Scientific Forecaster Discussion
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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
125 PM akdt Sat Sep 14 2019
high pressure will support mainly clear, mild weather across the
state today. A few showers are possible across portions of the
eastern interior including the upper Tanana Valley and fortymile
country. The next in a series of Bering Sea low pressure systems
will work its way east into the y-k Delta late this evening into
Sunday morning, bringing locally heavy rain to the lower Yukon. As
the low moves southeast into the Gulf of Alaska Monday, cool
Arctic air will be pulled south, causing a steady drop in
temperatures to persist through the end of the week across the
state. Modest snowfall will be possible late Monday into Tuesday
for the North Slope, and particularly the central and eastern
Brooks range as freezing levels fall sharply.
Aloft 500 mb...
a highly progressive pattern will feature a ridge axis moving
quickly east across the interior today and into Canada by Sunday
morning. Low pressure on the heels of the ridge will move east
from the central Bering Sea and track onshore near Nunivak Island
Sunday morning. This low will be reinforced from the north as an
Arctic low in the Beaufort Sea pushes rapidly southwest. A weak
ridge will still manage to move east across the southern interior
underneath the longwave trough. However, as the next Bering Sea
low approaches the coast Wednesday, it will merge into the Arctic
low, forcing the longwave trough to deepen even farther south and
causing a significant height fall into the late week. Beyond
Wednesday, models vary wildly with placement and strength of
features but essentially tell different versions of the same
story. Significantly colder temperatures are expected Thursday
into next weekend across the state.
North Slope and Brooks range...
weak surface high pressure 300 nm northwest of Point Barrow will
support northeasterly onshore flow across much of the Arctic coast
through the weekend. The high will weaken and erode as a polar low
drops south through the Arctic sea Monday. This will enhance
precipitation along the coast while gradually lowering
temperatures and freezing levels. A mix of rain and snow will be
expected along the coast late Monday into Tuesday with modest
snowfall possible for the northern Brooks range during that time.
West Coast and western interior...
pleasant weather is expected through this evening for the region
as high pressure slides east through the interior. Rain will begin
falling across the y-k Delta early Sunday as a low moves rapidly
through the eastern Bering Sea and onshore near Nunivak Island.
The bulk of the rain will be confined south of Nome to Galena
with totals of around a quarter to a half inch through Monday.
High temperatures in the mid 50s to 60 degrees today will begin
to fall into next week as cool Arctic air is pulled south.
Central and eastern interior...
high pressure will support mostly clear skies and high
temperatures in the mid to upper 60s today for much of the region.
Showers in the far southeastern interior will taper off this
evening as low pressure over the Panhandle tracks east into
Canada. Similar conditions are expected Sunday, though somewhat
cooler with high temperatures topping out in the low to mid 60s as
the next low encroaches from the southwest. A major cooling trend
will begin Monday as low pressure moves east through the northern
Gulf of Alaska. North winds will pull cooler air southward,
dropping freezing levels across the region as showers build over
the Alaska Range. Some light snow accumulation will be possible
across higher elevations of the Denali park Road late Monday. Low
pressure dropping south from the high Arctic will bring additional
moisture to the Brooks range and eastern interior. By early
Tuesday, higher elevations of the interior north and east of
Fairbanks may see some light snow as freezing levels fall to
around 2500 feet.
Coastal hazard potential days 3 and 4...none.
above normal temperatures for the interior will continue into
Sunday, but begin to sharply fall Monday. Relative humidity
values are expected to remain above 40 percent with excellent
overnight recovery. Some gusty winds to 30 mph are possible on
summits Sunday evening into Monday morning. Winds generally will
be north to east at 5 to 15 mph.
no areas of concern at this time.
Small Craft Advisory for pkz210-pkz220-pkz225-pkz230-pkz240-