228
FXUS66 KMFR 111922
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1222 PM PDT Thu Jul 11 2024

.DISCUSSION...Made some minor updates to sky cover for this
morning to better align with satellite observations regarding the
marine stratus along the coast. Away from the coast, skies are
clear across the region with the exception of wildfire smoke
dispersed across the area. A look at air quality sensors shows
mainly good air quality for most locations, with degraded air
quality focused in the vicinity of the Salt Creek and Shelly
fires. Overall, conditions will be very similar to those of
yesterday as above normal temperatures continue. Various heat
products remain in effect for most areas away from the coast and
south of the Rogue-Umpqua Divide, and details can be found at
NPWMFR. Today`s efforts will focus on the upcoming thunderstorm
threat east of the Cascades as well as gusty breezes through the
weekend. For more details on current thinking regarding the
upcoming pattern, see the previous discussion below. /BR-y

&&

.AVIATION...11/18Z TAFS...VFR ceilings will prevail for the
TAF period except for locations closer to the coast as lowering
ceilings will move in again this evening. These ceilings will
probably bounce between 1000 to 500 feet for most of the night.

Smoke from active fires will reduce visibility over small areas
through this afternoon. The Shelly fire in western Siskiyou County
is burning with the most intensity, so prepare for lower
visibility over sections of western Siskiyou County.

-Smith

&&

.MARINE...Updated 830 AM Thursday, July 11, 2024...A thermal
trough will continue to bring moderate to strong north winds to all
waters through the end of this week into at least the first part of
this weekend. Gale force winds are expected at times south of Cape
Blanco along with very steep, hazardous seas. Peak winds and seas
are expected this evening and again Friday evening. Elevated winds
and seas continue Saturday and gradually ease on Sunday, but some
amount of disturbed seas will persist into next week. -Spilde


&&

.FIRE WEATHER...Issued 400 AM Thursday July 11, 2024...

..Fire Weather Watch for Gusty Wind and Low RH for portions of
Oregon Fire Zone 624 and California Fire Zone 285 for Friday
afternoon and evening...

..Near critical fire weather conditions possible through at least
this weekend...

Hot, breezy, low humidities, and occasional unstable afternoon
conditions will persist through this weekend, and this will lead to
near critical fire weather conditions. Additionally, we have a
chance for thunderstorms this weekend, mainly across the eastside.

Single digit RH values are also forecast this week during the
afternoon hours across the eastside and some isolated westside
valleys in Northern California. While winds today will be breezy
with gusts 15 to 20 mph; conditions look to worsen on Friday.
Statistical and ensemble guidance is showing gusts 25 to 30 mph
for several locations in the Fremont-Winema National Forest as
well as the Modoc National Forest with the sustained critical
humidities. Will be issuing a fire weather watch as confidence is
beginning to grow there. Portions of fire zones 280 and 282 also
look to reach criteria, and would like to coordinate with the
Incident Meteorologist of the Shelly Fire before issuing anything
for those zones.

For the thunderstorm potential, it should be noted that the trend
stayed the same from yesterday to this morning for both Saturday
and Sunday. We were seeing slight increases early in the week, but
those trends have flatlined. A lot will depend on how a ridge of
high pressure sets up over the Four Corners region as this will
direct monsoonal moisture northward. There is about a 10-20
percent chance for isolated thunderstorms both Saturday and
Sunday.

-Schaaf/Guerrero

&&

.PREV DISCUSSION... /Issued 409 AM PDT Thu Jul 11 2024/

DISCUSSION...Satellite imagery shows marine stratus across most
of the southern Oregon coast and inland into the Coquille Basin.
Elsewhere remains cloud free. Our "groundhog" day of summer
continues with a ridge of high pressure continuing to dominate the
the western United States, including southern Oregon and northern
California. However, the ridge is beginning to break down
somewhat, and afternoon high temperatures while still hot, will
not be challenging records like they have been. That being said,
temperatures inland from the coast will be in the 90s to low 100s
with higher temperatures in the West Side Valleys. Smoke may
continue to be a limiting factor to the heat, but that comes with
another set of issues. At the coast, temperatures will still be
warm relative to their climatological normals, but temperatures
will be in the 70s. The evening shift updated our plethora of heat
products and are continuing the excessive heat warning for
Siskiyou County. Meanwhile, a heat advisory replaced the previous
excessive heat warning across Jackson, Josephine, and eastern
Curry Counties while a heat advisory continues for areas east of
the Cascades.

Additionally, with somewhat cooler high temperatures, overnight
low temperatures will be mild with lows in the upper 50s to low
60s. However, smoke from area wildfires may prevent overnight
relief from the heat since opening windows is not recommended in
areas of degraded air quality. The smoke forecast will largely be
downwind (toward the southeast) of area wildfires, with Siskiyou
and Modoc Counties forecast to receive the highest concentrations.
However, portions of Jackson County-- especially downwind of the
Salt Creek Fire, have degraded air quality as well. As such, the
Oregon Department of Environmental Quality is continuing their
air quality advisory for Jackson County through this morning.
Info about the air quality can be found on the Oregon smoke blog:
https://oregonsmoke.org

Despite the ridge slowly breaking down, temperatures will be
similar over the next few days with highs in the low 100s and lows
in the upper 50s to low 60s. These temperatures are expected each
day through the weekend.

Then, over the weekend, a low pressure system will develop off the
coast and California and shift northward while remaining offshore.
This will bring in some monsoonal moisture and additional energy
that could mean thunderstorms. The general thought at this point
is that isolated to potentially scattered storms will be limited
to areas east of the Cascades, but there are ensemble members that
do show a farther west extent while others show a more eastward
extent missing us completely. The threat begins Saturday afternoon
with Sunday looking to be the more favorable afternoon and
evening for thunderstorms. With everything being said and done,
there is a 15 to 20 percent chance of thunderstorms for portions
of the East Side both Saturday and Sunday afternoon and evening.
There is a 5% chance for thunderstorms west of the Cascades for
both evenings.

Beyond that, we return to a more stable southwest flow pattern
with above normal temperatures for interior locations. -Schaaf


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 9 PM PDT Saturday for ORZ024-026-029>031.

     Red Flag Warning from 2 PM to 8 PM PDT Friday for ORZ624-625.

     Fire Weather Watch from Saturday afternoon through Sunday
     evening for ORZ624-625.

CA...Excessive Heat Warning until 9 PM PDT Saturday for CAZ080>082.

     Heat Advisory until 9 PM PDT Saturday for CAZ083>085.

     Red Flag Warning from 2 PM to 8 PM PDT Friday for CAZ284-285.

     Fire Weather Watch from Saturday afternoon through Sunday
     evening for CAZ285.

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

     Gale Warning until 8 AM PDT Saturday for PZZ356-376.

&&

$$