060
FXUS66 KMFR 011020
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
320 AM PDT Tue Jul 1 2025

.SHORT TERM...

Showers continue to move north this morning with clearing
developing behind this first round of precipitation activity.
Temperatures were on the warm side earlier tonight with Medford
reporting 87 degrees at 4Z. However, the temperatures have fallen
notably as the high clouds have moved out.

Temperatures should be a few degrees cooler today according to
the models. We wouldn`t be surprised if Medford comes very close
to 100 again today as the environment doesn`t change that much.
The big story will be another round of thunderstorm activity this
afternoon and evening. The forecast soundings at MHS are looking
pretty favorable for convection. The BUFKIT data shows surface
based convection with very large inverted Vs and LFCs near 600mb.
This basically implies some of these storms should be dry, even
with precipitable water approaching 1.0 inches.

However, the soundings don`t look that great the farther one moves
north like near LMT and MFR. There is instability, but it seems
capped with 100 convective inhibition within most of the
soundings. With that being said, the SPC HREF thunderstorm
probability for one cloud to ground flash within 20 km of a point
is painting an 80 to 90 percent contour in Siskiyou and Klamath
County this afternoon, which is pretty darn high with all my years
looking at this product. In addition, the SPC SREF probability
for 100 cloud to ground flashes within 20km of a point is around
6% over roughly the same area, which is good, but could be higher
for a really big event.

Overall, we will see more thunderstorms today, especially in
northern California this afternoon with storms being dry at times.
Some strong gusty outflows are a real risk during the afternoon.
The best chances appear to be in Siskiyou and Klamath counties.

-Smith

.LONG TERM.../Issued 229 PM PDT Mon Jun 30 2025/ Models show a
kicker trough in the NE Pacific that should push the upper
trough/low onshore into California Tuesday night into Wednesday.
As such, flow aloft will shift more to the WSW west of the
Cascades and this should keep activity farther to east over the
East Side (mostly S and E of Klamath Falls) both Wednesday and
Thursday afternoons/evenings. This will also bring continued
cooling to the area (generally around -5F each day compared to
Tuesday).

There`s still some uncertainty with respect to the 4th of July.
Models are showing generally a WSW flow aloft with another trough
swinging through. The majority of the guidance keeps this trough
farther north, so thunder chances remain across NE sections of the
CWA or even just out of the area. But, a minority of solutions
show a somewhat deeper trough and the potential for
showers/thunder farther south across the East Side (perhaps Modoc
County). For now, have gone with just slight chances across the
northern part of the East Side, but keep checking back for updates
to see if it impacts the evening anywhere for fireworks shows. It
appears as if west side areas should remain dry. We`ll have to
wait and see if the marine layer will be deep enough for stratus
along the coast. Overall, temps will be near or just above normal
levels for this time of year, which means highs in the mid to
upper 80s for most valleys west of the Cascades and in the low 80s
for populated East Side areas. Coastal locations will have highs
in the mid to upper 60s.

This weekend into early next week, models are showing at least
some troughiness hanging along the coast with the upper ridge
setting up over the Four Corners of the SW U.S. ECMWF guidance has
a stronger upper low off the California coast, which might suggest
better thunder chances once again. But, uncertainty in position
and amount of moisture are wildcards at the moment, so the
forecast remains dry for now. -Spilde

&&

.AVIATION...01/06Z TAFs...Along the coast, from Cape Blanco north,
IFR/LIFR will continue through Tuesday morning, becoming a mix of
IFR/MVFR in the afternoon. Strong, gusty winds are expected along
the coast late Tuesday morning through Tuesday evening as well.
Elsewhere, conditions will be mainly VFR. However, isolated showers
or thunderstorms (10-20% chance) are possible for inland areas
overnight/Tuesday morning with gusty winds near storms. The chances
for thunderstorms increases Tuesday afternoon across inland areas
with strong gusty erratic outflows up to 30-40 kts possible with
these storms along with hail. Chances for thunderstorms are expected
at Medford (20% chance) and Klamath Falls (40%) chance on Tuesday.
Roseburg will see lower chances for thunderstorms (5% chance).


