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
000
FXUS66 KOTX 220913
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
213 AM PDT Sun Apr 22 2018

.SYNOPSIS...
Dry weather is expected much of this week, with our warmest
weather of the spring season thus far. By Thursday and Friday,
some of our lowland areas will have a shot of reaching 80 degrees
or more. Toward Saturday changes are possible, with some threat of
showers and maybe thunderstorms returning.



&&

.DISCUSSION...

Today through Monday night: The cirrus deck has moved out of the
region leaving us with mostly clear skies. However, satellite
shows another area of mid and high clouds currently moving onshore
over western Oregon and Washington headed east. The NAM is
representing this feature well in the 500-300 mb RH field,
associated with a weak wave in the upper level flow. It looks to
bring a deck of clouds to the region beginning this morning and
exiting by this evening, though the lee of the Cascades will
likely clear out earlier in the afternoon. Any precip chances from
this wave stay well south of the area in Central Idaho. Starting
this evening a strong high pressure ridge begins building in which
will give us sunny skies, temperatures in the mid 60s by Monday,
and our warmest week of 2018 so far. /bw

Tuesday through Saturday: Dry and warm weather expected most
of this period, but changes are possible by the end of the week.
Tuesday to Thursday the region will be dominated by high pressure,
briefly damped by a Canadian trough Tuesday night and Wednesday.
At the same time a cut-off low is projected to set-up off the
Pacific coast. Aside from some flat afternoon cumulus and
transient high clouds, the region will be mostly clear and dry.


Toward Friday and Saturday the cut-off low attempts to move
inland. Unsurprisingly models disagree over its precise evolution.
Cut-off lows have no solid steering mechanism and tend to move of
their own volition. With the ridge axis over the area early this
period shifting toward the northern Rockies the southerly flow
will help promote warming temperatures. Regional 850mb
temperatures in the lower teens warm to the middle to upper teens
by Friday, before dipping some Saturday. This will lead to the
warmer conditions, with many areas warming from the 70s Tuesday to
the upper 70s and 80s by Friday, before some cooling Saturday.
This warmth will come with some unstable conditions. Precisely how
much instability there will be and where it will set-up is
uncertain but any disturbances rounding the cut-off low and
ejecting through our region will bring a threat of showers and
thunderstorms. Friday the main risk will be south of the area but
I cannot entirely rule out some around the Blue Mountains. Some
guidance brings the threat north into the upper Columbia Basin,
Palouse and even toward the Spokane area Friday night. However
confidence is too low to include in the forecast at this time.
Saturday (into next Sunday) broader chances envelop the region,
but these still look to be isolated to scattered in nature and the
better risk will be around the mountains and southeast CWA.

The other issue will be rises on area waterways due to snow-melt,
more noticeably mid-week on. At this time none of the mainstem
river area projected to flood in the next week, but some may push
toward bankfull and these will be monitored. However small
streams/creeks may spill over, even without precipitation. /J. Cote`

&&

.AVIATION...
06Z TAFS: Occasional mid and high clouds are expected through
Sunday with winds generally 10 kts or less. VFR conditions will
continue at the TAF sites.  JW


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        56  35  64  40  71  44 /   0   0   0   0   0   0
Coeur d`Alene  56  34  64  37  70  40 /   0   0   0   0   0   0
Pullman        55  33  63  38  70  41 /   0   0   0   0   0   0
Lewiston       64  38  68  41  77  47 /   0   0   0   0   0   0
Colville       61  32  69  37  73  39 /   0   0   0   0   0   0
Sandpoint      55  33  62  35  68  37 /   0   0   0   0   0   0
Kellogg        55  34  62  36  70  39 /   0   0   0   0   0   0
Moses Lake     63  34  69  40  75  42 /   0   0   0   0   0   0
Wenatchee      62  39  68  42  73  47 /   0   0   0   0   0   0
Omak           62  36  69  40  75  42 /   0   0   0   0   0   0

&&

.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.