NWS Medford, OR wrote its last area forecast discussion before the first event at Jul 31, 9:43 PM PST, 2 hours 17 minutes earlier.
Area forecast discussion, Jul 31, 9:43 PM PST, 2 hours 17 minutes before
Area Forecast Discussion
National Weather Service Medford OR
1043 PM PDT Sun Jul 31 2022
Updated AVIATION Section
.DISCUSSION...Convection remains ongoing this evening along the
moist side of a deformation zone over our region as a result of
being squished between an area of low pressure to our west and
high pressure to our east. Lightning activity with these storms
has been vigorous at times, though thankfully a majority of it
has been in cloud. That said, 186 cloud to ground have been
registered so far with heavy concentrations along the Cascades,
especially around the Sprague River, Modoc Point, and Klamath
Falls area.
The pattern won't change much overnight and this means we will
need to keep a watchful eye on overnight storms. Isolated
thunderstorms riding along the coast range. However, more vigorous
storms will remain focused along the and east of the Cascades
tonight.
It's worth noting that the troposphere will only continue to
moisten into tomorrow. This means that some of these storms will
transition from being dry to wet, although rain will be focused
under the main core of the storm. Slow moving storms, which is
usually under about 10 mph will also become infrequent. While
ponding on roadways could be a problem with slow moving storms, in
general faster winds aloft should keep this on the lower
probability side of things. More present hazards from
thunderstorms beside cloud to ground lightning will be strong
outflow winds of 30-50 mph and small, wet accumulating hail up to
nickle size.
Heat related headlines will be ending tonight as a combination of
a deteriorating ridge of high pressure and smoke work to mitigate
the worst of the heat. However, smoke will act to hold overnight
temperatures up more than normal, so overnight relief could be
less than expected (or hoped for from this meteorologist). As
noted earlier, more moisture is being funneled into the region.
This may bring out that stick feeling that humidity creates, with
our region experiencing some of the highest max humidities tonight
and tomorrow night that we have observed in some time.
Finally, with southerly winds aloft, smoke from wildfires in
Siskiyou County, California will continue to move northward into
Oregon creating air quality concerns. Smoke from area wildfires
may create periods of degraded air quality. Please see the AQAMFR
or the Oregon DEQ website for more details; or visit the Air
Resource Board web page for those in NorCal. ~Miles
&&
.AVIATION...01/06Z TAFs...IFR/LIFR conditions in marine stratus
will continue to impact areas over the coastal waters and
along the coast through the TAF period. There was a little
disruption in the marine layer today, especially offshore, where
significant elevated instability led to quite a few cloud to water
lightning strikes beyond about 30NM from shore and south of Gold
Beach. The marine layer has deepened again this evening with
ceilings lowering back down to IFR/LIFR at North Bend as it presses
onshore into Coos County. There is still some elevated instability
present tonight and while showers are the most likely weather
phenomena, thunderstorms are possible again. The stratus will
retreat back to the beaches again Monday afternoon with a chance at
brief VFR at North Bend.
Inland, isolated to scattered showers and thunderstorms tonight
still pose the risk for gusty, erratic outflow winds, brief
downpours and hail. Overall, expect VFR, though any storms may
bring local MVFR. Areas of IFR/MVFR vis in haze/smoke in the
vicinity of the McKinney fire will persist in northern Siskiyou
County and into the south end of the Rogue Valley, up towards
Medford. We expect isolated to scattered convection again
Monday afternoon/evening, though smoke from the McKinney fire
will likely once again be a limiting factor. Most likely area for
scattered storms will be from the Cascades/Foothills eastward.
-Spilde
&&
.MARINE...Updated 900 PM PDT Sunday, 31 July, 2022...Low pressure
centered west of the Northern California coast will bring mostly
southerly winds south of Cape Blanco and variable winds north of
there through Monday evening. Isolated showers and thunderstorms are
possible during this time with down strikes possible through the
marine stratus and fog. Light north to northwest winds are then
expected Monday night through Wednesday as the offshore low drifts
westward. North winds are then likely to increase, possibly reaching
advisory levels Thursday afternoon. This is expected to build steep
seas to advisory levels Thursday evening into Friday. -Spilde
&&
.FIRE WEATHER...405 PM PDT Saturday, 30 July 2022...
Increasing smoke, cloud cover, and moisture has begun to lower
temperatures compared to the peak of this heat wave, but hot weather
is generally expected to continue through the weekend. Thunderstorms
in the Red Flag Warning area in Josephine and Jackson counties today
are likely to be somewhat muted by smoke from the McKinney Fire,
however thunderstorms are still likely in much of the warning area.
