Area Forecast Discussion
Issued by NWS Spokane, WA

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333
FXUS66 KOTX 152340
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
440 PM PDT Tue Oct 15 2019

.SYNOPSIS...
Dry and mild conditions cloudy skies will characterize Wednesday.
An active weather pattern returns Wednesday evening into the
weekend bringing several rounds of rain, mountain snow, and breezy
winds. Seasonal temperatures the next few days will trend cooler
than normal by the weekend.


&&

.DISCUSSION...

Tonight and Wednesday: The forecast for tonight into Wed is mainly
dry. Bands of rain over northwest Washington have made little
eastward progress today. A frontal system has more or less
stalled and won`t be shoved across the Cascades until Wed
afternoon. A weak upper level disturbance will cross the Inland
Northwest this evening, which may produce a few sprinkles across
northeast Washington and north Idaho. Look for a good deal light
echoes on radar tonight, but precipitation will likely struggle to
make it to the ground.

The majority of Wednesday will remain dry until a stronger upper
level disturbance shoves moisture across the Cascades. At this
time, the models prog rain to emerge east of the Cascades around
mid afternoon with rain chances increasing over the Idaho
Panhandle, Spokane and Pullman after sunset.

Wednesday Night: Rain amounts of a tenth to quarter of an inch
should be common Wed night over the Idaho Panhandle as a moist
frontal system slowly moves east. Snow levels over north Idaho
will be in the 6000-7000ft range which is well above pass level
(Lookout Pass 4700ft). For the Cascades, snow levels around 5000ft
may allow for light slushy accumulations over North Cascades
Highway (5500ft). Central Washington will likely be shadowed with
places like Wenatchee and Moses lake receiving very little rain.

Thursday: Our weather pattern change will arrive in force on
Thu as our region experiences another round of rain overnight.
Snow levels will remain relatively high 5000-6000ft. Look for
gusty winds to increase overnight with sustained winds of 15 to 20
mph with gusts to 30 mph over the Palouse, West Plains, and Upper
Columbia Basin which will likely persist into Fri. /GKoch

Friday through Tuesday...A progressive and occasionally
wet autumn weather pattern will continue through the weekend and
into next week. The Ensemble mean upper level flow patterns of the
GFS and ECMWF models depict a moist zonal regime on Friday which
should limit appreciable precipitation to the orographically
favorable high terrain of the Cascade crest area and the Idaho
Panhandle mountains while leaving the basin dry but mostly cloudy
and continued breezy and gusty. Both models depict a short wave
trough arrival Friday night which will promote a broadening out of
this precipitation regime to include the eastern basin and
possibly the deep basin as well...with Saturday looking unsettled
throughout the region as the the cool and probably unstable trough
cusp gins up a mass of showers...not a total wash out but most
locations will experience intermittent to frequent showers during
the day with the densest concentration over the eastern basin and
Idaho Panhandle.

Snow levels during this period will likely drop during the
passage of this system from 4000 to 5000 feet on Friday to perhaps
3500 to 4000 feet on Saturday...but Saturday morning there could
be some non-accumulating wet snow down to the floors of northern
valleys and possibly the higher benches of the eastern basin...but
this is a low confidence call at this time. By Saturday afternoon
snow levels will retreat back into the higher terrain.

Sunday...at this time...appears to be the drier of the weekend
days as the short wave trough passes off to the east and a more
zonal orographic flow returns. This will also bring rising snow
levels for the remainder of the extended period with snow
accumulations limited to the mountains. Despite these warmer
temperatures aloft...the surface layer will remain below average
and moderately breezy with the adjective "raw" being appropriate
for both Saturday and Sunday.

From Sunday night through Tuesday some minor model differences
crop up in the details of further minor short wave and energy
ripple timing...however there is decent agreement with the overall
idea of aiming a deep Pacific atmospheric river into the
northwestern US which augers for more wet weather leading into the
new work week with the potential for a great deal of rain and
very high elevation snow particularly along the Cascade crest and
the high terrain of Idaho. Some of the rivers draining the
Cascades will need to be monitored for rising flows but the
antecedent flows are low enough to bring reasonable confidence
that flooding is a minimal risk at this time. /Fugazzi

&&

.AVIATION...
00Z TAFS: Bands of mid and high level clouds are expected this
afternoon and through Wed morning. Virga or sprinkles may
accompany the passage of a weak upper level disturbance this
evening across northeast Washington and far north Idaho. Wind will
largely remain less than 10kts.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        40  61  44  56  39  52 /  10  10  70  30  60  30
Coeur d`Alene  40  62  44  55  39  50 /  10   0  80  40  70  40
Pullman        44  65  43  55  40  52 /  10   0  80  40  60  30
Lewiston       46  70  50  62  45  58 /  10   0  80  50  40  20
Colville       37  60  42  59  38  56 /  10  20  70  30  60  30
Sandpoint      37  58  43  54  40  49 /  10   0  90  70  90  50
Kellogg        40  62  42  52  39  47 /  10   0  80  80  90  80
Moses Lake     38  59  42  61  39  60 /  10  30  60  10  50  10
Wenatchee      42  55  42  59  41  56 /  10  50  70  20  40  20
Omak           40  56  41  58  38  55 /  10  50  80  20  60  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.

&&

$$



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