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fxus66 kotx 230919 
afdotx

Area forecast discussion
National Weather Service Spokane Washington
219 am PDT Sat Jun 23 2018

Synopsis...
scattered rain showers will linger over the Idaho Panhandle today
while much of central and eastern Washington remain dry and warm.
Summer will return on Sunday with sunshine and high temperatures
in the 80s. There will be a chance of thunderstorms Monday morning
followed by gusty winds in the afternoon as a strong cold front
moves through the region. Mild weather Tuesday and Wednesday will
give way to the chance for showers later in the week.

&&

Discussion...

Today and tonight: radar this morning shows some lingering
showers over the Idaho Panhandle moving out of the area while
satellite imagery indicates that the low pressure system has moved
in to western Montana. Water vapor imagery shows wrap around
moisture keeping extreme eastern Washington and the northern
Panhandle clouded in, and that will continue through the day as
the upper low slides down the Idaho/Montana border today wrapping moisture
and clouds around it. This means lingering showers over the
Panhandle on Saturday, diminishing in the evening. Otherwise,the
rest of the region will be dry and sunnier as a high pressure
ridge builds in from the west. This means a much more stable
airmass and a weakening pressure gradient. As such our breezy
winds in the basin and through the Cascade gaps will be weaker
than yesterday, gusting to 15-20 mph in the basin and 25-30 mph
around Wenatchee.

Sunday: Sunday will be very pleasant, with light winds and sunny
skies for everyone as the ridge axis crosses eastern Washington.
This also means temperatures will warm substantially from
Saturday, into the 80s and even low 90s in the deep basin.
Overnight an incoming cold front will cross the Cascades brining
renewed rain chances to north central Washington and progressing
east. /Bw

Monday: the potential for lightning in the morning followed by
breezy winds in the afternoon will make Monday a day to watch.

* Morning thunderstorms: the NAM, GFS, ECMWF, and sref produce a
similar convective signal across north central and northeast
Washington on Monday morning. Steep mid-level lapse rates along
and ahead of an advancing cold front will have the potential to
produce clusters of fast moving thunderstorms early in the day.
There is good agreement that cells will produce precipitation,
but elevated instability combined with rapid cell motion suggest
that not all lightning will be accompanied by much appreciable
rain. Fortunately, recent rains have raised moisture levels
across northern Washington, and we aren't at critically low fuel
moisture levels.

* Gusty winds and afternoon humidity: Post cold front winds will
become gusty by mid to late morning as low pressure deepens over
southern Alberta. The combination of deep cold advection, a
tight west to east pressure gradient, and momentum aloft (25 to
35kts in the 850-700mb layer) will contribute to widespread
breezy conditions on Monday. Sustained west/southwest winds of
15 to 20 mph will be common from central Washington across the
Columbia Basin onto the Palouse/West Plains. Localized gusts to
35 mph will be possible through the Cascade gaps impacting
Wenatchee, Chelan, Waterville and Vantage. With high
temperatures in the upper 70s and low 80s and humidity dropping
into the upper teens and low 20s, grass and brush fires will be
a concern.

Tuesday and wednesday: a dry westerly flow is expected to follow
monday's potent cold front. At this time, it looks like Tuesday
and Wednesday will be dry with temperatures at or below average
for late June.

Thursday through saturday: the westerlies are expected to buckle
late in the week with the development of another trough over the
inland northwest. The 18z and 00z runs of the GFS aggressively
carve a low over central Washington Thursday night into Friday.
The other models suggest a broader/flatter trough. If the GFS
verifies, Friday into Saturday will feature more showers and
thunderstorms along with cooler than average temperatures (highs
in the 70s). The European model (ecmwf) and Canadian models show less
precipitation and breezier conditions with high temperatures
ranging from the mid 70s to low 80s. /Gkoch

&&

Aviation...
06z tafs: some lingering showers around kgeg/ksff/kcoe until 08z.
Breezy and gusty conditions are expected at keat through the
Cascade gaps tonight into Saturday. Otherwise VFR conditions as
high pressure builds in through 00z Monday. Although there will be
overcast cloud deck about 5kft developing after 12z Sunday
kgeg/ksff/kcoe. Tc




&&

Preliminary point temps/pops...
Spokane 75 56 83 61 78 50 / 10 10 0 0 20 0
Coeur D'Alene 71 55 81 59 78 49 / 20 10 0 0 10 0
Pullman 72 53 81 59 75 47 / 10 0 0 0 0 0
Lewiston 78 59 87 63 82 54 / 10 0 0 0 0 0
Colville 78 55 85 57 83 46 / 10 10 0 10 60 0
Sandpoint 69 54 80 57 77 47 / 50 10 0 0 20 0
Kellogg 68 53 80 56 75 47 / 40 10 0 0 10 0
Moses Lake 83 55 89 59 82 49 / 0 0 0 20 10 0
Wenatchee 81 57 88 61 79 54 / 0 0 0 20 10 0
Omak 82 57 87 59 81 51 / 10 0 0 30 20 0

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...none.

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