Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 251138
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
338 AM PST Sun Feb 25 2018

.SYNOPSIS...
One more weather system will affect the Inland Northwest today.
This storm will bring strong winds to eastern Washington and
heavy snow to the Idaho Panhandle. After a few days of quieter
weather, a strong but milder storm looks likely for Wednesday and
Thursday.  Expect showery weather for next weekend.

&&

.DISCUSSION...
Today through Monday: Next Pacific system currently moving into
the area. With strong westerly winds already in place, this system
will be much like the previous, with a significant precipitation
shadow from the Cascades extending across almost all of eastern
Washington. The Panhandle should pick up significant snow so
advisories and warnings continue there.

Winds over the area will continue to increase this
morning, reaching their peak early this afternoon. Windiest
locations will be from Spokane to Ritzville to Pomeroy and across
the Palouse. A wind advisory is in place for this area.

The biggest uncertainty is the amount of potential drifting. The
snow on the ground from the past few days is still rather dry and
fluffy. So even areas that don`t receive additional snow this
morning could see drifting snow. This threat should decrease
around midday as the temperatures warm to above freezing.

This afternoon the precipitation should become more showery.
Showers could extend back to the west as far as Davenport and
Ritzville. I don`t expect a lot of rain or snow with these
showers. Rather, the main impact of any showers could be mixing
down very strong wind gusts, similar to last weekend.  The wind
and snow should calm down quickly this evening for much quieter
weather tonight and Monday.  RJ

Monday night through Saturday: The longwave pattern continues to
favor a cold northerly flow into Wednesday. Brief and fleeting
positively tilted shortwave ridging dropping down in this flow first
will allow for benign weather coupled with generally partly cloudy
skies. Tuesday morning clouds should thicken and lower as they
invade the sky from the northwest to signal the approach of the
first of a series of disturbances to influence Eastern Washington
and North Idaho. The substantial dry low layers of the atmosphere
located in lowland locations will take a while to moisten up and as
such the higher pops with the Tuesday system are reserved for the
higher terrain with a snow shadow of sorts over a large portion of
the Columbia basin and its periphery. Dirty shortwave ridging with
continued moisture fluxing through it allows for these pops to
linger in similar locations Wednesday. Thursday and Friday have
potential to be wet and warm as an area of low pressure drops down
off the coast, intensifies, and its moderate moisture plume is
oriented to focus a mild southwest flow across Eastern Washington and
Northern Idaho, thus high pops and QPF along with warmer
temperatures and a rise in snow levels are expected with this
warming trend to bring temperatures close to what would be
considered normal for this time of year. In addition the moisture
plume could move far enough to the south and east to allow a
transition to a more conditionally unstable airmass cluttered with a
number of smaller scale disturbances so either way pops for
precipitation will remain in some shape or form. By Saturday that
mentioned cold conditionally unstable airmass is better positioned
overhead and is less cluttered with disturbances which allows for a
drop in pops, temps, and clouds. /Pelatti

&&

.AVIATION...
12Z TAFS: Snow is developing over the Idaho Panhandle and
spreading onto the Palouse this morning. KPUW will likely see the
lowest conditions and greatest amount of snow. IFR and LIFR
weather is likely there. KGEG/KSFF will see a little VFR snow,
KCOE will have a better chance of some MVFR snow. KLWS should stay
dry and VFR. KMWH and KEAT should also remain dry and VFR, but
KEAT may see some late afternoon snow if the Puget Sound
convergence zone extends across the Cascades. I put a VCSH in the
KEAT TAF for this due to low confidence at this point. Winds will
be strong today at just about all of the TAF sites.  RJ

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        38  21  32  21  37  26 /  70  20  10  10  30  20
Coeur d`Alene  37  21  32  19  35  25 /  90  40  10  20  50  60
Pullman        36  23  32  19  34  27 /  90  80  10   0  40  30
Lewiston       42  28  39  22  41  31 /  70  60  10   0  30  20
Colville       39  14  36  20  37  23 /  30  10   0  30  40  30
Sandpoint      36  19  31  21  33  26 /  80  30  10  30  60  80
Kellogg        33  22  30  18  31  25 / 100  90  20  20  60  70
Moses Lake     44  25  42  25  46  28 /  10   0   0  10  10  10
Wenatchee      41  25  40  25  46  28 /  50  30  10  10  10  10
Omak           39  19  37  22  40  23 /  20   0   0  20  20  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 5 PM PST this afternoon for Coeur
     d`Alene Area-Northern Panhandle.

     Winter Storm Warning until 11 PM PST this evening for Central
     Panhandle Mountains-Idaho Palouse.

WA...Winter Storm Warning until 11 PM PST this evening for Washington
     Palouse.

     Wind Advisory from 8 AM this morning to 4 PM PST this afternoon
     for Lower Garfield and Asotin Counties-Spokane Area-Upper
     Columbia Basin-Washington Palouse.

     Winter Weather Advisory until 11 PM PST this evening for
     Northeast Blue Mountains.


&&

$$


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