491
FXUS66 KMFR 041157
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
457 AM PDT Tue Jun 4 2024

...Updated AVIATION forecast...

.DISCUSSION...Zonal westerly flow with weak ridging over the area
will continue today. A weak front is moving into the area this
morning and will bring a few isolated showers north of the Umpqua
Divide, Coos County and northern Cascades today into early this
evening. Afternoon temperatures for the interior will be warmer.

Dry weather is likely tonight into Wednesday. However there`s some
evidence supporting weak instability in southeast Modoc County late
this afternoon and early Wednesday evening along with increasing mid
level moisture and weak trigger. The combination of these could be
enough for an isolated thunderstorm or two to pop up late Wednesday
afternoon and evening.

A four corners high will set up Thursday and Friday with a southwest
flow over our area. While it will get warmer (hot for this time of
the year) for the interior, were not expecting any heatwave.
Afternoon temperatures Thursday and Friday will be in the mid 90s
for the interior westside valleys, upper 80s in the Umpqua Basin,
and upper 80 to lower 90s east of the Cascades. Overnight
temperatures will be mild, but still cool enough to provide cooling
and relief from the heating of the day. Most locations will be dry
Thursday and Friday. However models do show weak impulses moving in
from the southwest and this in combination with weak instability and
mid level moisture east of the Cascades could trigger isolated
thunderstorms late in the afternoon and early evening hours.

The weekend is expected to be cooler, but still with above normal
afternoon temperatures for the interior with upper troughing moving
into the area Saturday. Isolated thunderstorms are still possible
east ofthe Cascades Saturday afternoon and early Saturday evening
with the axis of the upper trough west of the Cascades. Sunday,
instability still exist east of the Cascades, but mid level
moisture is lacking and there`s little or no trigger. Therefore the
most likely scenario will be some building cumulus in the afternoon
hours.

The operational models show varying solutions for the start of next
week. The ECMWF shows an upper ridge building over the area while
the GFS shows a southwest flow aloft with the ridge southwest of the
area. The ECMWF Ensemble means show ridging for the start of next
week, but not a strong ridge, followed by weak upper troughing mid
to late next week. Therefore any warm up should be brief with a
cool down mid to late next week. Temperatures are still expected to
be above normal during this time, but the pattern is one that does
not suggest any heatwave. -Petrucelli


&&

.AVIATION...04/12Z TAFs...VFR levels continue over northern
California and southern Oregon, with radar indicating a few isolated
showers moving over Douglas County and the Cascades. Some low (10-
20%) precipitation chances will linger over the Oregon coast north
of Cape Blanco and the Cascades through this afternoon.

Atmospheric stability will start to develop this evening, which
would allow for marine stratus to develop along the Oregon coast
through the end of the TAF period. Models show some differences in
overall levels, but MVFR or IFR ceilings are expected. There`s more
variance in visibility outcomes, but lower visibilities are included
toward the end of the TAF period to highlight the possibility.
Inland areas will remain at VFR levels. -TAD


&&

.MARINE...Updated 230 PM Monday, June 3, 2024...Elevated and
gusty southerly winds will continue, with the strongest winds over
waters north of Cape Blanco. These winds will combine with fresh
swell to build steep seas in all waters, with isolated areas of
very steep seas possible north of Coos Bay this morning and
afternoon.

The front will leave area waters this afternoon but will be
followed by long-period westerly swell arriving in all waters early
Wednesday morning. Current guidance continues to expect this swell
being 10 to 13 feet at 14 to 15 seconds. This swell will maintain
steep seas in all waters as well as unusually high surf of 14 to 17
feet through Wednesday evening. A Small Craft Advisory currently in
place continues through Wednesday at 5 PM to describe the sea state
while a Beach Hazard Statement will be in place from 11 PM tonight
through Wednesday at 8 PM to address the high surf hazard along
Oregon beaches.

Active seas will continue as a thermal trough starts to build on
Wednesday afternoon and strengthens through the day Thursday,
bringing gusty northerly winds. Continuing westerly swell will
continue to support steep seas in all waters, with very steep and
hazardous seas developing over waters south of Cape Blanco through
at least Thursday afternoon. A Hazardous Seas Warning covers
expected areas of very steep seas from Wednesday at 5 PM through
Thursday at 5 PM. Areas of gale seas are possible Thursday night,
but additional information will help to confirm this possibility.

Current guidance shows the thermal trough weakening through Friday
with seas calming on Saturday before the thermal trough returns on
Sunday. Future guidance will help to determine if any additional
hazard products will be necessary later this week and over the
weekend, but some amount of activity looks to continue into next
week. -TAD


&&

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

CA...None.

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

     Hazardous Seas Warning from 5 PM Wednesday to 5 PM PDT Thursday
     for PZZ356-370-376.

&&

$$