Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 231137
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
437 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 ID/MT 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 ECMWF and Canadian models show less
precipitation and breezier conditions with high temperatures
ranging from the mid 70s to low 80s. /GKoch

&&

.AVIATION...
12Z TAFS:VFR conditions are expected as a high pressure ridge
builds into the region. The only site likely to see some scattered
showers today will be KCOE. Winds will be be breezy today through
the Cascade gaps and into the basin and KEAT could see gusts 20-25
kts this morning and afternoon. /bw


&&

.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...
ID...None.
WA...None.

&&

$$


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