Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 240549
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1048 PM PDT WED APR 23 2014

.SYNOPSIS...
Occasional precipitation chances, breezy conditions and relatively
cool temperatures dominate the weather pattern. The next organized
storm system will bring steady light rain late tonight and into
Thursday, followed by a threat of more scattered showers, and
perhaps some thunder, Thursday afternoon. Showers will remain a
threat into the weekend, before a relative lull comes for the
start of the new work week.


&&

.DISCUSSION...

Evening update: Rain continues to fill in across the lower
Columbia Basin as deep moisture continues to be transported ahead
an approaching warm front. As of 930PM...rain has materialized
from Lind to Moses Lake to Wenatchee. Amounts have only ranged
between a trace to 0.01" but this will change as a warm front
lifts toward the region. There is little doubt that widespread
rain will engulf a majority of the Columbia Basin...East
Slopes...and spread into the northern Mountains throughout the
next 6-12 hours and consequently, Pops have been nudged toward
100%.

Snow levels are currently on track which range from 4000-4500 in
the Cascades to 3500-4000` north and east. The threat for
accumulating snow at Stevens Pass is not as certain with
temperatures currently at 35F. Snow is likely by morning at
Sherman Pass and will be increasing during the early morning hours
at Lookout which is currently at the freezing mark.

Rainfall through 12z will generally range from a tenth to quarter
of an inch in the lowlands. Lower amounts are expected at
locations like Lewiston and in the foothills of the Blues due to
localized downsloping winds. This will also be the case for the
Camas Prairie and it is not out the realm of possibility that
these locations see only trace amounts of precipitation within the
overnight period. This will change however as the warm front lifts
north and a trailing cold front presses through btwn 12-18z. This
front will focus the steady pcpn southeast between the Blues...L-C
Valley...Camas Prairie and into the Central Panhandle Mtn as well
as the northern mountains and intensity into the moderate category
is a possibility.

What is more concerning is the potential for clearing and arrival
of a secondary wave. GFS/NAM indicate 400-700 J/kg of surface
based CAPE at 18z centered across the Central Basin which migrates
northeast through the aftn. There is some CIN but also a midlevel
shortwave which could provide the necessary lift. This could mean
two things...an early start to thunderstorms or at least the
potential for moderate to heavy showers bringing an additional
quarter to half an inch of rainfall. Will pass these thoughts on
to the night shift and see if any drastic changes show up with the
incoming ECMWF before adjusting timing/placement of thunderstorm
chances. /sb


&&

.AVIATION...
06Z TAFS: Steady rainfall continues to build northward through the
Columbia Basin with most terminals expecting pcpn by 08z. Cigs
will gradually lower and pcpn bcmg moderate temporarily as a cold
front presses through btwn 15-18z. The frontal passage will mark
the end of the steady rain and promote incr winds. A brief break
is possible however a destabilizing atmosphere will lead to widely
scattered -shra through late aftn with a good potential for isolated
thunderstorms. NAM/GFS indicate enough instability setting up btwn
MWH-GEG-COE to include vcts with the 06z issuance. Any storms will
have the potential for small hail and strong wind gusts. /sb



&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        40  58  38  54  37  56 / 100 100  40  40  30  20
Coeur d`Alene  36  53  37  53  36  55 /  90 100  70  50  50  40
Pullman        36  55  39  50  36  53 / 100 100  50  50  50  30
Lewiston       42  62  44  55  42  59 /  60 100  60  70  50  30
Colville       36  59  35  61  38  61 /  80 100  60  40  20  30
Sandpoint      38  51  36  54  38  54 /  50 100  80  50  50  50
Kellogg        33  50  36  52  36  50 /  60 100  70  70  60  60
Moses Lake     44  64  40  61  39  63 / 100  70  10  10  10  10
Wenatchee      45  63  43  61  41  62 /  90  60  10  10  10  10
Omak           44  62  36  62  34  62 / 100 100  10  20  10  10

&&

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

$$




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