364
FXUS66 KMFR 131147
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
447 AM PDT Sun Jul 13 2025

...New Aviation Section...


.AVIATION (12Z TAFs)...

Another similar story along/near the coast with a marine layer
creating a layer of LIFR/IFR conditions. This will continue
through the morning with some relief this afternoon before
redevelopment occurs tonight. Otherwise, expecting mainly VFR
conditions for inland terminals with one caveat. That one caveat
being the potential for an isolated thunderstorm or two this
afternoon and early evening which could impact KLMT. This chance
is so low that confidence was not high enough to include in this
TAF cycle. The more likely scenario is some blow off high clouds
from towering cumulus that don`t mature into a thunderstorm.

-Guerrero

&&

.PREV DISCUSSION... /Issued 311 AM PDT Sun Jul 13 2025/

DISCUSSION (Today through Saturday)...

Overview:

Our heat wave continues and will remain the highest overall
impact in the current forecast. This heat wave will have a role
on elevated fire weather concerns through the next several days.
Currently, we are not seeing an overlap of critical winds/RH
values to warrant a Red Flag Warning, but these hot conditions
coupled with breezy wind speeds will bring about elevated
concerns. These hot temperatures will also help create rising
motion, and the presence of limited moisture will pose at least a
small risk for a thunderstorm or two this afternoon and again
tomorrow afternoon. That said, these are very low end chances, and
most places will be thunderstorm free, but areas across northern
California and parts of the eastside could see isolated lightning
strikes.

Further Details:

An area of high pressure at 500mb has expanded over much of the
western CONUS. On the northern periphery of this H5 high, most
global models do have a weak disturbance progged to pass right
over the Medford forecast area. Many variables for thunderstorms
are lacking today. Overall, moisture is on the low end,
thermodynamics/kinematics are weak, but we will likely hit
convective temperatures. The latter being the main trigger for
parcels rising, and given the incoming wave there is at least low
end confidence for thunderstorms today. However, we are talking
about very isolated chances, and it should be noted there is a
scenario with very reasonable confidence where nothing happens
today across the Medford forecast area. Phasing of already weak
variables will be crucial, and the progged shortwave may dissipate
before peak heating which would further limit thunderstorm
chances. All that said, not enough confidence to remove
thunderstorm chances given this low end scenario. Another similar
story on Monday as another weak shortwave develops between the
northern periphery of the high and the base of a larger trough
over southwest Canada.

The aforementioned area of high pressure does appear to stick around
for the next several days, and will occasionally merge with another
high farther west over the Pacific. This will lead to an airmass
that will create daily hot afternoon temperatures with triple digits
possible for many low elevations west side areas (both OR and CA).
We have extended the heat hazards through Tuesday, and we may need
another extension before this heat wave start to settle down
starting as early as Thursday, but above normal temperatures are
still possible for later parts of the week with upper 90s possibly
flirting with 100.

-Guerrero

AVIATION (06Z TAFs)...

The marine layer remains just offshore north of Cape Blanco and
beyond 5nm from shore south of Port Orford. LIFR conditions have
returned to portions of the Coquille Basin, but not quite
affecting North Bend yet. LIFR conditions will return to North
Bend within the next few hours and persist into Sunday morning.
VFR conditions will prevail for all inland locations through the
TAF period.

Gusty winds are expected to return to the coast and Umpqua Basin
again on Sunday afternoon. Additionally, there will be a slight
chance of thunderstorms (10-15% chance) across northern California
and southern Klamath/Lake Counties, including at Klamath Falls,
Sunday afternoon and evening. Expect gusty and erratic outflow
winds with any thunderstorm that develops.

/BR-y

MARINE...Updated 300 AM PDT Sunday, July 13, 2025...The thermal
trough pattern will continue through the end of this weekend and
into next week. This will maintain strong gusty north winds and
steep to very steep wind-driven seas across all waters. Gales are
expected in the afternoons/evenings mainly south of Port Orford
and beyond 5 nm from shore. Conditions could begin to improve
around mid-week next week. Otherwise, daily conditions will remain
quite similar for the next several days.

FIRE WEATHER...Updated 300 AM PDT Sunday, July 13, 2025...An
Extreme Heat warning is in place for Jackson, Josephine, eastern
Curry, and western Siskiyou counties. A Heat Advisory is in place
for other inland areas. These products are in place through
Tuesday night. Typical diurnal afternoon breezy wind speeds are
expected through the next several day. Overnight easterly flow is
possible over area ridges, which may bring locally moderate to
poor RH recoveries. While elevated fire weather conditions are
possible through this stretch, we are not seeing the overlap of
critical winds and RH.

Upper level disturbance moves over the area this afternoon and
tomorrow afternoon. Given the heat, thunderstorm chances are
possible, but remain low (10%-20%) for southern Klamath County,
Siskiyou, Modoc, and Lake counties. On Monday, very similar
chances will exist.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning until 8 PM PDT Tuesday for ORZ024-026.

     Heat Advisory until 8 PM PDT Tuesday for ORZ023-025-029>031.

CA...Extreme Heat Warning until 8 PM PDT Tuesday for CAZ080-081.

     Heat Advisory until 8 PM PDT Tuesday for CAZ082>085.

PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Tuesday for
     PZZ356-376.

     Small Craft Advisory until 11 PM PDT Tuesday for PZZ350-370.

&&

$$