Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kotx 141028 

Area forecast discussion
National Weather Service Spokane Washington
228 am PST Thu Dec 14 2017

many of The Lowlands across eastern Washington and north Idaho
will continue to be covered by low clouds. Chances for light
precipitation increase Friday with snow over northeast Washington
and north Idaho and a chance of a wintry mix in the Cascade
valleys and Columbia Basin. It will be drier for Saturday before
another weak weather system brings light snow on Sunday. A
stronger and wetter system arrives next Tuesday into Wednesday.


today through Friday night: low clouds have re-established
themselves over the inland northwest and they will persist through Friday
morning. The lone exception to this will be over the Palouse were
southeasterly winds ahead of an incoming system will often push
out the low clouds.

The front for Friday is currently lying off the West Coast, with a
short wave inflection on the front down at 30n/150w. This wave
will move up the front and then drag it across our area on Friday
as a cold front. This isn't a favorable pattern for heavy snow for
our area. Since the front is coming from the northwest, the Lee of
the Cascades won't see much if anything, and the favored area will
be the Palouse, southeast WA, and the southern Panhandle.

The front will reach the Cascades Friday at sunrise, reaching the
Washington/Idaho border by noon. So snow will fall in the Spokane Metro area
during the afternoon hours which could impact the afternoon
commute. The Columbia Basin south of Moses Lake and Ritzville
could see some brief freezing rain or sleet. Rj

Saturday through wednesday: the weather pattern will remain
amplified and progressive through the period with good agreement
in solutions seen between the GFS and ecwmf. Chances for fog look
limited. The weekend will start off drier and cool under northerly
flow aloft and a chance of mountain snow showers in the upslope
reaches of north Idaho and southeast Washington. Meanwhile the
ridge axis of high pressure lies off the Washington coast with a stream of
mid and high level moisture, giving way to plenty of cloud cover.
The ridge axis is forecast to flop eastward through the region
Saturday night, bringing the swath of upper level moisture. On the
back side of the ridge axis, a westerly jet will take aim on the
region for Sunday as a weak low pressure system tracks across
southern British Columbia. Moisture and isentropic lift increases. Light
precipitation will develop across the northern zones from the
Cascades to north Idaho Sunday into Sunday evening. Snow looks to
be the predominant precipitation type with an inch or two possible
in the northern mountains. Although a nose of warming looks to
move across the central Washington and Columbia Basin into the Palouse
that could lead to a wintry mix before switching over the rain.
This weather disturbance skirts to the east late Sunday night.
Expect a brief dry spell for Monday aside from a small chance of
mountain snow. A stronger and wetter storm system takes aim on the
inland northwest by Tuesday into Wednesday. Again there's good model
agreement that a warm front lifts into the region on Tuesday with
breezy southerly flow and warming. Precipitation will start light
early Tuesday and steadily increase, mainly across the northern
zones. Precipitation type again will start off as snow, but
switches to rain in the valleys and basin by Tuesday afternoon. A
cold front sweeps through the region late Tuesday night into
Wednesday morning with falling snow levels and temperatures and
snow returning in most areas. Post frontal mountain showers and
brisk west to northwest winds will be found on Wednesday with
cooler temperatures. Wednesday night into Thursday will turn much
colder under northerly flow aloft. /Rfox.


12z tafs: low clouds continue to blanket the area. The cigs in
general are MVFR with the exception being kpuw. These conditions
should persist for the next 24 hours. There is the potential that
the low clouds may clear out of kpuw and even the kgeg/ksff area.
Confidence is low as to when this would happen if it does. Rj


Preliminary point temps/pops...
Spokane 31 26 32 25 32 24 / 0 0 80 20 10 10
Coeur D'Alene 32 26 33 25 32 23 / 0 0 90 40 10 10
Pullman 32 27 34 26 33 24 / 0 0 80 70 10 10
Lewiston 34 29 38 30 38 26 / 0 0 60 70 10 10
Colville 32 27 32 26 35 26 / 0 0 60 10 10 20
Sandpoint 32 26 33 26 34 24 / 0 0 100 30 10 20
Kellogg 28 26 33 25 31 22 / 0 0 90 60 20 10
Moses Lake 32 26 33 26 37 28 / 0 0 30 0 10 10
Wenatchee 32 28 35 29 38 29 / 0 0 10 0 10 10
Omak 33 28 34 27 34 28 / 0 0 20 10 10 10


Otx watches/warnings/advisories...
Idaho...air stagnation advisory until 10 am PST Friday for central
Panhandle mountains-Coeur D'Alene area-Idaho Palouse-Lewis
and southern Nez Perce counties-Lewiston area-northern

Washington...air stagnation advisory until 10 am PST Friday for east slopes
northern Cascades-lower Garfield and Asotin counties-Moses
Lake area-northeast Blue Mountains-northeast mountains-
Okanogan Highlands-Okanogan Valley-Spokane area-upper
Columbia Basin-Washington Palouse-Waterville Plateau-
Wenatchee area.

National Weather Service Glossary of Abbreviations