Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 290520
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1020 PM PDT THU APR 28 2016

.SYNOPSIS...
A cooler system will bring increased cloud cover and areas of rain
across Eastern Washington and north Idaho on Friday. High pressure
will build in Saturday through Monday resulting in a warming
trend. Temperatures early next week will climb to above normal
once again...with highs mainly in the mid 70s to lower 80s. High
pressure will move east for the middle of next week allowing
increased moisture to move in from the south...resulting in a
chance for showers and thunderstorms.

&&

.DISCUSSION...
Tonight through Friday night: Satellite imagery shows a weak upper
level low pressure circulation centered over southwest MT. The
track of this low will be peculiar in that it will lift north-
northwest into northwest MT through tonight into Friday. Much of
this moisture can actually be tracked from off of the Gulf of
Mexico rather than off of the eastern Pacific. Higher clouds are
already streaming in across the ID Panhandle this afternoon.
There is an easterly pressure gradient across the Panhandle,
which is resulting in downsloping off of the higher terrain. This
gradient will weaken overnight and flip to a more westerly
orientation. It will be during the late nighttime hours into the
morning hours on Friday when lower levels will really begin to
moisten up and orographics will play a bigger factor. Models
indicate a healthy amount of precip possible across the ID
Panhandle. The flow pattern at 700 mbs will be a bit more
northwesterly than due westerly where precip will be most
favorable across the Central Panhandle Mtns and extend down toward
the Camas Prairie. Around a half of an inch of precip will be
possible across these areas. Expect a steady rainfall through
Friday morning then transition to showers by the afternoon.
Showers will expand a bit further west in the afternoon where the
eastern basin and Northeast Mtns will see a better chance for
precip. Much of the region will be cloudy tomorrow even if not
under rain showers, which will result in a noticeably cooler day
compared to today. Many locations in the ID Panhandle are only
expected to warm up into the lower 50s. /SVH

Saturday through Thursday...An upper level ridge will build over
the region over the weekend into early next week bringing a
warming and drying trend. A few showers are expected to linger
over the Idaho Panhandle on Saturday...otherwise a dry forecast
Saturday through Monday morning. Monday afternoon the ridge axis
shifts east of the area allowing a weak wave to come around the
high and then up along the Cascades. Models are not very
consistent with this idea...but enough instability and lift is
shown by some guidance to warrant a slight chance of
thunderstorms. For Tuesday through Thursday an amplified pattern
sets up with the upper ridge east of the area over the Rocky
Mountain states...and a trough off the west coast. This places the
Inland NW in a deep southerly flow aloft. This will result in an
increase in mid level moisture as well as instability over the
area. Thus an increasing chance for showers and thunderstorms is
expected. The GFS shows CAPE values by next Thursday increasing to
1000-1500 J/KG with 25-40 kts of 0-6km wind shear. This could
support stronger storms...but since this is several days out
confidence is low in the details.

The building ridge this weekend followed by a mild southerly flow
for the early to middle of next week will result in a warming
trend through Tuesday or Wednesday. 850mb temperatures rising into
the 15-18C range will yield valleys highs climbing into the mid 70s
to lower 80s...which is about 15 degrees above normal. JW

&&

.AVIATION...
06Z TAFS: The region is under a broad upper level trough of low
pressure. A weak circulation over SW MT will increase moisture
over the region. Rain will increase overnight in areal coverage.
Expect MVFR cigs and vis possible at the KGEG, KSFF, KPUW and
KCOE TAF sites after 09Z with moderate rain possible at times
during the afternoon. Winds will increase in the afternoon across
the Cascade gaps and into KEAT and KMWH. Mountain obscurations
will occur over the next 24 hrs as this system moves through.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        46  54  41  65  45  72 /  50  80  40  10  10   0
Coeur d`Alene  43  53  40  65  43  72 /  90  90  50  30  10   0
Pullman        46  54  40  61  42  70 /  60  80  30  20  10   0
Lewiston       51  59  45  68  46  77 /  40  60  30  20  10  10
Colville       43  59  39  70  42  77 /  50  70  40  10  10   0
Sandpoint      45  53  39  63  39  70 /  60  70  50  30  20   0
Kellogg        39  50  38  60  40  68 /  80  90  50  30  20   0
Moses Lake     43  64  41  74  44  79 /  10  40  20   0   0   0
Wenatchee      48  62  45  74  49  80 /  20  30  20   0   0   0
Omak           44  65  42  73  45  77 /  20  50  20   0   0   0

&&

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

$$



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