Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 062116

Area Forecast Discussion
National Weather Service Spokane WA
216 PM PDT TUE OCT 6 2015

A ridge of high pressure will weaken tonight with a chance of
light rain spreading east across the region Wednesday. A big
shift in the weather pattern will bring an increasing risk for
rain...mild temperatures...and windy conditions late in the week
and into the weekend.


Tonight through Friday night...a warm front will bring some light
rain to the Inland Northwest, starting at the Cascade crest tonight
then spreading across the forecast area on Wednesday. The main
forcing mechanism will be moist isentropic upglide with the warm
front so precipitation amounts will be rather light. The upper level
ridge will rebound Wednesday night into Thursday with warming
temperatures and a slight chance of rain for the northern mountains
as another weak wave of moisture rolls through the ridge. The next
Pacific frontal system will approach the region late Friday with
another round of light rain and possible gusty winds for the Cascade
gap valleys into the Waterville Plateau. temperatures will continue
the above normal trend. /Kelch

Saturday to Tuesday: Periods of rain, cooler and breezy to
windy conditions are expected, before things begin to settle down
by Tuesday. The ridge near the northern Rockies pushes east and a
series of systems moves in from the west on a 100kt+ jet. These
systems also appear to tap some good plumes of moisture. In fact
the tap with the first system appears would contain the remnants
of tropical system Oho (currently east of Hawaii). The timing of
systems continues to waver from run-to-run. So confidence is only

The first system passes sometime between Saturday and Sunday.
Compared to yesterday models have sped up it, with cold front
passage and the highest precipitation threat spreads from west to
east between Saturday and Saturday evening, before the focus
retreats in the mountains overnight into Sunday morning. Models
show the potential for moderate to heavy rain amounts. It is too
early to have confidence in precise amounts but it is possible to
see over an inch near the Cascade crest and locally between a
quarter to a half over the eastern third of WA and north ID. Model
still indicate much lighter amounts in the lee of the Cascades and
deeper Columbia basin. The system also comes with a tightening
pressure gradient, good mixing and so the potential for some
breezy to windy conditions. Depending on how much rain falls, it
could lead to some blowing dust. If there was any location that
would see this potential more than others it would out toward
deeper Columbia Basin, where rain amounts should be lighter. Winds
then begin to subside some into Sunday afternoon. However all the
details of this system, including amounts and wind speeds and
timing, will continue to be fine-tuned.

The second system passes through sometime between Sunday
afternoon and Monday. This will renew the rain chance across the
region, first across the Cascades and northern mountains through
Sunday evening and across the rest of the region overnight into
Monday. Once again the of the Cascades and deeper Columbia Basin
will largely see the lowest threat of precipitation. The moisture
tap doesn`t look as pronounced as the first and overall amounts
look lighter than the first, but there still is the potential for
some locally moderate rain amounts. There also looks like another
increase in winds, but overall speeds look less. Details will
continue to be fine-tuned on this system too.

Drier conditions are projected going into Monday night and
Tuesday as westerly flow envelopes the region and the main
moisture plume sags south. Some orographic showers will remain a
threat over the Cascades, Idaho Panhandle and near the Canadian

Temperatures are projected to cool into this weekend, especially
by Sunday. Most guidance shows regional 850mb temperatures
dropping into the middle to upper single digits (Celsius). This
plus any cloud cover and precipitation, along with the zonal flow,
supports a general cooling trend. Value closer to or even lower
than normal will be possible. /J. Cote`


18Z TAFS: Mid and high level clouds will increase and lower today
ahead of a warm front moving into western WA. Expect VFR
conditions at all TAF sites through 18Z Wednesday. Precipitation
associated with the warm front will affect KEAT by around 18Z Wed,
then spread east Wed afternoon. /EK


Spokane        50  66  52  71  53  75 /   0  30  30  10  10  10
Coeur d`Alene  48  66  50  71  50  76 /   0  30  30  20  10  10
Pullman        49  66  53  74  53  79 /   0  40  40  10   0  10
Lewiston       52  72  53  79  54  84 /   0  30  20  10   0  10
Colville       46  68  49  70  47  74 /  10  20  30  10  10  10
Sandpoint      41  64  48  68  47  72 /  10  20  40  20  10  10
Kellogg        45  63  48  69  49  76 /   0  40  50  20  10  10
Moses Lake     49  71  52  76  51  77 /  10  20  10  10   0  10
Wenatchee      55  72  55  75  55  77 /  10  30  20  10  10  10
Omak           51  72  53  73  53  74 /  10  20  20  10  10  20



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