Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Medford or
917 PM PDT Wednesday Jul 23 2014
a couple of updates were made this evening. The first was to
cancel the red flag warnings on the east side just after 8 PM PDT.
The second was to increase sky cover for tonight and tomorrow
relative humidities have risen across the east side this evening
and, while winds are still a bit breezy, they are diminishing.
Therefore, the red flag warnings have been cancelled.
Sky cover is hanging on across the west side and the better
performing NAM guidance indicates it will continue to do so a bit
longer until flow becomes offshore around 12z / 5am PDT.
Aviation...based on the 24/00z tafs...
MVFR conditions at the coast will lower to IFR tonight...while
MVFR ceilings will continue in the Umpqua Basin. Mountain
obscuration will continue through this evening...especially on
west facing slopes...and then diminish late tonight as drier air
moves in. Gusty winds and associated turbulence should begin to
diminish late this evening. By late tomorrow morning most
locations will become VFR under a progressively drier and warmer
air mass. Sven
Marine...updated 205 PM PDT 23 July 2014...a thermal trough will
rapidly develop on Thursday then likely linger through the weekend
into early next week. This will likely result in moderate to strong
north winds and steep wind driven seas with the strongest winds
during the afternoon and evening hours in the outer waters south of
Cape Blanco. The low pressure deepens at the coast Thursday with
gales developing in the outer waters quickly by late Thursday
afternoon. The upper ridge moves inland Sunday with the thermal
trough weakening...resulting in decreased winds and wind waves into
the beginning of next week. Sven
Previous discussion... /issued 213 PM PDT Wednesday Jul 23 2014/
Discussion...rainfall associated with a cold front moving across
our area quickly fell apart as it encountered the Cascades, which
was expected. Now showers are increasing across the west side as
deep, moist, onshore flow continues in the wake of the front.
Observations sites continue to show measurable rain along the
coast and the Umpqua, but further south in the rogue, showers are
much spottier. This will continue to be the case through the
afternoon. There isn't much instability left as the main bulk of
the dynamics and cold air aloft are well to our north, but we
could see a few lightning strikes over our northern zones. Gusty
southwest to west winds will continue through evening over the
east side. Yesterday's lightning resulted in a lot of fire starts
over Northern Lake and Klamath counties, and even though
humidities are not particularly low, gusty winds could cause any
remaining fires to spread. We have a red flag warning in effect
for this reason and that lasts through the evening.
Showers will quickly diminish tonight, and it will be a rather
cool night for July area wide. Due to all the moisture, we may
see some fog or low clouds develop in the west side valleys
tonight, but nights are short and didn't feel it was Worth
putting in the grids.
The upper low that caused all this weather will zip east into the
northern rockies pretty quickly tomorrow. As a result, we will
warm up and dry out pretty quickly tomorrow, but high temperatures
will still be about 5 degrees below normal. We will be right back
to normal Summer weather by Friday. The thermal trough will
redevelop along the coast with increasing north winds along the
Coos coast and over the waters, and highs will jump back to around
normal all locations. This warming trend will continue into early
next week with temperatures jumping back above normal. Highs will
be around 100f in Medford over the weekend. The warmest day looks
like Monday with highs around 10 degrees above normal (102f in
Medford, for example).
The models show the possibility of disturbances moving up through
the southwest flow early to middle next week, which may present our
next chance for showers or thunderstorms. There is little model
consistency with any of these features, so attempting to nail down
specifics would be futile. Thus we simply have a slight chance for
thunderstorms painted across the east side. There is consistency
is the idea of it staying rather hot next week, though. -Wright
Pacific coastal waters...Small Craft Advisory for winds from 11 am Thursday to 11 am PDT
Sunday for pzz350-356-370-376.
Small Craft Advisory for hazardous seas from 11 am Thursday to 3
PM PDT Sunday for pzz350-356-370-376.
Hazardous seas warning from 11 am Thursday to 3 PM PDT Sunday
Gale Warning from 11 am Thursday to 11 am PDT Sunday for pzz376.