Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 191700
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1000 AM PDT Wed Jun 19 2019

.UPDATE...

There are only a few lingering clouds in the Umpqua Valley this
morning. We added those back into the forecast. There is some
cooler and unstable air to our north and that will make it`s way
into the region later this afternoon and tomorrow morning. As a
result, winds will be rather breezy late this afternoon into this
evening.

-Smith

&&

.DISCUSSION.../Issued 544 AM PDT Tue Jun 19 2019/
The latest nighttime derived satellite image that
allows us to see low clouds and fog shows clear skies over the
entire area. The exception is in portions of the Coquille Basin
where low clouds have been since around midnight. We don`t expect
the cloud cover to chance much, if at all after daybreak.

Dry weather will continue through at least the early part of next
week. There will be a pattern change on the way and the details are
noted below.

The upper ridge will retrograde westward today as upper level
troughing sets up over the Pacific Northwest. The ridge will remain
west of our area for the latter part the week into next weekend. A
portion of the ridge will briefly nudge towards southwest Oregon
bringing warmer weather, but only mid to upper 80s for interior
westside valley locations.

A stronger shortwave rotating around an upper low currently in
southern B.C. will drop in from the north and swing northeast of our
area Thursday. There is no over water trajectory, therefore no
precipitation is expected in our area. At the surface, a dry cold
front will move through bringing a cooler air mass over the region.
In fact, we may not get out of the upper 70s in the Rogue and
Illinois Valley Thursday afternoon. East of the Cascades, it may not
get out of the upper 60s in many locations.

The only concern in the short term will be near or slightly below
freezing temperatures for portions of the east side Thursday night
with the Klamath Basin standing the best chance for temperatures
below freezing. This is because we`ll have a dry cold front that
will drop in from the north. Behind it will be a cooler and drier
air mass with clear skies and light winds. Since there`s fairly good
agreement for this, a freeze watch has been issued. Please see
NPWMFR for more details.

Otherwise, were looking at dry weather to continue through next
weekend. There`s fairly good agreement the first hint of
precipitation in our area may not be until next Tuesday. This is due
to an large upper low moving southeast from the Gulf of Alaska and
there`s good agreement it will set up shop just off the
Oregon/Washington coast. This type of pattern is unusual for this
time of the year. If this were winter, the best chance for
precipitation would be along and west of the Cascades and this will
be case this time around, but since this is June, instability
showers and isolated thunderstorms cannot be ruled out.

If the upper low were to set up inland over our area, then we could
be dealing with a better chance for showers over most of the area
along with isolated thunderstorms. Right now this is not the case
since the cold core is offshore.

Of note: The individual ensemble members are in better agreement
with the majority of the individual members favoring the low setting
up offshore. The overall pattern depicted suggest a mean trough will
remain over the the area with a mean ridge over the gulf of Alaska
and the other over the south and plains of the U.S.

-Petrucelli


&&

.AVIATION...For the 19/18Z TAFS...There are some lingering MVFR
CIGS this morning, but VFR will prevail this afternoon and evening
with Gusty north winds near the TAF sites. a mix of VFR and MVFR
CIGS will probably make their way back into the Umpqua valley later
tonight. The air will be more unstable, so we`re not expecting MVFR
to prevail all night.

-Smith


&&

.MARINE...Updated 1000 AM PDT Wednesday 19 June 2019...Gale force
winds will continue into this evening mainly south of Port Orford.
The thermal trough pattern will continue into the weekend, but
weaken briefly Thursday as cooler more unstable air moves into the
waters.  Winds will then strengthen and resume gale force strength
south of Gold Beach from Thursday afternoon into Saturday.
Conditions hazardous to smaller crafts will occur north of Port
Orford through Saturday.

-Smith


&&

.FIRE WEATHER...Updated 230 PM PDT Tuesday 18 June 2019...A thermal
trough remains along the coast through tonight, and this will drive
another night of offshore (northeast) winds and moderate to locally
poor humidity recoveries in the coastal mountains. An upper trough
to our north causes pressure gradients to increase tomorrow, and
this will drive gusty winds during the afternoon and evening hours,
especially over interior west side valleys and the east side.
Temperatures will be a little cooler tomorrow, but it will remain
dry, so the combination of low humidities and gusty winds will
produce near critical fire weather conditions. The upper trough and
an associated dry cold front move through Thursday bringing cooler
and slightly more humid conditions, but winds will be gusty once
again.

Temperatures warm back up to around or slightly above normal Friday
through the weekend. Then another, possibly stronger, upper trough
moves over the area early to mid next week. This will bring the next
chance of showers to our area. Model consistency is high and thus
confidence is growing that this will occur. While models are modest
in the instability at this time, history suggests that troughs in
June bring lightning, and thus thunderstorms have been added to the
forecast for the east side early next week.

-Wright


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Watch from late Thursday night through Friday morning for
     ORZ029>031.

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Saturday for
     PZZ350-356-370-376.
     Gale Warning until 11 PM PDT Saturday for PZZ356-376.

$$



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