Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 191120
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
420 AM PDT SUN APR 19 2015

.SYNOPSIS...
Warm, dry weather is expected through Tuesday. Temperatures are
expected more than ten degrees above average. The arrival of a
cold front as early as Tuesday night will bring the first threat
for showers and cooler temperatures. After this, a number of
waves track across the Inland Northwest through at least Sunday.
With all of these, the heaviest amounts of rain will fall across
North Idaho, with snow levels high enough to not pose a threat to
any regional passes. Isolated thunder also is possible with each
of these waves.

&&

.DISCUSSION...
Today through Monday night: A ridge of high pressure will promote
dry and mild conditions, with occasional high clouds. This morning
WV/IR satellite shows the region in a northerly flow, with the
ridge axis just off the Pacific coast. Over the next 48-hours the
ridge axis slowly migrates inland and toward north Idaho. With
only minor mid-level ripples in the flow and no deep moisture,
this will bring dry conditions. Expect some periods of high
clouds, especially this morning and early afternoon and again
Monday morning and afternoon base on current model depictions,
along with some spotty flat cumulus around the mountains each
afternoon in the heating of the day. As for temperatures a
thermally induced pressure trough develops through early this
week, centered first toward western WA and the Cascades, then
gradually shifting later Monday (into Tuesday). This will support
a warming trend, with afternoon highs some 7-10 degrees above
average today and 9-13 degrees above normal on Monday. This
translates to many areas outside of the mountains seeing highs in
upper 60s to lower 70s. /J. Cote`

Tues through Sunday: Upper short-wave ridging over a northward-
surging thermal ridge Tues will help to produce well above normal
high temperatures in the 70s for most towns. A few 80s will be
possible for the Columbia Basin as well as the Lewiston and
Colville areas. We`re fairly confident that late Tues will be the
first chance of showers and organized thunder, first developing
along the Cascades then advancing north overnight. Following this
is the most uncertain part of the fcst as an approaching north-
south shearing upper trough reaches the Cascades Wed, with a
series of subsequent short-waves/frontal passages tracking across
the Pac Nw the rest of the week. Again...there are still big
enough inconsistencies in timing, position and evolution of these
waves that we continued with a conservative modification of the
fcst, keeping the threat of showers in the fcst each day through
the weekend. The GFS and ECMWF agree that one of the stronger
frontal passages will move through on Sat, followed by a short
break, then a much more moist fetch with a late Sunday or Sunday
nt front. Snow levels will remain high enough to not pose a
threat to the passes. Thunder is not out of the question each day
for essentially all zones. bz

&&

.AVIATION...
12Z TAFS: High pressure building into the region will result in
VFR conditions. Winds will remain weak and some passing high
cirrus can be expected to drop south into the region out of BC.
/J. Cote`


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        67  42  70  45  75  50 /   0   0   0   0   0  10
Coeur d`Alene  67  37  70  41  75  44 /   0   0   0   0   0  10
Pullman        66  39  69  40  74  46 /   0   0   0   0   0  10
Lewiston       71  44  73  46  78  49 /   0   0   0   0   0  10
Colville       71  40  74  41  78  46 /   0   0   0   0   0  10
Sandpoint      65  35  68  37  74  40 /   0   0   0   0   0  10
Kellogg        66  37  69  39  75  43 /   0  10   0   0   0  10
Moses Lake     72  42  75  43  79  50 /   0   0   0   0   0  10
Wenatchee      73  48  77  50  77  53 /   0   0   0   0  10  20
Omak           73  42  76  43  76  47 /   0   0   0   0  10  20

&&

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

$$




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