Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 241129

Area Forecast Discussion
National Weather Service Spokane WA
429 AM PDT Sat Jun 24 2017

Warm and sunny weather will be in place this weekend with
widespread 90s expected by Sunday. Monday will also be warm
with increasing clouds and chance for showers and thunderstorms
late in the day. A return to cooler, more average temperatures
are expected by the middle of next week, with breezy conditions
possible late Monday through Tuesday.


Tonight through Monday night: A ridge of high pressure continues
to amplify along the coast today, shifts into the Inland NW
Sunday, then slides to the east Monday. Conditions today and
tomorrow will be warm and sunny accompanied by light east to
northeasterly winds. Afternoon highs climb into the 80s and 90s
this afternoon then 90s for Sunday with isolated 100s in the lower
Basin. UV indices will be maxed out around 10 or within the
very high category. Per the EPA index, this means there is a very
high risk of harm from unprotected sun exposure. Taking extra
precautions such as finding shade periodically, wearing sunscreen,
hats, and sunglasses is highly recommended for those exposed to
sun exposure between 10AM and 4PM.

As the ridge axis slips to the east Sunday night into Monday, we
will see an influx of midlevel moisture leading to an increasing
risk for showers and thunderstorms. Two shortwaves will also come
into play, the deeper of the two will skirt the area from the
north with a second coming off the Ern Pac off the N CA Coast.
The air mass will be quite dry with the initial influx of moisture
Sunday night into Monday morning so thinking this will mainly
equate to accas (altocumulus castellanus) with spotty sprinkles.
However as the air mass continues to slowly moisten and upper
levels begin to cool, instability will continue to increase Monday
afternoon. There remains very low confidence whether surface based
convection will be able to fire prior to Monday evening due to the
uncertainty of a kicker to overcome a strong cap. If cells are
able to form, there is a potential for a few stronger cells
capable of hail and gusty winds. If the cap holds, Monday will
generally be warm with a mix of clouds and sun.

Confidence increases for showers and t-storms Monday evening and
night as the shortwave off the CA Coast treks inland through N
Oregon. There is a decent chance that showers and storms develop
along this feature and pass over areas of SE WA and NC ID. Exactly
how far north or south is still uncertain and leaning toward the
best chances south of a line from Avery to La Crosse at this time.
The forecast also carries a slight chance for t-storms in the NE
Mtns. The northern branch shortwave will be passing through
southern BC during this time ushering a cold front into the
region. This boundary may be enough to spark a few cells over the
northeastern Mtns Monday afternoon/evening.

The cold front presses into Central WA Monday afternoon bringing
a push of winds in the lee of the Cascades and Western Basin. The
combination of warm temperatures, increasing winds, and low
humidity will promote several hours of critical fire weather
conditions prior to sunset. Monday which looked to be the warmest
day of the week will likely fall close to Sunday`s readings give
or take a few degrees due to some cloudiness. /sb

Tuesday through Saturday: Any remaining shower or thunderstorm
activity will exit the area by Tuesday morning as drier air
filters into the region behind the front. The GFS has come into
better agreement with the EC keeping the upper level low further
north over central AB. The main concern Tuesday will be the breezy
to gusty conditions as the cross Cascade pressure gradient
remains tightened. The combination of dry and breezy conditions
following several hot and dry days will increase fire weather
concerns, especially for the finer fuels across the Basin.
Afternoon highs will be about 10 degree cooler Tuesday compared to

As the low/upper level trough continues to shift east the Inland
Northwest will sit in a northwest flow regime, becoming more zonal
toward the weekend. Models still disagree on the finer details but
enough weak waves clip the N Idaho Panhandle to keep the
occasional shower or thunderstorm mention in the forecast over
this area. Otherwise look for dry conditions elsewhere with high
temperatures in the mid 70s to mid 80s Wednesday, warming into the
mid to upper 80s by late week. /Kalin


12Z TAFS: Aside from a few flat mtn cumulus clouds in the
afternoon...all terminals can expect clear skies, light winds,
and warm temperatures through 12z Sun. /sb


Spokane        87  59  93  66  93  62 /   0   0   0   0  20  20
Coeur d`Alene  84  54  91  60  90  59 /   0   0   0   0  20  20
Pullman        84  55  92  62  90  60 /   0   0   0   0  20  30
Lewiston       91  59  98  67  97  64 /   0   0   0   0  20  30
Colville       88  51  92  57  93  56 /   0   0   0   0  10  10
Sandpoint      83  50  88  54  88  55 /   0   0   0   0  20  20
Kellogg        84  52  90  58  89  57 /   0   0   0   0  10  30
Moses Lake     93  56  98  65  98  60 /   0   0   0   0  10  10
Wenatchee      91  63  96  69  95  61 /   0   0   0  10  10   0
Omak           90  56  95  62  95  57 /   0   0   0  10  10  10



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