000
FXUS66 KOTX 130939
AFDOTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
239 AM PDT Mon May 13 2013

.SYNOPSIS...
A robust upper level disturbance will drag a cold front through
the region today and bring the first period of widespread
precipitation to the region in over three weeks. Look for locally
heavy downpours and thunderstorms as the front moves through the
region today. Behind the front expect temperatures near seasonal
norms with a chance of mountain showers and embedded
thunderstorms. The arrival of cooler, more seasonal temperatures
Tuesday through the upcoming weekend will allow many rivers to
recede.


&&

.DISCUSSION...
Today and tonight...For the early morning hours, some isolated
showers and perhaps a stray thunderstorm or two will linger over the
northern panhandle of Idaho where some mid level instability
interacts with a stalled mid level front. Then the weather pattern
across the region will turn much more active today as a strong upper
level trough and surface cold front sweeps through the Inland
Northwest. This trough is tapping into a fetch of deep moisture with
pwats nearing 200 percent of normal. The combination of this
moisture with strong upper level forcing will bring widespread
shower activity to the entire forecast area. The main area of
precipitation will be with the passage of the cold front that is
expected to reach the Cascade crest by mid-morning, move across the
Columbia basin around noon then into the Idaho panhandle by
mid-afternoon. The rising terrain east of the basin will benefit
from orographic flow enhancing lift. For these areas and also along
the Cascade crest, a quarter to a half inch of qpf will be possible.
The basin will generally see lower amounts from the frontal passage.

There will also be a chance of thunderstorms across much of the
forecast area today. The area of strongest potential will be across
the southeast zones where decent mid level instability and strong
shear will be located. SPC continues to highlight a slight risk of
damaging thunderstorms across the extreme southeast corner of the
forecast area. Large hail and strong winds will be the main
threat. As for the rest of the forecast area, any breaks in the
clouds behind the front will allow surface based instability to
develop as the cold pool aloft moves overhead during peak daytime
heating. There will be a risk of very heavy rain with any
thunderstorm development in this very moist environment.

Windy and gusty conditions will accompany the cold front and
continue through the evening hours. Sustained winds of 15 to 25 mph
along with gusts to 40 mph will be possible. There will also be
gusty and erratic winds with any thunderstorms that develop. Winds
will start to diminish by midnight, but will remain breezy
overnight, keeping overnight temperatures from bottoming out even
with clearing skies. /Kelch


Tuesday through Monday...Through this portion of the forecast we
will see a fairly typical spring progressive pattern with
multiple weak disturbances moving through westerly flow. This
will result in temperatures within a few degrees either side of
normal and a chance of periodic showers mainly over the mountains
with partly cloudy skies in between each passing wave.

the models are pointing at two stronger buckles moving through
the Inland Northwest. There are some timing differences. But it
looks like the first will be Thursday into Friday and the second
Saturday night into Sunday. Moisture and instability increase with
both waves and will result in a better chance of showers over most
of the area outside the lower east slopes and the deep basin.
Models soundings and stability parameters show enough instability
to increase pops and put a slight chance of thunderstorms into the
northern Washington and Idaho panhandle mountains for
Thursday...Friday and again on Sunday. None of these events looks
to be particularly robust...and confidence is much better for
showers than widespread. In between these waves we expect the
westerly flow to keep afternoon showers over the higher terrain.
Winds will mainly be out of the southwest...but are expected to
increase with each wave passage. /Tobin

&&

.AVIATION...
06Z TAFS: A stalled mid level front will result in abundant mid and
high level cloud cover tonight. Isolated rain showers will
continue to fall out of this. On Monday a fast moving strong cold
front will cross into Central and far NE Washington
12-18z...spreading through the remainder of Eastern Washington and
North Idaho between 18z Mon-00z Tue. Most areas will see a 3-6
hour period of rain with the front before rain changes to showers.
CIGS should stay primarily VFR although MVFR can`t be ruled out.

Instability ahead of the front around KLWS could trigger
thunderstorms but the best chances will be south and east of KLWS.
Then behind the front mid level cooling over North Central
Washington will result in towering cumulus developing KEAT/KMWH
around 21z with the chance for isolated thunderstorms mainly in the
Cascades...with the chance for thunder spreading east in the late
afternoon and evening.  Stronger winds aloft may result in very
gusty winds with storms that develop.  JW


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        65  40  62  43  65  46 /  80  50   0  10  10  10
Coeur d`Alene  68  40  62  41  65  43 /  80  50  10  10  10  10
Pullman        69  40  61  39  65  43 /  80  50   0  10  10  10
Lewiston       79  44  70  45  74  50 /  70  40   0  10  10  10
Colville       65  39  67  39  70  42 /  80  60  10  20  20  20
Sandpoint      62  40  62  38  65  40 /  80  80  20  10  10  20
Kellogg        68  41  58  41  63  45 /  80  70  10  10  10  20
Moses Lake     71  44  70  45  74  47 /  40  10   0   0  10  10
Wenatchee      70  44  69  46  71  49 /  60  10   0  10  10  10
Omak           71  41  69  40  72  41 /  70  20  10  20  10  20

&&

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

$$