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
788
FXUS66 KOTX 271748
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1048 AM PDT Tue Sep 27 2016

.SYNOPSIS...
A mild and mostly dry weather pattern is expected through
Wednesday. Temperatures will be above average, with several days
of highs in the mid 70s to mid 80s. Cold front passage on Tuesday
will produce breezy winds down the Okanogan Valley. A pattern
change is expected to arrive late in the week with chances for
showers beginning Thursday and continuing into the weekend. By
Saturday and Sunday, afternoon temperatures will likely be in the
60s...possibly cooling further into the 50s next Monday.


&&

.DISCUSSION...
Today and Wednesday: Satellite imagery shows a cold front moving
across central BC and down across the northern portion of
Vancouver Island. The water vapor channel shows a noticeable dry
slot along the back edge of the front extending out from 130W to
150W in the Gulf of Alaska. The cold front will be fairly slow
moving and become hung up over the region late this afternoon into
this evening. The only precip is expected right up along the
Cascade crest, and will otherwise be too dry at lower levels for
any precip. The main impact with this weather feature will be for
breezy winds down the Okanogan Valley. I decided to favor the
higher resolution model guidance for the winds as they should more
accurately resolve the complex topography across this area. The
ARW, NMM and HRRR models show winds becoming quite breezy through
the Okanogan Valley with winds picking up after 9:00 AM this
morning and peaking in the early afternoon. Expect sustained winds
of 15 to 25 mph with gusts to around 35 mph possible. The
northerly winds will also draw down much drier air with dew points
crashing from the lower 40s to the lower 30s through the
afternoon hours. The combination of breezy winds and low relative
humidity will heighten fire weather concerns for any new fire
starts.

Winds will weaken overnight on Tuesday into Wednesday. The cold
front will generally become hung up over the region with a thin
band of mid to high level clouds stretching across the basin into
the Northeast Mtns and Northern Panhandle. Temperatures will cool
down a bit compared to yesterday but remain above normal for
early fall with highs ranging from the mid 70s to mid 80s. /SVH


Wednesday night through Saturday...We are looking for a quite cool
and unsettled weekend coming. This is courtesy of a deep low
pressure system that will move out of the gulf of Alaska on
Wednesday and move southeast towards the WA/OR coast late in the
day Thursday. The low will then linger off the coast and be the
main weather producer in some form or another well into into next
week. The upper level flow will become southwest Wednesday night
and Thursday and gradually shift to the south as the low
approaches the coast Friday and Saturday. This flow pattern will
tap into some pretty deep Pacific moisture as well. PWATs will
increase to between 0.75 to 0.85 during this period. This is about
160-170 percent of average. The increase in moisture will increase
mid level instability. Lift will mainly be provided by terrain for
an increasing chances of showers Thursday through the weekend. In
addition, numerous short wave disturbances are expected to eject
off the main low and these will be the focusing point for more
intense showers. All of the components are coming together for at
least a chance for thunderstorms for the Idaho Panhandle and
mainly near the border with Montana Friday afternoon. Rainfall
amounts through Saturday afternoon will generally be light with
most of the mountain location seeing between a trace and a tenth
of an inch and little to none for the lower elevations. Snow
levels start out between 9000-11,000 feet on Thursday and are
expected to drop down to between 5000-6000 feet by Saturday. Only
a dusting of snow is expected for the Cascades Saturday morning.

Temperatures on Thursday will be in the 70s and still 5-10 degrees
on the warm side of normal. Temperatures will cool off 4-6 degrees
on Friday and 8-10 degrees on Saturday. High temperatures on
Saturday will have a tough time making it int the lower to mid
60s. Tobin

Sunday to Tuesday: Models begin to diverge on the exact placement
of the upper low as it crosses the region, but generally agree
with it passing on or about Monday. Multiple shortwaves will
rotate around the trough on Sunday and Monday with plenty of deep
moisture to work with, keeping rain likely. Sunday looks wet
mostly for areas around the basin, but the strongest shortwave and
most widespread rain come late Sunday and on Monday. The trough`s
continued influence will keep temps down in the upper 50s and low
60s. A tightening pressure gradient with the passage of a surface
low to the northeast on Monday will also bring gusty winds to the
Columbia Basin. /bwilliams

&&

.AVIATION...
18Z TAFS: A slow moving cold front will sag over the Inland
Northwest today. Strongest winds with the front are down the
Okanogan Valley that will then spill out over the Waterville
Plateau and into the Moses Lake Area. Sustained winds of around 20
kts are expected at KOMK weakening to around 10 kts as these winds
reach KMWH by 03Z. NE winds will funnel down the Purcell trench
towards morning and increase winds in KCOE toward 12kts.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        78  52  79  55  77  50 /   0   0   0  10  10  30
Coeur d`Alene  78  52  79  54  77  50 /   0   0   0  10  10  30
Pullman        79  52  80  54  76  49 /   0   0   0  10  10  40
Lewiston       85  57  85  59  81  54 /   0   0   0  10  10  10
Colville       79  44  78  48  79  45 /   0   0   0  10  10  10
Sandpoint      75  46  75  49  75  47 /   0   0  10  10  10  20
Kellogg        76  50  79  52  76  48 /   0   0   0  10  10  40
Moses Lake     81  49  80  49  79  45 /   0   0   0   0   0  10
Wenatchee      78  53  78  51  77  49 /   0   0   0   0   0  10
Omak           79  47  78  49  79  47 /   0   0   0   0   0  10

&&

.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.