Area Forecast Discussion
Issued by NWS Spokane, WA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KOTX 041126
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
426 AM PDT TUE AUG 4 2015

.SYNOPSIS....
Another warm, dry and breezy day is expected across much of the
Inland Northwest today. Cooler temperatures and breezier conditions
are expected Wednesday following the arrival of a cold front.
Another threat of showers and thunderstorms arrives next weekend
as yet another cosed low is expected to move into the region.


&&

.DISCUSSION...
Today through Wednesday: The upper level shortwave disturbance
producing some very light showers across the Northern Panhandle
will begin to exit the region early this morning. The focus will
then shift toward the deeper upper level low pressure circulation
spinning over central BC. The center of the low is progged to
slowly drift into southern BC by Wednesday afternoon.

Water vapor satellite imagery shows a well defined dry slot
pushing across Vancouver Island on the backside of a cold front.
This cold front will push east of the Cascades late this morning
and across the interior of eastern WA through this afternoon.
Decent cold air advection through the Cascade gaps will provide
good packing of the isobars and will keep winds breezy across
this area. Winds up at 850 mbs will be between 15-20 kts across
the basin into the Spokane Area and Palouse region. Enough
momentum transfer will also keep these areas breezy with winds
picking up through the late morning and afternoon. We will
continue to be dry today, especially with the cold front
delivering another punch of dry air down the lee side of the
Cascades. Breezy winds and dry conditions will provide the
potential for rapid fire spread of any new or ongoing fires with the
current Red Flag Warning remaining valid.

The little bit of moisture that has moved across the
northern mountains tonight will keep dew points up into the lower
to mid 40s across these areas before the drier air arrives. This
should be just enough moisture for some afternoon convection,
especially near the Canadian border. Instability will be weak, so
thunderstorm coverage will likely be isolated in nature.

Winds will increase across much of the region on Wednesday with
frontal passage. Chances for showers will increase across the
northern Cascade Mtns, which will lead to increasing RH values.
This will be a welcome sign for this area with wind speeds
remaining elevated. The higher dew points do not figure to spread
much further east, so RH values dipping into the teens are
expected to be common once again on Wednesday across the basin
and over into the lower elevations of the ID Panhandle.

Temperatures will continue to cool over the next couple of days.
High temperatures by Wednesday will be in the upper 70s to mid
80s, which will be slightly below normal for early August. /SVH

Wednesday night through Tuesday...The models are coming into
better agreement showing one closed low moving slowly out of the
region Wednesday night and Thursday...and another closed low
coming into the region Saturday. In between weather systems
expect a short lived and transient ridge of high pressure.

Wednesday night and Thursday...This close low tracks through central
B.C. And just grazes the northern mountains. Deep moisture is
lacking but there is some weak surfaced based and mid level
instability with the cold core to support showers and a few
scattered lightning strikes Wednesday evening and again Thursday
afternoon. Precipitation will be spotty and on the light side.
Winds will remain southwest to west but not as breezy as on
Wednesday. With the cooler air advecting into the region
temperatures will be down another 2-3 degrees over Wednesday and
likely the coolest temperatures of the week.

Thursday night and Friday will be dry with a warming trend as the
transient ridge builds into the region. Temperatures will quickly
climb back into the mid 80s and lower 90s which will be very near
seasonal averages.

Saturday and through the weekend...there are still some timing
differences but overall the trend is similar showing another
closed low dropping south along the B.C. coast Saturday, but this
time dropping further south to roughly the northwest Washington
coast Sunday before moving back to the northeast and through B.C.
Sunday night and Monday. While this disturbance will likely tap
into deeper moisture the storm track suggest that the main
moisture and dynamics will just clip the northern Cascades and
northern Washington mountains and that will be the focus for
scattered showers and embedded thunderstorms. Precipitation will
be spotty, but the convective nature concludes that some areas
could pick up some quick but heavy rain.

A secondary wave will take a more southerly route and track northeast
through Oregon and central Idaho. At this time it looks like this
wave will stay to the south of the Blue mountains and the Camas
Prairie. The forecast leans toward some low end pops in the
forecast but there is more confidence in mid and high level clouds
then showers.

Southwest flow will keep temperatures in the mid 80s to lower 90s
and near seasonal averages. Southwest winds will be on the increase
as the disturbance tracks through the region but only in the 5-15
mph category. Tobin


&&

.AVIATION... 12Z TAFS: A weak upper level disturbance will continue
to clear east of the Panhandle early this morning; however, the
region will begin to be influenced by a deeper upper level low
sliding southward across BC. This system will result in a chance for
showers and thunderstorms near the Canadian border this afternoon.
An approaching cold front will also result in breezy conditions this
afternoon across the region with gusts up to 25 mph possible. /SVH


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        87  59  80  57  77  57 /   0  10   0   0  10   0
Coeur d`Alene  87  57  79  55  77  53 /  10  10   0   0  10   0
Pullman        86  53  78  52  76  51 /  10  10   0   0  10   0
Lewiston       95  64  85  61  85  60 /  10  10   0   0   0   0
Colville       89  56  81  54  79  53 /  20  20  10  10  10   0
Sandpoint      85  50  78  50  74  47 /  10  10  10  10  10  10
Kellogg        86  54  77  52  74  50 /  10  10  10   0  10   0
Moses Lake     92  59  84  57  84  56 /   0   0   0   0   0   0
Wenatchee      90  66  81  63  85  64 /   0   0   0   0   0   0
Omak           92  57  81  56  84  57 /  10  10  10  10  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Red Flag Warning until 9 PM PDT Wednesday for East Washington
     Central Cascade Valleys (Zone 677)-East Washington Northern
     Columbia Basin (Zone 673)-East Washington Palouse and
     Spokane Area (Zone 674)-East Washington South Central
     Cascade Valleys (Zone 676).

&&

$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.