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Area forecast discussion 
National Weather Service Spokane Washington
420 am PDT Friday Aug 29 2014

Synopsis...
the Labor Day weekend will be cooler than normal with locally
breezy conditions over portions of central and eastern
Washington. With the exception of some isolated mountain showers,
the majority of the inland northwest will remain dry through the
weekend. A continuation of the cool weather pattern is expected
through next week. The best chance for showers and thunderstorms
will probably occur in the Wednesday or Thursday time frame.

&&

Discussion...
today through Saturday night: the weather will turn cooler, breezy
with mountain showers across the inland northwest as the weather
pattern evolves from a Flat Ridge to into an upper level trough.
Today will start the onset of the cooling with the arrival of a
cold front which will push across eastern Washington this
afternoon and reaching north Idaho by evening. Most of the
moisture will be in the mid to upper levels, which will lead to
little if any precipitation except for the mountains. The best
chance of showers will be the Cascade crest. The frontal band
weakens as it pushes east with spotty mountains showers in
northeast Washington and north Idaho. Instability is lacking with
the weakening front and will keep the mention of thunder for
today. Winds will kick up behind the front from the Lee side
valleys into the Columbia Basin with speeds of 15 to 25 mph.
Temperatures will cool a few degrees with readings near seasonal
normals. Winds and chance of showers decrease this evening as a
drier pushes in from the west and skies clear. 500mb heights
continue to fall into Saturday as an upper trough digs over the
region as a shortwave rolls through the flow by Saturday afternoon
and evening. Expect another chance of showers primarily for the
mountains. Instability will be the highest near the Canadian
border where the cold pool will reside. Will keep the mention of
thunderstorms across the north during Saturday afternoon and
evening. Westerly winds will kick up again especially in the Lee
side valleys into the Columbia Basin. More cooling expected with
widespread 70s across the low lands. /Rfox.

Sunday through thursday: cooler than average temperatures will be
the rule next week under a persistent longwave trough over the
Pacific northwest. The medium range models are in good agreement
that a large 500mb ridge will be anchored over the southeastern
and south central U.S. Bringing hotter than average temperatures
to portions of the country that received very little heat much of
the Summer. The prevailing mid-level flow pattern Sunday through
Tuesday is expected to be northwesterly which is generally a dry
pattern this time of year. The models are progging a progressive
shortwave in the northwest flow on Monday which may bring enough
moisture with it for mountain showers with the best shot of rain
along the Cascade crest. At most, light rain amounts are expected
given the lack of deep layer instability.

There is reasonably good agreement that the trough will buckle
Tuesday night into Wednesday bringing a reinforcing shot of
cooler air into the region. It also appears that an upper level
cold pool will set up over northern Washington and the far north
Idaho Panhandle on Wednesday suggesting the potential for widely
scattered showers and thunderstorms. At this time the best
combination of lift and instability looks to be over northeast
Washington and far north Idaho...away from the Cascade burn scars.
/Gkoch

&&

Aviation...
12z tafs: an upper level warm front will keep high clouds over the
region this morning, then a mid level cold front will slide across
the taf sites by afternoon. Expect west to southwest winds to
increase late this afternoon and early evening with local gusts to
25 mph. Clouds and winds will decrease overnight. /Rfox.

&&

Preliminary point temps/pops...
Spokane 81 53 73 48 71 50 / 0 10 10 10 10 10
Coeur D'Alene 81 52 72 45 70 47 / 0 10 10 10 10 10
Pullman 81 50 72 43 72 45 / 0 10 10 10 10 10
Lewiston 88 60 78 53 77 54 / 0 10 10 10 10 10
Colville 82 46 76 43 74 45 / 10 10 10 20 10 10
Sandpoint 78 51 70 39 68 44 / 0 10 20 20 10 20
Kellogg 77 52 68 47 66 49 / 0 10 10 20 20 20
Moses Lake 84 50 79 47 78 51 / 0 0 0 0 0 0
Wenatchee 82 56 77 56 78 56 / 0 10 0 10 0 0
Omak 82 52 77 50 76 50 / 10 10 10 10 10 10

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...none.
&&

$$

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