NWS Medford, OR wrote its last area forecast discussion before the first event at Jul 29, 7:45 AM PST, 5 hours 30 minutes earlier.
Area forecast discussion, Jul 29, 7:45 AM PST, 5 hours 30 minutes before
Area Forecast Discussion
National Weather Service Medford OR
845 AM PDT Fri Jul 29 2022
.DISCUSSION...Very hot temperatures are expected everywhere inland
from the coast. Please take steps to ensure you remain hydrated,
have a place you can escape the heat, and check in on neighbors
and friends who may not have heat. More information on the heat is
in the previous synopsis/discussion below.
The other concern for our operations today will be the
thunderstorm potential this weekend. Will be taking a deep dive to
see how the details play out, but fully expect fire weather
watches to come out in the afternoon package. Stay tuned for
additional updates this afternoon. -Schaaf
&&
.PREV DISCUSSION... /Issued 451 AM PDT Fri Jul 29 2022/
Updated Aviation Discussion.
SYNOPSIS...A strong ridge remains in place today into Saturday.
This will bring two additional days with very hot temperatures to
inland areas. High temperatures today are expected to be similar
to those observed yesterday. Then, the heat wave continues on
Saturday, with high temperatures expected to only lower a couple
degrees. Additionally, there will be a slight chance for
thunderstorms over inland areas today and Saturday. An upper low
will approach the PacNW on Sunday and move inland on Monday,
bringing a return to near normal temperatures by Monday. Ahead of
the upper low, expect an increase in mid level moisture and
instability over the area, resulting in a slight chance for
thunderstorms overnight Saturday night and Sunday morning,
followed increasing chances for thunderstorms Sunday afternoon and
evening. A slight chance for showers and thunderstorms continues
on Monday for areas east of the Cascades as this upper low/trough
gradually moves inland.
DISCUSSION...Today and Saturday, the main concerns are with the
heat wave and the slight chance for thunderstorms across inland
areas. Afternoon temperatures today will be very hot for all
inland areas, with temperatures similar to yesterday. This will
result in another day of potentially, record- breaking heat and
an elevated risk for heat-related illness. Excessive heat
warnings and heat advisories remain in effect across most the
area (see the NPWMFR for details). It is notable that yesterday,
record high temperatures were set at Medford, Klamath Falls,
Montague and Mount Shasta City. These areas may see record highs
again today. High temperatures will lower only a couple degrees on
Saturday for areas west of the Cascades but otherwise, expect
little change from the heat on Saturday.
Combined with this heat wave, models continue to support a slight
chance for thunderstorms this afternoon/evening and again during
the day Saturday as mid level moisture and weak disturbances move
up into the area from the south. Models are indicating a slight
chance for thunderstorms across Siskiyou County as well as into
the Siskiyou Mountains and areas just to the north this afternoon,
then expanding into portions of eastern Josephine, Jackson,
western Klamath and far eastern Douglas Counties early this
evening. However, moisture is limited and a weak cap in place may
result in mainly cumulus buildups. Any storms that form may have
higher bases and little rainfall along with gusty winds. This
slight chance for thunderstorms will continue Saturday
afternoon/evening for many areas inland of the coastal mountains.
Saturday night into Sunday, as the upper low approaches from the
west, models support a slight chance (15%) for thunderstorms
developing overnight due to elevated instability and mid level
moisture moving into the area from the south-southwest. The best
chance for any storms developing overnight will be over the
mountain from the Cascades west. Next, as the upper low nears the
coast, models support increasing chances for thunderstorms Sunday
afternoon and evening, especially across the Cascades, Siskiyous
and into western Siskiyou and northern Klamath counties. Models
and ensembles are overall showing better agreement in the
forecast for the Sunday afternoon/evening period and support a
15-25% chance for thunderstorms for most inland areas. The
National Blend of models indicates a 25% chance for thunderstorms
across Siskiyou County, northward into the Siskiyous, S. Oregon
Cascades as well as portions of eastern Jackson and Klamath
Counties. Gusty winds may accompany any storms that develop on
Sunday. While confidence is increasing for scattered
thunderstorms on Sunday, there remains variability in the GEFS
ensemble members and the ECMWF supports mainly isolated
thunderstorms. So we will monitor and evaluable this risk for with
the next set of model runs.
On Monday, a slight chance for thunderstorms will continue,
mainly from the Cascades east, as the upper low gradually moves
inland. Of note, the ECMWF is slower with the movement of the low
and the operational ECMWF as well as around 15% of the ensemble
members, keeping the chance for thunderstorms further west. So
this will be something to monitor closely. Behind the low, mid to
late next week, there will be a trend towards cooler temperatures
and generally dry weather.
AVIATION...29/12Z TAFs...Over the coastal waters and along the
immediate coast, IFR ceilings will continue before retreating back
to the coastal waters between 18-19z. IFR conditions are likely to
return to the immediate coast early this evening and lasting until
the end of the TAF period.
Inland, VFR conditions will continue through the TAF period. The
exception will be the Coquille Basin where marine stratus will
persist until 17-18z, before burning off.
Pockets of high-based convection are possible this afternoon and
evening over the higher terrain in the northern California, along
and east if Cascades. An isolated storm or two could affect portions
of the Rogue and Illinois Valley, including Medford Airport late
this afternoon and evening but confidence is not high enough to
include it in the Medford TAF. We'll late later shifts re-evaluate
this. As always, lightning and gusty erratic winds are expected in
and around any thunderstorms. -Petrucelli
MARINE...Updated 200 AM PDT Friday 29 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 this evening. -Petrucelli
FIRE WEATHER...Hot temperatures will persist through Saturday for
inland areas. Temperatures today will be similar to those observed
yesterday. Low humidities and afternoon breezes are likely again
today , especially east of the Cascades and into western valleys
in Josephine, Jackson and Siskiyou Counties. On Saturday, expect
little change in these conditions except for a couple degrees of
less hot conditions west of the Cascades.
A slight chance for thunderstorms will continue in the afternoon
and evening, today and Saturday. Any storms that develop may have
gusty winds and limited rainfall with them. As an upper low
approaches from the west Saturday night and Sunday, expect a
slight chance for thunderstorms over the mountains from the
Cascades west Saturday night followed by increasing chance for
thunderstorms during the day Sunday. There is a potential for
scattered thunderstorms on Sunday across Siskiyou County northward
into the Siskiyous and S. Oregon Cascades as well as eastern
Jackson and Klamath Counties. Gusty winds are expected with
storms that develop on Sunday. With the next set of model runs
today, we will be evaluating the thunderstorm chance/coverage for
this period and the potential for fire weather watches.
Heading into Monday, the mean model solutions support the upper
low gradually moving inland with a continued slight chance for
thunderstorms and showers, mainly from the Cascades east. Of
note, there remains variability in how quickly this low will move
inland with around 15% of the ensemble solutions supporting a
slower progression of the low moving inland. This will factor
into where and how much thunderstorms or showers may occur on
Monday.
&&
.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 this afternoon for
PZZ356-376.