544
FXUS66 KMFR 052341
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
441 PM PDT Fri Jul 5 2024

.UPDATE...Updated AVIATION Discussion.

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.AVIATION...06/00Z TAFS...A very dry air mass will lead to VFR
conditions for all areas through the TAF period. /BR-y

&&

.PREV DISCUSSION... /Issued 253 PM PDT Fri Jul 5 2024/

DISCUSSION...It`s another hot afternoon with temperatures
already in the 95-105 degree range in many west side valleys.
Temperatures will warm to the 105-115 degree range, nearly 15-25
degrees above normal for this time of year. Medford, Klamath Falls
and Mount Shasta will be in record breaking territory today, and
this trend will continue through early next week.

The warmest day of this stretch is coming tomorrow while the ridge
moves inland over western Oregon. Tomorrow will begin with morning
temperatures in the 50s east and in the 60s west. Tomorrow afternoon
is when Medford has a ~40% probability to tie the all time recorded
high temperature of 115 and Roseburg has ~45% chance for reaching
110. The Excessive Heat Warning west of the Cascades and Heat
Advisory east of the Cascades will be in effect through this time.
Winds tomorrow afternoon will also be stronger east into Klamath and
Lake counties where gusts near 30 mph are possible. This, combined
with low RHs, will bring a fire weather concern and Red Flag Warning
tomorrow afternoon.

Sunday will bring a cooldown of a few degrees, meaning there will be
temperatures comparable to this afternoon with highs nearing 105-110
at their peak. With the newest data in, have extended the Excessive
Heat Warning for Western Siskiyou, Jackson, Josephine counties
through Tuesday. There was an area of concern of an advisory into
more of the Umpqua Basin, but with probabilities nearing 50% on the
forecast temperatures in this area wanted to hold off on this.
Overall, highs in the 90s are forecast in the long term with triple
digits possible in the Rogue Valley. -Hermansen

AVIATION...05/18Z TAFS...VFR conditions will continue through the
TAF period with the exception of western Siskiyou County where the
Shelly Fire may cause some locally reductions. Afternoon gusts are
possible today near the coast and into the Umpqua Basin. -
TAD/Hermansen

MARINE...Updated 200 PM Friday, July 5, 2024...Northerly winds
under a persisting thermal trough continue to bring wind-driven
steep seas to all waters. While seas are just at Advisory
thresholds, the wide area and duration of the continuing hazard
supports a Small Craft Advisory for nearly all areas through
Saturday evening.

The pattern will then change as the thermal trough restrengthens,
and winds and seas increase again, especially south of Cape Blanco,
with at least Small Craft Advisory conditions then expected to
persist well into early next week. -BPN

FIRE WEATHER...Issued 230 PM Friday July 5, 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 from the
Cascades west in Oregon 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. The main areas of concern for this
afternoon and evening is the low elevation I-5 corridor from
Roseburg to Grants Pass, Medford, and Ashland. A red flag warning in
in place for portions of zones 616, 620, 621, 622 and 623 for today.

Worsening conditions are expected on Saturday with slightly hotter,
slightly drier, and slightly stronger winds expected across a
broader area, including east of the Cascades into zones 624 and 625.
The HDW (Hot Dry Windy) indices showing the condition as advertised
by the GEFS members to fall within the top 5% of these events over
the 30-year climatology from 1981-2010. In short, this is very
unusual to have the area this hot, dry and (breezy) for this time of
year. So, this occurring across the holiday weekend was the final
consideration. Despite no lightning, there will be other potential
sources of ignition.  A red flag warning is in place on Saturday for
zones 616, 617, 620, 621, 622, 623, 624 and 625 in Oregon and zone
280 in California. Brief or near critical conditions may also occur
in 281 and 282.

Hot, dry and gusty conditions continue into Sunday. Winds may trend
slightly lower though compared to Saturday but critical or near
critical conditions are likely. So a fire weather watch remains in
place for these conditions.

The heat continues Monday and Tuesday. Additionally, 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

&&

.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 ORZ616-620>623.

     Red Flag Warning from 3 PM to 8 PM PDT Saturday for ORZ616-617-
     620>625.

     Fire Weather Watch from Sunday afternoon through Sunday evening
     for ORZ616-617-620>624.

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

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

     Red Flag Warning from 3 PM to 8 PM PDT Saturday for CAZ280.

     Fire Weather Watch from Sunday afternoon through Sunday evening
     for CAZ280.

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 9 PM PDT Monday
     for PZZ350-356-370-376.

&&

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