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Area forecast discussion 
National Weather Service Spokane Washington
500 PM PDT sun Jul 13 2014

Synopsis...
a prolonged heat wave will continue across the inland northwest
through the majority of the work week. Mid to upper 90s will be
common, with triple digit heat in the Lewiston area and portions
of the Columbia Basin. Increased moisture will enter the area
tonight into Monday leading to an increased chance for showers
and thunderstorms for much of the region. A drop towards more
seasonal temperatures and dry conditions are expected as we
approach the weekend.



&&

Discussion...
..thunderstorms tonight into Monday may ignite new wildfires in
central and north central Washington...

Tonight into monday: all eyes will be on the upper level
disturbance moving onto the north Oregon coast this afternoon. By
late Monday afternoon this upper low is progged by the NAM and GFS
to be over the Spokane Metro. The main forecast challenge will be
the amount of lightning this system will trigger over central and
eastern Washington. Fuels from the Cascade crest to the
Washington/Idaho border are at critically dry levels.

At this time, our biggest concern for abundant lightning tonight
and Monday morning will be over the northern and central Cascades.
The best combination of mid-level instability (700-500mb Theta-E
lapse rates), upper level diffluence, and moisture flux is
expected over the Cascades tonight. The 12z/18z NAM and the 12z
GFS advertise that clusters of high based thunderstorms will
emerge from the convection currently over northwest Oregon and
track almost due north along the Cascades. Additional high based
cells are expected to develop over north central and northeast
Washington which will need to be closely monitored. It is possible
that some of these high based storms could track over the Palouse
and Ritzville/Moses Lake areas.

Daytime heating will likely prime northeast Washington, north
Idaho, and the ridges of the north Cascades for additional
thunderstorm activity Monday afternoon and evening. This forecast
becomes increasingly complicated. Convective debris from showers
and thunderstorms overnight could potentially inhibit
destabilization Monday. Cloud cover may not only compromise our
thunderstorm forecast, but ruin our temperature forecast, too. The
NAM and European model (ecmwf) are particularly bullish generating a good deal of
convective precipitation around Bonners Ferry, Metaline Falls,
Republic, and Mazama. Storm steering flow Monday afternoon will be
quite weak suggesting that thunderstorms Monday afternoon/evening
will be quite "wet". Locally heavy rain may dampen the potential
for wildfire ignitions. At this time red flag warnings will not be
extended into Monday afternoon, but the need for warnings will
continue to be evaluated through Monday morning. /Gkoch

Monday night through Wednesday night...the low responsible for the
convection on Monday will move east into Montana on Tuesday. A
ridge will move back into the area on Tuesday and Wednesday
bringing hot and dry conditions although instability will linger
over the Idaho Panhandle on Tuesday where a few thunderstorms are
possible. 850mb temps of 25-28c will translate to valley highs
Tuesday and Wednesday mostly between 95-102f. The hottest spots
like Wenatchee, Lewiston, Moses Lake, and Omak will be slightly
warmer with highs nearing 105f...where heat advisories may be
needed. Jw

Thursday through sunday: confidence is growing that the pattern
will be shifting out from under the bubble of high pressure.
Thursday and Friday look to be transitional days with the region
coming under northwest flow and a couple of weak disturbances
pushing through. These disturbances look to be fairly dry and not
much if any precip is expected. One for Thursday and another on
Friday will generally just result in some increasing wind. Winds
at 850 mb are not expected to be particularly strong up around
15-25 kts or so. Breeziest winds will be through the Cascade gaps
where the surface gradient will be at its strongest. This will
need to be monitored as we head into next week for the potential
of critical fire weather conditions due to wind and low relative humidity.

By the weekend, models are coming together with a trough digging
into the region. Where and when we may see any showers is still
highly uncertain. This will be dependent on any shortwaves that
rotate around the upper trough into the region, which is too
difficult to Pin Point at this time. Confidence is high that
temperatures will be on a cooling trend into the week. Expect
temperatures at least near seasonal averages with most locations
in the 80s by the weekend. /Svh

&&

Aviation...
00z tafs: an upper system coming into western Washington/or Sunday evening
tracks northeast over the next 24 hours, bringing a threat of
thunderstorms to most taf sites. The first threat will come
toward eat/mwh between 02-08z and linger through the night into
Monday morning. The threat expands east and northeast toward the
lws/puw later, toward 05-10z, and lingers through the night into
at least mid-Monday. Areas toward geg to Coe will see the threat
largely developing late overnight/Monday morning and remaining
moderate through the afternoon. At this time VFR conditions are
expected to prevail, but heavier storms are possible with gusty
winds, hail and brief reductions in visibility or ceiling toward
MVFR. Ongoing wildfires near the Cascades may produce some
reduction in visibility near eat, but with the incoming thunder
threat this is expected to keep vis in the VFR range. /J. Cote'



&&

Preliminary point temps/pops...
Spokane 71 90 68 95 68 98 / 10 40 30 10 0 0
Coeur D'Alene 67 90 64 92 61 96 / 10 40 30 10 0 0
Pullman 62 93 59 94 57 97 / 20 30 20 10 0 0
Lewiston 73 99 71 101 69 104 / 20 20 10 10 0 0
Colville 62 93 59 99 59 101 / 10 50 40 0 0 0
Sandpoint 60 86 58 90 57 94 / 10 60 50 10 0 0
Kellogg 64 87 60 89 65 94 / 10 50 50 10 10 0
Moses Lake 72 98 68 104 66 105 / 20 20 10 0 0 0
Wenatchee 76 97 73 104 73 104 / 20 20 10 0 0 0
Omak 70 97 65 104 66 104 / 20 20 10 0 0 0

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...red flag warning until 11 am PDT Monday for East Washington
central Cascade mountains (zone 682)-East Washington
central Cascade valleys (zone 677)-East Washington north
Cascades (zone 685)-East Washington south central Cascade
mountains (zone 680)-East Washington south central Cascade
valleys (zone 676).

&&

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