Grenada, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

962
FXUS66 KMFR 220104 AAA
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
504 PM PST Thu Nov 21 2024

.Updated...Aviation Discusion.

.AVIATION...22/00Z TAFS...Strong low pressure off the south Oregon
Coast willl move north along 130W tonight. This will allow for
continued abundant clouds and precipitation across the region for
the next 24 hours with widespread mountain obscuration. South winds
will increase with developing wind shear at all terminal this
evening into Friday morning. Winds will decrease after 18z Friday
but widespread MVFR conditions with local IFR and widespread
mountain obscuration will continue. -CC

&&


.SHORT TERM (Today through Friday night)...

Overview:

Snow levels continue to rise today with most areas above 5K feet as
of writing this, and this has resulted in widespread rainfall across
the region. Siskiyou County in northern California in particular has
received a lot of rainfall (upwards of 10 inches) on top of snowfall
(2-3 feet), and there is the concern for flooding across the area. A
Flood Warning is in place across Siskiyou County. In addition, we
have a Flood Warning across southwest Oregon, and we also have a
Flood Watch in place for parts of the South Fork Coquille River at
Myrtle Point. We are expecting upwards of 3-8 inches of additional
rainfall now through Saturday for these areas mention in northern
California and southwest Oregon. Highest amounts expected over
southern Siskiyou County in and around the Mount Shasta City and
Dunsmuir areas but as far east as Pondosa. Additionally, expecting
impacts from wind speeds through tomorrow afternoon, and we do have
wind hazards out for this threat.

Further Details:

A broad area of cyclonic flow is observed on mid-level water vapor
imagery from GOES-18. Analysis shows a couple distinct areas of
circulation within this broader area. Another closed surface low
will develop in this area, and will start to approach 130W by
midnight tonight. The pressure gradient is progged to maximize
around 1 AM to 2 AM tonight, and will remain strong overnight
through mid to late afternoon on Friday. Please see the latest high
wind warning and wind advisory for further information.

Within the aforementioned area of cyclonic flow, we will have a
steady strong upper level jet, and this will lead to divergence
aloft--with minor orientation changes--through the end of the short
term (into Saturday actually). Also during this time, a steady fetch
of moisture from the Pacific will be present. Given the strong
dynamics and forcing in place, we are looking at the potential for
impacts from flooding, especially low lying flood prone areas and
small creeks/rivers. We are looking at upwards of 6-8 inches of
additional rainfall for some areas in Siskiyou County and upwards of
3-5 inches in southwest Oregon. Please see the latest Flood Warning
and Flood watch for further details.

-Guerrero

.LONG TERM (Saturday Morning through Thursday)...

Unsettled weather will continue over the weekend into at least
early next week as an upper low off the British Columbia coastline
slowly moves south along the Pacific Northwest coastline into
Tuesday. Snow levels will drop Saturday morning to around 4000
feet...dropping to around 3000 feet Sunday morning. We were
generally be in a showery pattern...with not much accumulation
forecast...however we will dive deeper into this over the next 24
to 48 hours once we get past our current busy weather situation.

It does look like the weather pattern will become less active...
with periods of dry weather beginning mid next week. Looking through
the clusters and ensemble data...only about 10% of members are
showing an active weather pattern by Wednesday of next week. In
fact...both the 6 to 10 day and the 8 to 14 day outlooks from the
Climate Prediction Center show between a 40 to 60% chance of below
normal temperatures and a 30 to 40% chance of below normal
precipitation.

-Riley

&&

.MARINE...230 PM PST Thursday, November 21, 2024...Conditions
worsen this evening as another deep low pressure develops near 40N
130W this evening and moves north along 130W through early Friday.
Though this system will move closer to shore than the Tuesday
system, it will still be weaker than previous storm. Strong south
gales develop this evening and persist into Friday afternoon. There
will be a brief period tonight (around midnight) when isolated areas
could experience storm force wind gusts of 55 to 60 kt. Since this
will only be during about a 4 hour window and for isolated areas,
have decided to just stick with a Gale Warning for this storm since
it will be the main threat. Seas will rapidly build again, reaching
up to 20 ft late tonight through Friday. Conditions will begin
improving overall as winds ease late Friday into Saturday.

-Stavish

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 4 PM PST Friday for ORZ021-022-029>031.

     Wind Advisory until 4 PM PST Friday for ORZ026-029>031.

CA...High Wind Warning until 4 PM PST Friday for CAZ081-084-085.

     Wind Advisory until 4 PM PST Friday for CAZ084-085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 7 PM PST this
     evening for PZZ350-356-370-376.

     Gale Warning from 7 PM this evening to 4 PM PST Friday for
     PZZ350-356-370-376.

     Hazardous Seas Warning from 4 PM Friday to 4 AM PST Saturday for
     PZZ350-356-370-376.

&&

$$