Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Spokane Washington
214 PM PDT Thursday Jul 2 2015

Synopsis....
hot and dry weather will be featured into the Independence day
weekend. Hottest days will likely be today and Friday with many
valley sites topping the century mark. Breezes will be kicking up
as weather systems move across the strong upper level ridge.
Friday and Saturday winds are potentially looking more substantial
as a cool front tries to sag in from Canada eventually forcing
winds more from the north. It is still looking dry and warm even
into the beginning of next week.





&&

Discussion...
tonight though Saturday evening: hot and dry conditions will
continue across the inland northwest courtesy of a ridge of high
pressure. As of 2pm...several locations across the lower Columbia
Basin were already recording triple digit temperatures and the air
mass is only going to warm into Friday. The ridge however will
begin to weaken by the evening and this will allow a local
increase in winds and elevate the threat for wildfire spread. Our
first concern will be near the Cascade gaps starting around late
afternoon and evening on Friday. Confidence is higher that winds
will materialized in Ellensburg and red flag warnings have been
hoisted. Confidence is lower for the Wenatchee River Valley where
model consensus is only indicating winds 8-14 mph between 5-8pm.
There is an isolated run of the higher res nmm that would support
a low-end red flag but given the lack of support from MOS, will
hold off on upgrade at this point and let the next 2 shifts
examine the incoming 00z model guidance.

As the ridge deflates Saturday, we will look for increasing northerly
pressure gradients and eventually a dry cold front passage Saturday
afternoon and evening. Temperatures will remain warm but do come
down some from Friday. A bigger impact will be increasing
northerly winds which will be squeezing through the Okanogan
Valley and spilling into the western Columbia Basin. We should see
gusty winds in the Okanogan Highlands as well and red flag
warnings have been issued to address the concern for low humidity
and winds. We will also see an increase of north winds in Stevens
and Pend Oreille counties as well as the West Plains toward the
Hwy 2 corridor. At this time, these winds look to be a bit weaker
in a sustained standpoint but will have the potential to produce
gusts 20-30 mph, especially along exposed ridge-tops.

Temperatures during the 4th of July festivities will be quite comfortable
but winds will raise concern for wildfire starts. Even if humidities
climb out of critical thresholds by dark. Please be advised that
fuels around the region are generally as dry as they are by late
August and this will elevate the risk for wildfire ignitions
around fireworks whether there is a red flag warning or not. /Sb

Saturday evening through Thursday...northerly flow between the
edge of a ridge with axis over the Gulf of Alaska with departing
trof in northern Montana keeps some breezy conditions going
through the evening in some locations. This northerly flow has a
nice influence on temperatures for Sunday as they are about 10
degrees cooler in comparison to friday's high temps, yet they are
still above normal for this time of year given this ridge. The
ridge axis remains off the coast for the remainder of the forecast
which means there is potential for more weather disturbances to
drop down along the east edge of the ridge in a northwest to
southeast trajectory through Wednesday. The GFS and the European model (ecmwf)
suggest the best potential for such a scenario in the Tuesday and
Wednesday time intervals and limits the measurable precipitation
generated in the form of showers and thunderstorms to the extreme
northeast portion of Washington and the northeast edges of the
north Idaho Panhandle. By Thursday models suggest the ridge is
undercut by westerly flow and leaves eastern Washington and
northern Idaho somewhat of a split flow with the jet stream and
active weather associated with it well to the north and a closed
low over central California that has nuisance mesoscale
disturbances rotating around it well to our south. /Pelatti

&&

Aviation... 18z tafs: a dry and stable airmass will remain over
the aviation area allowing for VFR conditions at all taf sites
through 18z Friday with the exception of a small chance of
thunderstorms up in north Idaho near the Canadian border. /Pelatti



&&

Preliminary point temps/pops...
Spokane 69 100 67 96 64 89 / 0 0 0 0 0 0
Coeur D'Alene 63 97 63 94 61 85 / 0 0 0 0 0 0
Pullman 58 97 58 93 56 90 / 0 0 0 0 0 0
Lewiston 70 105 70 101 68 97 / 0 0 0 0 0 0
Colville 63 102 62 98 59 93 / 0 0 0 0 0 0
Sandpoint 59 96 55 93 54 85 / 0 0 0 10 10 0
Kellogg 60 97 61 92 58 86 / 0 0 0 0 0 0
Moses Lake 69 107 67 101 69 96 / 0 0 0 0 0 0
Wenatchee 75 105 72 101 72 98 / 0 0 0 0 0 0
Omak 70 104 68 98 64 96 / 0 0 0 0 0 0

&&

Otx watches/warnings/advisories...
Idaho...heat advisory until 9 PM PDT Friday for Lewis and southern Nez
Perce counties-Lewiston area.

Washington...heat advisory until 9 PM PDT Friday for lower Garfield and
Asotin counties-Moses Lake area-Okanogan Valley-upper
Columbia Basin-Washington Palouse-Wenatchee area.

Fire Weather Watch from Friday afternoon through Friday evening
for East Washington central Cascade valleys (zone 677).

Red flag warning from noon to 10 PM PDT Saturday for East
Washington northern Columbia Basin (zone 673)-East
Washington Okanogan Highlands (zone 687)-East Washington
Okanogan/Methow valleys (zone 684).

Red flag warning from 3 PM to 9 PM PDT Friday for East
Washington south central Cascade valleys (zone 676).

&&

$$

National Weather Service Glossary of Abbreviations