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Area forecast discussion 
National Weather Service Spokane Washington
248 am PDT sun Aug 2 2015

Synopsis....
another hot and smokey day will be on tap today with triple digit
heat over much of central and southeast Washington. The ongoing
drought combined with high heat and low humidity will contribute
to high fire danger throughout the inland northwest. Temperatures
on Monday should be a few degrees cooler with an increase in
clouds. Cooler, more seasonal temperatures and locally breezy
winds are expected Tuesday through Friday following the arrival
of a cold front.

&&

Discussion...
today through Monday night: expect one more hot and dry day
today, then expect conditions to gradually moisten up and cool
slightly. The ridge of high pressure will stay firm over the
inland northwest today as the surface trough spans from the
Columbia Basin to north Idaho. This ridge is expected to shift
east tonight into Monday as an upper trough of low pressure swings
down across b.C. This will enhance a moist southwest flow and
advect moisture and clouds into the region.

Temperatures: only a degree or two change in temperatures is
expected today as low levels remain warm. It will be another hot
and unstable day. This could make current wildfire more active
once again. Could see a few near record highs, today in Moses
Lake, plain, Stehekin and Omak. The heat advisory will continue
for another day in the lc valley as daytime temperatures top out
from 93 to 103. Monday's temperatures will cool a few more degrees
with mainly 90s expected.

Winds/humidity: downslope Cascade Gap winds will be another
concern today especially with the extremely dry humidity levels,
from the upper single digits to mid teens. Wind speeds will
lighten up this morning and could see some terrain driven
upslope/up valley winds in sheltered valleys. Surface pressure
gradients are expected to tighten to about 4-5 mb this afternoon
and should see a repeat of gusty gap winds into the evening across
the Cascade valleys, but speeds don't look to be as strong as
those on Saturday. Some local afternoon gusts of 15 mph are also
possible across the Columbia Basin as the dry and unstable
atmosphere mixes. Northwest to westerly winds will prevail for
much of the day on Monday although humidity values will gradually
increase.

Clouds/weather: areas of smoke will be a concern this morning and
into the afternoon as the wildfires remain active. The Wolverine
fire near Lake Chelan will be the main culprit although other
smaller fires especially near the Canadian border will add to the
smokey haze. High clouds will be on the increase today as cirrus
rotates in from the southwest. This moisture is associated with a
monsoonal fetch coming up from California. This moisture will
increase tonight especially across the Cascades and could squeeze
a few sprinkles. A weak disturbance in the moist southwest flow
will ripple up the Cascades Monday morning with a small chance of
elevated convection and more sprinkles. As the upper trough drops
across b.C., This will push the disturbance and moisture band
across the inland northwest Monday afternoon and evening.
Instability will remain and this could generate more high based
thunderstorms across northeast Washington and north Idaho. There
looks to be a better chance of measurable precipitation across
north Idaho late Monday night, albeit it will still be light.
/Rfox.

Tuesday and wednesday: a 500mb low will reside over British
Columbia Tuesday and Wednesday. The evening runs of the GFS and
European model (ecmwf) are in decent agreement that the majority of eastern
Washington and north Idaho will be under the influence of dry
westerly flow Tuesday and Wednesday. However, there may be enough
cool cyclonic flow aloft along the Canadian border to allow the
formation of widely scattered showers and thunderstorms Tuesday
and Wednesday. A 20-30 percent chance for showers and
thunderstorms has also been retained for the Idaho Panhandle
mountains along the Montana border Tuesday, but the evening models
have trended quicker pushing moisture out of the Panhandle. If
this trend continues, Tuesday will be a dry day for most of the
Panhandle. Tuesday and Wednesday look breezy with sustained 10 to
15 mph common across the basin, Palouse and Spokane area. Gusts to
20 mph will be likely in the afternoon with localized gusts in the
25 to 30 mph range through the cascasde gaps during the early
evening hours. Even though temperatures will be trending down
Tuesday and Wednesday, wind and low relative humidity levels could
be a concern given the exceedingly dry conditions following the
heat of the weekend.

Thursday through saturday: it is hard to get too excited about
chances for showers Thursday through Saturday. (Though....some of
US will be excited about the cooler, more seasonal temperatures.)
With the departure of the 500mb low out of British Columbia
Thursday night, the Pacific northwest will be under a flat
westerly flow Thursday and Friday. The persistent on-shore flow
should bring a gradual increase in our surface dewpoints Thursday
through Saturday, but probably not enough to produce much
instability. There is a hint of a weak shorwave trough on
Saturday, so a 20 percent chance of mountain showers and
thunderstorms enters ther forecast Saturday afternoon. /Gkoch

&&

Aviation...
06z tafs: smoke will continue to be the main aviation concern
through Sunday. The smoke will be most prevalent in portions of
central Washington near the Wolverine fire. Lower level smoke
will increase around Chelan tonight, with the bluesky model
keeping this smoke east of keat again...but impacting kmwh
overnight into Sunday morning. Confidence is not high concerning
timing of MVFR visibility as kmwh...so went with a compromise
between timing of bluesky model and persistance. Some improvement
is expected Sunday afternoon at kmwh as surface winds switch from
north-northwest to SW. Jw

&&

Preliminary point temps/pops...
Spokane 98 67 95 66 87 59 / 0 0 0 10 10 10
Coeur D'Alene 98 59 97 61 87 56 / 0 0 0 10 20 10
Pullman 98 56 93 58 86 53 / 0 0 0 10 10 10
Lewiston 104 68 99 68 93 63 / 0 10 10 10 10 10
Colville 100 57 98 59 89 55 / 0 0 10 20 20 20
Sandpoint 96 52 97 54 83 52 / 0 0 0 20 20 10
Kellogg 96 58 96 60 84 54 / 0 0 0 30 30 20
Moses Lake 101 66 97 62 93 59 / 10 0 10 10 0 0
Wenatchee 101 73 97 68 92 65 / 0 10 10 10 0 0
Omak 100 68 97 63 92 59 / 0 10 10 10 10 10

&&

Otx watches/warnings/advisories...
Idaho...heat advisory until 8 PM PDT this evening for Lewiston area.

Washington...heat advisory until 8 PM PDT this evening for lower Garfield
and Asotin counties.

&&

$$

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