111 
FXUS66 KOTX 060438
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
938 PM PDT Tue Oct 5 2021

.SYNOPSIS...
Today is the last day of mild temperatures. Expect breezy
conditions across central Washington this afternoon. A cold front
arrives Wednesday morning bringing more gusty winds and isolated
to scattered showers for eastern Washington and Idaho. Then, 
anticipate much cooler fall temperatures for the latter half of 
the week with spotty light mountain showers in the Idaho 
Panhandle. Many locations will experience near or below freezing 
overnight temperatures starting Thursday morning onward resulting 
in widespread frost. The next round of showers and breezy winds 
looks to be by next Sunday.

&&

DISCUSSION...
The cold front is at our door step pushing through the Cascades.
The 700mb temp this morning of 3C will see a 6C drop by Wednesday
morning, indicating the strength of the incoming cold front. Warm
advection ahead of the front and the tightening of the pressure
gradient has resulted in breezy south winds today and temperatures
reaching the upper 60s and low 70s as of early this afternoon. The
average last 70F degree day in Spokane, per the 1991-2020 climate
normal period, is Oct 7th. So this would agree well that we are
about due for seeing our last 70F temps of the year. As such, the
active storm pattern should make sure that we don't see any more
days of temperatures in the 70s for the next week to two weeks.

The cold front will push through central and eastern Washington
tonight through early Wednesday, weakening somewhat as it crosses
the Cascades and ejects north into BC and Alberta. Most of the
precipitation associated with this front will stop at the Cascades
with some light showers making the jump across the Okanogan
Highlands and far northeast WA/northern Idaho Panhandle overnight
into early Wednesday. The bigger impactful weather will be the
cool down of temperatures through late this week. 

Morning temperatures the next few mornings will be about 10 to 12
degrees cooler than we've been seeing which means closer to, if
not at or just below, freezing for many areas. As such, if you've
succeeded in keeping a garden or sensitive plants alive outdoors
thus far this week may be time to call it quits. Widespread frost
Thursday and Friday mornings should take place for nearly the
entire region except perhaps along the Columbia and Snake rivers.
/Dewey

Friday through Tuesday...
An upper trof will firmly be in place by Friday with temperatures
about 10 degrees below normal for this time of year. That pattern
will continue through the weekend and into early next week.

The main focus of the weather impacts will be felt Sunday as the
jet stream dips southward ahead of the next strong area of low
pressure. This arctic intrusion will bring with it an active day
of weather Sunday with windy conditions and widespread rain
showers. The biggest change to the forecast was increasing winds
by about 15 mph from what I inherited. The ensemble mean for wind
gust in the Columbia Basin is about 30-35 mph with about a third
of the members showing over 40 mph gusts. Given the location of 
the jet stream and the overall strength of the trof, confidence is
growing that this will be a widespread windy day. What is 
interesting is the EFI (Extreme Forecast Index) is barely 
highlighting Washington, northern Idaho, and western Montana for
this period. I believe the reason is that windy days in mid 
October are not that uncommon. This, thankfully, appears to be a 
relatively "normal" wind event for October. 

Even so, we will continue to message the drastic change in weather
late in the weekend as outdoor events and recreation will still 
be occurring. 

Behind the front late Sunday, winds will slowly die down as
pressure slowly begins to rise into early next week. Scattered
showers, especially in the mountains, will stick around with
high temperatures only reaching about 50 degrees. The mountains
will be in the 30s so snow showers at the higher elevations are
likely. 

Looking at the far extended forecast, the jet stream is expected
to maintain its southern position leaving the Pacific Northwest in
a cool and unsettled weather pattern. Some ensemble members are
pointing toward an outside chance of light snow mid next week.
This will be something to watch very closely over the next few
days to see if more members come into agreement. 
/AB 

AVIATION...
06Z TAFS: VFR conditions with thick mid-to-high level clouds will
continue through the early afternoon. Winds will relax tonight, 
but will pick up again for a breezy afternoon across the Basin, 
Palouse, and West Plains. Scattered light showers will continue to
move across the region with the cold front's passage. JS


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        45  58  35  59  33  58 /  20  20   0   0   0   0 
Coeur d'Alene  45  56  35  58  33  58 /  20  20   0   0   0   0 
Pullman        40  53  32  56  31  58 /  20  30   0   0   0   0 
Lewiston       50  59  40  62  41  64 /  20  30  10   0   0  10 
Colville       40  60  30  58  27  59 /  30  20  10   0   0   0 
Sandpoint      41  54  32  55  29  56 /  20  20  10   0   0   0 
Kellogg        45  52  37  57  37  58 /  30  30  10   0   0   0 
Moses Lake     44  62  32  60  32  60 /  10   0   0   0   0   0 
Wenatchee      44  61  39  59  40  60 /  10   0   0   0   0   0 
Omak           43  63  35  61  35  61 /  20   0   0   0   0   0 

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.

&&

$$