381
FXUS66 KMFR 120541
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1041 PM PDT Sat May 11 2024

.DISCUSSION...Updated Aviation and Marine sections...

.AVIATION...12/06Z TAFs...Along the coast and just offshore,
marine stratus is currently being observed along the coast to
around 15 nm from shore north of Cape Blanco and has pushed
farther south and is filling along the south coast tonight,
resulting in IFR ceilings. Breezes are expected once again in the
afternoon.

Inland, VFR ceilings will continue through the TAF period. The
marine stratus could work its way into the Coquille Basin late
tonight, but it should be shallow and burn off towards 18z Sunday.
-Petrucelli/Hermansen

&&

.MARINE...Updated 800 PM Saturday, May 11, 2024...The latest surface
analysis shows the thermal trough inland with winds and seas
diminishing. This is being supported by the latest ASCAT pass which
shows winds around 10 knots closer to shore near Gold Beach and
around 15 knots beyond 5 nm from shore. The latest high res guidance
shows an expansion fan southeast of Port Orford to around 40 nm from
shore late this afternoon into Sunday afternoon, and the combination
of seas and winds could result in low end small craft conditions.
Therefore adjustments were made to the coverage area for Small Craft
conditions to better match what the data is supporting.

The thermal trough will strengthen late Sunday afternoon with Small
Craft Conditions affecting all of the waters. The thermal trough
will strengthen further late Monday afternoon and likely remain a
factor for most of next week, with moderate to strong winds and
steep to very steel wind driven seas. Confidence is high enough for
gale force winds to develop late Monday afternoon and persist
through at least Tuesday afternoon. It`s not out of the question
Gales could persist beyond Tuesday afternoon. Thus a Gale Watch has
been issued for most of the southern waters, except withing 5 nm
from shore and for the northern waters west of Cape Arago and beyond
10 nm from shore west of Cape Blanco through Tuesday afternoon, but
it could very well go beyond Tuesday afternoon. Please see MWWMFR
for all of the details on the various marine headlines.
-Petrucelli/Smith

&&

.PREV DISCUSSION... /Issued 217 PM PDT Sat May 11 2024/

DISCUSSION (Today through Friday)...

Overview:

An overall quiet forecast with very little weather impacts to speak
about. That said, we do have a couple items that are noteworthy.
There will be a very slim chance at thunderstorms both this
afternoon (<15%) and tomorrow afternoon (<20%). The coverage area is
also very small, but given the threat for lightning it is worth
mentioning. The area would be mainly for eastern Siskiyou/western
Modoc Counties in northern California and parts of the eastside over
Klamath/Lake Counties. As mentioned, the main threat would be
lightning as we are not expecting any severe weather. Additionally,
with the warm weather continuing, we will have dry afternoons with
RH dropping into the teens to 20% range. This is especially true for
the eastside where these dry condition will last through next week.
As for winds, is does look like each afternoon next week could have
breezy wind speeds. Speeds may be around 10-15 mph nearly everywhere
over the land, but the eastside may be around 15-25 mph.

Further Details:

Current visible satellite indicates mostly clear skies over the
land, but we do have cumulus evident over the eastside as well as
isolated westside areas; however, the Day Cloud Phase Distinction
product doesn`t indicate much--if any--vertical growth. Models
are suggesting we could see around 100-200 J/kg of most unstable
CAPE this afternoon, but upwards near ~500 J/kg in the most
aggressive solutions. We do not have the best forcing/dynamics
around today, so even the 5-15% chance for showers/thunderstorms
today might be too much, but its still not a zero chance. Tomorrow
afternoon we have a better chance at hitting convective
temperatures, so confidence is a little higher having that trigger
mechanism, albeit still only around a 20% chance. Some of the
HiRes convective allowing models are hinting at potential
thunderstorms as well, so we`ll have to see how that all plays
out. All that said, lightning would be a threat today and
slightly more so tomorrow afternoon, but we are not expecting
severe weather or widespread lightning if it does occur.

At this time, there isn`t any one day in particular that stands out
for wind speeds, but the pressure gradient will strengthen each
afternoon with decent mixing each afternoon as well. The probability
for us reaching advisory level wind speeds any afternoon next week
is less than 20 percent at this time, but we should watch this trend
going forward given the warm and dry conditions forecast to persist
through next week.

-Guerrero

&&

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

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

Gale Watch from Monday afternoon through Tuesday afternoon for
     PZZ356-370-376.

&&

$$