115
FXUS66 KMFR 050337
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
837 PM PDT Tue Jun 4 2024

.SHORT TERM...A weak front is moving inland. Moisture with this
system is centered to the north. So little in the way of rainfall
has occurred. Coastal Coos and Douglas have reported light rain of
0.01 to 0.10 inches but inland areas have remained dry. Models
show this front bring some light rain int tonight for parts of
Coos, northwest Douglas and the south-central Oregon Cascades. A
high pressure ridge builds Wednesday into late this week. Marginal
mid level moisture coming up from the south and weak instability
may allow for some isolated showers and thunderstorms (10-20%
chance) in eastern Modoc County Wednesday late afternoon/evening.
This chance increases (10-20%) over a wider area Thursday and
Friday afternoon/evening across northern California and from the
Southern Oregon Cascades east.

Otherwise, expect a warming trend with high temperatures warming
in to the 80s and 90s across inland valleys Thursday and Friday.
There is a chance for 100 degrees in the Medford area as well as
the valleys across western/central Siskiyou County (20-40% chance
except 50-80% in lower parts of the Klamath River Valley in
western Siskiyou). For additional details on the expected heat
late this week, please see the previous discussion below.

Coastal locations will also see a warming trend mid to late week,
with the warmest temperatures across coastal areas in southern
Curry County. Additionally, beach conditions are expected tonight
through Wednesday as elevated wave/surf conditions are expected.
Please see the beach hazard statement (CFWMFR) for details.

&&

.AVIATION...05/00Z TAFs...IFR and MVFR marine stratus was occurring
early Tuesday evening north and west of I-5 on the Lane-Douglas
county line to near Port Orford in northern Curry County. These low
clouds will spread inland overnight and may spill over the Rogue-
Umpqua Divide into parts of the Illinois and Rogue valleys toward
daybreak, but shouldn`t last too long before conditions become VFR
again.

Farther south and east...VFR conditions are expected although
weakening mountain wave turbulence will occur near the Cascades and
eastward tonight.
Sandler


&&

.MARINE...Updated 830 PM Tuesday, June 4, 2024...Gusty south to
southwest winds will continue to diminish this evening as a weak
front moves out of the region. The combination of increasing seas
tonight into Wednesday followed by gusty winds Wednesday afternoon
and Thursday will keep a small craft advisory in effect. Late
tonight into Wednesday, seas will become swell dominated as a late
season swell builds into the waters. West swell of to 10 to 13 ft at
14 to 15 seconds will maintain steep seas for all areas through
Wednesday.

Meanwhile, a thermal trough will develop and winds will turn
northerly late tonight, then strengthen Wednesday into Thursday.
This will result in steepening seas south of Cape Blanco by
Wednesday afternoon, with very steep and hazardous seas developing
due to a mix of elevated swell and wind driven seas. Swell
diminishes on Thursday but gusty north winds peak south of Cape
Blanco, and could briefly approach gales south of Gold Beach during
the afternoon/evening. This will maintain steep to very steep seas
across all the waters, but seas will transition to wind driven,
especially south of Cape Blanco.

Friday into the weekend, the thermal trough pattern weakens and so
will northerly winds. Steep seas are likely to continue through
Friday, then subside on Saturday. This period of improved conditions
looks to be short lived, however, as guidance shows north winds
increasing again on Sunday and continuing into early next week.
Sandler

&&

.PREV DISCUSSION... /Issued 248 PM PDT Tue Jun 4 2024/

DISCUSSION...The short term models are in good agreement that light
showers/mist are likely to persist on and off in Douglas and Coos
county through late tonight. In the past 6 hours...there has been
no sign of measureable precipitation...however just north of
Douglas county along the coast...0.07" was observed in the past 3
hours.

Where cloud cover continues to persist...mainly along the coast
and in Douglas county...temperatures were similar to around 8
degrees warmer than yesterday. Elsewhere...temperatures were
anywhere from 10 to as much as almost 20 degrees warmer compared
to yesterday.

There are a few cu buildups this afternoon...not a ton of vertical
development...but it does make for some nice looking clouds in
the Rogue Valley and possibly a nice sunset?

