436
FXUS66 KMFR 022121
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
221 PM PDT Sun Jun 2 2024

.SHORT TERM...Through Wednesday morning...A warm front is
bringing light, steady showers across areas west of the Cascades
this afternoon. Amounts have been light so far, with Brookings
getting 0.25 inches of rainfall and other coastal areas at 0.1
inches or less. Roseburg has gotten a couple hundreths of an inch,
and sidewalks are wet in Medford. Radar shows that the Cascades
are blocking anything substantial from traveling farther eastward.
Overall, the coast and the Cascades will get 0.33 to 0.5 inches
of rainfall from this first front

A trailing cold front will bring more substantial precipitation this
evening into Monday morning thanks to a plume of moisture from an
atmospheric river. Periods of moderate to heavy rainfall are
expected along the Oregon coast, coastal ranges, and the Cascades.
NBM outcomes show areas north of Gold Beach getting 0.15 to 0.25
inches per hour through this evening and areas around Brookings
getting 0.4 to 0.5 inches of rainfall per hour from near midnight
and into Monday morning. The Cascades will also be seeing rainfall
rates of 0.25 to 0.33 inches per hour from this evening into
tomorrow morning. While these rainfall rates don`t meet any hazard
criteria, anything that impacts nighttime driving conditions is
noteworthy. Slick roads from layers of water or from oils brought to
the surface are possible hazards and are worth being aware of. Urban
ponding is also a possibility, especially in areas with poor
drainage or accumulated debris. Some amount of rainfall is expected
across the area, but in much lower and generally non-impactful
amounts.

Elevated and gusty winds are expected for areas east of the Cascades
early Monday morning into Monday afternoon, with gusts likely (40-
60%) to exceed 40 mph over higher terrain. A Wind Advisory is in
place for parts of Lake County expected to see the strongest winds,
including the Winter Rim, Christmas Valley, and areas east of Adel.
This Advisory is in place from 11 PM tonight through Monday at 5
PM. Please see NPWMFR for more details.

Conditions start to calm on Tuesday under zonal flow aloft. Slight
precipitation chances (10-30%) will linger over the coast north of
Cape Blanco. Inland temperatures will jump quickly, with west side
valleys forecast to reach the low to mid 80s and areas east of the
Cascades will be in the mid to high 70s. Increasing temperatures will
continue into the long-term forecast. -TAD

.LONG TERM...Wednesday through Sunday...

BY Wednesday morning, upper level ridging will have built in over
the western half of the country, bringing an end to the slight chance
of showers over the northern portions of the area. By Wednesday
evening, however, the ridge will shift slightly to the east, with
the main ridge axis extending north along the Rocky Mountains from
Mexico. Meanwhile, a closed low is expected to develop just west of
Baja California, creating a conduit for warm, moist air to feed
north from the tropics and into portions of southern Oregon and far
northern California. This pattern is then forecast to remain
relatively similar through the rest of the week and into the week,
before breaking down under pressure form the next approaching trough
over the weekend.

All of this will result in a very warm forecast for the area, with
inland high temperatures of around 15 to 20 degrees above normal for
early June. Some of our warmer spots, such as the Rogue Valley and
the valleys of Siskiyou County, may even touch on the triple digits
Friday and/or Saturday. Most coastal areas will be warm as well,
although not quite as warm as the inland areas, with the exception
of a very warm Bookings, where a Chetco effect is expected to
develop along with the thermal trough, and high 80s or low 90s are
quite possible Wednesday and Thursday. One thing could significantly
limit how hot highs will be late in the week: clouds.

With the moist inflow form the south, we will also be concerned with
a daily threat of afternoon and evening thunderstorms, or even
overnight thunderstorms, as some models suggest and the pattern
would support. The main area of concern for convection will be
northern California and areas along and east of the Cascades, where
moisture will be most abundant and lifting mechanisms will be
strongest, but we can not rule out a stray storm or two making it
over to the West Side. Wherever the storms may be, clouds are likely
to spread over much of the area, and these will be the wild card in
terms of how high the highs get throughout the rest of the week.

Late this weekend or early next week, another trough approaches the
area from the west, putting pressure on the ridge and Baja low,
shifting them to the east. However, the exact nature of this trough
is very uncertain, with a wide range of possibilities across the
model suites. There does seem to be two major possibilities. The
first would be a trough that simply replaces the previous one off of
Baja, while the ridge remains in control overhead, and this would
result in continued warmth and keep us under threat of convection.
The other solution has the trough arriving later, but fulling
eroding the ridge, allowing for a brief cooling trend and reducing
the threat of convection, at least temporarily. Hopefully the model
suites can come to a better consensus on the forecast, but this may
take several cycles given the known difficulty models have with
closed low scenarios. -BPN

&&

.AVIATION...02/18Z TAFs...MVFR and IFR levels are present along the
Oregon coast as a warm front approaches from the Pacific, with VFR
levels presently over inland areas. Radar is showing showers across
areas west of the Cascades, with rainfall frequently affecting
visibilities at North Bend. Very little activity is getting east of
the Cascades so far.

Showers will continue across areas west of the Cascades today.  A
cold front will arrive tonight and bring moderate to heavy rainfall
over the Oregon coast and the Cascades through early Monday morning.
Light rainfall is expected across all other areas. Heavy or steady
showers can locally lower ceilings and visibility as well as obscure
terrain, so extra caution is encouraged. Gusty winds and low level
wind shear will be possible over the Cascades and higher terrain to
the east, especially early Monday morning. Model guidance does not
show shear over any airports, but wide areas of shear from the
southwest and at speeds of up to 50 kts are present over Lake and
Klamath counties until 14Z. -TAD


&&

.MARINE...Updated 200 PM Sunday, June 1, 2024...Strong southerly
winds are increasing wave heights across the waters today with some
hazardous seas anticipated to develop later this afternoon into the
early evening hours. Eventually, the southerly winds will subside
and a 8 to 10 foot west swell will move into the waters behind the
cold front on Monday. Seas will likely remain hazardous to smaller
crafts through Tuesday as some southerly winds increase again ahead
of another cold front.

This high west swell will likely continue through most of the week
and even combine with some stronger northerly winds on Wednesday and
Thursday as weak thermal trough sets up along the southern Oregon
coast. Overall, seas hazardous to smaller crafts will likely
continue through the week.

-Smith


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 11 PM this evening to 5 PM PDT Monday for
     ORZ031.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM Monday to 5
     AM PDT Tuesday for PZZ350-356-370-376.

     Hazardous Seas Warning until 8 PM PDT this evening for PZZ350-
     370.

&&

$$

TAD/CZS/BPN