Wildfire in California, July 28 to 31, 2022

Area Forecast Discussion
National Weather Service Medford OR
917 PM PDT Thu Jul 28 2022

.DISCUSSION...

SYNOPSIS...
A strong, record breaking, and unusually long-lived heat wave
will peak today into Friday, and continue to impact portions of
southern Oregon and northern California through much of the
weekend. High risk for heat related illness will continue through
Saturday evening with temperatures challenging high temperature
records at most inland locations.

A slight chance of thunderstorms continues in the afternoon and
evening each day through Sunday, generally increasing Friday
through Sunday and centered from the coastal mountains to along
and near the Cascades. On Sunday, low pressure will approach
resulting some gusty westerly winds in the afternoon and evening
hours. It will also begin a cooling trend that's likely to bring
more seasonable temperatures through next week. -BTL

An update was issued earlier this evening, soon after the set of 18Z
data arrived, to fine tune the coverage of a slight chance of
thunderstorms this evening through Sunday evening. The tools/data
we have to work with, did a great job again with thunderstorm
activity that was indeed similar to slightly less active compared
to yesterday's 17 lightning strikes. Weak cells peppered the
radar screen with a quick estimate of 11 separate cells producing
in-cloud pulses, but only 2 lightning strikes.

As mentioned below in the day-shift discussion, the trend through
Sunday is expected to show an increase of thunderstorm
activity...especially for much of the area on Saturday and
Sunday. As was the case for the past couple of days, thunderstorms
on Friday will mainly be anchored to the terrain with weak
steering flow of around 5 mph. But, a subtle pattern shift is
expected to favor development over the Siskiyou Mountains as well
as the Marble Mountains and Cascades into Klamath County.

A cooling trend inland will begin Sunday and continue early in the
week, but stronger gusty, breezy westerly winds are expected east
of the Cascades. Instability and a slight chance of thunderstorms
may linger over portions of Lake and Modoc counties on Monday
afternoon. Otherwise, a stable air mass is likely for the
remainder of the week.

&&

.AVIATION...29/00Z TAFs...VFR conditions will continue throughout
the TAF period for all inland areas. Over the coastal waters and
along the immediate coast, MVFR and IFR ceilings are redeveloping
this evening, and will continue overnight before retreating back to
the coastal waters Friday morning.

Pockets of high-based convection are possible this afternoon and
evening over the higher terrain of northern California and along and
east of the Cascades. Lightning and gusty erratic winds are expected
in and around any thunderstorms. -BPN

&&

.MARINE...Updated 800 PM PDT Thursday 28 July 2022...Relatively
light north winds with seas at or below 5 ft will persist for most
areas into the weekend. A corridor of stronger north winds is
expected from Cape Blanco to Gold Beach and then beyond 5 nm from
shore from Pistol River southward. This will result in an area of
steep, 4-7 ft choppy seas through Friday evening. North winds
increase this weekend, and widespread steep seas may return to the
area at that time. -BPN/BR-y

&&

.PREV DISCUSSION... /Issued 309 PM PDT Thu Jul 28 2022/

Oppressive heat, generally a few degrees hotter than yesterday,
is baking SW Oregon and Northern California this afternoon and
will continue into this evening. As of last hour, at it's current
rate of ascent, the temperature at Mount Shasta City, CA was on
track to tie the all time high temperature record there of 105F,
reached on August 7th, 1981. This excessive heat and moisture
rising off of Mount Shasta, is giving rise to a cumulonimbus cloud
that could result in some cloud to ground strikes this afternoon
into this evening. Slow moving, cumulus build-ups are also
occuring now near Mount Bailey, Crater Lake NP, and in the
mountains west of the town of Weed.

Any thunderstorms today will be slow moving, and most likely
across the Cascades north of Lake of the Woods and in western
Siskiyou County in or near the Marble Mountains. Friday the threat
for thunderstorms will be in similar areas, though there's a bit
more concern for the Oregon Caves and Josephine County areas, as
well as into portions of the Bear Creek portions of the Rogue
Valley and portions of the Scoot and Shasta valleys.

Saturday and Sunday, as low pressure approaches, there will be a
little more wind to push thunderstorms off of the higher terrain
and out into some of the west side valleys. There will also be a
higher probability of gusty winds and rainfall from that activity
this weekend. In terms of fire start concerns, Sunday looks to be
the main day of concern across the area in terms of potential
lightning abundance.

Sunday will begin a cooling trend with seasonable temperatures
expected to continue through next week. ~BTL

FIRE WEATHER...200 PM PDT Thursday 28 July 2022...It will remain
very hot through the weekend, except for the coast and highest
elevations. It will also remain dry, except for isolated afternoon
and evening thunderstorms, mostly from the Cascades east and
Siskiyous south.

An upper level trough will approach the coast Sunday. This may bring
gusty afternoon and evening winds to areas east of the Cascades, and
also the possibility of scattered thunderstorms. Red Flag conditions
may develop Sunday due to the thunderstorms.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 9 PM PDT Saturday for ORZ030-031.
     Excessive Heat Warning until 9 PM PDT Saturday for ORZ024-026.
     Heat Advisory until 9 PM PDT Saturday for ORZ023.
     Excessive Heat Warning until 9 PM PDT Saturday for ORZ025-027.
     Excessive Heat Warning until 9 PM PDT Saturday for ORZ028-029.

CA...Heat Advisory until 9 PM PDT Saturday for CAZ084-085.
     Excessive Heat Warning until 9 PM PDT Saturday for CAZ080>083.

Pacific Coastal Waters...
     Small Craft Advisory until 5 PM PDT Friday for PZZ356-376.

DW/BPN