442
FXUS66 KMFR 242308
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
408 PM PDT Sat May 24 2025

.UPDATE...Updated Aviation Discussion.


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.AVIATION...24/00Z TAFs...For inland areas, VFR levels under clear
skies are expected across northern California and southern Oregon.
Along the coast of southern Oregon, MVFR ceilings under marine
stratus are expected this afternoon, becoming widespread later this
evening (along with local IFR) then persisting through Sunday
morning. Conditions along the coast will lift to VFR early Sunday
afternoon.


&&

.PREV DISCUSSION... /Issued 247 PM PDT Sat May 24 2025/

DISCUSSION...A strong ridge is building into the region,
resulting in dry and warm weather through the holiday weekend.
Much of this month has seen near or below normal temperatures, but
today, temperatures are expected to rise to levels more typical
of late June or early July.

The next upper trough will slowly move east towards the coast
late Sunday afternoon. Clouds will increase across the area as the
system approaches, and this will bring temperatures back down a
few degrees from today, but high will still be above normal for
this time of year. By Sunday afternoon, the trough will begin to
push onshore, and this will bring us a chance for showers and
thunderstorms over portions of the area. Sunday night into Monday
morning, the trough axis will pass overhead, but will weaken and
shunt off to the north as it does so, greatly reducing shower
chances in the morning, and ending all precipitation chances by
afternoon.

The best chance for thunderstorms will be on Sunday along and east
of the Cascades and north of Crater Lake, 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 due to low-level
moisture discrepancies-- is much higher with values approaching
1000 J/kg. Much less instability expected on Monday, but we 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 for strong winds will be highest Sunday
for East Side areas where DCAPE will be highest between the two
days of thunderstorms. Lastly, we are not expecting a lot of
rainfall with these showers, but a few areas could pick up a few
hundredths of an inch of rainfall. That said, most ensemble
members show very little rainfall accumulation, and most locations
in our area will remain dry.

Models are indicating that ridging will then enter the area and
remain in place through at least Wednesday or Thursday, keeping
the area dry and pushing temperatures back to well above normal
before the next trough arrives late in the week. During that
time, we will see some of the warmest temperatures of the season
so far. Wednesday and Thursday will be the warmest days of the
current 7 day forecast, with Wednesday`s high in Medford expected
to be in the low to mid 90s. That next trough will be lurking just
offshore, however, and will enter or pass near to the area late
in the week. If the trough passes through, we will see another
round of showers and cooler temperatures, but several models are
now showing it glancing off to our north, and this would keep the
area mostly dry, with the exception of the coast, and would only
allow temperatures to cool slightly before strong ridging and very
warm temperatures return for next weekend.
-BPN/Guerrero


MARINE....Updated 200 PM Saturday, May 24, 2025...Seas remain below
advisory conditions this afternoon with breezy winds and normal
swell heights. Westerly swell increases tonight ahead of a weak
front, with swell heights on Sunday evening. Conditions are expected
to remain below advisory levels, but local areas of steep seas are
possible in outer waters. This weak front will bring chances of
marine showers from Sunday afternoon through Monday morning.

Stable atmospheric conditions will prevent active weather through
the upcoming week, but thermal trough patterns may develop. Gusty
northerly winds look to build steep seas from Tuesday afternoon into
Wednesday. Current guidance brings steep seas as far north as
Reedsport. Early Friday morning, a more significant thermal trough
could develop, bringing steep to very steep seas and near gale
gusts. Please stay tuned as additional information helps to bring
clarity to these periods of possibly hazardous conditions. -TAD

&&

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

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$