Upper level high pressure over the desert southwest will continue
building north and west into southern Oregon and northern
California...continuing the warming trend. Temperatures are
expected to warm another 5 to 10 degrees across the area tomorrow.
With the continue warmth and with marginal mid level moisture...a
slight chance of thunderstorms will be possible (15-25% chance)
in far southeastern Modoc county late Wednesday afternoon into
Wednesday night.

-Riley

LONG TERM...Thursday through Tuesday, June 6-11, 2024...The hottest
weather of the season thus far is expected to end the work week. A
strong upper ridge will be centered from the Desert SW to west
Texas, the axis of which will extend all the way to coastal British
Columbia, Canada. This will allow a corridor of warm mid-level
temperatures to extend into SW Oregon and NorCal Thursday and
Friday. On Thursday, the core of the heat will be over NorCal with
temperatures in population centers generally peaking in at 90-95F,
but nearing 100F in portions of the lower Klamath/Salmon river
valleys. Farther north over inland SW Oregon, expect highs in the 85-
95F range, highest in Medford/Grants Pass. There could be a bit of a
Brookings Chetco effect on Thursday with highs of 75-80F. The coast
north of Cape Blanco will be cooler though with highs of 65-70F.

The peak of this mini hot spell will be on Friday. We`re forecasting
97F in the official forecast for Medford. As mentioned yesterday, we
aren`t expecting widespread record-breaking warmth with this event,
but a few records may be challenged/broken. Cities most likely
to challenge or break records are Mount Shasta, Klamath Falls and
Alturas. Mount Shasta City could reach or exceed their records for
both Thu/Fri (94F in 2013, 92F in 2015, respectively). Klamath Falls
is mostly likely to tie/break their record on Friday (91F in 1996),
as is Alturas (93F in 1996). The Friday record high of 101F set in
2015 here in Medford appears safe -- NBM probabilities of MaxT>=100F
are now 27%. The good news about the upcoming heat is that it still
looks like it should cool off enough at night to provide some
relief. This is likely the main reason NWS HeatRisk is only showing
values in the orange "moderate" (2) category, so we aren`t planning
any heat-related headlines. However, we still want to stress to
those sensitive to heat: 1) try to keep outdoor activities to
the cooler parts of the day, 2) stay hydrated, and 3) stay cool,
preferably in an air-conditioned building, during the peak afternoon
heating period (2-6 pm).

Most locations will be dry Thursday and Friday. However models do
show weak impulses moving in from the southwest. This, in
combination with weak instability and mid level moisture from
the Cascades/Siskiyou Mtns south and eastward could trigger isolated
thunderstorms each afternoon and evening.

This weekend, a weak upper trough will move across the area pushing
the upper ridge axis to the east. This will allow temperatures to
trend slightly lower, but still remain well above normal. With
the upper trough moving through, a slight chance of thunderstorms
persists from the Cascades eastward in Oregon. It`s also not out of
the question that something pops up near the Trinity Alps during
this time period, but right now thunder probabilities are fairly low
(<15%) and once again, most of the area will largely remain dry.

Model ensembles and clusters show a majority of members rebuilding
the ridge over the area Monday/Tuesday of next week with a
continuation of above average temperatures (perhaps rising into the
mid 90s again here in Medford). While the warm pattern could last
through mid next week, there are indications that upper
ridging will shift eastward at some point, bringing cooling at
least back toward normal. -Spilde


BEACH HAZARDS...Updated 230 PM Tuesday, June 4, 2024...Abnormally
high waves and surf are expected (tonight through Wednesday) due
to a late season west swell of 10 to 13 ft at 14 to 15 seconds.
This will result in surf heights of 16 to 19 ft, which is uncommon
for June. These higher than usual conditions could catch beach
goers off guard, especially those not familiar with the Pacific
Ocean. If people are caught off guard, they could be knocked off
their feet and pulled into the cold ocean waters, resulting in
hypothermia or worse. If you see someone get swept into the ocean,
do not go after them. Instead call 911 immediately and keep an
eye on them until help arrives. Avoid climbing on rocks and
jetties. Keep your distance from the ocean and remain out of the
surf zone to avoid hazardous conditions. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement through Wednesday evening for ORZ021-
     022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Friday
     for PZZ350-356-370-376.

     Hazardous Seas Warning from 5 PM Wednesday to 5 AM PDT Friday
     for PZZ356-376.

&&

$$

CC