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Area forecast discussion 
National Weather Service Spokane Washington
253 PM PDT sun Jul 5 2015

Synopsis....
hot, dry and mostly clear but smoky conditions will continue
across the inland northwest, at least into Monday. Another
system drops in around Tuesday with a threat of showers and
thunderstorms, with the best chances across the northeast
mountains. Drier conditions return around mid-week, before
additional shower and thunderstorm chances return toward Friday
into next weekend.

&&

Discussion...
tonight through Wednesday night: the inland northwest will be in a
more progressive northwest flow, with the next chance of showers
and thunderstorms arriving around Tuesday. But first tonight into
Monday a shortwave trough near the central Panhandle pulls east
into Montana and subtle shortwave ridging moves into the region.
With drier air and a stabilizing atmosphere, look for an end to
the lingering shower threat over far southeast Shoshone County and
mostly clear skies until Monday afternoon. The sky, however, will
still be milky white from the smoke from the variety of wildfires
from Alaska to the Pacific northwest. By Monday afternoon daytime
heating and the leading edge of the next system will bring a few
more clouds in from the north. As for winds, the gradients slowly
slacken tonight into Monday. This will lead to a gradual decrease
in winds, with the most notable decrease Monday afternoon when the
thermal trough reorganizes over the western Columbia Basin.

Between Monday night and Tuesday night the next system drops in
from the British Columbia. It is not as sharp or fast as the most recent system,
but it encounters some broader and better instability and so
carries a broader shower and thunderstorm threat. First on Monday
night a weak shortwave/jet streak skims by the northeast. With
some pockets of elevated instability there could be a few
shower/T-storms around the northeast mountains of Washington and north ID,
but overall look for some increased clouds and dry weather. Going
into Tuesday the main trough axis pivots into northeast Washington and
north Idaho. There is deeper moisture, especially across northeast Washington
and north ID, and expanding SBCAPE (around 200 to 700 j/kg, with
potential pockets around 1000 j/kg or so) especially across the
Cascade crest and the northern Washington and Idaho Panhandle mountains. So
look for an increased threat of showers and thunderstorms through
the afternoon, with the best threat toward from Stevens County to
boundary/Bonner and eastern Shoshone County where the lift is
best. Smaller chances will be found across the Okanogan Highlands
and from northern Spokane County through the higher Palouse. We
will have to think about potential abundant lightning and fire
weather concerns, especially around the northern mountains and
potentially the Cascades depending on the amount of lift.

From Tuesday night into Wednesday the shortwave begins to drop
south and shortwave ridging, broader subsidence and drier air
comes in from the north. This will allow for the threat of
precipitation to gradually shift to just southeast Washington and the
central Panhandle and wane. This will leave the remainder of the
County Warning Area dry with decreasing clouds. /J. Cote'

Thursday through Sunday..confidence is growing that the unprecedented
heat of late will finally ease as the deep upper level low west
of the Bay area gets slowly nudged toward the inland northwest.
The trigger to cause this ejection will be the approach of a
stronger upper level trough expected to move into the NE Pacific.
There are questions as to how quickly the low will surge north and
what impacts it will have. For Thursday there is good model
agreement that the low will move into central California which
will begin to shunt some monsoonal moisture northward toward our
forecast area. If it makes it this far it would likely only result
in a small chance of thunderstorms over the extreme southeast corner of
Washington and the southern Idaho Panhandle. By Friday this threat
will spread even farther north as the offshore trough moves closer
to the coast. This could impact most of the Panhandle and far
northern portions of Washington with a small threat of
thunderstorms. At least this is what the European model (ecmwf) model is
suggesting. Meanwhile the Canadian and GFS models keep the threat
confined to southeast Washington and the southern Panhandle. We suspect
that by Saturday we should see the most widespread thunderstorm
threat as the offshore trough pushes a weak upper level
disturbance through southern British Columbia while the
aforementioned upper level low weakens considerably somewhere over
southeast Washington or NE Oregon. Based on moisture availability and
potential instability the best chances for thunderstorms will
occur over the Panhandle and extreme eastern Washington. There
would also be a threat near the Cascades. This is no sure bet
through as the Canadian model shows that both of the upper level
features will wash out before arriving in the inland northwest. On Sunday
the models all show an amplification of the trough off the coast
with more consolidated southerly flow impacting the entire
forecast area. Whether or not this brings widespread thunderstorms
is questionable. The European model (ecmwf) would say yes while the Canadian and
GFS say perhaps not.

While the specific question of where and when thunderstorms could
occur is tough to answer at this time, our confidence is better
that the temperatures will be coming down. Thursday and Friday
still look unseasonably warm with widespread highs in the 90s to
lower 100s. Saturday and Sunday should deliver some cooling
although not dramatic. Highs will remain in the mid 80s and 90s
but the relative humidity levels will begin to creep upward which
is somewhat better news for dry fuel conditions. Fx

&&

Aviation...
18z tafs: a shortwave drops by the central Panhandle, with few
clouds. But taf sites will be VFR and dry. Winds will remain
breezy and gusty through this afternoon away from the sheltered
locations. Expect 10 to 20 mph, with local gusts to 30 mph. These
should subside between 22 to 04z. Location such as lws/eat/puw,
however, will be more sheltered and should experience lighter
winds. Expect some elevated layers of smoke from regional
wildfires. /J. Cote'




&&

Preliminary point temps/pops...
Spokane 61 92 67 93 65 94 / 0 0 0 20 20 10
Coeur D'Alene 58 90 61 90 61 91 / 0 0 10 20 20 10
Pullman 53 90 57 92 56 92 / 10 0 0 10 20 10
Lewiston 66 98 69 99 69 99 / 10 0 0 10 10 10
Colville 57 94 63 95 60 97 / 0 0 10 30 20 10
Sandpoint 51 88 55 87 53 90 / 10 0 10 30 30 10
Kellogg 52 88 57 88 57 90 / 10 0 0 20 20 10
Moses Lake 66 98 67 100 69 100 / 0 0 10 10 10 0
Wenatchee 72 99 72 100 74 102 / 0 0 0 10 10 0
Omak 62 97 68 97 66 99 / 0 0 10 20 20 0

&&

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

$$

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