Scientific Forecaster Discussion
fxak69 pafg 221207
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
407 am akdt Fri Jun 22 2018
a significant change in the weather is underway for the interior
with the passage of a frontal system that brought thunderstorms
ahead of it and cool moist air behind it. The low in the Bering
continues to be the driver of weather in that region. In the
Arctic the front that moved through the interior will move into
the Brooks range while stratus and fog continues in coastal areas.
Models are in general agreement with the overall pattern. However,
placement of features like areas of heavy precip along frontal
boundaries is a bit inconsistent.
Aloft: the low that had been largely stationary around Bristol
Bay will drift north and west today and should be located a little
south of Saint Lawrence Island tonight. Even though it moves away
from the Mainland, it will still influence weather on the West
Coast. The ridge of high pressure that was over the interior moved
north to be over the eastern Brooks range and will continue
moving north through tomorrow with a short wave pushing north
behind it. Generally southerly flow returns to the interior today
and Saturday before ridging builds back in from the Yukon on
Central and eastern interior: the front that arrived yesterday
continues to push through the interior. Rain showers are covering
much of the central and eastern interior and are slowly working
their way northwest. Showers should slowly taper off from south to
north through the day, except for places close to the Brooks
range, which will see precipitation into the night. Isolated
thunderstorms are also possible today, mainly in the Brooks range.
Behind the front cool, moist conditions will be in place for the
next couple of days with southerly flow. This also means some more
gap winds in the Alaska Range. The typical summertime ridge will
build back in from the Yukon on Sunday.
West coast: another shortwave attached to the low in the Bering
Sea will move northwest through the West Coast and western
interior today into tomorrow. Rainfall with this system is
expected to be heaviest in the Brooks range. Stormfall totals are
between 0.5 and 1.0 inches for some areas over the next 24 hours
or so. This could cause stream rises in drainages where this
precipitation falls. Right now models are rather uncertain as to
exactly where these areas of heavier precip will be.
North Slope and Brooks range: a shortwave will move to the north
over the Brooks range and onto the North Slope this afternoon into
Saturday, displacing the ridge in place. This will bring more
rainfall to the Brooks range and cooler temperatures. Some of the
rainfall in the Brooks range may be locally heavy; however, the
models differ some on the exact timing and placement of the
heaviest rainfall. Low level stratus and fog is expected to
continue at times through the weekend along the coast as a ridge
of high pressure persists.
Coastal hazard potential days 3 and 4...none.
the conditions that triggered red flag warnings for the interior
have since subsided with the passage of the front. Relative humidity values have
increased in the interior and temperatures have fallen, so areas
that saw nonconvective red flag warnings yesterday will not see
them again today. Convection will not be as active today so the
issuance of convection based warnings are not anticipated today.
Isolated thunderstorms are anticipated in the Brooks range and the
western interior. Relative humidity values will remain elevated through Saturday,
so not big fire weather concerns for the next couple of days. Some
drying occurs Sunday to drop relative humidity values to around 30 percent in the
warm temperatures aloft over the Brooks range combined with heavy
rainfall over the last several days and additional rainfall
expected over the next couple days will produce significant rises
on rivers draining the Brooks range and in particular The Sag
river. Current forecasts bring The Sag river into action stage
over the next few days. We will have to watch the rivers north of
the Brooks range over through the weekend.
Small Craft Advisory for pkz210-pkz220-pkz225.