Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 241205

Area Forecast Discussion
National Weather Service Medford OR
405 AM PST Tue Jan 24 2017

.Updated Aviation Discussion.

.DISCUSSION...Showers have ended this morning as an upper trough
pulls away to the south. Clouds have already cleared on the west
side, and they will gradually clear out elsewhere through the
morning. But given the clear skies, we`re starting to see fog form
in west side valleys, so we`ll be dealing with that once again. We
don`t have any in Medford just yet, but we`re getting close, and I
think we`ll fill in here by dawn. Once fog clears out today, it
will be mostly sunny with relatively quiet weather. A weak upper
ridge will slide through tonight, and the resulting inversion will
almost certainly lead to fog again tonight in the usual

A weak frontal system currently around 140W will move onshore
tomorrow and then dissipate. It may produce some showers, but it
doesn`t look particularly significant. After that, a much stronger
ridge develops over the PacNW which will likely remain in place
through at least the weekend and probably into early next week.
This will likely be a stagnant pattern with night and morning fog
and afternoon clearing. We`ll likely need an air stagnation
advisory for this period. The models are quite consistent in
showing the next chance for any significant precipitation coming
around mid next week as the ridge moves east and a wet, broad
system takes up a position just offshore. -Wright


.AVIATION...24/12Z TAF Cycle...A stable atmosphere has settled over
the region. Currently all TAF sites are VFR, but there is still
concern for a sunrise surprise to develop with conditions quickly
going from VFR to LIFR around 15z for Roseburg, Medford and Klamath
Falls. It`s not a slam dunk these conditions will develop and
confidence on the timing is only medium, but still felt it was
warranted enough to include it in the TAF`s. Any fog/low clouds
should burn off between 18-19z with VFR conditions through this
evening. The low clouds/fog conditions will be monitored closely, so
watch for updates on TAF`s this morning. -Petrucelli


.MARINE...Updated 300 AM PST Tuesday 24 January 2017...A weakening
low south of the waters will continue to move away this morning
and weak high pressure will build into the waters from north to
south. Seas will remain very high and very steep through late this
evening...then steep through Tuesday morning. A weak front will
move into the waters late Wednesday afternoon, then move onshore
Wednesday night. Weak high pressure returns Thursday, then move
inland Friday into next weekend. The models are in fairly good
agreement showing a high westerly swell arriving Wednesday evening
through Thursday evening, then gradually subsiding Thursday
night. -Petrucelli




Pacific Coastal Waters...Small Craft Advisory for hazardous seas
     until 10 AM PST this morning for PZZ350-356-370-376.

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