Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Spokane Washington
439 PM PDT Sat Oct 25 2014

Synopsis...
tonight into Sunday will be quite windy as a strong low pressure
system brings rain and gusty conditions to the inland northwest.
The weather will be relatively quiet on Monday before a moisture
laden storm system brings more widespread rain on Tuesday.
A mild autumn pattern is expected to return Wednesday and Thursday
with the potential of wet weather returning Friday into the
weekend.

&&

Discussion...

..windy conditions tonight and Sunday across central and
southeast Washington...

Tonight and sunday: a strong surface low lies off the Washington
coast is running a little deeper than the models indicate with
gusty southerly winds already across western Washington. This low
will lift northeastward and arrive in British Columbia overnight. As it does, it
will push a cold front across the Cascades this evening and into
north Idaho by early Sunday morning. Prefrontal showers are
already spreading across the Cascades and into northern mountains.
There is a small chance of embedded thunderstorms across the
northern mountains late this afternoon or early evening especially
on the backside of the cloud shield moving through the region.
Showers will steadily increase with the arrival of the frontal
with up to a 0.10" possible in The Lowlands and mountains seeing
about a 0.25". Although gusty southerly winds have developed
across the Blue Mountains and Camas Prairie this afternoon with
good mixing, the main wind event will arrive this evening and
overnight. The MM5 and hrrr has picked up a quicker onset of the
gusty winds this evening especially across the southeast
Washington, most likely due to the deeper surface low and its
track. Have opted to adjust the Wind Advisory and show an earlier
onset time with the gusty winds across the upper Garfield/Asotin
counties and southern Whitman, while keeping the current area
going for the rest of the Wind Advisory. Will also bump wind
speeds in the area which may be prolonged especially from 9 PM to
2 am overnight in this area. Winds look to taper off slightly
early Sunday morning and loose some of the gustiness, but daytime
mixing will bring a return of gusty southwest to west winds by
midday Sunday. Expect overnight lows to remain mild due to the
wind, cloud cover and precipitation. By Sunday, daytime highs will
be running 2 to 10 degrees cooler than today. /Rfox.

Sunday night and monday: winds will subside Sunday evening as low
pressure moves into the Canadian prairies. Cool/unstable
northwesterly flow behind the exiting storm system will bring a
good chance of accumulating snow to the Clearwater Mountains and
the ridges above 4500 feet in southern Shoshone County Sunday
night into Monday morning. Lookout Pass may have some slushy
accumulations Sunday night at 4700 feet. Any accumulations will
probably short-lived as temperatures warm into the 30s Monday.

Tuesday and wednesday: a moisture laden storm system will likely
bring the Pacific northwest another round of widespread rainfall
Tuesday into Tuesday night. This system is currently organizing
over the central Pacific and is ingesting Hurricane Ana. This may
sound ominous, but by the time this storm arrives on Tuesday it
won't be a particularly extraordinary system for this time of
year. Western Washington, the Cascades, and mountains of north
Idaho stand to get moderate rain. However, the 12-24 hour
duration of tuesday's storm is pretty typical of mid autumn storm
systems and does not appear to pose much of a flood concern at
this time. It appears that our short-term wind/rain storm tonight
into Sunday will be a more impactful storm than tuesday's system
with Ana's moisture contribution.

There is good agreement between the 12z runs of the GFS, European model (ecmwf) and
ensembles that a shortwave ridge will build over the inland
northwest Wednesday into Thursday. At this time, it appears that
mountain showers will linger into Wednesday with the best shot of
measurable rain in the morning. /Gkoch

Thursday through Saturday night: some uncertainty exists during
the far extended portion of the forecast. Through Thursday,
confidence is much higher, but trails off from there. A warm front
will lift north on Thursday as fairly deep as a digging trough off
the Pacific coast enhances southerly flow over the inland
northwest. This will likely trigger some showers as it lifts
north. What happens afterwards will be key, especially for those
who have outdoor plans on Friday night. How much the trough digs
before coming inland will be key, as a slower timing will keep
much of Friday dry, whereas a faster movement inland will be
cooler and more showery. Tried to cut the solutions down the
middle, which would keep higher chances over the Cascades while
chances trail downward as you move east.

It does look like thursday's high temperatures will be 10+ degrees
above late, late October highs. Once the cold front passes,
temperatures will once again fall back to where they should be.
This also means snow levels will fall as well, which could reach
some of the pass levels. TY

&&

Aviation...
00z tafs: some prefrontal convection may develop from the NE blue
mts into north Idaho late this afternoon with an embedded
thunderstorm possible but this will diminish after sunset. The
main band of showers will increase over the Cascades and push
eastward through the evening. Expect areas of MVFR with the rain.
Winds will veer from east to south with an increase in gustiness
this evening. The rain should taper off late evening and
overnight as south to southwest winds get stronger with gusts of
30-40kt possible. The winds should decrease slightly by early
Sunday morning but will increase and become gusty again after 18z
Sunday. /Ek




&&

Preliminary point temps/pops...
Spokane 44 53 35 50 39 49 / 70 20 20 0 20 80
Coeur D'Alene 43 52 34 48 36 49 / 70 40 30 10 20 80
Pullman 43 53 35 52 39 51 / 60 30 30 10 20 70
Lewiston 48 59 40 55 40 56 / 60 30 30 10 10 50
Colville 44 53 32 52 38 48 / 80 30 10 0 30 80
Sandpoint 42 49 33 48 34 47 / 100 90 20 10 20 80
Kellogg 42 45 34 45 33 43 / 90 50 50 20 20 80
Moses Lake 45 60 33 55 42 54 / 50 10 0 0 50 60
Wenatchee 45 59 39 55 43 54 / 50 10 0 0 50 60
Omak 42 56 33 52 39 50 / 60 20 0 0 50 60

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...Wind Advisory until 3 PM PDT Sunday for lower Garfield and
Asotin counties-Washington Palouse.

Wind Advisory from 8 PM this evening to 3 PM PDT Sunday for
Spokane area-upper Columbia Basin.

&&

$$

National Weather Service Glossary of Abbreviations