741
FXUS66 KMFR 081609
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
909 AM PDT Wed May 8 2024

.DISCUSSION...Made some minor updates to the forecast for this
morning. First was to cancel the Freeze Warning early. Freezing
temperatures were observed in portions of the
Shasta/Scott/Applegate Valleys, but for areas in the Illinois
Valley, gusty east to northeast winds kept temperatures elevated
overnight. Some freezing temperatures were also observed in the
outskirts of Jackson County, but temperatures have already risen
this morning, so the Freeze Warning was cancelled early.

There is some lingering cloud cover in the Umpqua Basin and across
portions of Lake County, but this will gradually dissipate over
the next few hours leading to sunny skies across the region this
afternoon. Temperatures will trend warmer today under
strengthening high pressure aloft and a strengthening thermal
trough at the surface. Temperatures will be about 10 degrees
warmer today compared to recent days, nearing values more typical
for this time of year. Expect some gusty north to northeast winds
today under this pattern, and the Chetco Effect will bring some
warmer temperatures to the Brookings area this afternoon (low to
mid 70s). Forecast updates included tweaking temperatures by a few
degrees for this afternoon as well as nudging winds towards the
latest guidance.

While temperatures will be near normal values today (upper 60s/low
70s west of Cascades, upper 50s/low 60s east), this will be last
day through at least early next week for near normal temperatures.
A sharp warm up is in store for Thursday into the weekend with
high temperatures reaching 10 to 15 degrees above normal. For more
details on this, please see the previous discussion below. /BR-y

&&

.AVIATION...08/12Z TAFs...Expect VFR to prevail today, though areas
of MVFR are possible in portions of the Umpqua Basin and Coquille
Basin early this morning. These shouldn`t last much longer than 16
or 17Z this morning. Expect gusty north to northeast winds again
this afternoon, peaking to 20 to 25 kt inland and around 30 kt at
North Bend, easing during the mid-late evening. -Spilde/Hermansen

&&

.PREV DISCUSSION... /Issued 852 AM PDT Wed May 8 2024/

Updated Marine Discussion.

MARINE...Updated 845 AM Wednesday, May 8, 2024...A strong thermal
trough will persist through tonight. This will result in moderate to
strong winds, with winds strongest south of Cape Blanco with gales
and very steep seas. Winds will increase north of Cape Blanco later
this afternoon into tonight. Wind speeds should remain on the high
end of Small Craft, however very steep wind driven seas will result
in Hazardous Seas Warning conditions for the all of the northern
waters. The thermal trough will weaken Thursday, but lingering steep
to very steep seas are possible. Lighter winds and seas expected
Friday into the weekend. -Petrucelli

DISCUSSION...

Temperatures aren`t dropping much this morning as dewpoints stay
in the mid 30`s across a lot of valleys west of the Cascades. The
exception appears to be the Scott Valley with temperatures
currently around 32 to 34 with dewpoints in the upper 20`s. Other
than the patchy freezing conditions across the forecast area this
morning, concerns are minimal given the current temperatures.

High temperatures will trend about 10 to 15 degrees higher today
compared to Tuesday as high pressure continues to build over
southern Oregon and northern California. A thermal trough will
strengthen along the southern Oregon coastline this morning with
some north east flow developing along the coastal range. Brookings
and Somes Bar in south western Siskiyou County will be the warm
spots later today with both pushing into mid 70`s with Somes Bar
potentially hitting the 80`s. Overall, this is pretty typical for
temperatures this time of year as Medford`s average high is 72.

Temperatures will continue to trend warmer by Thursday as high
pressure strengthens off the coast and winds becomes more
widespread out of the east. This should result in further bump in
temperatures with the most notable jump around Roseburg and North
Bend with an anticipated high of 83 and 75 degrees respectively on
Thursday. This warm up will push highs well above their normals
for this time of year.

The thermal trough will move farther inland on Friday with sea
level pressure dropping about 10 mb east of the Cascades and the
1000-500 mb thickness` rising over locations farther to the east
as well. These days are usually some pretty warm days and the
temperature forecast shows this with some highs potentially
hitting 90 degrees. The NBM gives Medford a 15% chance of hitting
90 and Roseburg a 40% chance of hitting 90 on Friday. Not much
will change on Saturday, although the temperatures might trend
down a degree or two. It`s worth noting that the NWS` heat risk
algorithm is showing an elevated heat risk for populated areas on
Saturday, perhaps due to the unusually warm high temperatures for
this time of year. Given that low temperatures are falling into
the mid 50`s, this elevated risk seems overdone.

Towards the start of next week, the NBM is predicting a 5% chance
of precipitation across sections of northern California as a weak
short wave could be moving through around Sunday evening or
Monday evening. To elevate the thunderstorm threat, we pushed the
probability of precipitation higher for those times. Any shortwave
this time of year will have that threat of kicking off
thunderstorms around the forecast area.

Towards the middle of next week it appears high pressure will
still remains in control. Temperatures have a higher probability
being warmer than normal versus cooler than normal for the middle
of May.

-Smith

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 PM PDT this
     afternoon for PZZ350-356-370-376.

Hazardous Seas Warning from 2 PM this afternoon to 5 AM PDT
     Thursday for PZZ350-370.

     Gale Warning until 5 AM PDT Thursday for PZZ356-376.

&&

$$

MNF/MAP/CZS