NWS Medford, OR wrote its last area forecast discussion before the first event at Mar 16, 9:39 AM PST, 2 hours 39 minutes earlier.
Area forecast discussion, Mar 16, 9:39 AM PST, 2 hours 39 minutes before
Area Forecast Discussion
National Weather Service Medford OR
1039 AM PDT Sun Mar 16 2025
...Updated Aviation Discussion...
.DISCUSSION...
We've been receiving plenty of flooding reports this morning
around Douglas County as the axis of heavy rain has been hitting
that region for the last 12 hours. Ensemble forecast data
continues to point at this being an unusually strong and wet
QPF/snow event for mid March and some of the daily records will
likely fall for our climate sites. Roseburg has observed 2.80
inches over the last 24 hours, which is a very healthy chunk of
rain for that area. The front and axis of heavy precipitation will
continue to sag south through the day and the flooding threat
will increase for urban areas in Jackson and Josephine County
through the remainder of the morning hours and early afternoon.
We'll also have to keep an eye on some of the major rivers, like
the Coquille River near Coquille. That river will move very close
to major flood at 25 feet, and that could impact a few
residential areas near the river by late tonight and early Monday
morning based on historical impact records in our hydro database.
As for snow, the previous AFD stated that snow hasn't been as bad,
although latest tripcheck reports shows the roads closed in the
high Cascades near Diamond Lake. This is likely due to heavy snow
load on the trees over the last 24 hours. The latest snow
measurements say 6 inches, although that is likely a low
measurement based on the QPF data we've seen across the region.
Using a 10:1 or lower ratio, its likely around 2 feet of snow is
on the ground near Diamond Lake.
Winds hazards will continue to drop off through the day as the
front sags south and wind gusts trend lower along the coast and
within southern Oregon. Quail Prairie in the higher terrain @3000
feet in Curry County is still gusting to 65mph as of typing this
AFD, so we might extend that high wind warning out a few hour more
hours along the coast.
-Smith
&&
..AVIATION...16/18Z TAFs...A strong low level jet persists across
the region this morning with speeds around 60kt at roughly 1500-
2000ft for inland areas. Rain showers are also expected to impact
the terminals today with coverage becoming more isolated to
scattered later this afternoon and tonight. Generally looking at VFR
to MVFR through this TAF cycle. A second front will arrive tonight,
bringing freezing (snow levels) from 5000 ft to 2000 ft overnight.
-Schaaf
&&
.MARINE...Updated 845 AM Saturday, March 16, 2025...Southerly
winds with gale gusts are expected to continue through the morning
hours for areas mainly south of Cape Blanco, building very steep and
hazardous seas through the day. South winds are expected to shift
west and diminishing from north to south through the late morning
hours. While wind speeds are expected to diminish, seas will remain
very steep and hazardous through this afternoon. Thereafter, steep
seas will continue through Monday afternoon for all waters. Winds
and seas are expected to gradually diminish Monday with below
advisory conditions possible Tuesday. Active weather could return
midweek and bring further unsettled conditions starting Wednesday as
strong southerly winds build steep seas once again.
-Guerrero/Schaaf
&&
.PREV DISCUSSION... /Issued 424 AM PDT Sun Mar 16 2025/
DISCUSSION...An atmospheric river event is well underway this
morning. Persistent onshore flow directed in a SW-NE fashion is
aimed directly into Lane, Douglas, Coos and Curry counties. Water
vapor imagery is showing the 300-400 mi wide band of high IVT (500
kg/m/sec) extending from the Oregon coast back to just north of
Hawaii, a strong indicator that the air mass is of subtropical
origin. This fire hose has been aimed at southern Oregon for the
past several hours, with the heaviest rainfall and highest
rainfall rates falling north of a line that spans roughly from
Crescent City across Medford to Crater Lake and into northern
Klamath County. In areas north of that line, 0.10-0.30"/hr
rainfall rates have persisted, but orographic ascent is aiding
precip production in the Curry Coast Ranges and is resulting in
some rates approaching 0.50"/hr at sites like Red Mound RAWS and
Flynn Prairie RAWS. There is a fairly sharp gradient in
precipitation totals so far. Over the past 6 hours (as of ~3 am
PST), totals north of that line range from 0.50"-0.75" for
portions of Josephine and Douglas Counties, 1.00"-1.50" along the
Coast and 1.50"-2.00" across the higher terrain of the Curry Coast
Ranges and the Rogue-Umpqua Divide. Meanwhile, south of that line
only a few hundreths to 0.10" have been recorded.
Overall, not much change in the current situation is expected
through the morning hours aside from some slight wobbling of the
front to the south. Hi-res models are showing precip rates could
peak between 12z-18z this morning, when some locations could see
up to 0.50-0.75"/hour rates, at least for a short duration of 1-3
hr. When all is totaled up, rain amounts of 3 to 6 inches will be
common along the coast, into the Umpqua Basin and over to the
Cascade Foothills. As mentioned earlier, orographic lift will
likely aid precip in the coast range mountains resulting in some
totals exceeding 8 inches. South of the Rogue/Umpqua Divide,
rainfall will likely be 1-3 inches, with the lower amounts
expected in the southern Rogue Valley. Many headlines are out for
the heavy rainfall, with areal flood watches up west of the
Cascades as well as many river/stream forecast point flood
watches/warnings. This includes Deer Creek at Roseburg, Elk Creek
at Drain, South Umpqua at Elkton, Coquille at Coquille, the South
and North Forks Coquille at Myrtle Point and the Rogue River at
Agness. Please see water@noaa.gov for the specifics on those
particular rivers and be on the lookout for more potential flood
advisories/warnings through the day today. Please do not drive
through flooded roadways. Most flood deaths occur in vehicles.
