUGH
OVER WESTERN CANADA/NORTHERN TIER OF THE CONUS. IF THERE WAS ANY
CHANGE TO SPEAK OF...IT WOULD BE THE DEPARTURE OF THE SHORTWAVE
ENERGY CURRENTLY OVER SOUTHERN OREGON/NORTHERN CA WHICH WILL ALLOW
A SLOW MODIFICATION OF THE AIRMASS BY THE END OF THE WEEK. THE
ONLY SENSIBLE WEATHER TO TALK OF THROUGH THE PERIOD WILL BE VERY
LIGHT SNOW SHOWERS ASSOCIATED WITH WEAK SHORTWAVE ENERGY DROPPING
DOWN IN NORTHERLY FLOW WHICH WILL CLIP FAR NORTHEASTERN WA AND THE
IDAHO PANHANDLE. THE FIRST WAVE EVIDENT OVER NORTHEASTERN BC THIS
EVENING WILL MOVE THROUGH THE NORTHEASTERN REACHES OF THE CWA
TUESDAY NIGHT THROUGH MIDDAY WEDNESDAY. THERE IS NOT A STRONG
SOURCE MOISTURE...BUT MODEST OMEGA THROUGH 850-500MB LAYER COUPLED
WITH THE FRIGID TEMPERATURES WILL EASILY RESULT IN MID AND UPPER-
LEVEL SATURATION SUPPORTING MOSTLY CLOUDY SKIES WITH SCATTERED
LIGHT SNOW SHOWERS. WHETHER ANY MEASURABLE PRECIPITATION FALLS IS
THE BIG CHALLENGE. TIME-HEIGHT PLOTS SUGGEST THE STRONGEST ASCENT
WILL BE BTWN 700-500MB AND WITHIN THE -25 TO -35 CELSIUS LAYER
SUPPORTING CRYSTAL GROWTH OF ICE NEEDLES/COLUMNS WHICH TYPICALLY
SUGGEST LITTLE TO NO ACCUMULATIONS. THEREFORE...THE FORECAST HAS
TRENDED DRIER IN REGARDS TO ANY QPF BUT CONTINUES TO ADVERTISE
NUMEROUS VERY LIGHT SNOW SHOWERS WITH ACCUMULATIONS GENERALLY LESS
THAN HALF AN INCH. LOW TEMPERATURES FOR WEDNESDAY WILL ALSO PROVE
A BIT TRICKY UNDER THE PASSING CLOUD SHIELD. WITH VERY LITTLE
WARMING FOR TUESDAY...IT WILL NOT TAKE LONG AFTER SUNSET TO REACH
OVERNIGHT LOWS THAT ARE IN THE FORECAST...HOWEVER...IF THE CLOUD
SHIELD IS SLOWER TO ARRIVE THAN EXPECTED...I THINK WE MIGHT BE TOO
WARM...OTHERWISE WE SHOULD SEE VERY LITTLE COOLING AFTER THE
ARRIVAL OF THE CLOUDS AND ANYWHERE FROM 2 TO 8 DEGREES OF WARMING
FROM TUESDAY'S READINGS. A SECOND SHORTWAVE DROPS IN FROM HE
NORTHERLY FLOW AGAIN WEDNESDAY NT INTO THURSDAY BUT THIS WAVE
LOOKS EVEN DRIER...WEAKER AND POSSIBLY FURTHER INLAND HAVING LESS
OF AN IMPACT OUTSIDE PASSING CLOUDS AND ISOLATED FLURRIES IN THE
IDAHO MTNS. THE AIRMASS WILL WARM FROM NEAR -16 CELSIUS AT 850MB
ON TUESDAY TO -8 CELSIUS BY FRIDAY. THE EC WARMS THE AIRMASS
NEARLY 24 HRS QUICKER REACHING THE -8 C MARK BY THURSDAY WHILE THE
GFS...GEM...AND GEFS MEAN DELAY THE WARMING UNTIL FRIDAY WITH
TEMPERATURES REMAINING WITHIN THE -12 TO -14 C RANGE THROUGH
THURSDAY. I PREFER THE LATTER SOLUTION WHICH FOLLOWS THE MODEL
CONSENSUS AND AVOIDS A TYPICAL MODEL BIAS OF SCOURING OUT THE COLD
TEMPERATURES A DAY TOO QUICK...ESPECIALLY WITH LITTLE TO NO MIXING
INDICATED AMONGST ANY GUIDANCE.
MODELS CONTINUE TO SUGGEST THE PATTERN WILL BEGIN TO SHIFT BY THE
WEEKEND AS MOIST PACIFIC ENERGY UNDERCUTS THE OFFSHORE RIDGE AND
FLOW ACROSS THE LOWER 48 TRENDS TOWARD A FLATTER ZONAL FLOW. THE
PATTERN CHANGE IS AND HAS BEEN WELL AGREED AMONGST ALL GUIDANCE
HOWEVER...THERE IS STILL A LOT OF UNCERTAINTY WHERE AND WHEN THE
ENERGY WILL MOVE ACROSS THE PAC NW. THE GFS IS AMONGST THE WETTEST
AND QUICKEST SOLUTIONS WITH THE GEM THE DRIEST AND FURTHEST SOUTH.
A COMPROMISE LOOKS TO BE THE EC AND THE FORECAST WILL TREND THIS
DIRECTION. /SB
&&
.AVIATION...
EAST-NORTHEAST WINDS HAVE DECREASED TO LESS THAN 20KTS AT ALL TAF
SITES AND WILL CONTINUE TO DECREASE THROUGH THE MORNING HOURS AT
ALL SITES. A DRY FLOW FROM OUT OF CANADA WILL RESULT IN DRY WEATHER
AND VFR CONDITIONS THROUGH 12Z TUESDAY. /TOBIN
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 15 -1 12 4 15 7 / 0 0 0 10 0 0
COEUR D'ALENE 14 -1 13 3 14 7 / 0 0 0 10 0 10
PULLMAN 14 1 12 4 16 9 / 0 0 0 0 0 0
LEWISTON 20 6 17 8 22 11 / 0 0 0 0 0 0
COLVILLE 18 0 15 8 16 9 / 0 0 0 10 0 0
SANDPOINT 9 -3 10 3 12 5 / 0 0 0 10 10 10
KELLOGG 8 -2 9 3 11 5 / 0 0 0 10 10 10
MOSES LAKE 21 -1 18 3 20 8 / 0 0 0 0 0 0
WENATCHEE 21 -1 17 3 23 9 / 0 0 0 0 0 0
OMAK 17 -2 19 4 21 8 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
