Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 040954
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
254 AM PDT Sat Apr 4 2020

.SYNOPSIS...A chance of lingering showers remains today and again
on Sunday. Cooler temperatures expected in the short term. A drier
and warmer period arrives Monday and is expected to last through
the week as high pressure builds in the area.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...Near term models are
remaining consistent with solutions regarding a brief dry period
today as a weak upper level ridge slides into the area. Meanwhile,
a trough offshore will continue to dive south, kicking up some
moisture into the southernmost portion of the CWA. Areas from
Seattle northward should not see as much moisture as a result.
The precipitation signatures for Sunday still appeared weak and
mostly terrain driven, therefore, the POPs were not zeroed out
entirely for this time frame.

Continuing on into Monday, the residual trough and precipitation
quickly exits the area in the early morning hours, giving way to
the upper level ridge building into the area. This ridge, per the
latest model runs, is just over two standard deviations above
normal. This means that an extended period of dry and warmer
weather is in store for Western Washington, with highs steadily
rising after Monday. This could perhaps be our longest dry stretch
since October.

.LONG TERM /TUESDAY THROUGH FRIDAY/...With the upper level ridge
firmly in place by Tuesday, temperatures will be on the rise.
Highs will easily secure a place in the low to mid 60s range
across the region by Thursday. This is something that various
deterministic model runs have struggled to capture recently, as
the temperatures seem to vary from too high to too low with each
run. The strongly positive anomaly signal on the ridge itself
lends itself to adjusting the temperature forecast up to reflect
this.

The high pressure regime won`t budge much through the rest of the
week, with highs in the low to mid 60s possible through Friday. As
far as the perceived longevity of this more typical spring like
pattern goes, deterministic model runs seem to fall out of
agreement in the extended. The ECMWF is more keen on keeping the
ridging pattern around for longer than the GFS is. A glance at the
7 to 10 day ensemble means from the ECMWF, GFS, and Canadian all
still show positive height anomalies over the East Pacific, and
negative anomalies over California. There is still hope for a
steady continued march into a more typical spring pattern in the
extended.

Kristell

&&

.AVIATION...Flow aloft becomes southwesterly today as a system moves
south of the area. Convergence zone activity will taper off over the
next several hours with mostly dry weather for the rest of the day.
VFR conditions through the period (outside of a few more hours of
MVFR cigs invof of convergence zone this morning) with light surface
winds.

KSEA...VFR conditions through the period. Southerly winds early
this morning become northerly today 5 to 10 kts.

CEO

&&

.MARINE...Winds have eased this morning as low pressure system
shifts toward OR/CA this weekend. Light northerly/northeasterly flow
will persist this weekend, becoming onshore early next week as high
pressure builds over the region.

CEO


&&

.HYDROLOGY...There is no river flooding expected in the next 7
days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$

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