Uitleg wetenschappelijke weersvoorspelling
Northern Alaska forecast discussion...updated
National Weather Service Fairbanks Alaska
343 PM akdt Monday Sep 15 2014
..updated to include fire weather...
The 15/12z model suite is in good agreement through the forecast
period. There are only subtle differences between the models on
timing and areal coverage of precipitation. Model guidance also in
agreement on the cooling trend this week with a return to
seasonable temperatures by the weekend.
A broad upper low over the Bering Sea and southwest Alaska will
continue to wobble around over the Bering Sea for the next 48
hours. This upper low is then forecast to make forward progress
east middle week and result in a broad upper level low/trough setup
over Mainland Alaska and the northern Pacific by the weekend. Its
surface reflection...a broad 997 mb low over the Yukon Delta will
continue to fill and weaken as it drifts north tonight. As it
drifts north it will be absorbed into a second low as it moves
east along the Aleutian chain over the next 24 hours. The
resultant low will make eastward progress by middle week and be a
broad surface low/trough complex over Mainland Alaska by weeks
An occlusion associated with the aforementioned surface low over
the Yukon Delta will remain draped over the Brooks range and
weaken through Wednesday evening. This will keep scattered to
numerous showers for the northern interior and North Slope.
Scattered showers are also expected along the West Coast through
middle week as the low wobbles over the Bering Sea.
There is a remote possibility for isolated thunderstorms from
Galena to Eagle this evening. Even though convective indices are
less than favorable...a shortwave rotating north this evening
around the upper low will provide some dynamic support with
cooling temperatures aloft to spark off a few lightning strikes.
Additionally...isolated showers may be sparked off over the
central and eastern interior with the shortwave passing overhead.
The shift in the overall synoptic pattern this week will allow for
a gradual cooling trend in both surface and h850 temperatures. By
weeks end...northerly flow will set up over the Bering Strait and
West Coast enabling much colder h850 temperatures (-1 c to -10 c)
to advect southward Friday into the weekend.
Very little change for the North Slope over the next 48 hours.
Expecting fog...stratus and occasional light drizzle to persist.
Have continued dense fog headline for zone 203 and added zone 204
thinking that dense fog will spread east overnight.
Coastal hazard potential days 3 and 4...north winds strengthening
through the Bering Strait Thursday and Friday could bring some
moderate surf to the North Shore of Saint Lawrence Island.
Fire weather...near red flag conditions for strong winds and low
humidity in zone 223 from Delta Junction south and in zone 226 in
the Alaska Range passes through 7 PM. Winds will diminish some
overnight to between 15 and 25 miles per hour. There is some concern for near
red flag conditions again on Wednesday for the Alaska Range passes
in zone 226 and zone 223 south of Delta Junction where winds will
be 15 to 3o miles per hour and relative humidity will approach 30 percent.
Hydrology...quarter to half inch of rainfall possible across the
Brooks range through Tuesday morning. No Hydro issues anticipated
at this time.
Small Craft Advisory for pkz235.
Gale Warning for pkz240-pkz245.