FXUS66 KOTX 091209
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
409 AM PST WED DEC 9 2009
.SYNOPSIS...
A COLD AIRMASS WILL REMAIN ENTRENCHED OVER THE INLAND NORTHWEST
TODAY RESULTING IN TEMPERATURES ABOUT 20 DEGREES COLDER THAN
NORMAL FOR THIS TIME OF YEAR. MEANWHILE...THE FLOW ALOFT WILL TURN
MORE NORTHWESTERLY TODAY...BRINGING A SLIGHT INCREASE OF MOISTURE
OVER EXTREME NORTHEAST WASHINGTON AND THE IDAHO PANHANDLE AS WELL
AS A FEW FLURRIES. THE WEATHER WILL REMAIN RELATIVELY DRY THROUGH
SATURDAY WITH A SLOW BUT STEADY WARMING OF TEMPERATURES. THE NEXT
CHANCE OF SIGNIFICANT PRECIPITATION WILL ARRIVE EARLY NEXT WEEK.
&&
.DISCUSSION...
TODAY AND TONIGHT...DRY CONTINENTAL POLAR AIRMASS WILL REMAIN OVER
THE INLAND NORTHWEST ONCE AGAIN TODAY...AS STRONG BLOCKING RIDGE
OF HIGH PRESSURE REMAINS FIXED OVER THE CENTER OF ALASKA.
DOWNSTREAM OF THE RIDGE...DEEP NORTHERLY FLOW CONTINUES TO SURGE
OUT OF THE NORTHWEST TERRITORIES AND INTO THE WESTERN US. WHILE
THE UPPER LEVEL SYNOPTIC SCALE PATTERN LOOKS SIMILAR TO
YESTERDAY...THERE ARE SUBTLE DIFFERENCES NOTED AS WEAK SHORTWAVE
TROUGHS MOVE THROUGH THE REGION. ONE SUCH TROF WAS CURRENTLY
LOCATED OVER THE CLEARWATER MOUNTAINS AND WAS MOVING STEADILY
SOUTHWARD. THIS FEATURE DID LITTLE MORE THAN INCREASE THE MOISTURE
CONTENT OVER THE INLAND NW. THE 00Z SOUNDING AT SPOKANE SHOWED A
PARCHED .05 INCH PRECIPITABLE WATER READING WHICH IS ONLY 15
PERCENT OF NORMAL. ACCORDING TO SEVERAL RECENT GOES BUFR SOUNDINGS
OVER NORTHEAST WASHINGTON...THAT VALUES HAS CLIMBED TO NEARLY .10
INCHES...WHICH STILL IS VERY DRY. NONETHELESS...THIS INCREASED
MOISTURE HAS RESULTED IN A LITTLE MORE CLOUDINESS...AS THE PASSAGE
OF THE SHORTWAVE TROF HAS COMBINED WITH VERY WEAK ISENTROPIC
ASCENT ON THE 280K SURFACE. DESPITE THE INCREASING MOISTURE...THE
DENDRITIC LAYER THUS FAR HAS REMAINED FAIRLY DRY AND THUS WE HAVE
SEEN VERY LITTLE IF ANY SNOWFALL. IN FACT...OTHER THAN SOME VERY
LIGHT ECHOES ON RADAR THIS MORNING...THE ONLY THING SUPPORTING
SNOW FLURRIES WERE A FEW OBS OVER SOUTHERN BC AND ALBERTA EARLIER
THIS MORNING. LOOKING UPSTREAM...THERE SEEMED TO BE A COUPLE OTHER
DISTURBANCES OVER BC AND ALBERTA HEADING SOUTH-SOUTHEAST. THE
APPROACH OF THESE FEATURES WILL CONTINUE TO INCREASE THE
PRECIPITABLE MOISTURE OVER THE REGION. BY LATE
AFTERNOON...PRECIPITABLE WATER VALUES WILL CLIMB TO .15
INCHES...TRIPLE YESTERDAY AFTERNOON VALUES...BUT STILL FAIRLY DRY.
MEANWHILE...THE DENDRITIC LAYER DOES BEGIN TO LIFT AND
SATURATE...A SIGN OF WEAK WARM AIR ADVECTION ALOFT. DESPITE THE
INCREASED SATURATION...THE ISENTROPIC LIFTING REMAINS VERY WEAK
RIGHT THROUGH THE NIGHT. THUS THE CHANCES FOR MEASURABLE
PRECIPITATION WILL REMAIN SMALL THROUGH THE PERIOD. WE WILL KEEP
ALL PRECIP FOCUSED OVER EXTREME EASTERN WA AND NORTH IDAHO.
