Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 241822
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1122 AM PDT Fri Mar 24 2017

.SYNOPSIS...
More wet weather is on its way. The next storm system will bring
widespread rain and mountain snow today, followed by showery and
breezy weather for Saturday. Several inches of snow will be
possible on Sherman, Stevens, and Loup Loup Passes. Sunday looks
dry. Unsettled weather returns Sunday night into Monday and
continues through next week, with several more rounds of rain and
mountain snow.


&&

.DISCUSSION...
Widespread rain continues to fall over much of the Inland NW late
this morning as rich plume of moisture remains oriented from SW
to NE east of the Cascades. Precipitation amounts since 5am have
generally ranged from 0.10 to 0.30 inches west of a line from
Chewelah to the Tri-Cities. Meanwhile east of that line the
precipitation has been either light or non-existent. This slower
transition eastward was not handled well by the GFS which would
have suggested up to a tenth of an inch of rain or more over most
of the ID Panhandle including the Silver Valley. Meanwhile the NAM
and SREF handled this slower movement much better. The band of
rain will continue to drift slowly eastward through the remainder
of the morning as the latest IR/WV images are showing warmer cloud
tops/drying moisture heading toward the Cascades. Surface
pressure rises are also advancing toward the Cascades which
indicates the cold front will soon be to the crest. Once the front
transitions over the crest during the next couple hours the
precipitation will turn more showery over the Wenatchee Valley,
Okanogan Valley, western Columbia Basin and Okanogan Highlands.
Not sure how widespread the showers will be, but the atmosphere
along and behind the front is quite unstable. Model soundings and
some HRRR reflectivity solutions suggest a very small potential
for thunder but the threat is too small to place in the gridded
forecast. The transition to the showers will also allow us to end
the winter weather advisory for the Okanogan Highlands. Although
we still expect to see some snow over Sherman Pass through the
early afternoon, the threat will not be widespread enough to
justify an extension. We have also altered the snow levels a
little higher than the Republic area, as local spotters informed
us the snow was no longer accumulating on the heavier traveled
roads. While the precipitation turns showery in the lee of the
Cascades, widespread rain will continue through most of the
afternoon elsewhere. Additional rainfall through 5 pm will range
from another 0.15-0.30 inches with locally heavier amounts north
and east of Spokane where orographic ascent will kick in. This
will not help the current batch of flooding across the area,
however it could be worse if this were a warmer air mass resulting
in a good amount of melting snow as well. fx

&&

.AVIATION...
18Z TAFS: Widespread precipitation will continue at all sites
through 20-22z or so with the exception of KLWS due to downslope
flow. The presence of the rain will result in periodic MVFR cigs
for PUW SFF COE GEG and a mix of IFR/MVFR conditions at EAT and
MWH. The latter two sites will see a rapid improvement as the cold
front, currently near the Cascades moves east of these sites.
This should result in VFR conditions, however there will still be
a threat of showers and perhaps a brief bout of MVFR conditions.
For the other sites, expect the rain to continue through 00-03z or
so with periods of MVFR cigs expected. LWS will also likely see
periods of rain but suspect cigs will remain in the VFR category.
Confidence in the forecast lowers late tonight. While we don`t
expect to see much more precipitation, there will be a chance of
seeing some low clouds forming late as moist southwest winds could
develop over the Palouse and drift northeastward into GEG SFF and
COE. Confidence isn`t high but put some scattered low clouds in
the forecast to address the situation. fx

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        46  36  50  32  50  38 /  90  60  30   0   0  80
Coeur d`Alene  45  36  48  33  49  36 /  90  90  70  10   0  80
Pullman        47  37  49  34  51  39 /  90  60  50   0   0  80
Lewiston       53  39  54  36  56  42 /  70  60  50   0   0  60
Colville       45  35  50  31  49  35 /  90  60  50  10   0  60
Sandpoint      43  33  45  30  46  32 /  90  90  60  20   0  50
Kellogg        44  34  44  31  47  34 /  90 100  70  20   0  60
Moses Lake     52  37  59  33  54  40 /  70  20  10   0  10  70
Wenatchee      49  35  53  32  47  36 /  40  20  10   0  30  80
Omak           48  35  53  31  48  37 /  70  20  10   0  20  80

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Weather Advisory until noon PDT today for Okanogan
     Highlands.

&&

$$



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