Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Spokane Washington
445 am PDT Monday Jul 6 2015
after a warm and sunny day today, another weather system will
drop down from Canada Tuesday with a threat of showers and
thunderstorms across the north. Drier conditions return around
mid-week, before additional shower and thunderstorm chances return
toward Friday into next weekend.
today through tuesday: today will be an in-between day. As the
weekend wave moves off to our east, we'll see quiet weather
conditions with slightly warmer temperatures and lighter winds.
The second wave that is currently up in northern British Columbia will slide
into our area on Tuesday, bringing the threat of showers and
thunderstorms to the northern part of the forecast area. Best
chance for precipitation will be in the northern Panhandle but we
could see thunderstorms develop as far west as the north Cascades.
These storms should fire over the northern mountains but the
northwest flow could easily take some of these storms off of the
mountains and into the Spokane/cd'a Metro area late Tuesday
afternoon. Cape values off the NAM model would support hail, but
these seem a bit overdone (as usual). The dry sub-cloud layer up
to 10,000 feet would be more supportive of strong gusty winds. The
WRF-arw does show a gust front propagating out of the mountains
and into the northern basin. For now i'll avoid specific strong or
severe wording until we get closer to the event. Rj
Tuesday night through Thursday...a short wave disturbance will drop
through the region on Tuesday. A chance for showers and embedded
thunderstorms will be kept in the forecast for Tuesday evening as
that wave progresses through the region. The focus will shift east
and south along the north and central Idaho Panhandle mountains,
with the convection coming to an end overnight. This will be
followed by weak high pressure building back into the region
Wednesday and Thursday for continued warm and dry conditions.
Temperatures will remain in the 90s to lower 100s and 15-20
degrees above normal. Conditions will remain dry with poor to
moderate relative humidity recoveries on mid slopes and ridges.
Fortunately it doesn't appear as if winds will be a big issue.
Friday through the weekend...a closed low currently meandering
around the central California coast will finally move inland on
Thursday and Friday and looks to merge with a trough that will
move through the Gulf of Alaska. This will deepen the trough off
the Washington/or coast and put the Pacific northwest in a southerly flow through the
weekend. The southerly flow will allow deeper subtropical moisture
to move north into the Pacific northwest and result in wide spread showers
and thunderstorms...likely just across the southeast zones on
Friday, then pushing north through the region Saturday and Sunday.
At this time the convection in the forecast was broad brushed and
as we get closer to the weekend we should be able to fine tune the
forecast. One thing we can expect will be slightly cooler
temperatures...slightly higher relative humidity and much better
overnight recoveries. Tobin
Aviation...12z tafs: the gusty northeast winds will subside this
morning. Skies will remain sunny today. By this evening some mid-
level clouds will move into the area. Wildfire smoke in the area
could reduce visibilities at times. Rj
thunderstorm coverage on Tuesday afternoon evening warrants the
issuance of a Fire Weather Watch. The best chance for lightning
will be over the northern Panhandle and northeast Washington, with
a lesser chance over the Okanogan Highlands and the north
Cascades. Precipitation amounts are expected to be light. These
storms could generate localized gusty winds. Rj
Preliminary point temps/pops...
Spokane 92 66 92 66 93 67 / 0 0 20 20 10 10
Coeur D'Alene 90 61 89 61 91 61 / 0 10 30 20 10 10
Pullman 90 57 92 57 91 57 / 0 0 10 10 10 10
Lewiston 98 68 99 69 98 69 / 0 0 10 10 10 10
Colville 94 63 95 60 96 61 / 0 10 20 20 10 10
Sandpoint 88 55 87 54 90 54 / 0 10 30 30 10 10
Kellogg 88 57 88 56 89 58 / 0 0 30 20 10 10
Moses Lake 98 67 100 70 100 68 / 0 0 0 10 0 0
Wenatchee 100 72 101 74 101 74 / 0 0 10 10 0 0
Omak 97 67 98 66 99 67 / 0 10 10 10 0 10
Idaho...Fire Weather Watch from Tuesday afternoon through Tuesday
evening for northern and central Idaho Panhandle (zone 101).
Washington...Fire Weather Watch from Tuesday afternoon through Tuesday
evening for East Washington north Cascades (zone 685)-East
Washington northeast (zone 686)-East Washington Okanogan
Highlands (zone 687).