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
923
FXUS66 KOTX 252139
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
239 PM PDT WED MAY 25 2016

.SYNOPSIS...
Expect mild weather with isolated mountain showers and
thunderstorms again on Thursday. The arrival of a cold front
Thursday night will bring cooler temperatures Friday and Saturday
along with a good chance for showers over the Idaho Panhandle and
the mountainous portions of Washington. Look for a gradual warming
trend after the Memorial Day weekend with upper 60s to mid 70s
by early next week.


&&

.DISCUSSION...
Tonight and Thursday: Under the weak ridge aloft and light winds,
shallow instability is leading to cumulus field blooming across
the mountains and isolated showers forming on the ridge tops this
afternoon. With the mid level winds from the northwest, most of
these showers should move off the ridges and bring light showers
to the valleys this evening. A few cells have the potential of
occasional lightning and small hail, but these cells would be
short lived, especially across the Okanogan Highlands and
northeast Washington. Although with the loss of daytime heating,
these cells will dissipate quickly. Breezy winds will persist
across the Columbia Basin to the Spokane area and the Palouse
through early evening, then the gusty downslope winds will
increase in the lee side Cascade valleys. The ridge will break
down on Thursday as an area of low pressure drops down from BC and
cold front sweeping toward the US/Canadian border late in the
afternoon. Anticipate increasing clouds through the day with
convection focused ahead of the front in the northern mountains.
Gusty southwest-west winds will increase Thursday afternoon with
gusts to 20 to 25 mph. More mild temperatures can be expected with
highs in the upper 60s to mid 70s. /rfox.

Thursday night through Friday night...Model agreement is quite
good that parts of the Inland Northwest will be impacted by yet
another upper level low and cold front dropping southeast via BC.
It appears the influence of the trough will be felt in the
Cascades and possibly the northern Washington mountains on
Thursday night before the threat of precipitation and the cold
front spreads into the Idaho Panhandle Friday morning. The
instability ahead of the cold front will support showers, but it
is likely too shallow for nocturnal thunderstorms. The front is
expected to shift into Montana by Friday afternoon with the upper
level cold pool remaining fixed over the far NE corner of
Washington and the northern Idaho Panhandle. Diurnal heating will
likely be sufficient to trigger some post frontal showers and
possibly a few thunderstorms. Model soundings suggest if we see
any thunderstorms form they will only be weak pulse type storms.
The threat of precipitation will likely plummet rapidly from north
to south across the forecast area given the positioning of the
upper level jet. Looks like locations south of Highway 2/I90 will
remain free from precipitation save the central Idaho Panhandle
while most of the precipitaiton will occur north of here. The
threat of precipitation is expected to taper off overnight. fx


Saturday through Monday...the all important holiday weekend forecast
is beginning to come into focus and while it is not looking like a
stellar weekend for outdoor activities...neither will it be a
dreary wash-out. The GFS and EC models are in reasonable agreement.
A progressive flow regime will prevail through the weekend with an
overall troffy pattern...but previous forecasts of a vigorous
upper low directly transiting the region have been tempered to
suggest a series of weaker disturbances...an ill defined one on
Saturday and Sunday and a slightly stronger one on Monday. This
suggests that while scattered afternoon and evening showers and a
few thunderstorms are still likely...these storms should be of a
hit-and-miss nature with substantial dry breaks between them. The
best chance of showers and storms will be over the Idaho Panhandle
and northern mountains each afternoon and evening. The deep basin
will probably remain dry as downslope flow produces a rain shadow
effect...with the eastern and northern margins of the basin
subject to isolated showers and a stray thunderstorm each day
Saturday through Monday. Temperatures will run 5 to 7 degrees
below normal...generally in the 60s while overnight lows should
remain around normal in the mid 40s. So...for barbequers and
campers outside of the deep basin zones preparations should be
made for generally dry and cooler than normal conditions
interspersed with an occasional brief shower in the afternoons and
evenings.

Tuesday and Wednesday...A drying and warming trend is expected to
develop during this period with both main modes suggesting at
least a weak upper level ridge rebounding over the forecast area
in the wake of Monday`s disturbance. Breezy northerly winds are
possible as some drier Canadian continental air filters into the
region. Temperatures should recover into the solidly normal
territory on Tuesday and a bit above normal by Wednesday. /Fugazzi

&&

.AVIATION...
18Z TAFS: Fog has lifted although some local MVFR cigs will linger
near KCOE and surrounding valleys through midday. Cumulus will be
developing through the afternoon especially over the mountains
with isolated showers. There is enough instability to support a
chance of thunderstorms over north Idaho this afternoon and early
evening. Gusty southwest winds will develop near KGEG-KCOE this
afternoon, while gusty northwest gap winds will develop near KEAT
this evening and overnight. May see some occasional gustiness near
KPUW toward morning. Otherwise lighter winds and VFR conditions
are anticipated by Thursday morning. /rfox.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        47  68  44  60  42  61 /  10   0  10  20  20  30
Coeur d`Alene  48  67  43  59  40  60 /  20  10  10  30  20  40
Pullman        45  65  43  57  41  60 /   0   0  10  10  10  20
Lewiston       51  70  48  64  47  67 /   0   0  10  10  10  20
Colville       46  71  45  61  42  64 /  20  20  30  60  50  60
Sandpoint      46  67  43  57  38  58 /  20  20  20  40  40  60
Kellogg        44  65  41  53  39  55 /  20  20  20  30  20  60
Moses Lake     52  74  46  68  44  70 /   0   0  10   0  10  10
Wenatchee      52  73  48  67  48  69 /   0   0  10  10  10  20
Omak           47  74  45  67  44  69 /   0  10  10  20  10  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$



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