673
FXUS66 KMFR 031107
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
407 AM PDT Wed Jul 3 2024

.DISCUSSION...A ridge is present off the coast and this will
continue guiding the short and long term forecasts with warm
temperatures and dry conditions. The Chetco effect was once again
present yesterday afternoon, and this will continue into this
afternoon. Highs near Brookings have been increased to near the
mid-90s. On average, highs will be 5-10 degrees above normal this
afternoon. This translates to 80s with 90s in more valley
locations west of the Cascades.

The concern for dangerous afternoon temperatures will begin tomorrow
as the thermal trough moves inland. More west side valley locations
are on track to break the triple digits tomorrow including Mt Shasta
City, Yreka, Medford and Grants Pass. After, the heat expands to
more west side locations including the Illinois Valley and Umpqua
Basin, which equates to highs in the 100-110 degree range.

The heat will be the worst Friday into the weekend. The probability
of reaching highs of 110 degrees in Medford is 70-80% Friday and
Saturday afternoons. There is even a 50% probability to reach 115
Saturday in Medford. For reference, 115 is the hottest high on
record for Medford. There will also be a factor of low temperatures
west side only falling to the low to mid-60s Friday and into the
weekend. With this in mind, it is crucial that precautions are taken
to prepare and deal with the heat. With the heat concerns in mind,
an Excessive Heat Warning and Heat Advisory exists for most
locations (with an emphasis on valleys) tomorrow morning through
Sunday evening. Please visit the NPWMFR for more information.

Early next week the ridge will move inland and temperatures will
fall from the weekend peak, although it will still be warm with
highs in the triple digits for the Rogue and Illinois valleys.
-Hermansen

&&

.AVIATION...03/12Z TAFS...VFR will prevail through the TAF period.
Gusty afternoon winds will return this afternoon, especially along
the coast. Stratus is expected to build in along portions of the
coast tonight with IFR conditions possible. Confidence is low that
IFR conditions will build in at North Bend. Stratus is present in
the Coquille Basin this morning, and this will lift later today.
-Miles/Hermansen

&&

.MARINE...Updated 200 AM Wednesday, July 3, 2024...A strong thermal
trough will maintain strong north winds, reaching gales south of
Port Orford, and steep to very steep and hazardous seas for all
areas through early Thursday. Winds will be strongest and seas will
be steepest this afternoon and evening. Conditions improve somewhat
early Thursday as the thermal trough pushes inland and expands
northward. North to northeast winds will ease some at this time, but
seas and winds will remain hazardous to small craft through the end
of the week, with hazardous warning level seas likely lingering
through Thursday night.

Conditions improve further over the weekend with sub-advisory
conditions likely for at least the inner waters. Strong high
pressure aloft will disrupt the thermal trough pattern, keeping
winds in the 15 to 20 kt range with about a 15% chance of winds
approaching advisory criteria in the outer waters for Saturday and
Sunday. This could lead to lingering steep seas in the outer waters
due to lingering fresh swell and continued wind driven seas. The
thermal trough rebounds early next week, with more widespread
hazardous conditions likely returning at that time. /BR-y

&&

.FIRE WEATHER...Updated 200 AM Wednesday, July 3, 2024...

...Near critical fire weather possible today through the next week
for much of southern Oregon and northern California...

...RED FLAG WARNING REMAINS IN EFFECT FROM 11 PM THIS EVENING TO 8
AM PDT THURSDAY FOR EAST WIND WITH POOR OVERNIGHT RH RECOVERY FOR
FIRE WEATHER ZONES 619 AND 620...

Fire weather concerns will remain elevated through the week due to
two different patterns. First, a strong thermal trough along the
coast will persist through tonight. This will bring moderate to
locally poor overnight RH recoveries to ridges this morning and
again overnight tonight, along with gusty northeast winds of 15-25
mph with gusts to 30-40 mph to the Coast Range/Kalmiopsis
Wilderness. As is typical with this pattern, it tends to take a
night or two of persistent northeast winds to bring down RHs enough
to present critical conditions, and that will be the case this time
as well. Of the winds/RH combo required for critical conditions this
morning, gusty winds will meet the criteria, but RH recoveries won`t
quite be low enough (30-50%). The pattern starts to transition late
tonight, so winds will be weaker compared to this morning, but RH
recoveries will be lower (20-35%). There will be enough overlap for
critical fire weather conditions and a Red Flag Warning remains in
effect for 11 PM tonight through 8 AM Thursday for portions of FWZ
619/620.

In the meantime, this pattern will also lead to near critical
conditions for portions of the area this afternoon. Minimum
humidities of 10-15% are expected in western and central Siskiyou
County with north winds of 10 to 15 mph and gusts to 25 mph
(strongest in the Shasta Valley near Montague). Similarly, northeast
winds also be near critical thresholds in the Illinois Valley at 10-
15 mph with gusts to 20 mph, and with minimum humidities of 10-15%.
However, Intel on fuels remains that the live fuels are not quite
there while dead fuels are. Therefore, will continue to headline the
near-critical conditions this week.

Strong high pressure aloft moves over the region for the latter half
of the week and through the weekend. The thermal trough will expand
northward, with weaker winds expected along the coast. Very hot
temperatures (100-110 degrees) and very low (low teens/single digit)
humidities are expected during this time away from the immediate
coast. While afternoon breezes won`t be quite as strong as today,
the extreme heat, and long duration of the heat will allow even
typically breezy afternoon conditions to result in dangerous weather
that is favorable for rapid spread of fire. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning from 8 AM Thursday to 9 PM PDT Monday for
     ORZ024-026.

     Heat Advisory from 8 AM Thursday to 9 PM PDT Monday for ORZ023-
     025-029>031.

     Red Flag Warning from 11 PM this evening to 8 AM PDT Thursday
     for ORZ619-620.

CA...Excessive Heat Warning from 8 AM Thursday to 9 PM PDT Monday for
     CAZ080-081.

     Heat Advisory from 8 AM Thursday to 9 PM PDT Monday for CAZ084-
     085.

PACIFIC COASTAL WATERS...Gale Warning until 8 AM PDT Thursday for
     PZZ356-376.

     Small Craft Advisory from 8 AM to 8 PM PDT Thursday for PZZ350-
     356-370.

     Hazardous Seas Warning from 8 AM to 8 PM PDT Thursday for PZZ356-
     370-376.

&&

$$