Wildfire in California, August 15 to 26, 2023

Area Forecast Discussion National Weather Service Medford OR 238 PM
PDT Tue Aug 15 2023

.DISCUSSION...An upper level ridge remains over northern California
and southern Oregon, bringing generally stable conditions through
the rest of the week. Temperatures will remain significantly above
average today and Wednesday, with the Oregon coast looking to be in
the mid 70s to low 80s. West side valleys will be in the mid-100s,
and east side areas will see temperatures in the mid 90s.

Overnight temperatures will not offer much relief for west side
valleys, with nighttime lows reaching the low 70s while usual lows
are in the mid 50s. This is important to consider because the
temperature at any point in the day will be about 10 degrees warmer
than usual. Outdoor activity that might be pleasant on a normal
evening might still be hazardous tonight and Wednesday night.

There are possibilities of convective activity this evening from
eastern Douglas county to northwestern Lake County. CAPE values of
300-500 J/kg and about 1 inch of precipitable water could provide
enough uplift and moisture for some isolated showers and
thunderstorms. The forecast for tonight has 25% chances for activity
in the Douglas-Klamath-Lake area and 15% chances across Siskiyou and
Modoc counties.  There will be similar chances tomorrow, with a
slight (15%) chance extending into parts of Jackson and Josephine
counties as well.

A Pacific low pressure system will help to lower temperatures
starting Thursday afternoon, with a cooling trend expected to
continue through the weekend. Southerly flow from the system will
bring extra moisture over the area, bringing moderate chances (25-
40%) of precipitation across northern California and areas east of
the Cascades.

In the long term, an upper level trough looks to drop down from the
north and pass over the area late in the weekend. How this trough
and the existing low pressure system interact will determine if and
where any further precipitation happens. Beyond the trough's
passage, high pressure is expected to develop over the central
United States and rebuild an upper level ridge. The exact
development of that ridge is uncertain, but National Blend of Models
outcomes only has a 20% chance of temperatures later next week. So
warming is expected, but triple digits are currently unlikely.
-TAD

&&

.AVIATION...15/18Z TAFs...A somewhat tricky forecast is slated
across the region. We have the potential for smoke and haze which
could impact the terminals, but not sure if this will result in
categorical differences. Nevertheless, it is worth noting as
satellite indicates smoke and haze from wildfires impacting southern
Oregon. The other tricky part is the thunderstorm potential and
whether the terminals will be impacted or not. It does look like
Klamath Falls would be a candidate along with Medford (lesser
chance). However, confidence and analysis has led to not adding this
mention, but may reconsider in subsequent TAFs if warranted. Lastly,
the return of the marine layer tonight along the coast may lead to
degraded ceilings and visibilities.

-Guerrero

&&

.MARINE...Updated 200 PM PDT Tuesday, August 15, 2023...Steep
seas will continue today with relatively calm winds until tonight.
Moderate to strong north winds are expected to return tonight. The
end result is a Small Craft Advisory for all of the waters through
at least Friday, but some uncertainty remains to exactly how strong
those winds speeds will be Friday afternoon/evening. Either way,
this will produce steep to very steep seas across all of the waters,
but an area of gales south of Cape Blanco may develop. Though winds
are currently forecast to peak on Friday, seas may remain steep to
very steep through the weekend. For perspective, areas south and
southwest of Cape Blanco will have a probability of 25% for
*sustained* winds to exceed 34 knots, and a probability of 75% for
*gusts* to exceed 41 knots. Furthermore, there is a 35% probability
of exceeding 48 knots for gusts. Current forecast shows sustained
winds around 30 knots and gusts around 40 knots for Friday
afternoon/evening. In other words, we are likely going to see Small
Craft Advisory conditions now through the weekend, but we may need
to strongly consider Gale fore winds on Friday given the probability
of gusts being 40 knots or greater.

-Guerrero

&&

.FIRE WEATHER...Updated 200 PM PDT Tuesday, August 14, 2023...The
two big weather concerns for the forecast period will be the extreme
heat expected through late this week and the thunderstorm potential
also continuing through the week.

A very hot air mass will be over the region this week and several
days of 100+ degrees is anticipated west of the Cascades with mid to
upper 90s east of the Cascades. Although high temperatures will
trend "slightly" less hot compared to yesterday,  still expect very
hot temperatures today. These unusually hot temperatures will
continue through Thursday. Although conditions may get close for a
brief time, we aren't expecting critical RH/wind conditions today as
minimum RHs trend slightly higher, temperatures trend slightly lower
and monsoonal/tropical moisture increases in the region...which
leads us to the thunderstorm concerns...

