Time and Day: 0645 Saturday
The Snapshot: Cool temps and partly cloudy today, heavy snow
tomorrow.
Current Observations: 3” of
snow overnight (4 if you count the two 12 hour periods) which is the first
snowfall we’ve recorded in 11 days. Temperatures are back to seasonal norms
with 23 degrees on the upper mountain and 28 in the base area. RH is in the 90’s
and the barometer is steady.
The Science: Weak high pressure is forcing a
warm front over the top of Washington this morning. Cool, dry air will remain
in place at Stevens Pass for a mostly dry, partly cloudy day. Things ramp up
tomorrow as upper level zonal flow takes aim directly at the Cascade Crest, and
a cold front sags from north to south across Washington. This pattern typically
favors Stevens Pass and I would expect moderate to heavy precipitation all day
Sunday and Sunday night. There will be a strong temperature gradient across the
state, with exact snowfall amounts depending heavily on how cold it is here
(insert Captain Obvious statement now). There is cold air pooled in the eastern
valleys but not much actual east flow, so how that affects this event will be
interesting. Right now it looks like the precip will be snow all day and night,
but it will likely be on the line at times.
The Long Range: Upper
level flow becomes WNW on Monday, with continued light orographic showers and
cooling temperatures. On Tuesday a deep upper level low enters
the region, which is currently north of the Aleutian Islands.
Sorry for the
preschooler’s handwriting, it’s what the Snippet Tool offers. Models have the
low deepening as it crosses directly over Haida Gwaii and across Washington
State. All kind of fancy words to describe moisture lifting into the atmosphere
will be in play and the end result looks to be heavy mountain snow on Tuesday
and Wednesday at lowering snow levels. The end of the week looks to finish dry
and cold, Thursday and Friday might be good days to quit your job.
24hr Precipitation ending at 4am:
Today 24hr water: >.25 Snow:
1-2”
Tomorrow’s 24hr water: 1-1.5” Snow:
12-14”
Trend and Timing:
Snow begins before daybreak Sunday,
becoming moderate to heavy and continuing thru Monday morning.
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24hr temperature
ending at 4am:
Low: 24 High: 30
Free air freezing level: 2,000
Trend and Timing:
Temps will be steady and cool on
Saturday, and begin to rise Sunday morning.
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24hr Winds (mph) ending at 4am:
Base: W 0-5
Ridge Top: W 5-10, then SW 10-20
Trend and Timing:
Winds will be light and westerly all
day Saturday and Saturday night before beginning to crank up around 4am
Sunday from the SW.
DV
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