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
000
FXUS66 KOTX 171855
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1055 AM PST Tue Jan 17 2017

.SYNOPSIS...
A prolonged period of active weather develops Today and continues
at least through Thursday. This will start out as a wintry mix,
with the potential for significant snow or ice for some, before
transitioning to warmer, wet weather later Wednesday into
Thursday. Localized flooding will also be possibility.

&&

.DISCUSSION...
Rest of today...Minor timing and refinements have been made to
the forecast for today. Primary change was to extend the freezing
rain advisory for the eastern basin until 10 pm tonight. There is
a minor outriding isentropic wave passing through the eastern
basin this morning and early afternoon. Spotter reports suggest it
is mostly sleet and freezing rain in the basin which verifies the
advisory already...and light snow in the northern mountains. The
10 am special Balloon sounding launched from WFO Spokane indicates
a shallow warm layer starting at about 2500 feet aloft to about
5500 feet. This layer characteristic suggest mainly sleet during
the rest of the afternoon in the Spokane area but the actual
chance of precipitation will be less than this morning as a break
period envelopes the region. To the south it is assumed this
elevated warm layer will be stronger and more conducive to
freezing rain for the Palouse and points south of I-90 this
afternoon as this band exits to the east. The main precipitable
water fetch will nose into the region tonight and begin the main
ice onslaught in the Cascades lee zones as well as further light
ice accumulation over much of the basin before warming up to
simple rain overnight. The afternoon package will refine this
potential. /Fugazzi

&&

.AVIATION...
18Z TAFS: The low level inversion over the region locking in
residual arctic air in the boundary layer will be gradually eroded
today...but this process will result in a widespread threat of
freezing rain at all TAF sites. An initial wave of moisture will
bring a few hours of light freezing rain with a hundredth or two
of an inch of ice accumulation mainly to the KCOE...KPUW and KLWS
TAF sites. KGEG...KMWH...and KEAT are in a break period between
moisture surges fro the rest of the afternoon The main surge of
freezing rain will arrive over the western TAF sites between 00Z
and 03Z and the eastern TAF sites between 04Z and 06Z tonight.
There is a reasonable chance temperatures will rise above freezing
overnight in the eastern TAF sites...with KMWH rising above
freezing Wednesday morning...but KEAT will likely remain below
freezing with periods of FZRA leading to ice accumulations of a
quarter of an inch by the end of the TAF period. /MJF

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        25  25  39  34  38  27 /  60 100 100 100  60  10
Coeur d`Alene  27  27  38  35  39  26 /  60 100 100 100  70  20
Pullman        32  30  40  34  39  28 /  50 100 100 100  70  10
Lewiston       29  29  43  37  42  30 /  40 100 100  90  60  10
Colville       26  26  36  34  38  30 /  50 100 100 100  60  10
Sandpoint      28  28  38  34  39  30 /  80 100 100 100  90  40
Kellogg        28  28  38  35  39  28 /  60 100 100 100 100  30
Moses Lake     18  18  36  30  38  25 /  20 100  90  80  10  10
Wenatchee      16  16  32  28  36  27 /  20 100  80  70  10  20
Omak           25  25  36  32  38  29 /  20 100 100  90  20  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 8 AM PST Thursday for Northern
     Panhandle.

     Freezing Rain Advisory until 10 PM PST this evening for Central
     Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse.

WA...Winter Storm Warning until 8 AM PST Thursday for East Slopes
     Northern Cascades-Northeast Mountains-Okanogan Highlands-
     Okanogan Valley.

     Freezing Rain Advisory until 10 PM PST this evening for Spokane
     Area-Washington Palouse.

     Freezing Rain Advisory until 8 AM PST Wednesday for Upper
     Columbia Basin.

     Ice Storm Warning until 9 AM PST Wednesday for Moses Lake Area.

     Ice Storm Warning until 4 PM PST Wednesday for East Slopes
     Northern Cascades-Waterville Plateau-Wenatchee Area.

&&

$$



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