196
FXUS66 KMFR 181819
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1119 AM PDT Fri Apr 18 2025

.Updated AVIATION Discussion...

&&

.AVIATION...18/18Z TAFs...VFR prevails area wide late this morning
with local IFR near the immediate coast from Brookings southward.
Wind gusts this afternoon and early this evening will be strongest
along the coast (peaking in the 20-30 kt range), with gusts up to 15
kt for inland areas. Onshore flow will develop this evening and
overnight, bringing the return of MVFR ceilings to the coast. A cold
front will sweep through the area Saturday, but with little, if any
precipitation (low chance -- 20% or less -- along the coast and over
the Cascades). MVFR ceilings at the coast should break up Saturday
afternoon. /BR-y/Spilde

&&

.PREV DISCUSSION... /Issued 345 AM PDT Fri Apr 18 2025/

SYNOPSIS...

Very dry conditions will persist over the next 24 hours before a
mostly dry cold front approaches the coast. The chances of
thunderstorms remain low Tuesday and Wednesday of next week east
of the Cascades.

SHORT TERM.../6AM THIS MORNING THROUGH SUNDAY NIGHT/
KEY MESSAGES:

-Very dry through today.
-A mostly dry cold front moves through Saturday.

--------------

Much like last night, it is pretty clear except for some high
cirrus moving through. It is indeed a dry morning with
precipitable water around 0.15 to 0.2 inches in eastern Oregon,
which is unusually low for this time of year. Relative Humidities
reflect this arid airmass with Klamath Falls reporting RHs around
21 percent as of typing this AFD. So more of a nerdy weather
feature with no impacts this morning, but it is indeed dry.

It will be another clear and dry day later this afternoon with
temperatures again similar to what was observed on Thursday.
Heading into tonight and Saturday morning, a mostly dry cold
front will approach the Oregon coast. Latest model data shows a
low chance of rain(~20%) in the high central Cascades Saturday
morning. A little snow could fall about 6000 feet. No weather
impacts are anticipated with this frontal passage.

The relatively cold air really struggles to surge into southern
Oregon and northern California given the weak northwest flow
late Saturday through Sunday. As a result, temperatures do trend
lower, although there is no drastic 10 to 20 degree cool down.

LONG TERM.../SUNDAY NIGHT THROUGH FRIDAY/
KEY MESSAGES:

-Low chance of thunderstorms around Lake and Modoc Tuesday and
 Wednesday
-Trending wetter by Thursday evening and Friday.

--------------

By next week, a trough will swing through southern
Oregon around Tuesday and bring a 10 to 20% chance of showers in
Lake and Modoc counties. There could thunderstorms as well as the
NBM guidance is showing a 15% chance of cloud to ground lightning
in the aforementioned areas, which is essentially GFS and ECMWF
MOS at this lead time. Forecast soundings are not that impressive,
although they do show a little convective available potential
energy west of Alturas.

Towards the tail end of the forecast period, ensembles are
hinting at more precipitation entering the forecast. In general,
the probability of precipitation is about 20 to 30 percent
Thursday evening and increasing slightly to 30 or 40 percent by
Friday. There is still a lot to sort out as some ensemble members
are definitely on the dry side through both days.

-Smith

MARINE...Updated 200 AM Friday, April 18th...A thermal trough
will maintain gusty north winds and steep, hazardous seas for all
areas into this weekend. The strongest winds and steepest seas
will be south of Cape Blanco. The thermal trough will vary in
strength with somewhat lighter winds and seas today. Even so, seas
could remain very steep (~10 feet at 8 seconds) beyond 5 NM from
shore and south of Port Orford.

North winds will peak in strength Saturday afternoon when gales are
expected from around Gold Beach southward and within 30 NM from
shore along with very steep seas up to 15 feet at 8 seconds. Very
steep and hazardous seas will spread north of Cape Blanco to about
Coos Bay and beyond 10 nm from shore, except in the vicinity of Cape
Blanco. Winds ease some Saturday night into Sunday, but steep to
very steep seas are likely to continue into early next week,
especially south of Cape Blanco. -Spilde/BR-y

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 8 AM PDT Saturday
     for PZZ350-356-370-376.

Hazardous Seas Warning from 8 AM to 11 PM PDT Saturday for
     PZZ350-356-370-376.

     Gale Warning from 8 AM to 11 PM PDT Saturday for PZZ356-376.

&&

$$