Turn around, don't drown.
Meanwhile, snow levels are hovering around 5000 ft in the
Cascades, and heavy snow is resulting in dangerous conditions. By
the time this event is over, snow totals will be measured in FEET
up at Crater Lake. Snowfall rates of 1"/hr up that way are nearly
certain with a 90-100% chance through the afternoon, and even a
60-90% chance of 2"/hr as well. Winter Storm Warnings remain out
for the Cascades/Siskiyous through this evening. Heavier precip
rates are keeping the snow level lower on Highway 97 north of
Chiloquin, whereas to the south, Klamath Falls and Lakeview are
both solidly in the warm sector with little or no precip. A winter
storm warning is out for northern Klamath and parts of northern
Lake County also through this evening. It should be noted, that
very strong winds are expected along with this heavy snow, and
periods of very low visibilities are expected. This is most likely
up in the Cascades and higher elevations east of the Cascades, so
it's best to remain out of those areas until this event is over.
Details on these winter weather hazards can be found at WSWMFR. An
interesting caveat to the snow level is on the back side of the
heavy precip later this morning/early afternoon. Models are
showing the snow level dropping to around 2500-3000 feet, which
could impact the Cascades Foothills (Highway 138 near Toketee
Falls) with a changeover to snow. So be aware of that possibility.
Some guidance is showing it getting down to 2000 feet, but the
probability of that occurring is very small (less than 10%
chance).
Speaking of strong winds, there is a plethora of High Wind
Warnings and Wind Advisories spanning the area. So far, gusts of
55 to 60 mph have been recorded along the coast, across the higher
terrain, the Shasta Valley and portions of the East Side/NorCal.
Meanwhile, gusty southwest winds are surfacing in parts of the
Illinois Valley and Umpqua Basin where we have a Wind Advisory in
place. Winds will gradually ease from northwest to southeast as
the day progresses, with an overall downward trend by this
evening. Please see NPWMFR for more details.
Another low pressure currently out near 140W will approach the
coast this afternoon, and be the catalyst for pushing this front
along. This will push the bulk of the precipitation south and
eastward, and areas east of the Cascades will get their share of
precipitation late this afternoon and evening. Snowfall will ease
up along the Cascades, and we'll likely see a transition from rain
to snow over the East Side as the frontal boundary presses east
of the Cascades this evening. This transition is likely to happen
as the heavier precipitation is easing up over there, so while
there may be some heavier snow amounts in the higher terrain,
snowfall overnight tonight will be fairly light with generally 1-2
inches expected tonight through Monday. The exception could be
along the Warners of Modoc County where advisory level snow
amounts are possible and could impact Cedar Pass on Highway 299.
For areas west of the Cascades, snow levels are likely to hover
around the 2500 ft mark, though some guidance shows the potential
for pockets of snow levels down to 1500 ft as a round of moisture
(considerably lighter than what's currently occurring) moves
through the region. This could bring some light snow during the
early morning hours on Monday to some of the passes north of
Grants Pass (Sexton, Canyon Creek, Camas Valley). If these lower
snow levels materialize, it's not out of the question to see some
snow flakes in the West Side Valleys, but at this time, any
accumulations should be minimal if any at all.
The upper trough swings through on Monday, maintaining widespread
showers across the region. Snow levels will hover around 3000 ft
during the day Monday, and with the hit/miss nature of showers,
any winter impacts should be limited to where showers are most
persistent. Showers will taper off late Monday into Tuesday when
we'll catch a break in this active pattern, giving the river
systems time to recede/recover. This break in the weather will be
short lived with another front quickly moving in late Wednesday
(more typical for this time of year) and active weather continuing
through the latter half of the week and into the following
weekend. We'll focus in on details with these upcoming systems
once we're past this current atmospheric river. /BR-y/Spilde
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 11 PM PDT this evening for
ORZ027>031.
Flood Watch through this evening for ORZ021>026.
High Wind Warning until 5 PM PDT this afternoon for ORZ021-022-
031.
Wind Advisory until 2 PM PDT this afternoon for ORZ024-026-029-
030.
CA...Winter Storm Warning until 11 PM PDT this evening for CAZ080-082-
083.
Flood Watch through this evening for CAZ080.
High Wind Warning until 5 PM PDT this afternoon for CAZ081-084-
085.
Winter Weather Advisory from 8 PM this evening to 5 AM PDT
Monday for CAZ085.
PACIFIC COASTAL WATERS...Gale Warning until 11 AM PDT this morning
for PZZ356-376.
Hazardous Seas Warning until 5 PM PDT this afternoon for PZZ350-
356-370-376.
Small Craft Advisory from 5 PM this afternoon to 5 PM PDT Monday
for PZZ350-356-370-376.
&&