Mount Shasta, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

083
FXUS66 KMFR 101754
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1054 AM PDT Tue Jun 10 2025

.Updated AVIATION Discussion...

&&

.AVIATION...10/18Z TAFs...Along the coast, areas of IFR/LIFR
conditions are gradually retreating back to the immediate coast with
improvement to VFR for coastal locations expected between 18z & 21z.
The lower conditions are likely to linger south of Gold Beach the
longest. VFR conditions along the coast are likely to be brief, with
IFR/LIFR expected to return in the early evening and continue into
Wednesday morning.

VFR conditions will prevail for all other areas through the TAF
period. Isolated to scattered thunderstorms are expected this
afternoon and evening south of the Umpqua Divide and from the
Cascades east in southwest Oregon and across Siskiyou and Modoc
counties in northern California. Heavy rain from thunderstorm cores
could briefly lower visibilities to MVFR, but the main hazards with
these storms will be strong and erratic outflow thunderstorm winds
and lightning. Hail is also possible and there is a 5% chance of
large damaging hail of 1 inch or more diameter, and strong winds of
60 mph, including for Medford (KMFR), Klamath Falls (KLMT), Montague
(KSIY), and Lakeview (KLKV). The probability of strong/severe
thunderstorms, and storm coverage will diminish after sunset, but
thunderstorm chances (15-30%) will persist late tonight into early
Wednesday morning for southern Klamath, Lake, northeast Siskiyou,
and northern Modoc counties. -DW/BR-y

&&

.PREV DISCUSSION... /Issued 351 AM PDT Tue Jun 10 2025/

Discussion...Today will be more active with storms covering a
larger portion ofthe forecast area. An upper trough will approach
from the west and put the area in a favorable position for
isolated to scattered thunderstorms along and east of the Cascades
and in northern California, with the instability parameters
greatest in Western Siskiyou County, northeast into Klamath and
Lake counties, and the southeast portion of Jackson County.

Given the position of the upper trough axis and stronger trigger
ahead of it could bring a heighten threat for isolated strong to
severe storms that will produce gusty winds near and withing storms,
and possible hail for the areas mentioned above. Also, the amount
of available moisture will be higher, therefore storms will have
a better chance of producing locally heavy downpours for the same
areas. This will include most of Jackson County, including
Medford, Phoenix, Talent, White City, and Ashland. Steering flow
will be from the southwest, therefore storms will tend to move
from southwest to northeast. However, the steering flow will be on
the light side at around 10 knots, thus, storms may not be quick
movers, increasing the possibility for localized urban flooding
in areas that experience heavier rainfall.

Storms are expected to decrease in coverage, but will continue
into the overnight hours Tuesday night into early Wednesday
morning, with the upper trough axis to the west. These are likely
to be isolated and confined to portions of Lake and Klamath
counties.

The upper trough axis is expected to be move east of the forecast
area later Wednesday morning with a drier air mass and stable
westerly flow pattern. The NBM and most of the high resolution
models indicate a dry Wednesday. But, there is some support in
the GFS, HREF, and SREF for a slight chance of thunderstorms to
pop up Wednesday afternoon from south central Siskiyou County
northeastward across northwest Modoc County into Lake County. We
will continue to lean toward the NBM for now and reassess with the
12Z suite of data. At the worst, the risk of storms still would
be far less than that of today.

From mid-week, we`ll be heading into a pattern of weak upper
troughing that will persist into Fathers Day weekend. The net
result will be cooler, more seasonable afternoon temperatures for
the interior with continued night and morning low clouds and
fog along and near the coast. Odds are it will be dry during this
time.

-Petrucelli/DW

MARINE...Updated 200 AM Tuesday, June 10, 2025...High pressure
offshore and low pressure inland are expected to persist into the
weekend. The highest seas are expected today into tonight, with
slight improvement to follow. The strongest winds and steepest seas
are expected south of Port Orford to around Pistol River and out 30
nm from shore. Seas will remain dominated by a mix of northerly wind
wave and fresh swell, with steep seas across all of the southern
Oregon coastal waters through Wednesday evening, then south of Port
Orford at least through Thursday evening. -DW

FIRE WEATHER...Updated 200 PM Monday June 9, 2025...Dry and
mostly hot weather will continue for one more day. The main
concern ahead will be isolated to scattered thunderstorms in the
afternoon and early evening hours on Tuesday. A stronger upper
trough will approach from the west, but the trend is for a slower
arrival of the upper trough axis. Even so, this will put the area
in a more favorable position for some storms be strong to severe
since the trigger is expected to be stronger along with greater
instability. So far, guidance is in pretty good agreement
suggesting storms will cover a larger potion of the area and the
shear number of storms will be higher. Due to the combination of
instability, stronger trigger and favorable dynamics, There is
concern for storms to produce gusty outflow winds, with hail
possible with storms are end up strong to severe. The one
difference compared to the last couple of days will be the amount
of available moisture. PWATS (the amount of moisture in a column
will be higher, and the sub layer won`t be as dry. Thus there
could be a heighten concern for locally heavy downpours. This will
include most of Jackson County. Steering flow will be from the
southeast, therefore storms will tend to move from southwest to
northeast. However, the steering flow will be on the light side,
thus, storms may not be quick movers, thus increasing the
possibility for localized flooding in areas that experience
heavier rainfall.

Current fuel conditions suggest they could end up being more
receptive to new starts if we have a significant mount of lightning.
Please use extra care when participating in activities that may
create sparks or embers. These can ignite fires that can quickly
grow out of control, especially around abundant dry or unmaintained
fuels.

With the slower arrival of the upper trough axis, we could see
isolated storms linger Tuesday night into Wednesday morning, then
once the upper trough axis shift east later Wednesday morning, then
threat for storms will shift east of the area.

Wednesday into Fathers Day weekend, it will be dry with a cooling
trend with upper troughing setting up resulting in temperatures near
or slightly below seasonal norms. -Petrucelli

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT
     Thursday for PZZ356-376.

Small Craft Advisory until 11 PM PDT Wednesday for PZZ350-370.

&&

$$