FXUS66 KMFR 230935

Area Forecast Discussion
National Weather Service Medford OR
235 AM PDT Tue Apr 23 2019

.DISCUSSION...A fairly quiet weather pattern is expected over the
next two days. Deep westerly/northwesterly flow through Wednesday
will bring some high clouds to the area, but generally dry
conditions with little in the way of impactful weather. The
biggest forecast challenge tonight involved evaluating the chance
of thunderstorms over the southern and eastern portions of the
forecast area. There will be some instability per GFS20 Lifted
Index values forecast to be sub-zero, and there is some moisture
per Precipitable Water values of around 0.75 inches. However, lack
of trigger (shortwave or frontal boundary) and northwesterly flow
in the low to mid levels suggests thunderstorm chances are low.
Additionally, the consensus of post- processed guidance and
convection-allowing models suggest no thunderstorms. Therefore,
we`ve left the forecast as is (though bumped up precipitation
chances to around 10 percent), and we kept dry conditions in for

Temperatures warm several degrees today compared to Monday, with
afternoon readings about 10 degrees above normal for this time of
year. Similar temperatures are expected Wednesday. Lack of trigger
again should prevent any thunderstorms on Wednesday afternoon,
though we have bumped up precipitation chances over eastern Siskiyou
and Modoc Counties Wednesday afternoon, as deep flow begins to
feature a slightly southerly component, and SREF calibrated
thunderstorm guidance is beginning to hint at enhanced convection

By Thursday, midlevel flow turns southerly enough to better support
thunderstorm formation, so we`ve maintained a slight chance of
thunder for eastern Siskiyou and Modoc Counties. Still, lack of
significant trigger doesn`t support much in the way of lightning. A
dry cold front moves through Friday and westerly flow and cooler
conditions squash any chances of thunderstorms.  Please see the
Monday`s dayshift long-term forecast discussion for more details on
the extended forecast. Keene

Friday through Monday Night...Over the last several
forecast cycles, the models have trended towards keeping any
significant weather-making systems away from the forecast area, with
prevailing high pressure and a continuing thermal trough pattern.
The pattern aloft is not quite so simple, with large troughs moving
by to both the north and south, but nearly all moisture flow into
the region remains cut off, and there are very few indications that
we will have any impulses or shortwaves to worry about. Overall, the
resulting weather for the forecast area will trend dry and warmer
than normal. It is worth noting that some ensemble members still
show hints of afternoon convection chances, particularly over
northern California and the East Side, but chances remain too low to
mention in the forecast at this time. -BPN


.AVIATION...For the 23/06Z TAFS...Along the coast and over the
coastal waters...Areas of IFR cigs/vsbys off the coast will move
onshore later this evening, then burn back offshore Tuesday morning.
The lower conditions will return to the coast Tuesday evening.  Over
the remainder of the area...VFR conditions will prevail through
Tuesday evening, although there will be late night through
morning VFR stratus decks over the Umpqua Basin with some
obscuration of higher terrain.


.MARINE...Updated 800 PM PDT Monday 22 April 2019...A thermal
trough along the coast will strengthen Tuesday afternoon and
evening and weaken Wednesday night. This will bring moderate
north winds and steep to very steep seas south of Cape Blanco
Tuesday into Wednesday. The stronger winds will spread north of
Cape Blanco Wednesday, then weaken. After a relative break on
Thursday, the trough will strengthen again, bringing strong north
winds that may reach gale force at times south of Cape Blanco
Friday through the weekend.

Note:  Buoys 46027 and 46015 are both out of service. According to
the National Data Buoy Center, 46015 is scheduled to be redeployed
in August. Redeployment of 46027 has not been scheduled. Buoy 46229
is the only operational buoy in the coastal waters between Newport
and Eureka.




Pacific Coastal Waters...Small Craft Advisory from 2 PM this afternoon to 5 AM PDT
     Thursday for PZZ356-376.
     Hazardous Seas Watch from late tonight through late Wednesday
     night for PZZ356-376.


NWS MFR Office Area Forecast Discussion