FXUS66 KMFR 292157
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
257 PM PDT Mon Jul 29 2024

.DISCUSSION...

KMAX is picking up on some fast moving echos moving through the
northern sections of the forecast area. Very little has hit the
ground as this moisture has moved through the forecast region. The
chance of precipitation is about 15 percent in northern Lake and
Klamath Counties this afternoon with a 10% chance of thunder in
the same area. It will be something to keep an eye on over the
next few hours with a little more increase in surface heating east
of the Cascades.

As for smoke this afternoon and evening, fires are still putting
out some smoke, although it seems to be a lower concentration
compared to previous days. The smoke plumes will track farther to
the east with the deeper westerly flow this afternoon through this
evening. The Oregon DEQ issued another air quality advisory due
to fire activity for Klamath and Lake counties.

For tonight, another round of fog along the coast is the next
weather feature to talk about. Models feel pretty confident in
lowering visibilities along the coast later tonight with arrival
of this round of moisture. BUFR soundings also show some pretty
strong inversions, which should support fog development along the
coast.

As we head into the week, temperatures will begin to trend warmer
with highs pushing through the mid 90's in valleys west of the
Cascades. A 500 mb ridge begins to build in Wednesday and further
strengthens on Thursday. We're currently forecasting high
temperatures in the mid 100's Thursday and Friday afternoon within
valleys west of the Cascades. The NWS HeatRisk algorithm is
picking up on major risk Thursday and Friday in the Rogue Valley
as low temperatures hover in the mid 60's. We held off on a heat
advisory for now as we are at the hottest time with many strong
heat events already occuring earlier this summer. In addition,
this mini episode of heat is only two days. None the less, it will
be warm heading into the weekend.

The next topic will be the potential for thunderstorms Friday into
Sunday with a low offshore ushering in some tropical moisture.
Model guidance and some of the ensembles show some upper level
energy from California riding over the ridge into this weekend.
This energy could kick off some thunderstorms over our forecast
area, especially around the Saturday time frame. Timing is a
little uncertain at this point, although the NBM picking
forecasting a 20-25 percent chance of cloud to ground lightning
over large areas of the forecast area is something to note.

-Smith

&&

.AVIATION...29/18Z TAFS...Marine stratus/fog and patchy drizzle with
IFR/MVFR  and areas of LIFR will impact all areas along the coast
and over the coastal waters today.  VFR is expected  inland through
early this evening, though some mid and high level clouds associated
with a weak front are expected. This front could bring some light
rain/drizzle again NW of the Umpqua Divide and along the coast into
this evening. tonight A deep marine push is expected west of the
Cascades tonight with some "spillover" possible into the
Rogue/Illinois valleys. Overall, ceilings will range from MVFR to
VFR inland, between 2000-5000 ft, but probably IFR/LIFR again along
the coast.

Winds this afternoon/evening will be more westerly with the densest
wildfire smoke staying away from the TAF locations. Some smaller
airports in northern Lake or Klamath Counties could see visibilities
as low as 3SM. -CC

&&

.MARINE...Updated 200 PM Monday, July 29, 2024...A weak front
will bring mostly light south to southwest winds and a chance of
light rain showers or drizzle through this evening. The front moves
inland tonight with relatively calm conditions persisting into
Tuesday. North winds return Wednesday and Thursday and seas could
become steep again, especially for areas from Cape Blanco southward
and beyond 10 nm from shore north of Cape Blanco.  Winds and seas
lower briefly on Friday. Then, a stronger thermal trough may set up
Saturday and Sunday. This would result in gusty winds and steep
seas,  highest south of Cape Blanco. These conditions may last into
early next week. -CC

&&

.FIRE WEATHER...Issued 200 PM Monday July 29, 2024...A mostly dry
cold front will pass through the area today, and some drizzle or
very light rain is possible along the coast and into the Umpqua
Basin. While winds are expected to increase as the front approaches,
humidities are expected to also rise, keeping most of the area well
under critical thresholds. East of the Cascades, particularly in
zone 625, humidities will be slower to rise, but conditions should
still remain below critical thresholds, although it will be very
close.

After the front passes, upper level ridging and the thermal trough
will quickly return to the area for the remainder of the week, with
temperatures once again rising to well above normal while humidities
and overnight recoveries worsen. Typically a period of instability
and thunderstorms tends to follow these periods of heat, and this
looks to be no exception. Confidence on any detail of timing and
location is much too low at this time frame, but we will continue to
monitor the potential for lightning next weekend. That being said,
the latest guidance suggests that thunderstorms will be most
probable along and east of he Cascades Saturday afternoon and
evening. -BPN

&&

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

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$