075
FXUS66 KMFR 191142
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
442 AM PDT Thu Jun 19 2025

.Updated Aviation Discussion.

.DISCUSSION...Satellite imege shows scattered mid and high level
clouds moving from southwest to northeast. At the same time,
marine stratus is forming along the Umpqua Divide, portions of the
Umpqua, and Coquille Basin. The marine stratus in these areas are
expected to expand in coverage between now and mid morning. The
marine stratus will burn off late this morning. Most locations
will be dry today. An upper trough will be moving towards the area
from the northwest this afternoon. The net result will be cooler
afternoon temperatures for the interior and gusty afternoon and
early evening breezes east of the Cascades and interior westside
valleys. Instability is marginal in southeast Lake and Modoc
county later this afternoon, this will result in cumulus build
ups, and could not rule out an isolated thunderstorm or two.

The upper trough will settle over the area Friday and Saturday.
The upper trough is pretty strong for this time of the year and is
likely to result in much cooler temperatures (15-20 degrees below
normal) for the interior with showers likely west of the Cascades
Friday afternoon, then over most locations Friday night through
Saturday. There is sufficient evidence to suggest isolated
thunderstorms are possible along and west of the Cascades,
centered along and north of the Umpqua Divide, and the coastal
counties Friday afternoon into early Friday evening. The main
driving factor for the slight chance for storms is marginal
instability from daytime heating and a cold air mass aloft.
Isolated storms will linger into Friday evening, then as we lose
daytime heating so do the isolated thunderstorms.

Instability parameters suggest instability is marginal at best
and there was not enough evidence to support a mention of
Saturday. The main reason for this is were expecting extensive
cloud cover which will be sufficent enough to limit the amount of
daytime heating, thus keeeping the afternoon temperatures below
their convective values.

The cool and unsettled weather will be short lived with dry and
warmer weather returning by the start of next weeek, but there is
some evidence suggesting another upper trough could settle back
into the Pac NW the latter part of next week. -Petrucelli


&&

.AVIATION...19/12Z TAFs...Expect some of the smoke from the
Applegate Fire to settle in underneath a low-level inversion until
17-18z, so locally reduced visibility can be expected in the
immediate vicinity of the fire. Smoke should disperse from the lower
layers as the inversion breaks.

Satellite image shows marine stratus forming along the Umpqus Divide
and portions of the Umpqua Basin. Roseburgh is clear at the moment,
but stratus could form there between 14-15z, even then it should be
for only a brief period of time with VFR ceilings expected. However
the surrounding higher terrain could end up partly obscured.

Expect another round of gusty N-NW winds for all TAF sites this
afternoon/evening. Peak gusts again will be in the 20-25 kt range. A
few afternoon/evening cumulus buildups may occur in extreme SE
portions of the forecast area, out near the Warner Mtns. -Petrucelli


&&

.MARINE...Updated 230 AM Thursday, June 19, 2025...Breezy north
winds continue all areas today, with stronger winds and steep,
hazardous seas south of Cape Blanco. An unseasonably cool and wet
system arrives Friday and Saturday with showers and breezy west-
northwest winds. An isolated thunderstorm is also possible. A
thermal trough, along with north winds and steep seas, returns next
week. -Petrucelli


&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this
     evening for PZZ356-376.

&&

$$