This afternoon and evening expect isolated to scattered
thunderstorms, mainly from the Cascades east and Siskiyous south.
Isolated thunderstorms are also possible in southeast Jackson County
today. The favored area for scattered thunderstorms today continues
to be  from the Fremont-Winema National Forest and westward into the
Cascades. A Red Flag Warning for abundant lightning on dry fuels
remains in effect for FWZ 617/623/624 for this afternoon and
evening.

Scattered thunderstorms are possible over a broader area on
Wednesday, and a Red Flag Warning has been issued to cover this
threat in zones 624/623/621/280/281/284/285. West of the Southern
Oregon Cascades, a slight chance for thunderstorms is also expected
on Wednesday, including in FWZs 617, 620 and 622.

Storms will begin as a mix of west and dry, then transition wetter
late today and Wednesday. Thursday into the weekend, the chance for
isolated to scattered thunderstorms continues. Despite storms
transitioning to wet, strikes outside of storm cores remain a
concern. Gusty outflow winds are also a concern, especially for
today as storms may start out on the dry side, then become wetter
late in the day. Gusts of 30-40 mph will be possible with any
outflow winds. -CC/BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 2 PM to 11 PM PDT Wednesday for ORZ621-
623-     624.

     Excessive Heat Warning until 11 PM PDT Thursday for ORZ021>024-
     026-028.

     Excessive Heat Warning until 11 PM PDT Thursday for ORZ025-027.

     Heat Advisory until 11 PM PDT Wednesday for ORZ027-030-031.

     Red Flag Warning until 11 PM PDT this evening for ORZ617-623-
     624.

     Heat Advisory until 11 PM PDT Thursday for ORZ028-029.

CA...Excessive Heat Warning until 11 PM PDT Thursday for CAZ080>082.

     Red Flag Warning from 2 PM to 11 PM PDT Wednesday for CAZ280>282-
     284-285.

     Heat Advisory until 11 PM PDT Thursday for CAZ084-085.

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

&&

TAD/BPN/JWG

Special Weather Statement
National Weather Service Medford OR
458 PM PDT Tue Aug 15 2023

ORZ027-030-160030-
South Central Oregon Cascades OR-
Northern and Eastern Klamath County and Western Lake County OR-
458 PM PDT Tue Aug 15 2023

...A strong thunderstorm will impact portions of north central
Klamath County through 530 PM PDT...

At 456 PM PDT, Doppler radar was tracking a strong thunderstorm near
Crescent, or 13 miles southwest of La Pine, moving west at 15 mph.

HAZARD...Winds in excess of 30 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Odell Lake, Crescent Lake, Crescent and Gilchrist.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4346 12162 4338 12205 4358 12208 4359 12207
      4361 12200 4362 12161
TIME...MOT...LOC 2356Z 079DEG 12KT 4354 12171

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

MCB

Special Weather Statement
National Weather Service Medford OR
501 PM PDT Tue Aug 15 2023

CAZ080-160030-
Western Siskiyou County CA-
501 PM PDT Tue Aug 15 2023

...A strong thunderstorm will impact portions of central Siskiyou
County through 530 PM PDT...

At 501 PM PDT, Doppler radar was tracking a strong thunderstorm near
Etna, or 24 miles southwest of Yreka, moving northwest at 15 mph.

HAZARD...Winds in excess of 30 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Etna and Greenview.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4150 12281 4137 12290 4148 12314 4159 12304
TIME...MOT...LOC 0001Z 123DEG 13KT 4148 12296

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

DW

Special Weather Statement
National Weather Service Medford OR
531 PM PDT Tue Aug 15 2023

ORZ027-030-160100-
South Central Oregon Cascades OR-
Northern and Eastern Klamath County and Western Lake County OR-
531 PM PDT Tue Aug 15 2023

...A strong thunderstorm will impact portions of eastern Douglas and
northwestern Klamath Counties through 600 PM PDT...

At 530 PM PDT, a strong thunderstorm was reported near Crescent
Lake, or 20 miles southwest of La Pine, moving west at 10 mph over
Willamette Pass.

HAZARD...Winds in excess of 30 mph and penny size hail.

SOURCE...Doppler Radar Indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Odell Lake and Crescent Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4361 12182 4348 12175 4339 12213 4344 12217
      4344 12214 4345 12215 4348 12213 4351 12213
      4351 12214 4356 12212 4361 12200
TIME...MOT...LOC 0030Z 082DEG 8KT 4352 12186

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

MCB