Lightning Strike in California, May 23, 2018

Area Forecast Discussion
National Weather Service Medford OR
907 AM PDT Wed May 23 2018

.DISCUSSION...The overall forecast remains on track, but did make
some minor adjustments this morning. Today will be cooler and pretty
active in terms of showers and thunderstorms, mainly east of the
Coast Range and Roseburg. Hi-res, near term models are showing
convection really getting going early this afternoon. Storm
motion will be from the south to southwest, and unlike yesterday,
storms are expected to move off the terrain and into the valleys.
So it's possible to see storms in the Rogue Valley sometime
between 2 and 4 pm. Brought up PoPs for the Rogue Valley for this
afternoon and also upped the QPF amounts for today. This
morning's sounding showed over an inch of PWAT and this is pretty
significant for this time of year. Given this amount of moisture,
expect storms to produce locally heavy rainfall, but with a storm
motion of 10 to 15 knots, flooding isn't really concern today. The
risk of severe storms is minimal, but still couldn't rule out
some strong storms or even an isolated severe thunderstorm, with
the amount of instability the models are indicating. Gusty winds
and small hail will be possible with any thunderstorms today.

The pattern will continue Thursday and Friday, but thunderstorm
coverage will be less. For more details on this, see the previous
discussion below. /BR-y

&&

.AVIATION...23/12Z The marine layer is compressed, and we're
currently observing IFR conditions at North Bend. LIFR conditions
are possible along the coast, but it has not occurred at the time of
this discussion. As for areas farther inland, the Umpqua valley
should see a stratus surge later tonight resulting in MVFR
conditions. As for tomorrow, thunderstorms are in the forecast and
it's possible to see a few of these storms roll over TAF sites MFR
and LMT with partial terrain obscuration if traveling through
clouds. -Schaaf/CZS

&&

.MARINE...Updated 300 AM PDT Wednesday 23 May 2018...North winds
have lowered and expect continued light winds and seas today into
Thursday. Seas will become dominated by a west swell of around
12 seconds today, persisting on Thursday. A low will move south of
the area towards the central California coast on Thursday and winds
may become light and variable at times, especially over waters south
of Cape Blanco. Behind the low, a thermal trough will develop along
the coast and north winds and seas will gradually increase over the
waters late Friday into the weekend. This may bring gusty north
winds and steep seas to the waters south of Cape Blanco this
weekend. Strong north winds and steep wind-driven seas may return to
most of the waters early next week. -CC

&&

.PREV DISCUSSION... /Issued 337 AM PDT Wed May 23 2018/

DISCUSSION...Current RADAR observations are showing ground
clutter across much of the nearby radar beam. Satellite imagery is
showing that the marine layer has brought in low clouds to the
coast all the way to the coastal mountains. Otherwise, there are a
few patches of clouds all around the forecast area. This trend is
expected to continue.

Temperatures today will be 5 to 10 degrees lower than they were
yesterday, but healthy CAPE and LIs will allow for thunderstorms
to become a bit more widespread than they were yesterday. The
highest chances for showers and thunderstorms will be along the
higher terrain, particularly across the Cascades, Siskiyous, and
Warner mountains; but storms will be possible anywhere west of
the coast.

This pattern is to continue for the next few days. The
probability of any of these storms becoming severe is extremely
low, but the storms could produce occasional lightning strikes and
gusty winds. Meanwhile, the coastally trapped wind reversal is
being strongly indicated by the NAM and should build through
southern Oregon by this afternoon. This could bring light drizzle
and fog to those areas.

Later in the week, another low will move eastward into California.
The models are in general agreement of this scenario, and have
been a little bit more progressive as of late. This system will
move out of the area early on Saturday morning. Temperatures will
be near normal on Friday and Saturday.

This change will be a relatively short-lived one and a weak ridge
will build back in over the weekend particularly on Sunday. The
beginning of next work week will return to the ridge pattern of
warmer temperatures and mostly sunny skies. -Schaaf

&&

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

CA...None.

Pacific Coastal Waters...None.

MNF/BMS/CC