Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Medford or
258 PM PDT Fri Mar 24 2017
Short term...tonight through Monday night...the front has all
but passed through the area, and while the bulk of the
precipitation has moved to the east, numerous showers will
continue through this evening and into tonight. Wind and winter
weather advisories have come to an end, but snow showers may drop
some additional light accumulations, and some breezes are still
possible, especially in the aforementioned showers. Most
precipitation should end overnight, but some residual showers
could continue into Saturday morning.
High pressure and upper level ridging will attempt to nudge in on
Saturday, and should provide some clearing and what may turn out
to be a pleasant afternoon. The break in the wet pattern will be
short lived, however, as the next front will begin to make its way
into the region late Saturday night or early Sunday morning.
Sunday will turn out to be another wet and windy day with snow
levels between 4000 and 5000 feet. Models have backed off a bit
with the amount of moisture that the system has available, but it
will take a bit for the front to pass, and the duration of the
precipitation will make up for the lower rates. Other than the
speed and lower moisture content, the system will be very similar
to the one that juts passed, and wind and/or winter weather
advisories may be needed for Sunday afternoon and evening.
Uncertainty still remains too high in terms of timing and
magnitude, so will leave the final decision on headlines for the
Post-frontal showers will then continue into Monday, but clearing
is expected by Monday afternoon and evening as ridging builds
into the West Coast. -Bpn
Long term...Tuesday through Friday.
In general terms, the seasonably wet pattern looks to continue
through the long term. Our area will be between a ridge offshore of
central and Southern California and a trough in the Gulf of Alaska.
A series of disturbances in a westerly flow will move into the
Pacific northwest. As such, the main uncertainty is the timing and
southward extent of these systems.
The probability of precipitation throughout the long term was
adjusted to reflect a blend of the latest 12z European model (ecmwf) and GFS ensemble
data, and will be highest in the western and northern portions of
our area. Temperatures and snow levels were nudged higher, closer to
Specifically model agreement is not bad on Tuesday into Tuesday
night with a warm front likely focusing rain on Washington. The
GFS keeps rain north of our area while the European model (ecmwf) is a bit stronger
and farther south...spreading rain into southwest Oregon and
northern Klamath County.
Model agreement diminishes Wednesday but the probability of
precipitation increases with the trailing cold front likely to
weaken as it moves through the Pacific northwest Wednesday through
Wednesday night. There is considerable uncertainty on whether we
will or will not receive the brunt of what is likely to be a front
of moderate/seasonably typical strength.
It will be cooler and there is a chance of Post-frontal showers in a
northwest flow as an upper trough moves inland on Thursday.
Ridging is likely to follow Thursday night into Friday with a
pattern similar to that of Tuesday...the next front will likely
track inland north of our area with the highest probability of
light rain at the coast north of Cape Blanco. -Dw
Aviation...24/18z taf cycle...ceilings are a mix of VFR and MVFR
with the MVFR and areas of mountain obscuration mainly in the
vicinity of scattered showers. There is also a slight chance of
thunderstorms into early this evening over the coastal waters inland
to the coastal range. Conditions will be persistent overnight into
Saturday morning with a slight decrease in the coverage of showers
and an increase in west side valley MVFR. -Dw
Marine...updated 200 PM PDT Friday 24 March 2017...seas will
remain steep into Saturday afternoon due to a combination of
moderate westerly swell and fresh short period southwest swell. Seas
will be highest in the outer waters and near Cape Blanco with seas
just a foot or two below advisory criteria in the near shore waters.
Improvement will be brief with the next front likely to produce
advisory winds late Saturday night then arrive early Sunday morning
with another round of very steep seas and possible gales. We have
issued a gale watch with winds rising as early as mid morning
Pacific coastal waters...gale watch from Sunday morning through Sunday afternoon for
Small Craft Advisory for hazardous seas until 11 PM PDT Saturday