TEMPERATURE FORECASTS WILL AGAIN BE TRICKY. THE MODELS HAVE BEEN
DOING POORLY WITH THIS AIRMASS AND GENERALLY HAVE BEEN TOO COLD.
TODAY'S SURFACE TEMPS SHOULD BE SOMEWHAT SIMILAR TO
YESTERDAY...ALTHOUGH THERE WILL BE WARMING...PARTICULARLY IN THE
MOUNTAINS WHERE 850 MB TEMPS WILL CLIMB 1-3C VS YESTERDAY.
NIGHTTIME LOWS WILL BE TRICKY AS WELL AND MUCH WILL DEPEND ON
WHERE CLOUD COVER SETS UP. THE BEST CHANCES OF CONSIDERABLE CLOUD
COVER WILL RESIDE OVER THE ID PANHANDLE...WHICH SHOULD MODERATE
THE NIGHTTIME LOW TEMPS AND KEEP THINGS ABOVE ZERO. FX
THURSDAY THROUGH FRIDAY NIGHT...MODELS KEEP THE COLD AIR IN PLACE
OVER THE INLAND NORTHWEST WITH NO REAL WEATHER FEATURES MOVING OVER
THE AREA TO SCOUR OUT THE COLD AIR. TEMPERATURES WILL REMAIN WELL
BELOW AVERAGE FOR THIS TIME OF THE YEAR. VERY LIGHT SNOW
SHOWERS/FLURRIES ARE POSSIBLE...MAINLY ACROSS THE NORTHERN IDAHO
PANHANDLE.
SATURDAY THROUGH TUESDAY...MODELS WERE IN FAIRLY GOOD AGREEMENT
SHOWING A WEATHER SYSTEM MOVING INTO SOUTHERN OREGON/NORTHERN CAL FOR
SATURDAY. HOWEVER THE 00Z GFS TRENDED NORTH WITH THIS FEATURE. THE
00Z EC AND CANADIAN BOTH FAVOR THE SOUTHERLY TRACK...AND WILL
CONTINUE WITH THAT IDEA. IT LOOKS TO BE A FAIRLY UNSETTLED
THROUGH THE WEEKEND WITH MAINLY OROGRAPHIC SHOWERS...BUT NO
SIGNIFICANT PRECIPITATION. A FRONT FROM THE NORTH WILL CLIP THE
US/CANADIAN BORDER LATE SUNDAY/EARLY MONDAY...KEEPING TEMPERATURES
BELOW AVERAGE. MONDAY A SHORTWAVE RIDGE MOVES IN AHEAD OF THE NEXT
BIG WEATHER FEATURE. A NEARLY VERTICALLY STACKED LOW WILL APPROACH
THE SOUTHERN BC COAST MONDAY NIGHT. THE FLOW SWITCHES TO THE SOUTH
AND WARMER AIR WILL BEGIN TO CREEP INTO THE AREA. LOTS OF UNCERTAINTY
WITH THIS SYSTEM ATTM. DEPENDING ON HOW FAST THE COLD AIR CAN BE
SCOURED OUT WILL MAKE THE DIFFERENCE BETWEEN A WET START TO THE
WORKWEEK OR A SNOWY ONE. /NISBET
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH 12Z THU. THE
MAIN WEATHER OF CONSEQUENCE WILL BE MID LEVEL CIGS ASSOCIATED WITH
WEAK DISTURBANCES MOVING IN FROM THE NW. CIGS SHOULD RANGE FROM
050-070 AND WILL IMPACT KGEG...KSFF...KCOE...AND KPUW. A FEW SN
FLURRIES WILL BE PSBL...BUT THEY SHOULD OCCUR N AND E OF KGEG AND
WILL SPARE ALL TAF SITE. CLEAR SKIES ARE EXPECTED TO PREVAIL AT KMWH
AND KEAT. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 16 5 21 9 22 14 / 10 0 0 0 0 10
COEUR D'ALENE 18 8 21 10 25 16 / 10 10 0 0 0 10
PULLMAN 14 6 22 9 26 16 / 0 0 0 0 0 10
LEWISTON 18 8 26 10 31 18 / 0 0 0 0 0 10
COLVILLE 21 10 21 10 24 16 / 0 10 0 0 0 10
SANDPOINT 15 8 18 6 20 13 / 20 20 10 0 10 10
KELLOGG 14 5 20 8 22 14 / 20 10 10 10 10 20
MOSES LAKE 21 3 22 6 23 13 / 0 0 0 0 0 10
WENATCHEE 21 7 21 11 27 17 / 0 0 0 0 0 10
OMAK 21 6 18 8 25 16 / 0 0 0 0 0 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
