Alturas, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

057
FXUS66 KMFR 191149
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
449 AM PDT Sat Jul 19 2025

.Updated AVIATION Discussion...

&&

.AVIATION...19/12Z TAFs...MVFR conditions persist along the coast
north of Cape Blanco and into the Coquille Basin while LIFR
conditions are present south of Gold Beach. These lower conditions
will clear to VFR later this morning around 19-21z. Inland, VFR
conditions will prevail through the TAF period. Wildfire smoke will
maintain hazy conditions, but shouldn`t impact visibilities except
for in the vicinity of active fires, especially in southwestern
Siskiyou County.

&&

.PREV DISCUSSION... /Issued 342 AM PDT Sat Jul 19 2025/

DISCUSSION...The upper level pattern has transitioned to a more
west to northwesterly flow pattern as low pressure over British
Columbia gradually moves southward this morning. A weak
front/boundary is moving through northern Oregon this morning,
with the tail end expected to linger across southern Oregon
through this afternoon. Satellite shows some mid-high level cloud
cover associated with this boundary, draped across the Cascades
and northern portions of Klamath/Lake Counties. Radar even shows
some light returns to the north across Deschutes County, but
surface observations remain dry.

Meanwhile, air quality has improved across the region compared to 24
hours ago, mainly north of the OR/CA border. Northern California
locations continue to see degraded air quality due to smoke from the
Green and Butler fires. Overall, Oregon locations should remain
improved today, pending fire activity. With another round of gusty
winds this afternoon, any near surface smoke that accumulates this
morning should be pushed east and southeastward. Once again, for the
Rogue Valley, depending on fire activity from the Board Shanty fire
(south of Grants Pass), wind direction will be favorable for
bringing a push of smoke into the valley this afternoon/evening if
there is increased fire activity today. For northern California
locations, guidance does show at least a brief period of improved
conditions this afternoon as winds increase, but given the closer
proximity to active fires, improvement could be short-lived.

With the pattern transition, we`ll see a more stable air mass in
place in terms of thunderstorm/cumulus build up potential, and
thunderstorms remain out of the forecast for the weekend. Aside from
a subtle cooling trend west of the Cascades today, and for more of
the area on Sunday, conditions today and Sunday will be quite
similar to those of Friday. Expect another round of gusty west to
northwest winds this afternoon and evening and again on Sunday,
which will maintain heightened fire weather concerns. This is
especially true for areas east of the Cascades and moreso for
Modoc/southern Klamath/Lake Counties (more in the Fire Weather
section below). Although the focus will be east of the Cascades,
please be extra cautious if using anything that could create a spark
over the next few days regardless of where you are.

Through the weekend, the position of the parent trough puts the
forecast area at the base of the trough. On Monday, however, a
reinforcing shortwave looks to dig the center of this trough farther
south over WA/northern OR. This will bring us the "coolest" day of
the forecast period on Monday, with afternoon highs anticipated to
be 5 to 10 degrees cooler than normal. For reference, the current
forecast for Medford is a high of 87 degrees on Monday, and the
normal is 92 degrees. Models are showing a front moving through the
region overnight Sunday into early Monday morning as this trough
digs, and it should be noted that there is the chance for
precipitation with this front. There are position differences
between the GFS/EC and their respective ensemble suite, and this
will have implications on whether precipitation actually occurs. The
GFS/ensembles have the trough farther inland which keeps the
majority of it`s solutions dry. The EC/ensembles bring the trough
slightly farther west, resulting in enough over water trajectory to
potentially bring some moisture with it. Despite these differences,
and the resulting low confidence in precipitation vs none, if any
precipitation does occur, it should be fairly light - with only
about a 10-20% chance of measurable precipitation, mainly north of
the OR/CA border.

Tuesday looks to be a transition day as the trough elongates over
the area. Energy gets cut off from the parent low, forming a low
pressure off the coast of California - which will become the focus
of our attention for the remainder of the week. If you`ve been
following along this summer, you`ll note that this is a classic
thunderstorm pattern for the region. Naturally at this time range,
there are differences in position/location/strength of this low
pressure. We`re leaning on the National Blend of Models for this
time frame, which currently keeps the forecast dry but expect
adjustments to the forecast as confidence increases when details
become more clear.

MARINE...Updated 200 AM PDT Saturday, July 19, 2025...A weak
thermal trough along the coast will maintain gusty north winds
south of Cape Blanco today into early Sunday. This will result in
low end advisory level winds and steep seas south of Port Orford
through then. Winds weaken Sunday as an upper level trough settles
over the region and disrupts the thermal trough pattern.
Relatively light winds and seas are expected Monday and through
much of next week.

FIRE WEATHER...Updated 330 AM PDT Saturday, July 19, 2025...Fire
weather conditions will remain elevated today. The forecast area
will remain at the base of an upper level trough centered over
southern British Columbia. The transition to west to northwesterly
flow aloft will result in a more stable air mass in terms of
thunderstorm/cumulus build up potential through the weekend, and
thunderstorms remain out of the forecast through at least Monday.

Gusty west to northwest winds are expected in the afternoon/evenings
through the weekend. Conditions today will be quite similar to
Friday`s, though with a subtle cooling temperature trend and
increasing RH trend for areas west of the Cascades. East of the
Cascades, however, gusty west to northwest winds (20-25 mph, with
isolated areas gusting to 30 mph) will combine with low daytime
humidities (10-15%) to result in near critical conditions. A weak
front/boundary will be draped across southern Oregon today, roughly
along a line from Summer Lake/Chiloquin/Howard Prairie/Happy Camp.
Daytime humidities will trend slightly higher north of this
boundary compared to Friday, while areas south will see continued
daytime humidities in the mid-low teens today. These near-critical
wind and RH values will remain headlined in the Fire Weather
Planning Forecast.

The upper level trough will sag farther southward on Sunday, and
this will bring another round of gusty winds Sunday
afternoon/evening. However, daytime humidities will trend higher for
most areas on Sunday as temperatures trend cooler, so near critical
conditions are less of a concern on Sunday. The exception will be
far southeastern FWZ 625/285 where low daytime humidities linger for
another day.

By Monday, the upper level trough deepens over northern OR/WA, and
this will be the coolest day of the forecast period. Minimum RHs
will trend higher for all areas on Monday, and there will even be a
slight chance (10-20%) for some very light precipitation for areas
north of the OR/CA border. See the discussion above for more
thoughts on precipitation potential. By Tuesday, the trough
elongates over the region, resulting in another day of "cooler"
temperatures. Guidance shows energy from this trough forming another
low pressure off the coast of California around mid-week. This
pattern would result in the return of thunderstorms to the forecast
for the remainder of the week. There are differences on the
position/location/strength of this low, so stay tuned for updates to
the forecast as the time gets closer.

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Sunday
     for PZZ356-376.

&&

$$