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fxus66 kotx 280953 
afdotx

Area forecast discussion
National Weather Service Spokane Washington
253 am PDT Wed Jun 28 2017

Synopsis...
a weak weather disturbance will bring the threat of thunderstorms
to the northern mountains on Wednesday. A few cells may survive
into portions of the upper Columbia Basin and Spokane area.
Otherwise, the weather will be dry and mild through the remained
of the week. The weekend will see continued dry weather but warmer
temperatures. Monday and Tuesday have the potential to be dry and
breezy raising concerns for grass fires heading into July fourth.

&&

Discussion...

Today through Thursday night: the inland northwest is under the influence of
northerly flow sandwiched between a ridge over the Gulf of Alaska and
low in central Saskatchewan. The axis of the upper-level jet will
be centered over wrn Washington today then shift into ern Washington Thursday as
the ridge slowly translates inland. Shortwave energy spinning up
on this favored cyclonic side of the jet will pass through the
region bringing a threat for showers and T-storms. 2am satellite
reveals one circulation passing over the wrn Columbia Basin at
this hour but due to the very dry antecedent air mass, mainly
cirrus is being observed. The next area of darkening noted on
water vapor is in southern British Columbia and will be the focus for today.
Models have trend even further west with the track of this
shortwave. What becomes more important will be how quick boundary
layer moisture can recover today. The evening cam models are
developing convection across the northern mountains by midday with
northerly flow drifting this activity south/southeast. A few
cells may survive the trip off the higher terrain into the upper
reaches of the Columbia Basin and Spokane- cd'a area and Silver
Valley or send an outflow boundary capable of initiating new cells.
There is a wide range of model solutions how this pans out and how
far west this activity expands. A few cam ensemble members even
allow a few cells to survive as far west as Banks Lake. These
members are an outlier from the general model consensus but will
need to be monitored with the potential for decaying cells to
produce outflow winds to 30 mph and the proximity of ongoing
wildfires. Confidence is higher for the northeastern zones. Hrrr
and our local 1km WRF do support cells producing outflow winds
near 30 mph across NE Washington and north Idaho including Hwy 2 corridor from
Wilbur to Spokane to cd'a. Isolated to scattered lightning and
brief downpours will be the other threats.

With the wave dropping in from the north, pressure gradients will
remain tight across the east slopes continuing to bring breezy
north/northwest winds to the Cascades...western basin...and Okanogan Valley.
Steady west/SW winds of 10 to 15 mph accompanied by gusts near 20 mph
are expected across the central and eastern basin. Temperatures
this afternoon will be close to tuesday's readings or 80s.

Wednesday will be a quiet weather day as high pressure builds toward
wrn Washington and the northerly jet weakens and shifts toward the Washington/Idaho
border. Expect fair cumulus fields in the afternoon and dry
conditions. Temperatures will warm 1-2 degrees coupled with
lighter winds. /Sb

Friday: a warm high pressure ridge is expected to translate
across the Pacific northwest on Friday. Look for temperatures to
shoot up into the upper 80s to low 90s Friday afternoon. The GFS
model has consistently generated a cluster of showers and
thunderstorms over the upper Methow Valley and far northern
Cascades Friday afternoon and evening. Of the most recent model
runs, the GFS is the quickest to push the upper ridge axis
eastward. Forcing and instability appear to be marginal, so we are
only carrying a 20 percent chance of thunderstorms Fri afternoon
and evening for the mountains north of Lake Chelan.

Saturday and sunday: the weekend will continue to be warm with
afternoon temperatures in the 80s with a few 90s in the l-c valley
and deep Columbia Basin. A 30 percent chance of showers and
thunderstorms is in the forecast for Republic, Kettle Falls,
Northport, Priest Lake, and Bonners Ferry Saturday afternoon and
evening. A shortwave trough is expected to track along the
Canadian border Saturday. The models are generating a weak surface
low over far NE Washington and pooling a bit of low level
instability in the vicinity of this low. Instability and deep
layer shear are expected to be relatively weak, so cells are not
expected to be severe. Brief heavy downpours and lightning appear
to be the main hazards with storms on Saturday. A flat high
pressure ridge is expected to bounce back on Sunday yielding a
dry, warm day with mainly clear skies.

Monday and Tuesday (july fourth): a broad 500mb trough is
expected to make landfall along the British Columbia coast Monday.
Increasing onshore flow is expected to tighten the west to east
surface pressure gradient Monday and Tuesday. We should see a
gradual cooling trend early next week, but winds will likely
increase into the 10 to 20 mph range over the Columbia Basin,
Palouse, and West Plains. Localized winds gusting to 30 mph or
more often occur through the Cascade gaps in patterns like this
including areas like Wenatchee, Chelan, Waterville, and Vantage.
The Prospect of gusty winds and low humidity Monday and Tuesday
will raise concerns for wildfires heading into the July fourth
Holiday. /Gkoch

&&

Aviation...
06z tafs: expect dry weather and mostly clear skies through
Wednesday morning. Then a mid level wave will track across NE
Washington and north Idaho Wednesday afternoon and evening with a
chance of showers and thunderstorms over the mountains. A few
model solutions suggest this activity may clip kgeg/ksff but kcoe
stands the better chance. For now kept thunder out of all taf
sites given the better chances for storms over the mountains but
can not completely rule out a storm with gusty outflow winds at
kgeg/ksff/kcoe after 21z Wed. Jw



&&

Preliminary point temps/pops...
Spokane 81 57 83 61 88 61 / 20 10 0 0 0 0
Coeur D'Alene 79 52 80 56 86 57 / 20 20 0 0 0 0
Pullman 76 53 80 56 85 59 / 0 10 0 0 0 0
Lewiston 85 58 87 61 92 63 / 0 0 0 0 0 0
Colville 81 53 85 54 89 56 / 40 20 0 0 0 10
Sandpoint 77 48 79 51 83 53 / 30 20 10 0 10 10
Kellogg 74 51 77 53 83 55 / 20 20 10 0 0 0
Moses Lake 86 56 89 58 94 60 / 0 0 0 0 0 0
Wenatchee 86 60 88 63 92 63 / 10 0 0 0 0 0
Omak 83 56 87 57 92 59 / 10 10 0 0 10 10

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Otx watches/warnings/advisories...

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