941
FXUS66 KMFR 042148
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
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


&&

.AVIATION...04/18Z TAFs...A weak front will move onshore today.
This will result in a mix of MVFR/VFR ceilings and some light rain
showers across NW sections of the forecast area, but it will remain
dry south of the Rogue-Umpqua Divide and east of the Cascades.
Mountain wave turbulence can be expected in the vicinity of the
Cascades and eastward. Brief gusty W-NW winds (to around 20 kt) are
forecast for Medford and Klamath Falls this afternoon.

Tonight into Wednesday morning, VFR will prevail at Klamath Falls
and also Medford for most of the night. MVFR and even some IFR
ceilings are expected at North Bend and Roseburg as marine stratus
infiltrates the area. These may spill over the Rogue-Umpqua Divide
into portions of the Illinois and Rogue valleys toward daybreak, but
shouldn`t last too long before conditions become VFR again. -Spilde


&&

.MARINE...Updated 230 PM Tuesday, June 4, 2024...Gusty south to
southwest winds will diminish this afternoon as a weak front moves
out of the region. Though there will be a brief period of improved
conditions this evening, have decided to just continue the small
craft advisory through into the next hazard. 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. /BR-y

&&

.BEACH HAZARDS...Updated 230 PM Tuesday, June 4, 2024...Abnormally
high waves and surf are expected 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 from 11 PM PDT this evening 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.

&&

$$