Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 042230
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
230 PM PST WED MAR 4 2015

.SYNOPSIS...
Mild high pressure will build over the Inland Northwest the next
few days bringing a prolonged period of dry weather. Any
meaningful precipitation is not expected until Tuesday or
Wednesday next week. A warming trend is expected over the next few
days. By Friday, most areas will be about 10 degrees above
average, and the mild weather is expected to carry into early next
week.

&&

.DISCUSSION...
Tonight through Fri Nt...Under a building upper ridge, light
winds and mostly clear skies, expect another cold night with low
temps below normal. There are two subtle waves that will produce
increasing cloud cover over the area...one Thur and the other Fri.
Both of these have warm advection/modest isentropic ascent as the
main synoptic-scale forcing for ascent as the low-level flow backs
to southwesterly with wave passage. However, due to the lack of deep
ascent, a stable environment, and dry air below about 700mb, any
light pcpn should be limited to the mtns close to the BC border
and possibly as far south as the Cntrl Idaho Panhandle.bz


Saturday through Wednesday: Dry conditions continue through at
least Monday, with mild temperatures, before the next opportunity
for precipitation returns. Through at least Monday the jet stream
remains north of the Canadian border, lifting as far north as
northern BC/AB by Sunday. This directs the Pacific shortwaves away
from our region. Aside from some middle to high clouds, the
weather looks dry. The only potential exception skims by the
northeast WA/north ID border with BC Saturday afternoon when the
tail end of a shortwave passes. A few models show an isolated
shower threat here. The threat is too small to put in forecast,
but it will be monitored.

Between Monday night and Wednesday models attempt to bring a
system in from the Pacific. Precisely how this will evolve is not
clear as there is a fair amount of model disagreement. Most
recently the GFS trended quicker, bringing a system in from the
Gulf of AK Monday night and Tuesday. The ECMWF keeps that system
entirely north and instead carries a system from the Central
Pacific inland Tuesday night or Wednesday. The DGEX is more in
line with the GFS, but slower. The Canadian model is more in line
with the ECMWF. Depictions are likely to waver over the next
several days. However the GFS seems like the biggest outlier.
Based on recent performance and in comparison to other models, the
GFS seems to bring the precipitation in too quick. What is more
starkly different at this time is the temperature and snow level
difference between the GFS and ECMWF. Next Wednesday the GFS was
showing snow levels near 0 and the ECMWF was showing snow levels
near 7000 feet. The GFS will be monitored, but it was largely not
used for the latter part of the forecast. Either way look for
some increasing threat of precipitation across the region Tuesday
and Wednesday. Confidence is highest across the Cascades and
northern mountains.

As for temperatures, milder air surges in. Regional 850mb
temperatures will be on the rise through the end of week, leveling
in the lower to middle single digits C. This correlates to surface
highs reaching 10 to 15 degrees above normal. Confidence is
reasonably high through Monday. Thereafter confidence drops some.
The quicker solutions push highs back down toward seasonal norms
by Tuesday. Slower models push temperatures up even more. Again
trending away from the GFS, I keep things mild through Tuesday,
then offer a relative cool down Wednesday. /J. Cote`



&&

.AVIATION...
18Z TAFS: Under strengthening upper ridging...expect clear skies
and light winds to prevail at the TAF sites in eastern Washington
and north Idaho through at least Thurs morning. bz


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        22  49  30  54  33  56 /   0   0   0   0   0   0
Coeur d`Alene  20  49  28  54  30  55 /   0   0   0  10   0   0
Pullman        25  52  29  56  34  57 /   0   0   0   0   0   0
Lewiston       26  57  33  58  36  61 /   0   0   0   0   0   0
Colville       19  52  28  55  30  57 /   0   0   0  10   0  10
Sandpoint      18  45  26  48  28  51 /   0   0   0  10  10  10
Kellogg        19  46  30  50  31  52 /   0   0   0  10   0  10
Moses Lake     21  54  29  59  34  61 /   0   0   0   0   0   0
Wenatchee      29  53  36  58  38  62 /   0   0   0   0   0   0
Omak           23  53  30  54  33  61 /   0   0   0   0   0   0

&&

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

$$




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