Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 311552
Area Forecast Discussion
National Weather Service Medford OR
852 AM PDT TUE MAY 31 2016
.UPDATE...High pressure dominates the area, and with clear skies,
there is little need to make any changes this morning. Today will
be the first of several very warm days, with very little chance
for precipitation until late this weekend. For more information,
see the previous discussion below. -BPN
.Aviation...For the 31/12Z TAF cycle...After isolated low clouds
and fog clear from the coast this morning, VFR conditions are
expected everywhere through tonight. Gusty north to northwest winds
will affect the immediate coast this afternoon. SK
.Marine...Updated 3 AM PDT Tue 31 May 2016...Offshore high
pressure and a thermal trough along the coast will continue to
produce gusty north winds this week with short period wind waves and
fresh swell continuing to dominate the waters. Winds will be
strongest beyond 3NM from shore south of Cape Blanco. Winds will
trend lower Wednesday night into Thursday. Wind speeds will be at a
minimum on Thursday but the decrease will not last long. North winds
are likely to increase again Friday into the weekend. Wright/SK
.Fire Weather...Dry conditions are expected again today, and a
sharp warming trend is expected for most of the forecast area.
Confidence is high that the valleys W of the Cascades will see high
temperatures in the 90 to 100 degree range as the thermal trough
shifts inland and remains W of the Cascades today and Wednesday.
Expect minimum RH for western valleys to be in the mid teens with
moderate to poor humidity recoveries tonight and Wednesday night.
Tonight will likely be the driest of the week. The thermal trough is
expected to shift east of the Cascades Wednesday but onshore push
will be confined mainly to Douglas County of Oregon.
A slight chance of thunderstorms is introduced on Wednesday for
mostly southern and eastern Siskiyou County as instability
increases. Confidence is not high on how much rain these storms will
produce. Stability increases Thursday and Friday so no thunderstorms
are expected. Much above normal temperatures inland will continue
into the end of the week. FB/SK
.PREV DISCUSSION... /Issued 617 AM PDT TUE MAY 31 2016/
Updated aviation, marine, and fire weather discussions.
SHORT TERM...Strong high pressure will be centered over the
Pacific Northwest today and will shift east to Idaho Wednesday.
the thermal trough at the surface will shift inland from the coast
this afternoon bringing the coastal winds onshore while giving the
interior the warmest temperatures so far this year. 90s will be
common over the west side with lower to middle 80s east of the
Cascades. while these interior readings will be quite warm at
15-25 degrees above normal, no records are expected today.
Wednesday will be a little cooler across the west side as the
upper heights lower and the onshore gradient produces a slightly
increased onshore flow and some morning clouds on the Coos coast.
However, it will be a slightly warmer day for the east side. a
bit of instability is apparent over Northern California around
Mt. Shasta and Mt. Eddy and the slight thunderstorm chance there
looks good. A weak shortwave moves onshore through Oregon
Wednesday night and the marine clouds should affect the Coos
coast again in the morning hours. Temperatures should be just a
touch cooler versus Wednesday.
Wow. The models continue to indicate a massive ridge to rebuild
over the region Thursday through the weekend. This will bring a
good chance for record-breaking highs both days in addition to
increasing chances for thunderstorms Sunday and beyond as an upper
low migrates through California. Previous extended discussion
LONG TERM... /Issued 216 PM PDT MON MAY 30 2016/ Friday through
Monday Night...Friday into the weekend, models continue to show
agreement that the ridge will strengthen over the area while a
closed low to the south gradually moves inland into the central
California coast. This pattern is expected to bring warming
temperatures to the area Friday and Saturday. Peak temperatures
are expected on Saturday with highs in the 90s to near 100 in
western inland valleys and in the upper 80s to near 90 for valleys
east of the Cascades.
For Sunday, the GEFS, GFS and ECMWF have trended further north with
the track of the closed low, bringing it into central to south
central California. This low is forecast to send southerly mid level
moisture into the area as well as shortwave activity. Although
temperatures are expected to be slightly lower on Sunday, compared
to Saturday, daytime heating will provide plenty of instability.
Have expanded the chance for thunderstorms over inland areas on
Sunday. Moisture, instability and shortwave activity continue
overnight Sunday into Monday morning so have kept a slight chance
for thunderstorms in during this period. On Monday, models show the
low gradually moving inland to the east-northeast into Nevada.
Continued moisture around this low will bring additional chances for
showers and thunderstorms to the area. Of note, the track of this
low remains the main factor in determining which areas will see the
best chance for thunderstorms and model ensemble solutions continue
to show variability with the track as it moves inland.
Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Wednesday for PZZ356.
Small Craft Advisory for hazardous seas until 11 PM PDT
Wednesday for PZZ350-356-370-376.
Small Craft Advisory until 11 PM PDT Wednesday for PZZ376.