Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 301207

Area Forecast Discussion
National Weather Service Spokane WA
507 AM PDT Thu Mar 30 2017

Today will be breezy over much of central Washington while the
Idaho Panhandle and portions of eastern Washington will experience
scattered afternoon showers. The weather on Friday will be mild
and dry with light winds. The weekend and early next week will
feature average temperatures and scattered light showers, mainly
over the mountains.



Today and Tonight: The weather today will be breezy across central
and north central Washington as a surface low organizes over
southern Idaho and northeast Nevada. The northwest pressure
gradient will favor gusty winds through the Okanogan Valley,
Waterville Plateau, Moses Lake area, and Upper Columbia Basin. By
early afternoon, look for sustained winds around 15 mph with gusts
of 20 to 25 mph in these areas. The Idaho Panhandle and eastern
third of Washington can expect scattered showers today as an
elongated upper level trough creeps over the region. Afternoon
destabilization will contribute to small cells capable of brief
heavy rain, graupel, and maybe some small hail. A few lightning
strikes may accompany some of the strongest cells, but the
atmospheric profile may be a bit too cool for more than a strike
or two. A Flood Watch remains in effect for much of the Idaho
Panhandle and portions of northeast Washington following
yesterday`s rainfall. Field and small stream flooding continues to
be an issue after weeks of above average precipitation. The day
shift will call various county agencies this morning to check the
status of flooding. Today`s showers won`t be widespread enough to
worsen flooding, so we may be able to drop some or all of the
counties from the Flood Watch later this morning.

Previous forecast discussions mentioned the possibility of a wrap
around band of rain/snow this morning for the Blue Mountains and
Camas Prairie. The models have trended further south with this
deformation band. Trends on satellite and radar support the
southerly track advertised by the latest model runs. If there is
any accumulation this morning, it appears as if it will be an inch
or less on grassy surfaces above 4000 feet around Anatone and
Winchester. /GKoch

Friday: A dry day? A day with light winds and a good deal of
sunshine? Afternoon temperatures in the 50s? Will we be able to
handle a truly nice early spring day? If we had a "Nice Day
Advisory", we`d need to issue one for Friday so people could
prepare for such a rare occurrence in the spring of 2017. Mid-
level high pressure will build over the region bringing a rare day
of no precipitation across eastern Washington and north Idaho.
Areas of valley fog in northeast Washington and north Idaho should
dissipate by mid to late morning giving way to partly cloudy
skies. Bands of high clouds will be on the increase in the
afternoon as the next frontal system moves into British Columbia.

Saturday through Monday night: A swift westerly aloft
will take over the Inland NW for Saturday guided by a 120kt+ jet
aloft. With a low in the Gulf of Alaska, an elongated cold front
will push through the region. The GFS seems to be the juiciest
with Pwats of near a half an inch with the front, while the ECMWF
and Canadian trend toward drier solutions. Yes, there will be
moisture, although not quite the caliber of Wed`s system. In
addition, the westerly flow will enhance downsloping in the lee of
the Cascades into the Basin with mostly dry and breezy
conditions. This should also be the mildest day of the week. The
models are trending to a solution that brings showers across the
northern mountains Saturday morning, then pushing across extreme
eastern Washington into Idaho panhandle for the afternoon and
evening hours. This convection may spark an isolated thunderstorm
but guidance shows low confidence with this. The front looks to be
a fast mover with showers decreasing Saturday night with drier
air moving into the region. Sunday should start off on the dry
side with shortwave ridging, although a weak trough aloft will
approach from the west. Low level moisture in sheltered valleys
and clearing aloft will increase the fog potential especially in
northeast Washington and north Idaho. This upper trough shows
signs of stretching and splitting, directing the main energy south
of the region into Oregon and leaving colder air aloft and
instability over the Inland Northwest. Anticipate orographic
showers to increase during the afternoon and evening hours under
the westerly flow, daytime heating and the passage of the upper
trough axis. Mid level moisture does increase with trough axis
passage with scattered mountain showers and snow levels 3k to 4k
ft. By Sunday night into Monday, the trough axis slowly exits
north Idaho as an upper low spins up and tracks into Montana and
Wyoming. Instability and orographic showers will return to extreme
eastern Washington and north Idaho especially by the afternoon
and evening hours. Anticipate temperatures to trend slightly
cooler for Sunday into Monday, and remaining below normal for the
start of April. /rfox.

Tuesday through Thursday: Tuesday a shortwave builds in over the
region bringing us a mostly dry Tuesday and even into the first
half of Wednesday. The only exception could be a few hit and miss
mountain showers. Enjoy the dry weather because late Wednesday
into Thursday another moist frontal system is ushered in,
bringing more rain. Southwest winds will tap into a good Pacific
moisture feed, with PWATs from 0.75 to 0.90. These winds will also
advect in some warmer air with temps steadily climbing each day.
Widespread highs in the upper 50s won`t be out of the question by
Thursday. /bwilliams


12Z TAFS: Widely scattered showers over the Idaho Panhandle will
become more concentrated with afternoon destabilization.
Airports with a decent shot of showers this afternoon are
Sandpoint, Bonners Ferry, Coeur d`Alene, Pullman, and Lewiston.
The strongest cells will have the potential to produce brief heavy
rain and soft hail (up to pea size) in the 20z-01z time frame.
Showers should diminish quickly this evening with the loss of
afternoon heating and dry north advection through the evening.


Spokane        52  34  54  37  56  36 /  30  20   0   0  20  10
Coeur d`Alene  50  33  54  36  54  34 /  40  20   0   0  20  20
Pullman        50  32  51  35  55  35 /  50  30   0   0  20  20
Lewiston       56  36  56  37  59  38 /  50  20   0   0  10  20
Colville       52  32  55  34  54  34 /  20  20   0   0  20  10
Sandpoint      48  32  53  33  51  32 /  30  20   0   0  30  20
Kellogg        46  33  50  33  50  33 /  50  40   0   0  20  20
Moses Lake     61  35  60  39  62  37 /  10  10   0   0  10  10
Wenatchee      57  36  57  39  59  37 /  10   0   0   0  20  10
Omak           56  32  57  36  58  33 /  10  10   0  10  20  10


ID...Flood Watch through Friday morning for Central Panhandle
     Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis and
     Southern Nez Perce Counties-Lewiston Area-Northern

WA...Flood Watch through Friday morning for Lower Garfield and Asotin
     Counties-Northeast Blue Mountains-Northeast Mountains-
     Spokane Area.


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