Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 281810

Area Forecast Discussion
National Weather Service Spokane WA
1110 AM PDT Fri Jul 28 2017

Expect very warm weather with light winds into the weekend.
There`s a slight chance of thunderstorms from the Blue mountains
to the Camas Prairie late today, but otherwise it will remain dry.
Hot weather will return for next week with some triple digits
temperatures likely.


Satellite shows the Diamond Creek wildfire in the northern
Cascades has been very active overnight. Could see more areas of
smoke in the surrounding areas this morning.

Today through Saturday night: More very warm and dry weather can
be expected across the Inland Northwest. A west-southwest flow
will be over the region with slight cooling from yesterday`s dry
cold front. There is a stream of upper level moisture that is
moving across the region and will get hung up over southeast
Washington and the southern Panhandle. A weaker secondary impulse
in the upper flow will brush this area as instability increases
this afternoon. There is the potential for a thunderstorm over the
Blue mountains or Camas Prairie late this afternoon into the early
evening, although both models indicate a weak cap in this area
similar to yesterday. Also these areas are on the northern
periphery of the moisture/instability with a better chance of
activity forming to the southeast. The GFS has been trending
wetter under this scenario with actually measurable precipitation.
Think this is overdone with the scope of dry conditions across the
region the high cloud bases that develop from any possible
convection. Will lean toward mainly dry convection if it does
form. Otherwise expect temperatures similar if not a degree cooler
than yesterday with lighter west to southwest winds and less
gustiness. Patchy smoke may be an issue with the recent fires
especially in the late night and morning hours, especially across
north central Washington into northeast Washington. Downslope
northwest winds will increase across the Cascades tonight. By
Saturday into Saturday night, slight ridging aloft develops with
an influx of more dry air. Any mid to high level moisture slips
south of the region. Low level temperatures will start to climb
with a couple degrees of warming under light winds. /rfox.

Sunday...Model consistency is good that a weak shortwave trough
and cold front will ripple rapidly eastward through the region.
This feature will be associated with little moisture but it will
bring a subtle cooling as well as an increase in winds. Suspect
the winds won`t be quite as strong as what we saw yesterday as 850
mb speeds max out between 10-15 mph. Nonetheless with a packed
surface pressure gradients in the lee of the Cascades we will
likely see breezy winds in the Kittitas and Wenatchee Valleys and
spilling out into the western Columbia Basin. These conditions
will once again pair with relative humidity levels in the teens to
lower 20s and will likely lead to enhanced fire potential.

Monday through Thursday...Model consistency is good with the
overall synoptic pattern which features a deep low heading into
the Gulf of Alaska and a very strong upper level ridge building
northward from the southwest US. Each day we will see a gradual
warming trend as the center of the high moves toward southern
Idaho or northern Nevada. 500 mb heights over the Inland NW climb
into an impressive 592-595dm range. This should result in
continued dry weather for most of the forecast area. It will also
push 850 mb temps above 27c by Wednesday and Thursday in eastern
Washington. This 27c mark is important since it coincides with the
warmest temperatures we have seen this summer on July 7. If the
EC and GFS are correct we could see 850 mb temps top out just shy
of 30c on Thursday. This would certainly result in triple digit
heat across most of the forecast area and we have trended the
forecast accordingly. This heat will also combine with a very dry
air mass with relative humidity values possibly dipping into the
single digits. While our confidence in the temperature forecast is
rather good, things become much less confident in regards to
monsoonal moisture. The GFS suggests it could pivot north-
northeast around the periphery of the high and could skirt the SE
corner of Washington and into NC Idaho. However the EC and
Canadian models keep this moisture south of our forecast area. We
will follow this idea for now, but pops may need to be nudged
upward if model agreement grows. By Friday the upper level ridge
axis shifts east of our forecast area and we should see the
beginning of a cooling trend. Dry conditions will continue with
not much chance of measureable rain for the next 7 days. fx


18Z TAFS: VFR conditions will prevail at the TAF sites through
the period. Anticipate more high level clouds from KLWS to KPUW
and there is a small chance of -tsra toward the Blue Mountains and
Camas Prairie late today into tonight. Expect lighter and more
terrain driven winds. Wildfire smoke will persist in the northern
valleys, especially west of KOMK. JW


Spokane        89  62  93  63  92  62 /   0   0   0   0   0   0
Coeur d`Alene  89  56  92  57  91  56 /   0   0   0   0   0   0
Pullman        89  58  92  58  90  56 /  10   0   0   0   0   0
Lewiston       97  66 100  67  98  65 /  10   0   0   0   0   0
Colville       91  53  94  55  94  54 /   0   0   0   0   0   0
Sandpoint      88  49  90  50  90  50 /   0   0   0   0   0   0
Kellogg        88  56  90  56  89  55 /   0   0   0   0   0   0
Moses Lake     93  57  96  59  96  58 /   0   0   0   0   0   0
Wenatchee      92  63  94  66  94  65 /   0   0   0   0   0   0
Omak           94  60  97  61  96  61 /   0   0   0   0   0   0



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