Sunday into Monday low pressure offshore and a broad southerly flow
will continue to bring isolated to scattered showers and
thunderstorms across the forecast area. Watches and warnings have
been updated to highlight the locations of most concern for
lightning abundance. Part of the adjustment was to reduce headlines
across the west side due to the mitigating effects of the smoke from
the McKinney Fire on thunderstorm strength and lightning abundance.
Today through Monday storms will trend from dry to increasingly
wetter as temperatures come down and moisture levels rise. The
threat for showers and thunderstorms may linger next week due to the
low offshore becoming nearly stationary. ~BTL
&&
.PREV DISCUSSION... /Issued 607 PM PDT Sun Jul 31 2022/
SYNOPSIS...Hot temperatures will persist this afternoon, then
lower slightly Monday and Tuesday. Meanwhile, an upper low just
off the coast of southern Oregon and northern California will
remain near stationary. This will result in continued chances of
thunderstorms and showers over the next few days. Additionally,
with southerly winds aloft, smoke from wildfires in Siskiyou
County, California will continue to move northward into Oregon
creating air quality concerns.
KEY POINTS:
*Excessive Heat continues today across portions of southern
Oregon and northern California. Stay hydrated, take frequent
breaks in air conditioning, find cooling stations, and check on
your friends and neighbors if they do not have air conditioning.
Remember, never leave pets or people in cars.
*Smoke from area wildfires may create periods of degraded air
quality. Please see the AQAMFR or the Oregon DEQ website for
more details.
*Thunderstorms may produce occasional to abundant deadly cloud to
ground lightning, gusty and erratic winds, and small hail.
*Lightning may ignite new wildfires. More information is available
in the fire weather section below.
*Smoke from the McKinney fire will likely complicate the forecast
in regards to heat and thunderstorms.
DISCUSSION...We are split between two weather patterns--a low
pressure system off the coast and a ridge of high pressure
centered near the 4 corners region of the US. This is bringing in
deep southwest flow aloft as well as monsoonal moisture from the
Desert Southwest. Ensembles are pretty sure that the
aforementioned low will remain relatively stationary before
retrograding westward as the 4 corners ridge nudges westward
slowly by the weekend into next week.
This means that we are expecting thunderstorms each afternoon and
evening across a broad area of southern Oregon and northern
California. Satellite and Radar have already recorded some showers
and thunderstorms away from the smoke of the McKinney fire in
Douglas County, the Cascades, and in northern California as well
as for the Marine Waters. Expect this to continue with additional
thunderstorms possible this afternoon and evening. Storms may
become strong with wind gusts to 50 mph and small hail. Storms
should also be on the wetter side as opposed to the drier side.
The Storm Prediction Center has backed off on the organized threat
for severe weather on Monday, and we agree with that assessment.
However, one or two storms may over achieve on Monday and become
strong to severe with gusts to 60 mph and nickel sized hail. While
we expect thunderstorms again Tuesday, we have also added them for
Wednesday but have admittedly less confidence.
The other portion of the forecast is the heat. The excessively
high temperatures have decreased for areas west of the Cascades
due to smoke from the McKinney fire. Have adjusted temperatures
downward in some West Side locations to account for this. Still,
with the smoke; relief from the heat will be limited for those
areas with other areas remaining relatively hot; so will allow the
heat advisories and excessive heat warnings continue until their
conclusion tonight. More information is available in the NPWMFR.
The ridge of high pressure and subsequent thermal trough should
build back into the area late this weekend into next week. -Schaaf
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 11 PM PDT this evening for ORZ030-031.
Red Flag Warning from noon to 11 PM PDT Monday for
ORZ617-623>625.
Excessive Heat Warning until 11 PM PDT this evening for
ORZ024-026.
Excessive Heat Warning until 11 PM PDT this evening for
ORZ025-027.
Red Flag Warning until 11 PM PDT this evening for
ORZ617-623-624.
Excessive Heat Warning until 11 PM PDT this evening for
ORZ028-029.
CA...Heat Advisory until 11 PM PDT this evening for CAZ084-085.
Red Flag Warning from noon to 11 PM PDT Monday for CAZ284-285.
Excessive Heat Warning until 11 PM PDT this evening for
CAZ080>083.
Red Flag Warning until 11 PM PDT this evening for
CAZ280-281-284.
Pacific Coastal Waters...
None.