Scientific Forecaster Discussion
fxus66 kmfr 201055
Area forecast discussion
National Weather Service Medford or
355 am PDT sun Oct 20 2019
Discussion...low pressure has moved east and there's nothing on
radar at the time, though there's plenty of higher stratocumulus
over areas west of the Cascades. High pressure over the eastern
Pacific is set to build north over the next few days and this
will initiate as a warm front lifting north across the area today.
This will allow mid levels to saturate through a deeper layer
with lowering ceilings - most areas should not see much if any
sun today. East side areas will see some this morning, but clouds
should fill in by noon. Areas of rain are likely over the Cascades
and Siskiyous and west side higher terrain, and most valley areas
should also see up to a few hundredths. Modoc and lake counties
are mainly slight chance candidates for light rain today with
chances increasing as you progress west and north from there.
The ridge builds in tonight with dry weather likely through
Monday, then a weak front clips the north on Tuesday. High
pressure should build in stronger Wednesday through Friday.
Temperatures next week should be near to several degrees above
normal. Next weekend the GFS ensemble is advertising a shift to
cooler northerly flow with an amplified upper ridge along 140w.
The nbm and ekd ensembles as well as the GFS and ec deterministic
guidance are all aiming in the same direction. Stavish
Aviation...for the 20/12z tafs...coast and Umpqua basin... VFR
ceilings are expected to reduce to MVFR this morning with showers
and patchy IFR. Showers will diminish this evening, but ceilings are
likely to lower and thicken with a mix of LIFR/IFR/MVFR and more
widespread mountain obscuration into Monday morning.
Elsewhere, showers into this evening will be less numerous with
areas of mountain obscuration and mainly VFR ceilings. Patches
of valley IFR are likely late Sunday night into Monday morning.
Marine...updated 245 am PDT Sunday 20 October 2019...the long
period west swell will continue to lower slowly into Monday. But,
south winds with a warm front will remain strong and gusty today.
The combination of wind waves and swell will produce steep seas
through this afternoon with the strongest winds and highest seas
north of Cape Blanco.
Winds will decrease behind the front this evening while high
pressure builds over the offshore waters. The high will persist
Monday then a weaker front will brush the waters north of Cape
Blanco late Monday night into Tuesday.
High pressure will strengthen at mid-week with a thermal trough
deepening over the South Coast. This will result in gusty north
winds and likely steep to very steep wind driven seas, with the
strongest winds and highest seas south of Cape Blanco. This pattern
may persist into next weekend. -Dw