Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 281147
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
447 AM PDT SAT MAR 28 2015

.SYNOPSIS...
Today will be quite windy, especially in the morning. West winds
of 15 to 25 mph with gusts over 30 mph will be common throughout
the Inland Northwest with gusts as high as 45 mph over the
Palouse. Showers will linger over the Idaho Panhandle through
early this afternoon. The weather Sunday and Monday should be mild
and relatively dry. Another fast moving front on Tuesday will
bring more showers, wind, and onset to another few days of
unsettled weather.


&&

.DISCUSSION...

...Windy Today with the Highest Gusts This Morning Over the
Palouse...

Today: A cold front will race eastward this morning. By sunrise
most of the precipitation behind this front will clear eastern
Washington with showers lingering in Idaho through early
afternoon. Windy conditions are expected over most of the Inland
Northwest today, especially this morning.

* Winds: A Wind Advisory remains in effect for the Palouse and the
  Pomeroy area through 11 AM. As of 2 AM, the surface cold front
  extended from southern Alberta through northwest Montana into
  the southern Idaho Panhandle. Strong pressure rises in central
  Oregon had contributed to the tightening of the southwest
  gradient across Washington and north Idaho. As cold air
  advection steepens our low level lapse rates during the next
  couple of hours, momentum transfer from 850mb and above will
  become more efficient allowing wind of 40 kts to mix to the
  surface in east and southeast Washington. The rising terrain of
  the Palouse, Foothills of the Blue Mountains, and the Pomeroy
  area should experience the strongest winds under the core of the
  low level jet. The West Plains and Waterville Plateau may also
  experience gusts of 40 mph or more which will be close to
  Advisory criteria. The highest gust potential will be this
  morning. By afternoon, low pressure will be racing through the
  Canadian Prairies and our surface gradient will relax a bit.
  Breezy conditions will persist through sunset, but gusts should
  decrease into the 30-35 mph range by early afternoon.

* Precipitation: The surface front has outpaced the mid-level
  front driving most of the rain showers. We have seen a marked
  decrease in the amount of lightning as deep low level cold
  advection has taken a bite out of our instability. Little more
  than a handful of lightning strikes are expected for the
  remainder of this event with the best possibility along the
  Canadian border under the 500mb cold pool. Snow levels will fall
  to 5000 feet by late morning leading to some light accumulations
  on the high peaks of the Idaho Panhandle and the Cascades above
  pass levels.

Sunday: A flat ridge of upper level high pressure will develop
tonight in the wake of today`s storm. At this time, the models are
in decent agreement that the core of the Polar Jet will be
directed toward Vancouver Island and southern British Columbia
Sunday and Sunday night. Low rain/snow chances have been retained
along the Cascade Crest mainly north of Stevens Pass Sunday along
with a mention of a 20 percent chance over the mountain ridges
along the Canadian border near Northport and Priest Lake. The
remainder of the Inland Northwest should be dry with the most
significant cloud cover (mid/high clouds) north of Interstate 90.
/GKoch

Monday through Thursday:  The active spring like weather will
continue well into next week. Monday will be a transition day
with mostly dry conditions as midlevel flow buckles to the
southwest ahead of the next trof approaching. This will nudge any
lingering cloud cover northward bringing a strong potential for an
abundance of sunshine and mild temperatures across the region. The
next upper-level trof will push into the region Monday night and
linger through Thursday bringing several rounds of showers, gusty
winds, and more seasonal temperatures. The first round of showers
will accompany the leading cold front Monday night. Gusty winds
will develop behind the front and persist into Tuesday. Meanwhile,
the atmosphere will become increasingly unstable as the Polar jet
noses into southern Oregon and 500mb temperatures cool near -30C.
A combination of forcing along smaller scale circulations (ie vort
max), orographic ascent, and diurnal heating will promote numerous
clusters of showers and possibly a few thunderstorms. Overall, it
will be unsettled and showery but not the steady rains experienced
on the 25th. Monday will be the warmest and driest day. Tuesday
will be the windiest day with the potential for sustained winds
15-30 mph and gusts in excess of 40 mph. Winds remain breezy
through the week but not near the speeds expected Tuesday.

Thursday night through Saturday: The persistent trof lingering
through Thursday will finally eject to the east as yet another
deep upper-level trof near the coast. There should be a short-
lived break as one system departs and the second approaches the
coast but models are not in good agreement on the extent of this
break. GFS has a break of roughly 6-8 hours before the next
frontal system arrives Thur nt into Friday. This has support from
its ensemble mean but not the ECMWF which is roughly 24-30 hours
slower. So timing is a bit sketchy at this time but model
consensus is suggesting this will be another multi day trof and
much cooler than the previous few largely in response to high
pressure nosing into the Gulf of AK and drawing cooler air south
through Wrn Canada. As previously mentioned, numerous rounds of
showers will be possible from a combination of elements but in
comparison to the system for Tue-Thur, snow levels will be lower
for several days, thunder chances will be lower due to lack of
charge separation, and graupel or snow could fall to some valley
floors. In addition, look for temperatures to cool back several
degrees below normal. We will be keeping a very close eye on this
event with the potential for early freeze warnings. /sb

&&

.AVIATION...
12Z TAFS: Strong post-frontal winds will impact the TAF sites
through mid to late afternoon today. West winds sustained 20 to
25kts with gusts up to 35kts are expected with the highest gusts
at KGEG and KPUW. Rain over the Idaho Panhandle will decrease to
scattered showers between 15-18z. Mixing this morning should lead
to improvement in ceilings, but a broken cumulus deck will likely
bring a 2500 to 4000 deck back to Coeur D`Alene, Sandpoint, and
possibly Spokane Felts by 17-19Z. Winds will diminish quickly with
the setting sun. /GKoch


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        59  38  58  40  64  42 /  20   0  10  10  10  20
Coeur d`Alene  58  36  58  39  64  40 /  50   0  10  10  10  30
Pullman        57  38  58  41  65  42 /  40   0  10  10  10  30
Lewiston       67  40  64  42  69  44 /  20   0   0   0  10  20
Colville       63  37  60  39  64  39 /  20  10  20  10  10  30
Sandpoint      56  35  56  36  61  39 /  70   0  10  10  10  40
Kellogg        53  36  56  38  62  38 /  90  10  10  10  10  40
Moses Lake     68  39  65  40  69  44 /   0   0  10   0  10  10
Wenatchee      66  42  64  45  68  43 /  10   0  10  10  10  20
Omak           67  38  62  39  67  40 /   0  10  10  10  10  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory until 11 AM PDT this morning for Idaho Palouse.

WA...Wind Advisory until 11 AM PDT this morning for Lower Garfield
     and Asotin Counties-Washington Palouse.

&&

$$



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