Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 122230
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
230 PM PST FRI FEB 12 2016

.SYNOPSIS...
A cold front will pass through the region tonight with continued
precipitation chances and slightly lower snow levels. Unsettled
weather will continue through the weekend into early next week
with valley rain, high mountain snow and breezy winds expected.
Temperatures will be quite mild on Monday with many locations
seeing highs in the mid 50s to low 60s. Near record high
temperatures are possible.


&&

.DISCUSSION...
Tonight through Saturday night...The region will be in an active
weather pattern as a pair of Pacific frontal systems move through
the Inland Northwest. First up is a cold front and associated
upper trough that will pass through the area tonight. This will
bring some light rain and mountain snow to the region. Snow
levels will start out around 5000 to 6000 ft this evening except
for the northern Cascade valleys where persistent fog and low
stratus has kept temperatures in the mid 30s today. The Methow
Valley may see some light snow tonight but as the cold front
reaches the east slopes, winds will shift to downsloping westerly
winds that will limit the amount of precipitation. Areas closer
to the crest may pick up a few inches of snow overnight. The cold
front will usher in breezy conditions tonight and Saturday,
mainly across the basin, Palouse and into the Spokane area. Wind
gusts of 20 to 30 mph should limit valley fog formation
overnight. Overnight temperatures will remain above freezing for
the breezy areas but should drop close to or below the freezing
mark for the more sheltered northern valleys. The upper trough
will track over the forecast area on Saturday with
instability/upslope showers for the immediate Cascade crest and
the Idaho panhandle possible for much of the day. Daytime
temperatures will be in the 30s to low 40s across the northern
half of the forecast area with low 50s for the southernmost
valleys.

The next Pacific warm front will follow quickly Saturday night, with
little in the way of a break between systems. This one will have a
tap into deep Pacific. Snow levels will start out around 3000 to
3500 ft Saturday evening and will be on the rise across the south.
Closer to the Cascade crest, precipitation should remain snow and several
inches may accumulate before the warm air takes over. Confidence
in snow levels is only fair at best and it looks like any
significant accumulations below 4000 ft will be very local and
close to the crest so no winter weather highlights are planned as
yet. Temperatures at 850 mb (5000 ft) will increase to around 5
to 6 C overnight as warm air pushes in from the south. This warm
air, along with 850mb winds of 25 to 35 kts will take a toll on
the mid slope snow pack. Valley rain combined with melting snow
will add to area creeks and streams, bringing some of then close
to bankfull over the weekend. /Kelch

Sunday through Friday...The models have been pretty consistent
showing zonal flow, or weak ridging Sunday through Wednesday. In
addition there will be a series of warm frontal systems that will
move through the region. This will keep the forecast warm, wet,
and unsettled. By mid-week there is some differences showing up in
the models on how to handle a stronger low pressure system
expected for Wednesday night and Thursday. Some of the models
close it off with a slower timing Thursday and Thursday night and
others bring the low through as an open wave with a faster
solution.

For Sunday through Tuesday...An atmospheric river will be pointed
directly at the Pacific Northwest. Strong westerly flow will
result in a rain shadow for the lower east slopes and well in the
basin. So the focus of the precipitation will be over the Cascade
crest and the Idaho Panhandle mountains. Precipitation amounts
will range from a trace to around a tenth for the basin, Palouse,
and north into the Spokane-Coeur D`Alene area. The Cascades could
see a couple of inches of precip and the Panhandle mountains 1.0
to 1.5 inches will be possible. Temperatures will be on the
increase, rising to the 40s and 50s on Sunday and the 50s to lower
60s Monday and Tuesday. This will be 10-15 degrees above
normal.with several location across the Inland Northwest reaching
near record temps. Snow levels will be 3500-4000 feet across the
north and 4500-5500 across the south Sunday morning but then shoot
up above 6000 feet by late in the day Sunday. So this will mean
precipitation as valley rain and high mountain snow.

The next parameter to note will be increasing southwest winds
Sunday night, but mainly Monday. Southwest winds 20-30 mph with
gusts 30-40 mph are expected. A high wind advisory may be needed
for Monday during the day. The other thing to look at will be the
combination of warm temperatures and strong winds. This
combination is perfect to rapidly melt snow. This will likely
result in rapid rises on area stream and small rivers. Current
river forecasts for next week show rapid rises but all rivers
remaining below Flood, at least at this time. The areas of concern
will be for the Idaho zones including the St Joe, Palouse and
Coeur D`Alene river basins and also the Little Spokane river.
Another area of concern will be up on the waterville Plateau where
abundant snow pack will likely get reduced by quite a lot. A
Hydrologic outlook had been issued to cover these river rises and
please stay tuned.

Wednesday through Friday...With so much model discrepancy at the
end of the extended forecast period it was better to go with a
broad brush approach with the idea that we will fine tune as we
get to next week. A chance of lowland rain and high mountain snow
was kept in the forecast through the Friday, with temperatures
kept on the warm side of normal. Tobin

&&

.AVIATION...
18Z TAFS: MVFR/IFR conditions in fog and low stratus will improve
back to VFR for most areas after 21z today. After Sat 00z- 06z,
the next round of more widespread light pcpn will once again bring
ceilings down to MVFR. Gusty southwest winds should keep ceilings
from dropping below MVFR. Expect gusts of 20 to 25 kts after 10Z
Sat. /EK



&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        35  44  35  47  43  55 /  60  40  70  30  50  10
Coeur d`Alene  35  43  35  46  41  53 /  70  60  80  50  60  40
Pullman        37  46  38  50  46  56 /  70  40  90  50  70  20
Lewiston       40  52  42  56  48  63 /  50  40  90  40  60  10
Colville       33  41  32  42  37  51 /  60  50  60  20  40  30
Sandpoint      34  40  33  41  37  50 /  90  60  80  60  70  60
Kellogg        34  38  33  40  38  46 / 100  80 100  80  90  60
Moses Lake     34  48  37  52  43  61 /  20  10  50  10  20  10
Wenatchee      33  41  34  47  39  57 /  30  10  60  20  20  10
Omak           30  39  31  40  34  49 /  30  10  60  20  20  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Air Stagnation Advisory until 10 AM PST Saturday for Moses Lake
     Area-Northeast Mountains-Okanogan Highlands-Upper Columbia
     Basin-Waterville Plateau-Wenatchee Area.

     Air Stagnation Advisory until 10 AM PST Tuesday for East Slopes
     Northern Cascades-Okanogan Valley.

&&

$$


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