589
FXUS66 KMFR 042120
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
220 PM PDT Fri Jul 4 2025

.SYNOPSIS...Low pressure system will bring another round of
showers and storms this afternoon and evening, along and east of
the Cascades. While this low will move eastward today allowing
high pressure to briefly return, another low will dig south off
the coast and could bring a return of active weather early next
week.

Key Points:

*Thunderstorms mainly along and east of the Cascades, but an
 isolated storm possible in the Shasta Valley. Despite these
 storms being wet, new fires may start where lightning reaches the
 ground.

*A few storms may overachieve and bring gusty winds and hail.

*Breezy winds are expected this afternoon and evening.

*Temperatures start increasing over the weekend and a moderate
 heat risk returns on Monday.

*A 15% chance of thunderstorms is in the forecast in the early
 half of next week.


&&

.SHORT TERM...Tonight (7/4) through Monday (7/7)...Radar is
already showing showers and a few thunderstorms today east of the
Cascades associated with a low pressure system that is overhead.
The severe weather threat is largely to the east of our area, but
does include eastern Lake county with a 5-14% chance for damaging
winds over 60 mph. That being said, storms like to overachieve,
and there is up to a 5% chance that a storm could become strong or
even severe with gusty winds and hail. Otherwise, lightning will
be a concern today, especially with folks spending time outside.
The thunderstorm threat remains largely along and east of the
Cascades and a 15% chance for an isolated storm is possible in the
Shasta Valley. These storms will continue through the early
evening, and the focus should begin moving northeast out of our
area between 8pm and 9pm.

Otherwise, expect a relatively pleasant day with cooler than
normal temperatures and some breezy winds across southern Oregon
and northern California. This afternoon will likely be the coolest
afternoon for a long time, so we recommend you enjoy it if that is
your thing.

The trough that has brought us thunderstorms most of the week will
finally exit to our east tonight allowing for conditions to
stabilize over the weekend. This will allow for temperatures to
moderate to be above normal again and conditions to dry out across
the board. By Monday, much of the area could be in an area of
moderate HeatRisk. This translates to about a 40 to 60% chance of
reaching the century mark in the Rogue Valley and Grants Pass as
well as for portions of the Seiad Valley and the Somes Bar/Happy
Camp areas. With drier weather, this could lead to additional fire
weather concerns, but will allow the fire weather section to
detail that more closely. -BS

.LONG TERM...Monday Afternoon (July 7) through Friday (July
11)...Another low pressure system will approach the US West coast
and dig southward off the California Coast. Depending on the
track, this could disrupt the heat building in and bring
additional chances for afternoon and evening thunderstorms
beginning as early as Monday. Right now, ensembles are suggesting
a 10-15% chance for a thunderstorm in our typical spots (east of
the Cascades and in northern California), and have used the NBM
thunderstorm probabilities as opposed to the traditional POPs as
the blend tends to wash out convection. This low exits our area on
Wednesday night.

Meanwhile, temperatures will be warm, but not overly hot with this
low disrupting the ridge and thermal trough pattern. However,
after Wednesday, the ridge returns as does the thermal trough. As
a result, expect warmer and drier conditions in the late half of
the week; with heat risk creeping toward the major category.
Should this continue, we may need to consider heat headlines.
However, this being several days out; will wait for additional
runs before issuing any headlines. Stay tuned to the forecast for
updates to this situation. -BS

&&

.AVIATION...04/18Z TAFs...Isolated to scattered thunderstorms be
the main concern again this afternoon and evening along and east of
the Cascades, mainly for Lake and eastern Klamath counties. Isolated
showers and storms may extend all the way to the Shasta Valley in
northern California. IFR/MVFR ceilings/visibilities are expected
near any storms as well as gusty outflow winds and even hail.

Also, a mix of IFR and MVFR at the coast extends into the coastal
valleys. Expect slow improvement into the afternoon. But, the lower
conditions return to coastal areas during the evening. Elsewhere,
VFR will continue. -BS


&&

.MARINE...Updated 200 PM PDT Friday, July 4, 2025...Conditions
will remain relatively calm today. The thermal trough pattern
returns Saturday, bringing gusty north winds and steepening wind
waves. This will result in conditions hazardous to small craft
south of Cape Blanco. The region of steep seas will likely expand
early Sunday, reaching all of the waters during Sunday evening,
while very steep seas will be possible south of Gold Beach during
Sunday afternoon into Monday. Have gone ahead and issued a
hazardous seas watch for these areas. Steep seas then are likely
to persist into Tuesday morning. The outlook is for a brief
improvement in conditions Tuesday into Wednesday. -BS/DW


&&

.FIRE WEATHER...Updated 200 PM PDT Friday, July 4, 2025...An upper
level trough is swinging through the region today, bringing below
normal temperatures, higher daytime humidities and gusty winds
(gusts of 15-25 mph common). Additionally, isolated to scattered
thunderstorms continue east of the Cascades this afternoon. The best
coverage of storms today is expected across Klamath/Lake Counties,
and there is a Red Flag Warning in effect until 8pm this evening for
abundant lightning on dry fuels for much of Fire Weather Zones 624
and 625. Isolated storms are possible as far south as the Modoc
plateau and westward to the Medicine Lake area, but the higher
chances/coverage will remain north of the OR/CA border today.

For the remainder of the holiday weekend, more typical summer
conditions will return in terms of temperatures and humidities. The
persistent thunderstorm pattern finally shifts eastward, and
thunderstorms drop out of the forecast for the rest of the weekend.
Temperatures will trend warmer Saturday into early next week, and
daytime humidities will trend lower. Temperatures look to peak on
Monday and Tuesday when high temperatures reach into the mid to
upper 90s and maybe even the triple digit mark for some West Side
and NorCal valleys. Temperatures trend slightly cooler from mid-week
onward, but still remain above normal through the end of the week.

Meanwhile, confidence is increasing in yet another low pressure
redeveloping offshore of California on Sunday and persisting through
around mid-week. There have differences in exact location and
trajectory of this low, which leads to low confidence in details
regarding timing and location of thunderstorm chances. However,
considering models have been consistent in at least showing the
presence of this feature, confidence is growing in thunderstorm
chances returning to the region for the early part of next week. The
deep southerly moisture flow will be cut off during our break this
weekend, so it`s possible that this next pattern would have less
thunderstorm coverage compared to what we have seen over the past
week. We`ve introduced a 10-15% chance of thunderstorms for parts of
the East Side and Siskiyou County, but we anticipate changes to this
forecast over the next day or so as models become more consistent in
resolving this feature. At this time, it looks like thunderstorms
could arrive as early as Monday and linger into Wednesday. Stay
tuned for updates.

Otherwise, the forecast will be for continued near to slightly above
normal temperatures, seasonal humidities, and the typical diurnal
wind patterns, although general east flow late this weekend into
early next week could lead to drying, especially across the
ridgelines, where poor to moderate recoveries are possible. /BR-y


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 8 PM PDT this evening for ORZ624-625.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM Saturday to
     5 PM PDT Monday for PZZ350-370.

     Small Craft Advisory from 8 AM Saturday to 5 PM PDT Monday for
     PZZ356-376.

     Hazardous Seas Watch from Sunday afternoon through Monday
     afternoon for PZZ356-376.

&&

$$