Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 201820
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1120 AM PDT WED AUG 20 2014

.SYNOPSIS...
Cooler temperatures and the occasional threat of showers and
thunderstorms will linger the rest of the week and into the
weekend. However, the vast majority of this precipitation will be
in the North Idaho Panhandle.


&&

.DISCUSSION...
Forecast update to increase precip chances across the northern
mountains for this afternoon. Some residual elevated convection
is continuing to march eastward along the Canadian border in the
Northern Panhandle late this morning. This is expected to push
across some thunderstorms near Bonners Ferry and Porthill. Once
this cloud cover associated with the nocturnal convection clears
the region, we will see a redevelopment of showers and
thunderstorms over the higher terrain from west to east. This set
up looks very similar to what happened yesterday. The HRRR model
has been consistent with thunderstorms developing over the East
Slopes of the Northern Cascades into the Okanogan Highlands around
noon. These storms will generally push to the east at approximately
20 mph through the afternoon. A redevelopment of thunderstorms
today will be more toward the mid and late afternoon hours for the
Northeast Mountains and the Northern Panhandle. Looks like there
will be a slight northwesterly component to the steering flow for
these thunderstorms today, so the northern Upper Columbia Basin to
the Spokane/Coeur d`Alene corridor will see a chance for isolated
to scattered thunderstorms as well. Thunderstorms are expected to
hold off for the Spokane/Coeur d`Alene corridor until the late
afternoon and evening hours.

The 12Z model runs continue to show upwards of 700-1000 J/KG of
surface based CAPE across the northern mountains this afternoon.
The 0-6 km bulk shear will be slightly stronger today at around
20 kts or so. This shear is still a bit weak for much in the may
of concern for strong to severe thunderstorms; however, we did see
a storm pulse up quickly to severe levels yesterday over the
northern Upper Columbia Basin in a weakly sheared environment, so
it will not be out of the realm of possibility today as well. Due
to the weak shear though, thunderstorms will be of the pulse
variety. Any stronger storms that due develop will likely collapse
fairly quickly. I did add small hail, heavy rain, and frequent
lightning to the forecast across the northern mountains today
considering that these impacts were observed with the thunderstorm
activity yesterday. /SVH

&&

.AVIATION...
18Z TAFS: An are of isolated thunderstorm activity will track
across the Northern Panhandle late this morning. A resurgence of
thunderstorms is expected across the northern mountains today once
we warm to our convective temperature. These thunderstorms are
expected to push into the vicinity of KGEG, KSFF and KCOE by late
this afternoon and early evening. Impacts from convection today
will include: outflow winds up to 35 mph, small hail and brief
downbursts of heavy rain. Showers and thunderstorms will wind down
after 06Z this evening. /SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        80  56  79  52  75  52 /  20  40  10  10  20  30
Coeur d`Alene  79  55  77  50  74  50 /  10  50  10  10  30  40
Pullman        80  50  79  46  76  51 /  10   0  10  10  20  40
Lewiston       85  59  85  57  83  58 /  10   0   0   0  20  30
Colville       76  54  79  52  78  50 /  70  50  50  50  40  30
Sandpoint      77  52  73  51  72  50 /  60  60  50  50  50  30
Kellogg        75  53  73  51  71  49 /  20  40  20  20  40  50
Moses Lake     86  56  84  53  82  56 /   0   0  10  10  20  20
Wenatchee      84  60  83  59  80  59 /   0   0  10  10  20  20
Omak           86  59  84  55  80  55 /  40  20  20  40  30  20

&&

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

$$



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