520
FXUS66 KMFR 072115
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
215 PM PDT Sun Jul 7 2024

.DISCUSSION...A strong high pressure ridge is centered over the
area and will remain in place into Tuesday. The ridge axis
gradually shifts eastward on Tuesday and moreso, on Wednesday, as
a weak upper trough moves into the region from the northwest.
Overall, there is high confidence that this pattern will bring
continued very hot temperatures and very dry conditions through
Tuesday. High daytime temperatures combined with abnormally warm
overnight low temperature, will result in little relief heat. So
excessive heat warnings (NPWMFR) are in place for inland areas
west of the Cascades through Tuesday with heat advisories are
areas east of the Cascades. This is a strong, long durations heat
wave for early July with record high temperatures forecast today
through Tuesday, including at Medford, Klamath Falls, Mount Shasta
City and Alturas. High temperatures are forecast to be between
105 and 115 for inland valleys west of the Cascades and near 100
east of the Cascades. Even coastal areas will be above normal with
high temperatures in the upper 70s to upper 80s through Tuesday.

In addition to the heat, today there will be breezy to gusty late
afternoon and evening winds across western and central potions of
the area, including Douglas, Josephine, Jackson, western Siskiyou
and Klamath counties. This combined with extreme heat and dryness
will result in elevated fire weather conditions. Red flag
warnings (RFWMFR) are in place today. Please see the fire weather
discussion below for more details.

On Tuesday, the ridge remains in place with the ridge axis
beginning to shift slightly eastwards. There will also be a weak
shortwave that moves up from the south. Models continue to show
very little in the way of moisture with this disturbance to
support any thunderstorm development. Currently we are forecasting
continued dry weather. However, we will continue to monitor this
period for any potential changes.

On Wednesday, as the shortwave upper level trough moves into the
Pacific northwest, north of the area, the ridge will weaken
slightly. This will result in less hot (but still well above
normal) temperatures across inland areas. Temperatures are likely
to remain in the upper 90s to around 105 for inland valleys. With
the trough nudging into the PacNW, we do expect an increase in
west to northwest winds in the afternoon/evening. This pattern of
ridging over the area with a weak trough to the north remains in
place through late in the week. So expect continued above normal
temperatures through the period.

&&

.AVIATION...07/18Z TAFS...Patchy low clouds are expected to remain
off the coast today, then areas of IFR/LIFR are forecast to move
onshore tonight and early Monday morning. These conditions will
mainly affect areas north of Cape Blanco and from Brookings south.
Elsewhere, VFR is expected through the TAF period.
-CC

&&

.MARINE...Issued 2pm PDT Sunday July 7th 2024...The pattern will
remain generally unchanged through mid week as high pressure
remains offshore with low pressure inland and a weak thermal
trough along the Curry county coast. Moderate north winds south of
Cape Blanco will however expand northward across the outer waters
Monday night and Tuesday. North winds are likely to increase
across all waters Thursday and Friday as the thermal trough
strengthens. -MTS

&&

.FIRE WEATHER...Issued 200 PM Sunday July 7, 2024...The main
concern for this period remains heat, winds, low humidities and
unstable conditions contributing to fire danger early this week. The
combination of wind and low humidity is expected to reach critical
conditions for inland areas along and east of the Interstate 5
corridor again 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, 623, 624, and 280 for
today.

The main difference from Saturday is that winds are forecast to be
weaker east of the Cascades. Given the on-going holiday weekend, and
despite no lightning in the forecast, there will continue to be
conditions favorable for the rapid spread of any new or existing
fires, even in areas that are not currently under Red Flag Warnings.
Particularly, brief or near critical conditions may occur in 281
and 282.

Heading into Monday, a slight nudge lower of temperatures by a
couple degrees, and similarly nudge lower of wind speeds is enough
to make additional west side Red Flag conditions more of a
borderline scenario. West side conditions will be mostly borderline
again Tuesday, with similar low-end-breezy afternoon and evening
winds with the exception a more impactful nudge higher in minimum
relative humidity values from the coast across Douglas County. The
same setup bringing the slight cooling and higher coastal moisture
for Tuesday may also bring a few afternoon cumulus buildups for
western Siskiyou and northern Klamath counties.

By midweek, expect the edge to be taken off of the heat. Though no
longer as extreme, expect temperatures to still be well above normal
and accompanied by slightly stronger afternoon/evening winds.
Instability with an accompanying risk of thunderstorms could develop
east of the Cascades as early as Saturday.
-BPN/DW

&&

.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>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.

     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/CC/CC