502
FXUS66 KMFR 161606
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
906 AM PDT Thu May 16 2024

.DISCUSSION...Satellite imagery shows marine stratus made it as
far inland as the Camas Valley this morning. The thermal trough,
while still present, weakened enough to allow for a coastal eddy
(within about 2-4 NM from shore) from Brookings southward. This
resulted in a "fickle finger" of stratus/fog there this morning,
bringing an end to their mini heat wave. The clouds should break
up in most areas this afternoon, though could hold on in some
areas along the coast north of Cape Blanco. The remainder of the
area will be mostly sunny. Compared to yesterday, maximum
temperatures west of the Cascades will be near or even a little
lower today. Brookings could still reach well into the 70s this
afternoon, but it will be tricky given the stratus/fog this
morning. East of the Cascades and in NE California, today will
likely be the warmest day with high temps about 2-5F higher than
yesterday.

A cold front will move through tonight into Friday. A deeper
marine push will bring some clouds farther inland tonight into
Friday morning with some light rain showers or drizzle possible
(20% chance); best chance is north and west of the Umpqua Divide.
Clouds bank up against the Cascades/Siskiyous early Friday morning
with some even here for a while in the Rogue Valley, but these
should break up late Friday morning/afternoon. The frontal passage
should lead to about 5-15F of cooling on Friday (biggest temp
drop on the East Side). However, coastal areas will have highs
similar to today. -Spilde


&&

.AVIATION...16/12Z TAFs...Along the coast and just offshore, IFR
ceilings will persist for most of the TAF period, from Cape Blanco
north. The TAF at North Bend shows ceilings improving for a 2 hour
period late this afternoon and early evening, but confidence on the
duration is low and it could last beyond 2z. Meanwhile VFR ceilings
are expected to be the predominate condition south of Cape Blanco.

Elsewhere, VFR conditions will continue through the TAF period with
gusty afternoon and early evening breezes. -Petrucelli


&&

.MARINE...Updated 830 AM Thursday, May 16, 2024...A thermal
trough pattern, while weaker today, will maintain gusty north
winds and steep to very steep seas through tonight north of Cape
Blanco and through Friday morning south of the cape. The thermal
trough will restrengthen with possible gales south of Cape Blanco
again Friday afternoon and evening. North winds and steep seas
will likely persist this weekend. -Spilde


&&

.PREV DISCUSSION... /Issued 500 AM PDT Thu May 16 2024/

Updated Aviation Discussion.

SHORT TERM...A high pressure ridge will remain in place today
with offshore northeasterly winds. This will bring a pattern of
continued above normal temperatures, dry weather and afternoon
breezy to gusty north to northeast winds (especially along the
coast and for areas west of the Cascades).

High temperatures today will be similar across inland areas as
compared to yesterday. Along the coast, temperatures are forecast
to be lower in the Brookings area, compared to yesterday, but
still above normal. Clear skies are expected, except for along the
coast from Cape Blanco north and over the coastal waters where a
deepening marine layer is resulting in low clouds and fog.

Then, tonight into Friday, a weak trough will move inland just
north of the area. This will result in a chance (15-20%) for light
rain in Coos and Douglas counties overnight/Friday morning. Models
indicate that any rainfall that develops will be light (under 0.10
inch) with the best chances for light rain over the upslope areas
in the coastal mountains and Cascade foothills in Coos and Douglas
counties. Otherwise, expect slightly cooler temperatures (closer
to seasonal averages) across the area on Friday. As the trough
shifts eastward late Friday, breezy to gusty afternoon northerly
winds are expected to develop.

AVIATION...16/12Z TAFs...Along the coast and just offshore, IFR
ceilings will persist for most of the TAF period, from Cape Blanco
north. The TAF at North Bend shows ceilings improving for a 2 hour
period late this afternoon and early evening, but confidence on the
duration is low and it could last beyond 2z. Meanwhile VFR ceilings
are expected to be the predominate condition south of Cape Blanco.

Elsewhere, VFR conditions will continue through the TAF period with
gusty afternoon and early evening breezes. -Petrucelli

MARINE...Updated 230 AM Thursday, May 16, 2024...The thermal
trough pattern weakens some today and gales will ease. Despite this
subtle improvement, gusty winds and steep to very steep and
hazardous seas will persist through the end of the week. Conditions
may improve overall over the weekend as the upper level pattern
transitions, though expect conditions to remain hazardous to small
craft for areas south of Cape Blanco as northerly winds continue.
/BR-y/Petrucelli

PREV DISCUSSION... /Issued 203 PM PDT Wed May 15 2024/

LONG TERM...Friday 5/17 through Wednesday 5/22...The long term
forecast begins with a slight pattern change. While southern Oregon
and northern California will be mostly under the influence of a
ridge of high pressure for most of the weekend, a trough of low
pressure will dig southward over eastern Washington and Idaho. While
this will not bring rainfall to our area, this could cause breezy to
gusty northwesterly winds--particularly in the afternoons.
Additional troughs will dig southward following this trajectory, and
maybe a bit more southward over the weekend helping to keep us
somewhat cooler with additional afternoon breezes and some fair
weather cumulus clouds.

By Monday, an additional trough pushes southward, but this front
will be closer to central Oregon. This could bring additional breezy
winds, but also our first shower chances--particularly along the
higher terrain of the Cascades and coast range in Douglas and Coos
County. Rainfall will be relatively light, and thunderstorms are
generally not expected (less than a 10 percent chance).
Temperatures, however, will be several degrees cooler than over the
weekend.

Then on Tuesday into Wednesday, another low spins southward, this
time over western Oregon and could bring additional showers and
thunderstorms (chances are just less than 15 percent at this time).
Winds will continue to be relatively breezy and temperatures will
remain slightly below normal through mid-week. Since the weather
will be based on a low pressure system that has not formed yet, the
confidence is relatively low--especially since the impacts will be
tied to the location of the low. Used the National Blend of Models
and am forecasting the most likely scenario at this point since
clusters are in general agreement over the large scale and differ
over some of the smaller features. Keep an eye to the forecast for
updates. -Schaaf

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Friday
     for PZZ350-356-370-376.

Hazardous Seas Warning until 11 AM PDT Friday for PZZ356-376.

&&

$$

MAS/MAS/MAS