&&

.MARINE...Updated 200 AM PDT Tuesday, July 1, 2025...Gale force
winds are expected south of Port Orford and near the coast through
this evening. Meanwhile, small craft conditions are expected over
the rest of the waters with relatively weaker winds. North winds
and seas will diminish some later tonight into Wednesday, but the
southern waters could still experience conditions hazardous to
smaller crafts. -Smith


&&

.FIRE WEATHER...Updated 230 PM PDT Monday, June 30, 2025...The
main concern ahead will be isolated to scattered thunderstorms for
most areas away from the coast into this evening, then again Tuesday
afternoon and evening in northern California, and Cascades east in
Oregon. An 18z (11am pdt) upper air launch was done and it shows a
dry layer below 500mb with a small cap just under 500mb, and a low
level inversion. The low level inversion will break, and the
question will be the small cap around 500mb. Given the expected
increasing instability and trigger, the expectation is for the that
small cap to be broken, thus providing the opportunity for storm
development. The latest meso analysis shows areas where mid level
lapse rates are highest gradually moving northward. Right now the
highest vales are in northern California, and southern Fire zones
624 and 625. Mid level lapse rates basically is a measure of the
temperature change with height and the higher the value, the more
unstable the atmosphere.

Satellite image and radar are showing thunderstorms firing up in
northern California. The trend is for storms to increase in
number and coverage area as the afternoon progresses. Storms
early this afternoon may not produce much of any precipitation to
start, then the chance for wetting rain could increase mid to late
this afternoon and evening. The main reason for the increase
chance in wetting rain is steering winds will be light and high
moisture content throughout the column of the atmosphere. Thus,
storms will be slow movers providing the bigger window of
opportunity for storms to produce locally moderate to heavy
precipitation. However, that does not mean that all storms will
produce wetting rain. Some could also produce little to no rain,
because of the dry sub layer below.

The general consensus among the CAMS (convective allowing models)
that show simulated reflectivity show storms developing in
northern Cal this afternoon, then migrating north towards portions
of the Rogue Valley late this afternoon and early evening.

Keep in mind, lightning strikes outside of the precipitation cores
are possible. Due to the prolonged period of dry and warm to hot
weather, lightning efficiency will be high to very high for fire
starts. We also have to be mindful of gusty and erratic outflow
winds near and away from the core of thunderstorms.

Given the above mentioned and increasing confidence for both
The Red Flag Warning for this afternoon and evening remains in
effect and the Fire Weather Watch for abundant lightning on dry
fuels Tuesday afternoon/early evening has been upgraded to a Red
Flag Warning or the same zones Tuesday afternoon/early evening.
Please see RFWMFR for more details.

It will be hot again this afternoon with highs in the upper 90s to
low triple digits for the interior westside valleys and low to mid
90s east of the Cascades.

Tonight, some evidence points towards the potential for nocturnal
storms, but confidence on this is low and it will be something that
we`ll need to monitor. The most likely scenario will be isolated
convective showers later this evening and overnight tonight.

Tuesday, the thunderstorm threat is expected to be along and east of
the Cascades and northern California. Guidance and instability
parameters are in better agreement suggesting storms could be
isolated to scattered Tuesday afternoon into early Tuesday evening
in the same Fire zones as what were expecting this afternoon/early
this evening. Like today, steering winds will be light, and unlike
today, there should be more available moisture in the column of the
atmosphere, with PWATS between 1.00-1.25". Therefore storms
Tuesday will be slow to move with locally heavy rain.

Wednesday, the focus for storms should be confined to portions of
Lake county, and portions of Northern California as the upper low to
the south gets kicked eastward as an upstream upper trough moves in
from the west. Even then, storms are expected to be isolated.

The concern for thunderstorms could carry over into Thursday as an
upper trough approaches the area from the west with the best chance
for storms along and east of the Cascades and portions of northern
Cal. -Petrucelli

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...Red Flag Warning from 2 PM this afternoon to 8 PM PDT this
     evening for CAZ280-281-284.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this
     evening for PZZ350-356-370-376.

Gale Warning until 11 PM PDT this evening for PZZ356-376.

&&

$$