NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS66 KMFR 100138 AFDMFR

Area Forecast Discussion National Weather Service Medford OR 538 PM PST Sat Dec 9 2023

UPDATE
Updated the aviation section.

AVIATION
10/00Z TAFs...Mid and high level clouds are advancing into the northwest portion of southwest Oregon ahead of a trof well offshore. A moist flow ahead of the trof is bringing rain, thicker clouds and lower ceilings north of KOTH and KRBG.

These lower ceilings and rain will slowly sag southward overnight as the trof approaches the coast. Ceilings look to stay mostly VFR with some isolated MVFR ceilings occurring along and north of the Umpqua divide after sunrise.

Mostly MVFR ceilings and mountain obscuration over the coastal and Cascade mountains are expected to develop after 18Z from the Umpqua divide northward along with steady precipitation. South of that line some rain and MVFR ceilings can be expected west of the Cascades.

Eastside should see VFR ceilings with very little precipitation throughout the TAF forecast period. -Sargeant

PREV DISCUSSION
/Issued 222 PM PST Sat Dec 9 2023/

SHORT TERM...

The leading edge of the next atmospheric river and warm front has hit areas in central Oregon this afternoon. Most of the precipitation is falling to our north today, although the axis of moisture will slide to the south by Sunday. This will result in a very good chance of rain for all locations and perhaps some snow above 8000 feet. Those chances of rain decrease as ones moves farther to the south and east. Those waiting for snow over the higher terrain and mountains will have to wait a bit longer as the airmass is fairly warm with this precipitation event on Sunday.

A cold front will slide down from the north as a short wave swings through the region Sunday evening. The cold front doesn't appear to move that far to the east farther inland. Instead it looks like some cooler air just shoots down the coastline. In any case, the chance of rain will persist Monday morning with snow levels decreasing down to 6300 feet Monday morning. Showers are the most likely precipitation mode for most of Monday.

By Monday night, high pressure will begin to build with a thermal trough setting up along the Oregon coastline. Some light easterly flow will begin to develop, which should result in some drier and warmer air along the Oregon coastline, especially on the ridges.
This is a good pattern for fog in the valleys during the morning as high pressure builds after some wetting rain in the soils.
We added fog into the forecast to show this concern.

Overall, an active weather pattern for the next few days, although impacts should be minimal to the public at large. The fog Monday night into Tuesday could pose some issues with aviation or perhaps the morning commute.

-Smith

LONG TERM...Tuesday through next Saturday. Tuesday starts with an upper ridge over the west coast with the upper trough that brought precipitation to the region moving eastward, leaving continued low level moisture in the valleys. Ensemble plots are in very good agreement with the upper ridge shifting to the east by Wednesday afternoon, with the next front moving rain into the coast Wednesday.
Models then begin to diverge greatly, but the majority are keeping precipitation from the Cascades westward into Thursday. Although the ensemble plots diverge greatly Thursday afternoon into Friday, the majority of the ensemble members are showing ridging and dry with morning west side valley fog. Roughly half of the ECMWF and GFS meteograms are showing precipitation reaching inland to Medford next weekend, with an increasing number of members keeping a wet pattern after next weekend through most of the following week. -Sven

MARINE
Updated 200 PM Saturday December 9, 2023
Strong south winds ahead of an approaching cold front will continue over the coastal waters tonight into Sunday morning. The strongest winds will occur north of Port Orford.

The strong winds combined with a large westerly swell will create hazardous conditions to small craft for all waters through Sunday evening.

A cold front will pass through the waters Sunday into Sunday evening with very slowly improving conditions while winds and high and steep seas remain highest in the northern portion of the waters. Moderate seas are likely by late Sunday night.

A weak thermal through develops along the coast early Monday with winds becoming northerly. Swell heights will diminish while sea conditions south of Gold Beach may barely cross the threshold into becoming steep Monday into Monday night.

Noticeable improvement is likely Tuesday into Wednesday. Forecast uncertainty increases from Wednesday onward, but a building long period west-northwest swell at 17 to 18 seconds is possible late Wednesday into Thursday morning.
-Sven/Sargeant

MFR WATCHES/WARNINGS/ADVISORIES
OR
CA
None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 10 PM PST Sunday for PZZ350-356-370-376.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Medford, OR,