Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 181123
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
423 AM PDT SAT APR 18 2015

.SYNOPSIS...
A weak cold front has moved through the region overnight and will
produce slightly cooler temperatures and some breezy winds for
the weekend. The weather will remain dry however. Temperatures
will warm next week with Tuesday being the warmest day. Following
this warm and dry period, expected much cooler and showery
conditions for the remainder of the week.

&&

.DISCUSSION...
Today and Tonight...Dry and breezy conditions will prevail today
in the post frontal air mass. Gusty northerly winds will be
channeled down the northern valleys and into the Waterville
Plateau and portions of the Columbia Basin this morning before
diminishing later this afternoon. The surface pressure gradient
will relax as surface high pressure rebuilds over the region. Last
nights passing cold front brought little moisture to the forecast
area so relative humidity this afternoon will dip into the teens
across most of the northern valleys and into the basin. There is
some concern that the elevated winds will overlap the low RHs
briefly this afternoon for the Okanogan Valley, Waterville plateau
and portions of the Upper Basin. Confidence is low since by the
time RHs hit minimums for the day, upslope southerly flow will be
at odds with the northerly synoptic flow, resulting in lower wind
speeds. After sunset, winds will diminish further and RHs will
start to recover. Temperatures today will be a bit cooler than
Friday but still above seasonal normals. Overnight temperatures
will also remain on the mild side. /Kelch


Sunday through Sat...Upper short-wave ridging over a northward-
surging thermal ridge Sunday through Tues will help to produce
well above normal high temperatures in the upper 60s and 70s for
most towns. Following this is the most uncertain part of the fcst
as an approaching north-south shearing upper trough reaches the
Pac Nw coast Wed...then moves inland the rest of the work week.
Again...there are still big enough inconsistencies in timing, position
and evolution of the slow-moving frontal boundary model guidance
has moving over Ern Wa and N Idaho that the most prudent approach
was to not make big changes to the fcst, but simply trend toward a
wetter and cooler scenario...again...starting late Tues Nt and
Wed. The biggest difference between the GFS and the somewhat more
preferred ECMWF (or rather the ensemble mean), is that all of Ern
Wa and N Idaho is under the threat of widespread pcpn with the
slower and more sheared character and track of the frontal system
across the region. The GFS is much drier across the Upper Columbia
Basin, which is not preferred. The best agreement is that the NE
Wa mtns and the Idaho Panhandle will still see the most pcpn...
roughly around one half inch by Sat. Snow levels will remain high
enough to not pose a threat to passes. Thunder is not out of the
question Tues Nt through Sat for all zones. bz

&&

.AVIATION...
12Z TAFS: A ridge of high pressure will rebuild over the region
resulting in mostly clear skies and VFR conditions at all TAF
sites through 12Z Sunday. /EK



&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        66  40  66  43  71  46 /   0   0   0   0   0   0
Coeur d`Alene  65  36  66  39  70  42 /   0   0   0   0   0   0
Pullman        64  39  65  40  69  41 /   0   0   0   0   0   0
Lewiston       70  42  69  44  73  46 /   0   0   0   0   0   0
Colville       68  38  69  41  73  41 /   0   0   0   0   0   0
Sandpoint      64  34  63  36  69  36 /   0   0   0   0   0   0
Kellogg        64  35  64  38  68  40 /  10   0   0   0   0   0
Moses Lake     72  40  71  41  76  45 /   0   0   0   0   0   0
Wenatchee      71  46  72  48  77  51 /   0   0   0   0   0   0
Omak           70  40  72  43  76  44 /   0   0   0   0   0   0

&&

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

$$




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