Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 281211
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
511 AM PDT Fri Apr 28 2017

.SYNOPSIS...
Expect the cool, and unsettled weather to last another 24 hours.
High pressure will move into the region on Saturday for a short
lived dry period before more unsettled weather moves into the
region late Saturday afternoon and lingers into early next week. A
warming and drying trend returns Tuesday and Wednesday, but more
cool and unsettled weather is expected by late in the week.


&&

.DISCUSSION...

Morning update: Added some patchy fog to the northern valleys.
Clearing skies to the north with light winds are allowing fog to
form mainly in areas that saw rain showers yesterday. Cameras show
some areas of fog expanding at 12Z.

&&

.AVIATION...
12Z TAFS:Showers are moving out of the region this morning and
all terminals should remain dry through the morning. Clearing
skies to the north have allowed patchy fog to form in northern
valleys which could spread to KSFF between 13Z and 16Z. A weak
disturbance moves through by mid day bringing shower chances to
all sites except KMWH and KEAT by the afternoon or early evening.
These taper off overnight and clouds will decrease into Saturday./bw


&&

.PREV DISCUSSION... /issued 242 AM PDT Fri Apr 28 2017/

Today through Saturday: Shower chances stick around for the
mountains and eastern Washington today before a drying trend
begins tonight, bringing more sun and clearing skies Saturday.
This morning scattered showers continue over southeast WA and the
Idaho panhandle associated with a disturbance which crossed the
region overnight. Some wet snow is possible at Lookout Pass but
anything that sticks won`t last long. Showers will continue to
diminish through the early morning hours and we get a brief break.
As the surface high pressure center moves closer to the coast on
Friday, one more weak wave ahead of the incoming high pressure
ridge will kick off showers later this morning/afternoon. These
will be relegated mainly to the Idaho panhandle and northern
mountains. A few isolated showers are possible in the east basin
as well, but no significant accumulation is expected. Instability
looks too weak for thunder, even with some afternoon heating.

tonight things improve as the ridge axis begins to move onshore
bringing clearing skies and dry conditions. Saturday will be the
nicest day of the period, especially the first half of the day.
The ridge quickly gets flattened late Saturday and clouds increase
by the afternoon/evening hours ahead of the next wet system.
Temperatures will be on rise, increasing by a few degrees each
day, though still a bit below normal for late April. Highs in the
upper 50s to perhaps low 60s for the deep basin. /bw

Saturday night through Monday night: The weak ridge will get
flattened Saturday night as a fast moving disturbance moves
through British Columbia. The ridge will try to rebound on Sunday
but another wave will move through the region on Monday and keep
showers in the forecast through the first part of next week.
Moisture with the first wave increases to over 200 percent of
normal and will result in a good chance of showers for most areas
outside of the deep basin. Showers for the Idaho Panhandle may be
locally heavy at times. Northwest flow puts the focus of the
heaviest precipitation across the Panhandle mountains where around
a quarter of an inch will be possible through Sunday afternoon.
Otherwise amounts will be a tenth or less and the basin will get
skipped.

There will be a lull in the showers Sunday evening as high pressure
struggles to strengthen, but that will be short lived as the next
wave moves into the region on Monday. This wave doesn`t have as
much moisture but will still result in mountain showers late in
the day on Monday, with the showers likely lingering across the
eastern mountains well into Monday evening.

Tuesday and Wednesday: High pressure will build into the region
through this period, but now maybe not to the strength of previous
model runs. Temperatures are still expected to rise into the 60s
to lower 70s. But now it appears as if the ridge axis will track
east on Wednesday. This will allow a surge of Pacific moisture to
over top the ridge and result in showers across the northern
mountains near the Canadian border.

Thursday and Friday: The current models runs really fall apart
Thursday and Friday with varying solutions. For now the forecast
will hold on to the idea that ridge shifts into western Montana on
Thursday, with a break down of the ridge on Friday. The flow will
become southwesterly on Thursday. This will result in warm
advection with temperatures rising well into the 60s and and 70s.
But it will also increase the moisture. A chance for mountain
showers were added back into the forecast for late in the day on
Thursday and temperatures were lowered by a few degrees
accordingly. For now will go with a cold front sagging into the
region from the northwest Thursday night and Friday. If this
solution verifies it will bring cooler temperatures, widespread
showers, gusty winds, and the chance for thunderstorms back to the
region. Tobin

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        55  37  57  43  58  38 /  30  10  10  60  30  10
Coeur d`Alene  54  35  57  40  56  36 /  40  20  10  70  50  20
Pullman        52  36  57  43  57  38 /  30  10  10  60  50  10
Lewiston       59  39  64  47  63  41 /  30  10   0  40  50  10
Colville       60  36  59  41  60  37 /  30  10  10  40  20  10
Sandpoint      52  35  55  38  54  35 /  60  40  10  80  60  20
Kellogg        47  35  53  38  51  34 /  60  20  20  80  80  30
Moses Lake     64  36  63  47  68  39 /   0   0   0  10  10   0
Wenatchee      62  39  62  45  63  41 /  10   0  10  10  10   0
Omak           63  37  62  44  66  39 /  20  10  10  20  10   0

&&

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

$$



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