273
FXUS66 KMFR 062147
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
247 PM PDT Sat Jul 6 2024

.DISCUSSION...A multiday heat wave is in progress as a strong
ridge of high pressure remains in place over the region. This is
bringing very hot and very dry conditions to inland areas.
Dangerous, excessive heat remains the main concern into early next
week. Excessive heat warnings remain in place In addition, breezy
to gusty during the late afternoon and evening are expected
today. These winds combined with heat and low humidities will
result in elevated fire weather concerns across many areas of
southwest Oregon and into western Siskiyou County. Breezy to gusty
winds are forecast again on Sunday afternoon evening, especially
in Douglas, Joephine, Jackson, southern Klamath and western
Siskiyou counties. Red Flag warnings are in effect for these
conditions today and Sunday. Please see the RFWMFR and the fire
weather discussion below for details.

With this heat wave the hottest temperatures are likely to occur
today through Monday, with afternooon high temperatures near or
above 110 degrees in many valleys west of the Cascades and highs
near 100 for valleys east of the Cascades. Overnight lows will
remain above normal as well with only brief or very little relief
from the heat. On Tuesday, a weak trough is forecast to move up
from California and this result in slighly less hot temperatures.
However, excessive heat is still expected into Tuesday,
especially across inland valleys west of the Cascades. This is a
multiday heat wave with dangerous, excessive heat and little
nighttime relief. Record or near record high temperatures are
forecast including for Medford, Klamath Falls, Alturas and Mount
Shasta City today and potentially again on Sunday and Monday.

For areas along the coast, expect little in the way of low clouds
expt some patches of fog near Brookings and and north of Cape
Blanco are possible in the overnight and morning hours.
Temperatures will be above normal for coastal locations as well
with highs in the upper 70s to upper 80s through Tuesday.

As the shortwave trough moves up from the south beginning
Tuesday, we are watching for any risk of thunderstorms. Moisture
aloft still looks to be scarce with a very low chance (5%) for
thunderstorms from the Cascades east and Siskiyous south. A broad
tough moves into the region from the west mid to late week. This
will allow temperatures to trend less hot. There also a continuing
low chance (5%) for thundertorms, mainly across northern
California or from the Southern Oregon Cascades east. Confidence
is low in the details during this period.



&&

.AVIATION...06/18Z TAFS...VFR prevails across the CWA for the next
24 hours. Gusty north winds (~30kt) will impact North Bend
through early this evening. Winds ease and light fog or mist could
develop along the immediate coast late tonight or first thing
Sunday. This may reduce conditions to MVFR or even briefly IFR;
otherwise, VFR prevails there too. -Spilde


&&

.MARINE...Updated 800 AM Saturday, July 6, 2024...Wind-driven steep
seas persist in all waters today as northerly winds continue. This
afternoon, northerly winds will pick up in most waters. The
strongest winds will be angled to the southwest of the cape, with
sustained speeds of 25 kt and gusts up to 35 kt. Lesser winds of 20
kt gusting to 30 kt will develop to the west and to the north of
Cape Blanco. These winds won`t be enough to change the sea state but
are still worth acknowledging.

Elevated winds south of Cape Blanco will continue into next week,
supporting a continuing Small Craft Advisory limited to these
southern waters through Monday evening. More widespread products may
be needed in the middle and end of the week as a thermal trough
strengthens, bringing gusty winds to all waters and possible periods
of gale gusts to waters south of Cape Blanco. -TAD/CC


&&

.FIRE WEATHER...Issued 200 PM Saturday July 6, 2024...Heatwave
underway and main concern for this period remains heat, winds, low
humidities and unstable conditions contributing to fire danger
through the weekend. The combination of wind and low humidity is
expected to reach critical conditions for inland areas along and
east of the Interstate 5 corridor today. Forecast humidities range
from the upper single digits to low teens and winds range from
sustained 6-12 mph with gusts to around 20 mph. A red flag warning
in in place today for portions of zones 616, 617, 620, 621, 622 and
623, 624, and 280 for today.

Conditions on Sunday will be very similar to today, although winds
are forecast to be much weaker east of the Cascades. Given the
recent holiday, and despite no lightning in the forecast, there will
continue to be other potential sources of ignition, and rapid spread
of any new or existing fires will be a significant concern. A red
flag warning has been issued for Sunday for zones 616, 617, 620,
621, 622, 623, and 624 in Oregon and zone 280 in California. Brief
or near critical conditions may also occur in 281 and 282.

Heading into Monday, a weak upper level wave is forecast slide
through the region, and temperatures are expected to cool be a few
degrees, while humidities improve my a few percentage points. This
is expected to be just enough improvement to preclude additional Red
Flag issuances, but conditions will be borderline, and just close
enough to still warrant some concerns.

The heat continues into next week. Additionally, by midweek, a short
wave trough is advertised to come up the northern California coast
which is a pattern often supportive of thunderstorms. But, not
seeing the moisture to get us worried at this point and model
guidance is showing a only a very low chance (10% or less) for
thunderstorms Tuesday afternoon/evening and into Wednesday, mainly
for the Cascades east and Siskiyous south. Watch for updates on this
development. -CC/BPN


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 9 PM PDT Tuesday for ORZ023>026.

     Red Flag Warning until 8 PM PDT this evening for ORZ616-617-
     620>625.

     Red Flag Warning from 2 PM to 8 PM PDT Sunday for ORZ616-617-
     620>624.

     Heat Advisory until 9 PM PDT Tuesday for ORZ029>031.

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

     Red Flag Warning until 8 PM PDT this evening for CAZ280.

     Red Flag Warning from 2 PM to 8 PM PDT Sunday for CAZ280.

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 9 PM PDT Monday
     for PZZ356-376.

&&

$$

CC