850
FXUS66 KMFR 252208
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
308 PM PDT Wed Sep 25 2024

.DISCUSSION...

A cold front is moving farther inland with light precipitation
falling mainly along the coast. Coos Bay observed close to 0.2
inches with the frontal passage and Roseburg observed 0.01 inches.
This tells a story of how dry it is farther to the east and south
as this front begins to move onshore.

Wind is the other big story this afternoon with some RAWS sites
reporting wind gusts up to 50 mph east of the Cascades. The
atmosphere is very well mixed with 10C/km lapse rates up to 600
mb. In addition, it seems winds are stronger than what the models
were anticipating based on forecast soundings and 700 mb flow. We
decided to issue a wind advisory into this evening given that we
are already observing wind advisory wind gusts in higher terrain
of Lake County. Winds are anticipated to die down quickly this
evening by 8 to 10 pm once an inversion sets in.

Once the front moves through, we`ll see more zonal flow aloft as
a weak area of high pressure sets in. Temperatures will be normal
for the late fall on Thursday with highs in the lower 80`s and
clear skies. Otherwise, it will be a pretty typical fall day for
southern Oregon and northern California.

Things become a little more interesting on Friday as a dry cold
front shoots down the coast and pushes into northern Oregon.
Temperatures here in southerly Oregon actually warm up into Friday
and Saturday and we should see another instance of the Chetco
effect in Brookings with some North east winds in that section of
the forecast area.

By this weekend, an upper level wave will move into the state of
Washington. Our area will see some cooler onshore flow and the
coast should trend cooler into the weekend. On the other side of
things, inland areas will remain in the upper 80`s with eastside
locations in the lower 80`s. It looks like another dry cold front
will sag into our area on Sunday. The NBM is predicting
temperatures to trend 3 to 6 degrees cooler on Sunday afternoon
as some of the cooler air sags south.

We`ll have to monitor how strong the high pressure ends up being
Sunday night and Monday morning east of the Cascades. If we do see
a strong area of high pressure, it will become pretty hot and dry
for locations west of the Cascades on Monday with east flow off
the Cascades. The GFS does give hints of this, although we didn`t
really catch this looking at some of the 12Z ensemble data. In any
case, it will be something to watch.

-Smith

&&

.AVIATION...25/18Z TAFS...An approaching weak front is pushing
MVFR/IFR conditions in along the coast and over the coastal waters
this morning. These conditions will push farther inland throughout
the rest of the day, with rain expected along the coast and into the
Umpqua Basin this afternoon and into the evening. These same areas
will see MVFR/IFR ceilings and visibilities overnight and into
tomorrow morning due to fog and/or low stratus. Terrain obscurations
are expected in these areas as well, especially along the coastal
mountains.

Other inland areas will remain at VFR levels throughout the next 24
hours. Gusty winds will affect areas east of the Cascades this
afternoon and early evening as the front moves to the east. Winds in
these areas will calm in the late evening and overnight. -BPN/TAD

&&

.MARINE...Updated 200 PM, September 25, 2024...A weak front is
passing through the region today, producing breezy winds and
showers, but conditions will remain relatively calm through Thursday
evening.

Steep northwest swell will build into the area by Friday morning,
and will continue through Saturday. Meanwhile, the thermal trough
will reestablish itself along the coast Friday, producing gusty
north winds and steep wind-driven seas. This combination of
conditions will result in a period of chaotic and potentially
hazardous seas Saturday, then on Sunday, swell will diminish with
winds possibly increasing to gales. Overall, expect hazardous
conditions through the weekend due to a combination of strong winds
and steep to very steep seas.

Winds and seas will ease a bit early next week, but continued north
winds and steep seas are likely to keep at least small craft
advisory conditions ongoing through at least mid-week. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 8 AM Friday to 5
     PM PDT Saturday for PZZ350-356-370-376.

&&

$$