618
FXUS66 KMFR 271112
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
412 AM PDT Mon May 27 2024

.DISCUSSION...

The quiet weather pattern continues this morning with some lower
stratus along the coast within Coos County and coastal areas in
Douglas County. The weather feature for today will be the
low(5-10%) chance of cloud to ground lightning in Lake County and
a small section of Siskiyou County near Mt Eddy. This seems pretty
optimistic given how weak the lifting mechanisms will be today.
Although, one could analyze a stationary front right off the
coast later this afternoon. We think the GFS and NAM are overdoing
convection given that storms are triggering from hitting the
convective temperature and also require deep mixing. Other than
thunderstorms, it will be a warmer Spring day with highs pushing
into the mid 80`s here in the Rogue Valley and temperatures
trending about 10 degrees higher compared to yesterday.

The same concerns persist into Tuesday as the upper level trough
moves closer to the coast. The best chance for thunderstorms will
be east of the Cascades, although most of the action will
probably be outside of our forecast area. HREF probabilities are
notably higher on Tuesday, although are east of Lake County. Temperatures
trend lower, especially west of the Cascades with some stronger
onshore flow. It`s also worth noting 700 mb flow is slightly
stronger and wind gusts up to 30 mph east of the Cascades is a
reasonable prediction given how deep mixing will be.

Eventually, the upper level trough will progress through the
forecast area on Tuesday night with a cold front following up the
trough passage. There is a low chance for some showers in the
Cascades and along the coast, but precipitation will be light and
likely under 0.1 inches.

Heading into Thursday and Friday, temperatures will gradually
warm up as a weaker ridge builds over southern Oregon. The
temperatures on Friday will be roughly 10 degrees warmer than the
normals for this time of year in late May, although remain a
limited heat risk to those sensitive to heat. Next weekend appears
rather quiet with high pressure remaining in control and highs in
the mid 80`s west of the Cascades.

By next week Monday and Tuesday, things could become more
interesting. The ensembles are showing a risk of a warm front and
almost atmospheric type river event hitting the Pacific Northwest.
IVTs are in the 90th percentile for this time of year 7 days out
in the NAEFS, which is notable. Right now, the best probability of
precipitation chances are to our north, although the NBM as a 25%
chance for many areas in our forecast area observing 0.25 inches
of rain over 24 hours ending at 4am on June 4th.

-Smith

&&

.AVIATION...27/06Z TAFs...VFR conditions will prevail through the
TAF period for most areas. Marine stratus will develop tonight along
the Oregon coast, with MVFR ceilings expected to persist into Monday
morning. This marine stratus is likely to seep into the Umpqua Basin
late tonight, but may not quite reach Roseburg. Have gone with a
scattered MVFR deck for Roseburg to reflect this thinking. The lower
conditions are expected to clear to VFR by late Monday morning, with
VFR prevailing into Monday evening. Expect the typical uptick in
afternoon breezes Monday afternoon. /BR-y

&&

.MARINE...Updated 200 AM Monday, May 27, 2024...Relatively calm
conditions will continue through Tuesday. Expect some locally gusty
north winds (15 to 20 kt) south of Cape Blanco within 20 nm from
shore today. Otherwise, relatively light winds and seas are
expected, and a weak upper trough will bring some slight (10-25%)
chances for showers north of Cape Blanco on Tuesday.

An upper ridge will build on Wednesday and remain in place through
the rest of the week with a strong thermal trough developing. This
will bring increasing north winds, with conditions hazardous to
small craft likely for all areas by Thursday. Strong north winds may
reach gales (50-90% chance) south of Cape Blanco, with the highest
chance for locations south of Gold Beach. Gusty winds and steep to
very steep and hazardous seas are likely through the end of the
week. Conditions may improve over the weekend. /BR-y/Hermansen

&&

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

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$