Area forecast discussion
National Weather Service Spokane Washington
701 PM PDT Sat may 25 2013
Synopsis...
Memorial Day weekend is expected to be a little cooler than
average, and a series of weak upper level disturbances will bring
the potential for scattered showers through Monday. The moist,
showery weather pattern is expected to linger into late next week.
&&
Discussion...
update: showers over the northern mountains are waning early this
evening and are expected to die out with sunset tonight. Much of
the inland northwest is left with some altocumulus cloud cover due
to this convection earlier in the afternoon. Models are consistent
in this cloud cover dissolving through this evening into tonight. A
low pressure system off of northwest Oregon is pushing across some
rainfall into the coastal areas early this evening. This
precip is not expected to begin to push east of the Cascades
until Sunday morning and the bulk of this precip will remain
across Oregon. However, we will see increasing mid and high level
cloud cover from the west as this system pushes eastward tonight.
The previous forecast was a little fast with this cloud cover into
the Idaho Panhandle and into northeast WA, so sky cover was trimmed
back a bit through the overnight hours (especially across the
northeast portion of the forecast area).
Clearing skies and weak winds across the northern valleys will
result in another chilly night with low temperatures once again
approaching freezing. We will see good radiational cooling tonight
with a slightly drier air mass off the surface. Models show a
fairly wide range of low temperatures, so confidence is not great
as we have had a warm bias the last few nights and we may still be
a bit on the warm side even though the forecast is reflecting the
colder side of the model guidance.
Surface dew point temps this evening are starting out in the upper
30s to lower 40s in these northern valleys. As these areas radiate
tonight we may see a few spots develop fog, but with a slightly
drier air mass above the surface, I elected to add in some patchy
frost across these areas instead. This drier air should allow
these dew point temps to drop as they approach saturation with the
moisture in the boundary layer depositing on the surface as frost. /Svh
&&
Aviation...
00z tafs: cumulus cloud cover and northern mtn showers will decrease
in coverage this evening. A shortwave trough of lower pressure just
off the northwest Oregon coastline will push inland tonight. This
will spread some mid and high level cloud cover across the region.
Showers are expected to develop out ahead of this wave with showers
pushing northward out of Oregon late Sunday morning. All terminals
will see a chance for some showers through the day on Sunday, but
the best chances will be across the southern half of the region from
keat to kpuw and klws. /Svh
&&
Preliminary point temps/pops...
Spokane 43 67 47 66 47 62 / 10 30 20 30 30 50
Coeur D'Alene 39 68 46 65 44 61 / 10 30 40 40 20 60
Pullman 40 64 45 66 45 60 / 10 50 40 20 30 50
Lewiston 46 69 50 73 51 67 / 10 50 40 20 30 50
Colville 39 73 46 70 45 68 / 30 20 20 50 20 50
Sandpoint 36 67 44 64 42 62 / 10 20 40 50 20 50
Kellogg 39 65 46 62 46 58 / 10 40 50 50 30 60
Moses Lake 46 68 49 72 50 70 / 10 30 20 10 30 30
Wenatchee 48 66 50 69 52 68 / 10 40 10 10 20 40
Omak 40 69 46 71 46 68 / 20 20 10 20 30 50
&&
Otx watches/warnings/advisories...
Idaho...none.
Washington...none.
&&
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