744
FXUS66 KMFR 241747
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1047 AM PDT Sat May 24 2025

...Updated AVIATION discussion for 18Z TAFs, MARINE discussion...

.AVIATION...24/18Z TAFs...VFR levels under clear skies are expected
across northern California and southern Oregon this morning and
afternoon. Normal diurnal winds are forecast. MVFR ceilings under
marine stratus may build over North Bend tonight, but that layer is
not expected to reach into the Umpqua Valley. -TAD

&&

.MARINE....Updated 1045 AM Saturday, May 24, 2025...With winds
calming over the waters, seas are currently below advisory levels.
These conditions look to continue through the weekend and into next
week. Westerly swell looks to increase on Sunday ahead of an
approaching weak front, but currently not expected to reach
hazardous levels. The weak front may bring marine showers both
Sunday and Monday. Northerly winds are forecast to increase on
Monday and Tuesday, possibly building areas of steep seas. -TAD

&&

.PREV DISCUSSION... /Issued 318 AM PDT Sat May 24 2025/

DISCUSSION (Today through Friday)...

Overview:

Relatively quiet conditions are expected through today, but we will
see precipitation chances increase tomorrow as an upper level system
impacts the region. This will lead to showers and perhaps a couple
thunderstorms Sunday and Monday. This is of course over the holiday
weekend, so anyone with outdoor plans should have a plan in place
for lightning. Not expecting severe weather at this time, but a
couple storms could be strong with lightning and gusty winds as the
main threats. Thereafter, warm conditions expected through mid-week
with Wednesday potentially having highs around the low to mid 90`s
for westside areas. For Medford, this would be the first 90 degree
day this year.

Further Details:

Ridging will develop over the area today. This ridge will be in
place until Sunday at which point an upper trough and associated
front will begin impacting the region. This open wave will have most
of the dynamics north of our area, but the base of the trough will
slide over the forecast area through Monday. The best chance for
thunderstorms will be on Sunday as MUCAPE values are the highest
albeit only a few hundred J/kg to upwards near 500 J/kg. However,
the NAM--in typical fashion--is much higher with values approaching
1000 J/kg. Much less instability expected on Monday, but cannot rule
out a thunderstorm on this day. Both of these days could produce
lightning and gusty winds with any storms that form. Since its
Memorial Day weekend, expecting a lot of outdoor activities, and
anyone with outdoor plans should have a plan in place for
thunderstorm activity. Bulk shear values are not overly impressive,
so not expecting storms to maintain long enough for hail production.
However, DCAPE values are progged to be around 1000-1300 J/kg which
seems reasonable given the inverted-v sounding profiles. These
values could easily produce wind speeds around 45 to 55 mph with any
downburst through evaporative cooling processes. This threat will be
highest Sunday for eastside areas where DCAPE will be highest
between the two days of thunderstorms. Lastly, not expecting a lot
of rainfall with these showers, but a few areas could pick upwards
near a 0.10" of rainfall. That said, most ensemble members show very
little rainfall accumulation.

On Tuesday, another ridge will build in over the forecast area. Then
another trough comes through the PacNW beginning on Wednesday.
Wednesday will be the warmest day of the current 7 day forecast.
However, not expecting record temperatures but we will be close. For
perspective, Medford`s record high temperature for May 28th is 99
degrees and we are forecasting 95 for a high. Another round of
precipitation expected late Wednesday into Thursday. At this time,
instability values are low to nonexistent, so not expecting
thunderstorms through middle of next week, but given the time of
year this could change over the coming days.

-Guerrero

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT early
     this morning for PZZ356-376.

&&

$$

JWG/JWG/JWG