Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 241136
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
436 AM PDT Sun Jul 24 2016

.SYNOPSIS...
A warm and mostly dry summer pattern will arrive this weekend and
persist through next week. However, there will be a chance for
thunderstorms near the Canadian border Monday through Wednesday...
and possibly the Lewiston region next weekend. High temperatures
in the 90s will be common for nearly all towns Thursday through at
least Saturday.


&&

.DISCUSSION...
Today: Shortwave ridging of higher pressure today will produce
sunny skies across the Inland Northwest. Temperatures at 850 mbs
will jump up to around 20 Celsius, which will translate into above
normal temperatures with highs up into the 80s to low 90s.

Monday and Tuesday: The flow pattern will become zonal for the
beginning of next week. Lower levels of the atmosphere will warm
further with highs in the upper 80s and 90s. Moisture will
increase over the region late Monday into Tuesday ahead of a weak
upper level disturbance. Models show around a 1000 J/kg of surface
based CAPE over the east slopes of the northern Cascades for
Monday afternoon. The convection will have a cap on it with 10-25
J/kg of CIN closer to the crest. This CIN will be stronger further
away from the crest. The shortwave trough of lower pressure will
take until at least late Monday afternoon to arrive into the
Cascades. There is some uncertainty with how much convection will
get going, but the steering flow will be weak will want to push
the convection off of the crest to the east. It is possible that
some of this convection will impact burn scars in the northern
Cascades. With P-wats up to near an inch, thunderstorms will be
capable of very heavy rain. Thunderstorms will also be slow moving
with any that do drift over a recent burn scar capable of
producing flash flooding.

There is a modest amount of mid level instability across the
mountains for Monday night. Surface based convection is expected
to transition to a chance for some nocturnal elevated convection
for the overnight hours Monday. There is more uncertainty with
this portion of the forecast because of how weak the upper level
forcing is. Thunderstorm coverage will be more isolated in nature
and not as much of a flash flood threat.

Afternoon convection on Tuesday will be focused across the
northern mountains on Tuesday with a small chance that some
convection will for across the northern fringe of the Columbia
Basin. Surface based CAPEs will be between 1000-2000 J/kg;
however, there will also be 30-60 J/kg of CIN as well. The
coverage of thunderstorms will be limited by the weak dynamics
aloft. Shear will be very weak as well, so thunderstorms would
more likely pulse up quickly but then dissipate just as quickly.
Main concern will be for heavy downpours, small hail and lightning
strikes. /SVH

Tue Nt through Sunday Nt: We continued with the overall trend
of slowly warming temperatures, with only an isolated threat of
showers and Thunderstorms. This pcpn will be limited to those
towns and mountains closest to the BC border in the afternoon/evening
hours of Wed...as well in the Nrn Blue Mtns next weekend.
Concerning this latter mention of pcpn for the weekend, this is
the toughest (most uncertain) part of the fcst only because we`re
seeing some signs of nocturnal convective pcpn as an elevated
plume of conditionally unstable lapse rates aloft accompanies a
weak short- wave that moves NE through Oregon and clips SE Wa.
Temperatures will be well above normal with highs in the 90s for
most towns through Saturday. Fri and Saturday will be the hottest,
with triple-digit readings possible for a handful of locations. bz

&&

.AVIATION...
12Z TAFS: Weak high pressure will allow VFR conditions and light
winds to prevail at all TAF sites for the next 24 hours or more.
/SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        86  60  92  65  90  62 /   0   0   0  10  10  10
Coeur d`Alene  86  55  91  58  90  59 /   0   0   0  10  10  10
Pullman        85  50  90  55  88  55 /   0   0   0  10  10   0
Lewiston       93  61  98  67  96  66 /   0   0   0  10  10   0
Colville       89  51  94  59  90  55 /   0   0   0  10  40  20
Sandpoint      82  49  87  54  86  55 /   0   0   0  10  30  20
Kellogg        83  52  88  55  87  55 /   0   0   0  10  10  10
Moses Lake     90  57  95  65  94  61 /   0   0   0   0   0   0
Wenatchee      90  65  94  70  91  65 /   0   0   0  10   0   0
Omak           91  60  96  66  93  64 /   0   0  10  20  10  10

&&

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

$$


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