Weather Service Report


987 
FXUS66 KMFR 221720
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
920 AM PST Sun Jan 22 2017

.UPDATE...
Updates have been made to the forecast this morning to add small
hail to the isolated thunderstorm areas from Western Siskiyou
County, western portions of Josephine and Douglas Counties, the
coastal counties, and the coastal waters through this afternoon. 
Snow levels were also lowered in these areas to account for snow 
potential down to 1200 feet in Western Siskiyou County and 1700 
feet in the Sexton Pass area this morning, rising slightly this
afternoon. Finally, updates were made to sky cover and shower
probabilities to be consistent with current data trends. BTL 

&&

.DISCUSSION...
Strong low pressure, to the tune of about 970mb on the 1500Z/7am
PST NCEP surface analysis, is wound up near 46N 131W this morning.
The low did deepen to about 974mb as it moved inside of 130W about
150 nautical miles west of Cape Blanco per the 0600Z analysis
overnight. Observed wind gusts reached 79mph at Flynn Prairie in 
the Curry County Coastal Mountains, a whopping 124mph at Squaw 
Peak above the Applegate in the Siskiyous, and 61mph in the hills 
north-northwest of Ashland and Talent. Snow occured throughout 
the Shasta Valley, with over a foot in some locations near the 
towns of Weed, in Tennant, and Mount Shasta City.

Snow levels this morning have dipped to as low as about 1200 feet
in Western Siskiyou County and to 1640 feet at Hayes Hill in
Josephine County. A dusting of snow was also seen at Jacksonville
Hill. A couple of small hail reports were received from Curry
County along with rumbles of thunder. The hail covered the ground
to a depth of 1/4" to 1/2" according to one spotter report.

Today will be a showery day, with what could be termed "rainbow
weather" for many valley areas, in that we'll see breaks of sun,
but also showers. Showers will be most numerous along and near 
the coast and in western Douglas, Josephine, and Siskiyou 
Counties, where isolated thunderstorms with small hail will 
continue to be possible. There will a second areas of showers 
focused across southern Lake County and Modoc County. BTL 

&&

.AVIATION...22/12Z TAF Cycle...A strong front is now moving 
onshore. This is bringing strong gusty southerly winds and low level 
wind shear to the area, including KOTH, KRBG, and KMFR. Strong winds 
have also surfaced at KMFR and KLMT with gusts to 35 kt. Areas of 
MVFR cigs have developed along the coast and are spreading inland.
The higher elevations are seeing IFR conditions in snow, and LIFR 
conditions have developed in the Mount Shasta area. The lower 
conditions will continue into Sunday morning, but VFR will return to 
most areas Sunday afternoon, except for MVFR cigs in the Mount 
Shasta area through Sunday evening. There is also a slight chance of 
thunderstorms west of I-5 through Sunday morning, then along the 
coast and offshore through Sunday night. Areas of MVFR cigs will 
return to the coast and west side Sunday night into Monday morning. 

&& 

.MARINE...Updated 130 AM PST Sunday 22 January 2017...A strong storm 
is now moving north along 130W and this is bring gale to storm force 
winds to the area.  The storm will move to the north later this 
morning and winds will diminish, but gale force winds will continue 
as the weakening storm loops back south offshore Sunday into Sunday 
evening. Winds will diminish slightly Sunday night into Monday, but 
seas will remain very steep due to the combination of wind waves and 
heavy westerly swell through Monday evening. Winds will diminish 
Monday night and remain relatively light through the remainder of 
the week, but there will be several rounds of moderate westerly 
swell, the largest of which will move through Wednesday night into 
Thursday.

&&

.PREV DISCUSSION... /Issued 322 AM PST Sun Jan 22 2017/ 

DISCUSSION...Radar and satellite imagery this morning are 
showing an impressive band of clouds and moderate to heavy 
precipitation lying along the oncoming frontal boundary. The band
has been accompanied by some isolated lightning strikes as it 
moved onshore, but so far none have struck anywhere but over the 
open ocean. Gusty winds, and in some places, heavy snow, will 
continue this morning until this band passes. As the remnants of 
the offshore convection pass through, snow levels may drop 
temporarily in some locations, and quick bursts of wet snow are 
not out of the question for areas that until now have only seen 
rain. Otherwise, most of our passes will see issues due to snow 
this morning, along with the high mountains and the Mount Shasta 
area, with strong winds along the coast, in the Shasta Valley, and
in the Ashland to Medford portion of the Rogue Valley. Numerous 
headlines remain in place for wind and snow across the region, and
these appear to be covering the event well, so no changes have 
been made. For more information and details, see the Winter 
Weather Message, PDXWSWMFR, and the Weather Message, PDXNPWMFR. 

The system bringing us our active weather this morning is in no 
hurry to leave us, and will spin around just offshore through
tonight and into Monday, before sliding south along the coastline
and out of our immediate area by Monday night. Once the main line
of wind and precipitation passes this morning, conditions will 
gradually improve, but showers and some breezy winds will stick 
around until the system exits. Upper level ridging will then build
into our area Tuesday. 

Models are showing a weak front attempting to press into the
Pacific Northwest on Wednesday, but indications are that it will
have a rough time once it encounters the high pressure that should
be in control by then.The front will likely die as it passes
onshore. Only the coast should see more than a few hundredths of 
an inch of rain, while the rest of the area is only likely to 
receive scattered light showers. 

The ridge should then return with gusto, and remain in control
through the weekend and into early next week. Skies will 
therefore be mostly clear, and overall, daytime temperatures 
should see a gradual warming trend with cold overnight lows. 
However, as is normal for high pressure this time of year, valley 
inversions will be strong, and fog and/or low clouds are likely to
form in many of our local valleys overnight and persist into the 
mornings.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST this morning for 
     ORZ029>031. 
     Winter Weather Advisory until 10 AM PST this morning for ORZ027. 
     Winter Storm Warning until 10 AM PST this morning for ORZ028. 
     High Wind Warning until 7 PM PST this evening for ORZ021-022. 
     High Surf Advisory until 10 PM PST Monday for ORZ021-022. 

CA...Winter Storm Warning until 4 PM PST this afternoon for 
     CAZ082-083. 
     Winter Storm Warning until 4 PM PST this afternoon ABOVE 3000 
     FEET for for CAZ080. 
     Winter Storm Warning until 4 PM PST this afternoon for CAZ081. 
     Winter Weather Advisory until 4 PM PST this afternoon for 
     CAZ085. 
     Winter Storm Warning until 4 PM PST this afternoon for CAZ085. 

Pacific Coastal Waters...Gale Warning until 10 PM PST this evening for 
     PZZ350-356-370-376. 
     Hazardous Seas Warning from 10 PM this evening to 10 PM PST 
     Monday for PZZ350-356-370-376. 

$$

BTL/BPN/15

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Western Regional Climate Center, wrcc@dri.edu