Area Forecast Discussion
Issued by NWS Spokane, WA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
000
FXUS66 KOTX 231150
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
450 AM PDT Thu Mar 23 2017

.SYNOPSIS...Following a break in the wet weather today...another
storm system will deliver widespread rain and mountain snow
overnight into Friday. Several inches of snow will be possible on
Sherman, Stevens, and Loup Loup Passes. Cool and unsettled
weather will continue into next week as several more rounds of
rain and mountain impact the Northwest.

&&

.DISCUSSION...

Today and tonight: A flat ridge of high pressure strengthens over
the region today giving the Inland NW a well deserved break from
the wet weather. Areas of stratus and fog this morning should give
way to areas of sunshine this afternoon. The air mass has cooled
and despite a light southwest wind...temperatures will only be
warming into the 40s to lower 50s, a few degrees shy of normal.

A warm front lifts into the region starting tonight with
thickening clouds and widespread precipitation developing around
midnight across much of Central WA. There should be little to no
rain shadow effect in the lee of the Cascades with easterly winds
developing at the surface and southerly flow 850-700mb. There may
be some localized shadowing around Wenatchee given the flow
pattern descending off Mission Ridge...otherwise precipitation is
a good bet for communities along Highway 97 west to the Cascade
Crest. Snow levels look to wetbulb between 2500-3000 feet...and
locally lower in the upper Methow Valley. As such, a few inches of
snow will be possible for Sherman, Loup Loup, and Stevens Passes
by the Friday morning commute. Confidence is lower however Mazama
and Winthrop may also wake up to light snow accumulations.  /sb

Friday and Saturday: The low currently near 40N/140W will push a
weather disturbance into the Pacific Northwest Friday.
Precipitable water values well over 150% of normal will move into
southern WA in the morning. Widespread rain is expected through
most of the day. Rain may be moderate to heavy at times. Have
increased the amount of precipitation we could receive Friday and
Friday night. Locations in the deep Basin and Wenatchee
valley/Waterville Plateau should see less than a quarter of an
inch. All other valleys should see a quarter to a half inch of
rain. The mountains will generally see a half to three quarters of
an inch. Snow levels will be 3500-4500 ft and we should add a few
more inches of snow into our mountain snow pack. We will have
some good upslope easterly flow into the Cascades Fri morning and
then the snow focus turns to northeast WA and north ID in the
afternoon and evening hours. The chance of precip will decrease
during the evening and overnight hours across the central part of
the state. Then Saturday afternoon the trough axis passes with a
chance of showers through the afternoon. The chance of showers
will decrease through the evening and overnight hours.

Sunday: A shortwave ridge will move over the Inland Northwest for
a dry day.

Sunday Night through Thursday: The ridge moves east as the next
weather system begins to move onshore. Another period of
widespread precipitation is expected Sunday night and Monday.
Monday night onward the models start to diverge more on the
weather pattern, but either way it continues to look unsettled.
The Columbia Basin will have a lower chance of precip while
extreme eastern WA, north ID and the Cascades will have a higher
chance of precipitation. Temperatures will generally be at or
slightly below average for this time of the year. /Nisbet

&&

.AVIATION...
12Z TAFS: Favorable southwest winds continue to lead to increasing
stratus development around Spokane and Cd`A this morning with
cigs expected to lift to VFR 18-20z. Fog currently at the Lewiston
terminal should dissipate 16-18z with some uncertainty on exact
timing. Otherwise...look for VFR skies for all terminals aft 19z
with mid and high clouds increasing from the west and lowering
5-7K AGL arnd Moses Lake and Wenatchee Thur nt with onset of -ra.
Precipitation to spread east into the remaining terminals shortly
after 12z Fri. /sb


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        49  35  46  37  50  32 /   0  20 100  60  50  10
Coeur d`Alene  47  33  44  36  48  32 /   0  10 100  80  70  10
Pullman        49  37  48  37  49  34 /   0  20 100  70  60  10
Lewiston       55  39  54  40  54  37 /   0  10  90  70  60  10
Colville       48  33  46  35  48  31 /   0  20  90  50  50  10
Sandpoint      46  29  43  33  45  30 /  10  10  90  80  60  20
Kellogg        44  32  44  34  44  31 /  10  10  90  90  70  30
Moses Lake     56  40  54  37  57  33 /   0  50  70  30  10   0
Wenatchee      51  36  49  35  51  33 /   0  80  60  30  10   0
Omak           51  36  49  36  52  30 /   0  70  90  30  20  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.