Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Medford or
423 am PST Wednesday Feb 10 2016

Short major changes made to the forecast this morning.
The ridge axis has now moved into the Great Basin, and the
southwest flow over US is allowing lots of high cloud to stream
over the area. In addition, there is a fair amount of marine
stratus just off the coast this morning. We've got a weak
shortwave moving over US now, but nothing has shown up on radar
nor at any of the observing sites, so it's likely just a cloud
producer. There is a weak front around 130w right now, and this
front will fall apart as it reaches our coast this afternoon. It
may produce some light rain or sprinkles at and just inland from
the coast, but nothing much more. Another shortwave will move up
through the southwest flow tonight, and it may touch off some rain
showers primarily over the waters and coast, but some light rain
can't be ruled out inland as well.

The pattern will remain roughly the same Thursday with
precipitation trying to come in from the west but making little
progress as it encounters the ridge parked just to our east. By
Friday, rain becomes more likely over all areas, but especially
the west side as a slightly stronger front approaches. This front
will also encounter a fair amount of resistance, but the models
generally agree that we'll see some rain, so the higher probability of precipitation we
have look warranted. -Wright

Long term...(saturday through tuesday)...a more westerly jet
stream will bring a warm front inland on Saturday. Snow levels
on Saturday will range from around 5500 feet in Oregon and up to
7000 feet in The Mount Shasta area. Both the GFS and the European model (ecmwf) are
in a fairly good agreement so confidence is high on our forecast
area seeing measurable precipitation.

By Monday however both models strengthens the ridge over the West
Coast in response to an upstream trough in the Gulf of Alaska
although the ridge on European model (ecmwf) is not as strong and allows some
overrunning. As a result we are keeping Monday dry but re-
introduce chance probability of precipitation for Coos and Douglas counties on Tuesday.
Both models indicate we may shift back to a wet patter around the
middle of next week. /Fb


Aviation...for the 10/12z taf cycle...
a weak frontal boundary pushing in from the Pacific today will bring
some light rain and drizzle to the coast and Coast Range and a brief
period of wind shear between 15z and 18z this morning north of Cape
Blanco. Partial terrain obscuration of the Coast Range and possibly
some valley MVFR conditions are expected on the west side of the
range this morning. LIFR ceilings along the lower Klamath River
valley from Happy Camp the Illinois Valley north to
Grants Pass...and in the Umpqua basin over and around Roseburg
should dissipate by late morning. This afternoon through tonight VFR
is expected to prevail for all areas. Btl


Marine...updated 300 am PST Wednesday Feb 10 2016... a weakening cold
front will continue to move in today resulting in gusty south
winds...building seas...and some light rain or drizzle.
This cold front will then linger over the area with periods of
showers expected through Friday morning before it moves inland.
Seas will build further tonight through Thursday...likely peaking in
the 14 to 16 foot range at 18 seconds Thursday night into Friday
morning. Another frontal system is now expected Saturday night into
Sunday. Btl


Mfr watches/warnings/advisories...


Pacific coastal waters...
- Small Craft Advisory for hazardous seas until 4 PM PST this
afternoon for pzz350-356-370-376.
- Small Craft Advisory until 4 PM PST this afternoon for pzz370.
- Small Craft Advisory for hazardous seas from 10 PM this evening to
4 PM PST Sunday for pzz370-376.



National Weather Service Glossary of Abbreviations