427
FXUS66 KMFR 150046
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
546 PM PDT Sun Jul 14 2024

Updated AVIATION Section

.DISCUSSION...The satellite picture looks similar to this morning
with the main difference of less stratus at the coast. Cumulus is
continuing to build with some activity in northern Siskiyou County
that is moving northward. Central/eastern Siskiyou County,
northwestern Modoc County and central/southern Klamath and Lake
counties have a 25-35% probability for lightning in this area, and
this is the most widespread lightning risk coverage that is present.
These thunderstorm chances will continue through 8-10 PM tonight.

Overall, temperatures will be near 5-10 degrees above normal the
next few days, which will mean temperatures will still range from
50s and 60s in the mornings to 90s/low 100s in the afternoons
inland. The Rogue and Shasta Valleys and areas in western Siskiyou
County have an 85%+ probability to hit 100 through Tuesday. For
lows, last night`s temperatures were warmer than expected because of
the incoming cloud cover. Tonight`s temperatures were increased
slightly considering lingering cloud cover. The trend of warmer than
normal conditions will continue through the rest of the week. Please
still take precautions when having to be out in the heat this next
week.

The main smoke concerns lie in Siskiyou County with the Shelly Fire
while haze is present in other parts of Southern ORegon and Northern
California. This afternoon there will be southerly flow, and this
will bring more smoke of the Shelly Fire east into Modoc County and
southern Lake and Klamath counties. By morning, more of the smoke
will spread farther into southern Oregon, including Jackson County.

Monday afternoon`s chances for thunderstorms will be in similar
locations as today thanks to the upper level wave, but it will
extend into parts of Jackson and Josephine counties, including
Medford, Ashland, and Cave Junction.

Dry conditions are favored to return Wednesday. From Thursday
through the weekend, the probability for reaching 100 degrees in
Medford lowers to 25-45% while highs and lows are forecast to be 5-
10 degrees above normal. -Hermansen

&&

.AVIATION...15/00Z TAFS...Isolated to scattered thunderstorms
are affecting areas from Siskiyou County east-northeastward across
Modoc and into southern Klamath and Lake counties this evening. Due
to their very high cloud bases, not much rain is reaching the ground
with these storms. So, VFR prevails in these areas with the main
risks this evening being cloud to ground lightning and gusty,
erratic outflow winds of 35-45 kt. This activity should wane with
the loss of instability tonight into Monday morning, though an
isolated overnight cell or two is still possible (about a 15%
chance). Inland west side locations should remain VFR through Monday
morning.

Meanwhile, coastal IFR/LIFR marine stratus/fog is present north of
Cape Blanco this evening, including at North Bend with patchy
IFR/LIFR south of Gold Beach. Expect the lower conditions to prevail
through the overnight into Monday morning north of Cape Blanco,
while areas of stratus/fog fill into those other areas south of Gold
Beach. All lower conditions peel back to the beaches again between
16-18Z Monday with gusty north winds around 25kt Monday afternoon.

Expect another round of isolated to scattered thunderstorms Monday
afternoon/evening in the same general areas and with the same
weather risks as today (lightning and outflow winds). However, cells
could reach farther to the NW into portions of Jackson/Josephine
counties, including the Rogue Valley.

Smoke from the Shelly fire in western Siskiyou County could bring
visibility reductions in the immediate vicinity of the fire with
MVFR visibility 15-25 miles away, especially to the NE (toward
Montague) as S-SW winds carry the main plume in that direction.
-Spilde

&&

.MARINE...Updated 230 PM Sunday, July 14, 2024...Steep to very steep
seas will continue at 5 to 9 ft at 7 to 8 seconds this evening.
North winds will be strongest this evening between Cape Blanco and
Nesika Beach from 3 to 20 nm from shore. North winds will trend
lower tonight into Monday. Even so, the main update is to extend the
low end Small Craft Advisory conditions expected late tonight
through Monday night with the mix of wind wave and fresh swell
producing steep northwest seas of 5 to 7 ft at 7 to 8 seconds.

Winds and seas will gradually subside Tuesday into Thursday. A
thermal trough is expected to return late in the week with steep
seas and advisory strength northerly winds possible.
-DW

&&

.FIRE WEATHER...Issued 300 PM Sunday July 14, 2024...Thunderstorm
potential remains the focus of the forecast efforts through at least
Tuesday. Strong high pressure will linger over the Great Basin
region into next week and a weak low pressure will move northward
just offshore of the California coast. This is a pretty classic
thunderstorm pattern for this area as the flow turns more southerly
and moist unstable air moves into the region.

Today is the big day in terms of most thunderstorm coverage. We
expect scattered thunderstorms across much of the East Side and
across northern California this afternoon and evening. Storms have
already started over western Siskiyou and eastward into Modoc
County. Cloud cover is limiting daytime heating over much of Lake
and some of Klamath County, but there should be enough moisture and
instability for additional storms to kick off this afternoon. A Red
Flag Warning remains in effect for these areas, and more details can
be found at RFWMFR.

As we head into Monday, storms look more isolated east of the
Cascades compared to today while the threat for areas west of the
Cascades has increased. We`ve decided to cancel the watch for FWZs
285/284/282 and upgrade FWZ 280/281 while also adding in FWZ
621/620/622. High resolution convection models are showing some
storms moving north from western Siskiyou County into Jackson and
Josephine Counties tomorrow afternoon. There is some concern for
nocturnal convection Monday night into Tuesday as low pressure
starts to move closer to the region. Confidence is rarely high for
these scenarios as models just don`t handle elevated convection
well. However, pattern recognition raises some concern for overnight
thunderstorms, potentially even West Side activity Monday night. Due
to low confidence, have left the mention of thunderstorms out of the
forecast for now, but it should be noted that the chance is not
zero.

For Tuesday, moisture is shifting northward and thunderstorm
activity will shift northward as well. The best chances for Tuesday
look to be across northern areas, but timing will be key as the
trough gets closer to the region. We`ll be in a bit of transition
pattern as drier air moves up from the south. The trough will be
taking on a negatively tilted orientation which is a common wind
maker pattern for us well. Strong gusty south winds are possible
across northern California and this could combine with low daytime
RHs to result in near critical to critical fire weather conditions.
for Tuesday afternoon. This could potentially include the Rogue
Valley, but confidence in thunderstorm potential limits confidence
in the strong winds/low RH potential as well.

Tuesday night into Wednesday, low pressure finally swings through
and out of our region. Given the negative tilt of the trough, it
could kick off some nocturnal storms again, but it looks more like a
situation where storms develop along the Douglas/Lane County border
and then moves north out of our area. Moisture looks to be well
north and east of the region on Wednesday, so thunderstorm chances
drop out of the forecast after Wednesday afternoon. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 11 PM PDT this evening for ORZ621.

     Red Flag Warning from 11 AM to 9 PM PDT Monday for ORZ620>622.

     Red Flag Warning until 11 PM PDT this evening for ORZ624-625.

CA...Red Flag Warning until 11 PM PDT this evening for CAZ280>282.

     Red Flag Warning from 11 AM to 9 PM PDT Monday for CAZ280-281.

     Fire Weather Watch from Tuesday afternoon through Tuesday
     evening for CAZ281.

     Red Flag Warning until 11 PM PDT this evening for CAZ284-285.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Tuesday
     for PZZ350-356-370-376.

     Hazardous Seas Warning until 8 PM PDT this evening for PZZ376.

&&

$$

ANH/MNF/DW/MAS