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 48 49 50
648
FXUS66 KOTX 250924
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
224 AM PDT Wed Apr 25 2018

.SYNOPSIS...
The warming trend continues with afternoon temperatures well into
the 70s today. Many lowland places will exceed 80 degrees
Thursday and especially on Friday. Expect a pattern change to bring
cooler temperatures and the threat for showers this weekend into
early next week.

&&

.DISCUSSION...
Today through Friday: Dry and unseasonably warm weather continues
for the rest of the work week with a ridge of high pressure over
the region. Anticipate subtle changes each period. A weak
shortwave will pass across BC this morning, dragging a band of
cirrus through the region, followed by drier air in its wake.
Skies will start off partly sunny, but should clear through the
day. Surface winds will become northerly and should be the most
pronounced in the Okanogan Valley into the western Columbia Basin
this afternoon as a surface area of high pressure settles into BC.
Tonight into Thursday, the surface high spreads across the
Canadian Rockies into western MT, which enhances easterly flow
across the Inland NW. A low level thermally induced pressure
trough remains across western Oregon and builds into Washington.
By Thursday night into Friday, the ridge of high pressure begins
to shift east as low pressure in the Pacific pivots inland across
Oregon. A band of high level moisture will sweep across Oregon
into southern Washington as the low level pressure trough marches
eastward. The warmest day look to be Friday across the Inland NW
with max warm air advection and low level thermal ridge spanning
the region. Could see afternoon temperatures reaching the 80
degree mark in several locations. Meanwhile, instability and
moisture mounts across southeast Washington into the southern
Panhandle with the advancing pressure trough Friday afternoon.
There looks to be a small chance of showers and thunderstorms over
the Blue mountains late that day, although a strong cap will need
to be released for this activity to develop. /rfox.

Friday Afternoon and Saturday: The ridge that has been in place
for most of week will begin to shift East as an upper level trof
begins to press into the region. A low associated with this trof
will move onshore along the OR/CA border by late Friday afternoon.
Models are in good agreement with the the initial arrival of this
system. Euro and UKmet are running slightly slower than GFS by a
run. The late in the day impacts will allow Friday to still be the
significantly warmer than normal with 850MB temps in the mid 50s
range and sfc temps pushing 80. The first impacts from the Low
will be showers developing in SE WA region. Models indicate around
800 J/kg of Cape in the that area but extremely high CIN might
hinder any development of thunderstorms outside of the slight
chance in extreme SE WA along the OR border. By late Friday
night/ early Saturday, the entire region is under the influence of
the Low. The Models begin to differ on the strength of the Low
and the ridge by mid morning Saturday. This is lowering confidence
on the trajectory and timing of the Low exiting the region. This
leads to forecast of widespread rainshowers with cloud cover
keeping the temperatures around 15 degrees cooler than Friday.
Snowmelt due to warm temps are expected to cause rises for the
regions streams and rivers causing some to reach minor flood or
action stage on Saturday.

Sunday through Wednesday: The low is still trudging through the
Pacific Northwest widespread rainshowers to the Inland Northwest.
With the Low passing to the South, the wrap around moisture will
bring likely showers to the ID Panhandle with the rest of the
region expecting chance showers. Continuous cloudy sky will help
bring a drop in temperatures for the beginning of the week with
highs reaching only into the 50s to low 60s for most. Temperatures
will begin to rebound by midweek. Rivers and streams are expected
to begin to lower during this period. /JDC

&&

.AVIATION...
06Z TAFS: VFR conditions will continue at all TAF sites across
Central and Eastern Washington and north Idaho through 06z
Thursday. High clouds associated with a weak system will pass
through the region through Wednesday morning before skies clear.
JW


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        74  45  78  49  80  48 /   0   0   0   0   0  20
Coeur d`Alene  72  42  77  46  80  47 /   0   0   0   0   0  20
Pullman        72  43  78  46  80  46 /   0   0   0   0   0  40
Lewiston       79  46  83  50  84  52 /   0   0   0   0   0  40
Colville       75  42  79  44  82  49 /   0   0   0   0   0  10
Sandpoint      70  39  73  42  78  46 /   0   0   0   0   0  10
Kellogg        70  39  74  43  79  47 /   0   0   0   0   0  10
Moses Lake     78  43  82  47  84  50 /   0   0   0   0   0  30
Wenatchee      76  49  80  52  81  50 /   0   0   0   0   0  30
Omak           77  43  81  49  84  52 /   0   0   0   0   0  20

&&

.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.