Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Spokane Washington
239 am PDT Mon Oct 24 2016

dry but cloudy weather is expected through midday today.
Temperatures will be quite mild across southeastern Washington
this afternoon. Rain and High Mountain snow chances return to the
Cascades and north central Washington this afternoon and across
the remainder of the area tonight. A wetter system arrives
Wednesday, with the potential for moderate to locally heavy
rainfall across the east slopes of the northern Cascades.
Occasional wet weather will then continue at times through the end
of the week.


today through Tuesday...satellite reveals a deep and tightly
wound low pressure system off the Pacific coast this morning.
There is good model agreement in maintaining this low pressure
either as a closed feature or a deep trough just off the coast for
the next 48 hours at least. However...the southwest flow ahead of
the low will transport a fetch of deep moisture into the
forecast area this afternoon and tonight an fling off an occluded
front through the region to work with this moisture and produce
another round of rain mainly tonight...but beginning this
afternoon in the Cascades and deep basin and continuing into
Tuesday in the Idaho Panhandle mountains.

Today will be a largely cloudy but dry and mild day for most of
the forecast area. High altitude moisture will maintain a thick
deck of cirrus and altostratus which will effectively hide the
sun...but the southerly flow in the mid levels will transport
some mild air allowing temperatures to peak around 10 degrees above
normal over much of the region...particularly the eastern reaches
of the forecast area despite the lack of sun and the shortened
late year daylight period. This afternoon the front will approach
the Cascades and allow an onset of light rain as clouds thicken
and lower through the day. Snow levels will remain at or above
6000 feet as precipitaiton begins.

Tonight will bring the main event as an occluded front crosses the
forecast area from west to east. Despite the deep moisture
feed...there will be only a short period of isentropic rain ahead
of the front and a short period of heavier showers immediately
along the front...leading to a general rainfall total in the range
of a few hundredths in the deep basin to a tenth or two over the
higher basin and up to a third or half an inch in the mountains.
Not enough to cause any Hydro concerns or mudslides.

Tuesday will bring lingering orographic showers over the
mountains ringing the basin...and plenty of clouds elsewhere...butthe
main weather regime in the Columbia Basin will be breezy but
essentially dry conditions with temperatures back in the normal
range for this time of year. /Fugazzi

Tuesday night through Friday night...general longwave pattern of a
large troff off the coast with ridging to the east in the interior
allows for a prolonged interval of southerly steering flow over
eastern Washington and northern Idaho. Significant shortwave
features of note utilizing this warm southerly flow up over the area
include a rather wet warm front moving through Wednesday that is
followed up with the slow passage an occluded frontal zone Wednesday
night. The moisture feed into these features is well maintained and
should allow for a fairly wet Wednesday and Wednesday night due to
prolonged rainfall with snow levels remaining quite high (generally
above 5500 feet msl). The frontal features get pushed away to the
northeast by negatively tilted shortwave ridging getting pumped up
into the region ahead of a digging low pressure system off the
central California coast which will allow for pops to show a
decreasing trend going into Thursday with perhaps even a dry
Thursday night. The earlier mentioned low off the central California
coast continues its trek north/northeast and spreads more
precipitation along with rather high snow levels through eastern
Washington and northern Idaho Friday and Friday night. Temperatures
will trend slightly on the warm side of what would be considered
normal for this time of year given the warm trajectories of approach
for passing weather features provided by this longwave pattern.

Saturday through Monday... models continue to advertise a
large trough off the coast that will periodically spin
disturbances through the area. This, combined with occasionally
pushes of moisture from the south, will lead to continued rain
chances. While it won't be raining through this entire period of
the extended forecast, model consistency isn't high enough to
nail down when these drier periods might be. Otherwise, expect
plenty of clouds and temperatures near, or even slightly above
normal for this time of year. /Kalin


06z tafs: mid level clouds will thicken across the region tonight
with a few sprinkles possible. Northerly winds of 12-15 kts at
kcoe, and easterly winds of similar magnitude at kpuw will
continue through at least the morning hours on Monday. Surface
inversion will also strengthen through tonight with southerly
winds of around 25 kts at the top of the mix layer. The shifting
winds through the mix layer will create some low level wind shear
late tonight into Monday morning for klws, kpuw, kgeg, ksff and
most notably at kcoe. A weak cold front will begin to cross east
of the Cascades late Monday afternoon. Rain will begin at keat
and kmwh between 23-02z and arrive at kgeg, ksff, kcoe and kpuw
after 03z. /Svh


Preliminary point temps/pops...
Spokane 63 46 57 45 50 47 / 10 90 20 10 90 70
Coeur D'Alene 63 47 56 44 50 48 / 10 100 40 10 90 70
Pullman 67 47 57 46 56 49 / 10 80 50 20 90 30
Lewiston 70 50 64 49 60 51 / 10 70 40 20 80 20
Colville 60 45 56 40 49 46 / 10 100 40 10 70 90
Sandpoint 59 44 54 40 48 45 / 10 90 70 10 80 80
Kellogg 62 44 53 42 48 46 / 10 90 80 10 90 50
Moses Lake 62 43 62 45 55 48 / 10 70 10 20 90 60
Wenatchee 58 43 61 44 50 46 / 40 90 20 20 90 70
Omak 60 44 58 41 49 46 / 30 100 30 10 90 90


Otx watches/warnings/advisories...


National Weather Service Glossary of Abbreviations