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000
FXUS66 KOTX 060450
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
950 PM PDT Wed May 5 2021

.SYNOPSIS...
Thursday will be unseasonably warm with afternoon temperatures in
the upper 70s and 80s. The arrival of a vigorous cold front
Thursday afternoon and evening will bring gusty winds and the
chance for evening showers and possibly a few thunderstorms.
Cooler, breezy, and showery weather will likely arrive Friday and
persist into the weekend. Next week will be dry with temperatures
warming above average by mid week.

&&

.DISCUSSION...

Tonight: The weather tonight will be mild with overnight low
temperatures about 7 to 10 degrees above average. Lows in the mid
40s to low 50s are more typical of mid to late June than early
May. Bands of high clouds are expected this evening and into the
overnight, evidence of the front scheduled to arrive Thursday.

Thursday: Tomorrow will be the warmest day of the season so far
for the Idaho Panhandle and the eastern third of Washington. Most
lowland locations across the Inland Northwest will reach the upper
70 and 80s as warm southerly flow increases ahead of an advancing
cold front. The L-C Valley will likely be the warmest spot in the
region with upper 80s. Lewiston and Kamiah may flirt with 90
degrees.

Thursday Night: The weather will become interesting by mid to
late afternoon as the cold front reaches the Cascades.
* Winds: Gusty west winds will likely bleed through the Cascade
  gaps reaching places like Ellensburg, Wenatchee, Entiat and
  Chelan between 3 PM and 5 PM. By early evening, the surface
  front will produce a wind shift to the west or southwest across
  most of eastern Washington and north Idaho. Sustained winds of
  15 to 20 mph will be common across the Columbia Basin and
  southeast Washington with localized gusts to 35 mph. At this
  time, winds look to be strong enough for a few hours in the
  evening to raise some patchy dust from the Waterville Plateau,
  to Moses Lake to Ritzville and Pullman, but shouldn`t be as
  significant as some of our wind events from late March or April.
*Thunderstorms: The low level air mass ahead of the front will be
 quite dry and is expected to be the limiting factor in
 thunderstorm coverage and potency. We will be watching the
 surface front closely late for thunderstorm development in the
 afternoon and early in the evening, but at this time the models
 forecast a pretty formidable convective cap over Washington and
 north Idaho. But by mid evening, the arrival of colder
 temperatures aloft behind the front may be sufficient to generate
 high based showers, some may be strong enough to produce
 lightning, brief downpours, gusty winds, and small hail. The
 environment will probably lack the instability and deep layer
 moisture for strong storms, but some of us may get an evening
 lightning show.
*Rain: Scattered, high-based, quick moving showers and
 thunderstorms will deliver localized beneficial rains, but this
 front won`t give our region the widespread rain it really needs.
 The Basin, Palouse, and West Plains will get more wind from this
 front than rain. /GKoch

Friday through Tuesday: Temperatures will be a lot cooler
following Thursday`s frontal passage. Friday, afternoon temps in
the 60s and overnight temps down to the 30s are expected, both of
which are about 5 degrees below average. This continues until
around Monday and Tuesday when temperatures will warm up to around
average thanks to an upper level ridge nosing in.

Regarding winds, somewhat breezy conditions are also expected
Friday afternoon due to sufficient daytime heating. Although
Friday will be cooler than Thursday, the mid and upper levels of
the atmosphere will also be cooler, so the afternoon heating of
the lower levels will promote around dry adiabatic lapse rates
and vertical momentum mixing of stronger winds aloft. Another
thing - current thinking is that blowing dust is not very likely
Friday, but we could see some patchy blowing dust around Highway
2 in the Basin since this is where fields have been worked
recently. For now, we have left blowing dust out of the forecast.

Precipitation wise, we expect some lingering rain, mainly in the
mountains, as the front clears out early Friday morning. Also, as
the afternoon heating kicks in, there will be enough support for
some popup showers and maybe a couple of weak thunderstorms, with
isolated lightning strikes and brief downpours possible. For the
rest of the period, it will be pretty dry aside from some chances
for light orographic showers mainly for the Idaho Panhandle. RC

&&

.AVIATION...
06Z TAFS: Bands of high clouds will increase through the night
with cloud bases generally above 12 thousand feet. A relatively
light wind regime is expected through the night. Gusts 15-20 kts
is expected to develop after 21Z for GEG-SFF-MWH ahead of a cold
front. Winds will increase further aft 00Z for all TAF locations
and continue to be breezy through the evening hours. -shra are
possible for GEG-SFF-COE-PUW aft 03Z. Thunderstorms are also
possible, but confidence wasn`t high enough to add them.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        48  83  44  60  36  60 /  10   0  30  10   0   0
Coeur d`Alene  46  82  46  59  36  57 /  10   0  40  10   0  10
Pullman        49  82  43  57  36  56 /   0   0  30  10   0  10
Lewiston       51  87  51  64  42  64 /   0   0  30  10   0  10
Colville       43  84  41  63  33  63 /  10  10  40  30   0   0
Sandpoint      45  79  48  58  36  57 /  10   0  50  30  10  10
Kellogg        50  80  45  53  38  52 /   0   0  40  30  10  20
Moses Lake     51  83  44  66  36  69 /   0   0  20   0   0   0
Wenatchee      52  80  45  62  40  65 /  10  10  10  10  10   0
Omak           50  82  45  65  37  68 /  10  10  20  10   0   0

&&

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

&&

$$