Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
234 PM akdt Thursday Aug 25 2016
Current models are in generally good agreement out through Sunday
and then become increasingly divergent thereafter. The
operational GFS solution is well supported by its ensemble mean
in the extended period. The 00z run of the European model (ecmwf) appears to be an
outlier and it did not agree with any of the other models and
departed considerably from its ensemble mean. The 12z run of the
ECMWF also starts to diverge from the GFS after Sunday. The GFS
and its ensemble mean are preferred for the extended period.
very weak ridging now over northern Alaska will be slightly
dented by a weak short wave trough moving across the northern
Mainland late tonight through Friday evening. The short wave is
now over the Chukchi Sea and it will exit eastward into Canada by
late Friday night as it moves around stronger ridging rebuilding
over the West Coast and the northern Bering Sea. This rebuilt
ridge will then weaken Saturday night as a weak cutoff upper low
over the southern Bering Sea drifts slowly eastward towards the
West Coast and as a short wave approaches the Chukchi Sea
from the west.
a weak pressure pattern will persist over most of the northern
Alaska Mainland through the weekend. The northwest coast will see
south to southwest winds to around 20 mph Saturday and Saturday
night as the outer fringe of the circulation around a strong low
moving northward across the russian Arctic waters expands eastward
to the northwest coast. A ridge of high pressure will dominate the
West Coast from the Seward Peninsula southward Friday into
Saturday. A weak trough moving eastward across the Arctic
Ocean will brush the northwest coast Saturday night, followed
by an eastward moving 1035 mb high which will arrive over
the chukotsk peninsula, the Chukchi Sea and the western
Bering Sea by Sunday evening.
Rain over the Alaska Range and the southeast interior will
taper off to isolated to scattered showers by Friday morning.
Coastal hazard potential days 3 and 4...none.
no issues. Afternoon humidities Friday and Saturday are
expected to be 50 percent or higher in most areas of the
rainfall amounts mainly in the range of 0.25 to 0.5 inch with a
few higher values have occurred over the Alaska Range and the
southeast interior during the last 24 hours. Additional amounts
over the southeastern interior and the eastern Alaska Range
are expected to range from 0.1 to 0.25 inch tonight. The
extreme southeast interior may see another 0.1 to 0.25 inch
Friday, with additional amounts elsewhere being less than 0.1
inch in isolated to scattered showers. These rainfall amounts
are not expected to cause any hydrologic issues.
Rf Aug 16