Weather Service Report


392 
FXUS66 KOTX 170010
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
510 PM PDT TUE SEP 16 2014

.SYNOPSIS...
Today into Wednesday will feel like summer with afternoon
temperatures in the 80s. Cooler, more seasonal temperatures will
follow the passage of a weak cold front on Thursday. Thursday
will also be locally breezy with a chance for light rain showers.
Sunshine and light winds will return on Friday, and look for warm
temperatures once again this weekend.

&&

.DISCUSSION...
Tonight and Wednesday: Currently a weak wave is still in the
process of passing through the area that has shifted our ridge of
high pressure eastward now over western Montana. This initial
eastward shift is the first hit of the eventual ridge breakdown
later in the week. As of 2pm, weak echos on radar were being
indicated on a line from Omak to Coolin and areas slightly south.
The echos were likely due to weak forcing associated with the
passing wave. Not much in the way of precipitation is reaching the
surface as indicated by observations, so the majority is likely
attributed to virga or very light showers. Moving through the
afternoon and into the evening I anticipate the wave to continue
to push north with only virga or some very light showers the
continued extent.

Overnight we can expect mainly calm conditions as we await the next
more potent storm system later Wednesday. Starting as early as
tonight we will start to see some moisture filtering in ahead of
the main system allowing for increased cloud cover. This should
help to keep our overnight temperatures from falling as much as
previous nights. Tomorrow brings another warm day to the region
as we remain firmly entrenched within the mild southwesterly flow
pattern. Overall we can expect similar conditions as today with
warm temperatures and filtered mid and high clouds. As we move
into the afternoon is when the front end of the approaching system
finally reaches the Cascades. Tomorrow afternoon is when the
mention of precipitation enters the forecast for these areas.
Overall this is a rather low impact portion of the forecast as we
await the main incoming system. /Fliehman

Wednesday night through Friday night...A splitting trough will
move through the region Wednesday night and Thursday. The best
dynamics and moisture will remain south in Oregon/NorCal with a
secondary wave area moving through central/southern B.C. The front
that will accompany the splitting trough is not overly strong.
Southwest Tuesday night and Wednesday will increase the usable
moisture with Precipitable waters going up to nearly an inch,
which is well above normal. The models have been in decent
agreement indicating the best instability and moisture will move
through my southeast zones Thursday afternoon. Showers will be
possible for all the higher terrain outside of the Columbia basin
and the Palouse...the focus will be from southern Shoshone county
then following the higher terrain north over the northern
Panhandle and west into the northeast mountains. In these area
there will be a chance of showers and the possibility of some
embedded thunderstorms. Instability parameters indicate no real
organization to the thunderstorms and we are expecting just a few
pulse type storms.

The surface gradient will tighten through the day Thursday and
the 850mb winds around 20 kts should easily mix down to the
surface. This will result in breezy southwest winds with gusts up
to 25 mph across the basin, Palouse and Spokane area.

High pressure will rebuild back into the area quickly on Friday
and Saturday. Northwest flow on Friday will keep conditions dry
with temperatures cooling down several degrees but remaining on
the warm side of normal. This will mark the beginning of a warmer
and drier period expected through the weekend. /Tobin 

Saturday through Tuesday night: A brief period of northwest flow
will be replaced by another ridge of high pressure for the
weekend. This will bring warming temperatures and altogether shut
down any chances for precipitation. Temperatures will peak on
Sunday (although they will be almost as warm on Saturday) 10 to 15
degrees above normal (widespread 80s). The dry air that will
overspread the region will also allow for good cooling after the
sunsets. Temperatures will cool closer to where they should be at
night, but will warm quickly through the morning. 

Changes may be on the way for next week, although it may take a
few days for it all to take effect. A large trough over the Gulf
of Alaska will transition our flow pattern to more southwest, and
a shortwave looks to move near or over the Inland Northwest in the
Monday/Tuesday time-frame. This will begin the ridge breakdown
process. How much the ridge is suppressed will determine what
happens as a more organized system moves toward the region mid-
week. Lots of time to look, but there could be higher rain chances
in the offering beginning mid next week. ty

&&

.AVIATION...
00Z TAFS: High pressure shifts east and the southwest flow brings
moisture and energy up from the south. Look for some middle and
high clouds, thickening especially Wednesday. A slight chance of
showers comes toward the Cascades...mainly after 12-18Z. Some
smoke from nearby wildfires may also lower VIS toward MVFR
conditions, mainly around PUW and LWS Wednesday morning. Otherwise
look for VFR, dry conditions. /J. Cote'


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        57  84  58  79  56  75 /   0  10  10  20  10  10 
Coeur d'Alene  53  84  54  79  55  74 /  10  10  10  30  30  10 
Pullman        54  86  54  80  54  75 /  10  10  10  20  10  10 
Lewiston       60  90  62  84  59  80 /  10  10   0  20  20  10 
Colville       51  85  53  81  51  78 /   0  10  20  30  20  10 
Sandpoint      47  79  49  75  52  71 /  10  10  10  30  30  20 
Kellogg        55  82  54  75  52  69 /  10  10  10  30  30  20 
Moses Lake     56  87  59  83  56  82 /   0  10  10  10  10  10 
Wenatchee      60  86  63  81  61  81 /   0  10  20  20  10   0 
Omak           54  88  59  81  55  80 /   0  10  20  30  20  10 

&&

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

$$


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Western Regional Climate Center, wrcc@dri.edu