Ketchikan, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

344
FXAK67 PAJK 031423
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
523 AM AKST Tue Dec 3 2024

.SHORT TERM...Once again, for about the third day in a row, the
tale of today`s weather is the tale of two boundaries, the cold
air to the north, and the warm air pushing in from the south.
Luckily, today looks to finally have a winner, which is beginning
to show on elevated observations in the north. Unfortunately for
those in the north, persistent drainage flow from the north in the
Chilkat Valley and down from White Pass may cause ideal conditions
for wintry mix and freezing rain development. Observations at
elevations 2000 ft and above are currently showing temperatures
warming over time, around 32 degrees at time of writing. While
guidance has consistently had trouble with boundary layer
temperatures and inversions, a very typical issue in SE AK, what
has rung true is the warming at 2000 ft and above. With the
incoming front from the south, this could result in a prolonged
freezing rain event for Haines and Haines Highway, with freezing
rain moving along Haines Highway as temperatures aloft warm. The
big issue is slight variations in temperature both aloft and at
the surface can easily transition precipitation type into either
snow or wintry mix, particularly if the cold boundary layer
extends higher than expected, or temperatures aloft do not warm in
a timely manner. For the Klondike Highway, this will not be an
issue, as temperatures are expected to remain below freezing, but
isothermal in nature. With southerly flow, an isothermal profile,
and less than optimal moisture working its way to Skagway, snow
totals around White Pass look to be around 4 inches at the storm
peak, around Tuesday afternoon.

For information related to the southern panhandle, refer to the
hydrology section.

.LONG TERM...Headed into the long term period, the active weather
looks to continue as onshore flow and the overall steering pattern
continue to guide systems into SE AK. Precipitation chances look
to diminish slightly during the day on Wednesday. Another wave
with two embedded lows, one moving into the south central
panhandle, and one moving into the far northern gulf coast, will
move into the area late Wednesday into Thursday bringing more
rain and winds to the area. right now most winds look to remain
below gale force looking at ensemble wind speeds. Heading into the
end of the week and into the weekend, another frontal band arrives
on Friday, although most precip will fall as rain given the
continuing warmer air funneling into the area. There is the
possibility of a lull in the weather on Saturday, as ensemble
guidance indicates a ridge may try to build over the area, but
confidence in this remains low. There are some indications in the
ensembles of a significant rain producing system early next week,
but at this time details remain difficult to pin down.

&&

.AVIATION...Flying weather this morning features a new front
coming in from the SW. Heavier steadier rain has already started
up across the south from this feature with mostly MVFR ceilings or
vis resulting from it. Farther north some lower ceilings and
lingering light precip are creating scattered pockets of MVFR (or
IFR at Juneau) conditions. Some wintry precip (snow, sleet, and
freezing rain are all possible) is expected around Haines and
Skagway today. Rain is expected to spread north and east through
the morning with widespread MVFR conditions with isolated IFR in
the heavier rainfall today. Southerly winds are also expected to
increase this morning across the southern panhandle with the
associated turbulence and low level wind shear. Overall conditions
are expected to improve Tuesday night as the front moves into
Canada taking the winds and higher precip rates with it.

&&

.MARINE...Widespread near gales to gales along the gulf coast
through Tuesday, which will extend into Clarence Strait. As this
system originates far in the south, dynamic fetch from consistent
southerlies is expected to bring wave heights much higher than
expected, from 15 ft to 20 ft from south to north along the coast
respectively. Areas between Cape Suckling and Icy Cape are
expected to take the brunt of the 20 ft wave heights, maximized as
gales begin to diminish. For the inner channels, winds are
expected to shift increasingly southerly over Tuesday and increase
to at least a fresh breeze. Lynn Canal remains a headache for this
forecaster, with guidance keen on switching winds to southerly too
soon. Expecting a slow transition to southerly as winds will be
hard to mix out colder, denser air from the north.

&&

.HYDROLOGY...Raising freezing level and a fully saturated profile
is currently moving into the southern panhandle, associated with
a warm occluded front from the south. Low level moisture
transport, indicated from the most recent sounding, show a less
impressive jet at 45 knots around 2000 ft compared to Monday. The
result is less efficient precipitation compared to Monday`s
widespread rates of 0.3 and greater. MIRS rain rate mosaic
indicate that rain rates between 0.20 - 0.25 in/hr are in Dixon
Entrance. Furthermore, pockets of cooler cloud tops indicate that
some embedded convective features are present, which will likely
cause localized heavier rainfall. These are co- located with MIRS
data indicating rain rates up to 0.35 in/hr. Area creeks and
streams remain high with nearby soils fully saturated from recent
heavy rains could flood with additional heavy rain.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory from 9 AM this morning to 9 PM AKST this
     evening for AKZ318.
     Flood Watch through this evening for AKZ320-325>332.
     Strong Wind until noon AKST today for AKZ323.
     Strong Wind until 6 AM AKST early this morning for AKZ328-330-
     332.
MARINE...Gale Warning for PKZ642>644-651-652-662>664-671-672.
     Small Craft Advisory for PKZ012-022-033-036-053-641-661.

&&

$$

SHORT TERM...NC
LONG TERM....GFS
AVIATION...EAL
MARINE...NC
HYDROLOGY...GJS

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