000
FXUS66 KOTX 140532
AFDOTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1031 PM PDT Mon May 13 2013

.SYNOPSIS...
The arrival of cooler, more seasonal temperatures will continue
through the upcoming work week and weekend which will allow many
rivers to recede.

&&

.UPDATE...
The strong showers and thunderstorms that developed earlier this
evening have decreased and moved east. Some scattered showers
remain across northern WA and the north ID panhandle, which will
continue for the next few hours and then decrease overnight.

.DISCUSSION...
Tonight: Observations show the cold front pushing across the
western basin early this afternoon. Light to moderate rainfall has
blossomed along the leading edge of the front. This wave is also
forcing some thunderstorms across northeast Oregon as daytime
heating produces an increasingly unstable atmosphere at low and
mid levels. These thunderstorms are expect to begin to develop
further northeast into the Northeast Blues, Camas Prairie and into
the Central Panhandle Mountains through the afternoon. Strong
shear profiles will support organized thunderstorms with some
possibly becoming severe through approximately 9:00 PM this
evening. The main threat will be for strong outflow winds and
possibly some severe hail. As a result, we have issued a Severe
Thunderstorm Watch for Asotin, Lewis and Nez Perce counties as
these counties will see the best chance for severe weather.

The other area of focus for thunderstorms later this afternoon
into this evening will be behind the front. Clouds have already
began to clear out around the Wenatchee Area up to Omak. As this
clearing progresses further eastward across the region, afternoon
heating combined with cooler temperatures aloft, will promote
steepening lapse rates. As a result, I do expect some thunderstorms
to begin to develop over these western zones in the next couple of
hours and continue to develop eastward behind the front through at
least the early evening hours. This system will push east of the
region overnight with showers and thunderstorms diminishing with
nightfall. /SVH

Tuesday through Friday: Seasonal weather expected for the upcoming
week with a progressive spring pattern. A series of weak weather
systems will move through the region with a chance of showers.
This will help the river levels taper off across northern Cascades
and northern mountains, especially for the Okanogan and Kettle
Rivers. The potent upper level trough responsible for the active
weather today, will quickly exited the region, allowing for a
drier, more stable westerly flow across the Inland Northwest for
Tuesday and Tuesday night. Any convection will be limited to the
higher mountain peaks. Temperatures will be on the cooler side but
more seasonal with widespread 60s for daytime highs and lows in
the 40s. The next in a series of Pacific troughs will pivot toward
the Washington coast on Wednesday with a weak frontal boundary
pushing east of the Cascades by Wednesday morning. This front will
weaken as it pushes across northeast Washington and far north
Idaho by afternoon. The best chance for light showers will be over
the northern mountains and but looks to stable to produce thunder.
The upper level trough axis will migrate inland for Thursday into
Friday. This feature will help destabilize conditions and lead to
showery conditions especially during the afternoon and evening
hours. The negative tilt orientation of the trough and increased
instability could support an increased threat of thunderstorms
especially over northeast Washington and north Idaho. Again more
seasonal temperatures are expected through Friday. /rfox

Friday night to Monday: A progressive pattern will continue shower
chances, especially around the mountains, and seasonal temperatures.
Friday night to Saturday a stretching upper trough edges east.
This feature will provide focus for moisture and instability with
shower chances through much of the region Friday night. The
highest threat will be across the north WA and ID mountains, as
well as over the Cascades in the onshore flow. The lowest risk
will be in the lee of the Cascades and deeper Columbia Basin. Some
convective instability will keep a threat of thunderstorms going
over the northeast WA and ID mountains early Friday evening too.
Overnight into Saturday the shower threat retreats to the mountain
zones as the trough axis continues to edge east and some drier air
intrudes from the west. Saturday night and especially Sunday the
next trough moves across the Cascades. This will renew the threat
of showers across the region, but precipitation is by no means
certain. Moisture and instability is limited. The highest risk
will remain again in the mountains. A threat of thunderstorms also
returns to northeast WA and ID where a couple hundred joules of
CAPE. This is when the trough axis and best lift is passing.
Sunday night into Monday high pressure builds in and the overall
precipitation threat will be minimized. The Panhandle mountains
will keep the primary shower threat. Temperatures are expected to
linger near or just slightly above seasonal norms much of the
period, but some warming is suggested toward Monday (into Tuesday
before another possible system toward the middle of next week).
/J. Cote`

&&

.AVIATION...
06Z TAFS:
Winds are expected to remain elevated through 08z and then decrease
overnight. KSFF, KCOE, KPUW could see some shallow fog form towards
daybreak as winds continue to decrease. Mainly mid and high level
clouds expected Tue with lighter winds.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        40  63  43  66  45  67 /  10   0   0  10  10  30
Coeur d`Alene  40  63  40  65  42  65 /  10   0   0  10  10  40
Pullman        40  63  40  67  43  67 /  10   0   0  10  10  30
Lewiston       44  72  44  74  50  74 /   0   0   0  10  10  20
Colville       39  67  40  69  41  71 /  10  10  10  20  20  40
Sandpoint      40  63  40  65  40  65 /  30  10   0  20  10  40
Kellogg        41  63  41  63  45  62 /  30  10   0  10  20  40
Moses Lake     44  70  45  72  47  76 /   0   0   0  10  10  20
Wenatchee      44  69  48  70  49  72 /   0   0   0  10  10  20
Omak           41  69  41  71  41  72 /   0   0  10  10  10  30

&&

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

&&

$$