Uitleg wetenschappelijke weersvoorspelling
Northern Alaska forecast discussion...updated
National Weather Service Fairbanks Alaska
643 am akst Sat Dec 20 2014
current operational models and ensemble means indicate a
continuation of a benign weather pattern over the northern
Alaska Mainland for the upcoming week.
a weak upper level ridge extending east-west across the northern
Alaska interior will gradually become reoriented north-south along
or near the alcan border by Sun afternoon. A weak low pressure
trough over central Siberia will move eastward to northwest Alaska
and the West Coast by Tuesday...bringing a colder air mass aloft to
these areas. Current models appear to be in good agreement on the
handling of this feature out through Tuesday. Beyond Tuesday...the GFS
continues to be more bullish than the European model (ecmwf) moving the trough
eastward across the northern Mainland...dragging the colder air
with it. This solution appears to be an outlier...operational
European model (ecmwf) and the GFS/ECMWF/naefs ensemble means indicating a weak
southwest flow pattern predominating...with warmer temperature
In days 7-10..operational GFS/European model (ecmwf) building a strong upper
high but differ on placement...GFS builds the ridge axis over northwest
Canada with southerly flow across Mainland Alaska...European model (ecmwf)
builds the high over southcentral Alaska...western interior
and northwest Alaska with the extreme astern interior on
the colder northerly flow side of the ridge. Both models
indicate heights approaching 654 decameters in the core
of the high center.
a high pressure ridge extending east-west across the Arctic Ocean
will recede northeastward into the Canadian archipelago by Monday
night. A broad but rather weak low pressure trough will expand
northward across the northern Alaska Mainland and into
the western Beaufort Sea by Monday morning. These two factors will
combine to result in gradually decreasing winds over the Arctic
coast...Chukchi Sea and Bering Sea. Winds over the forecast area
are expected to be generally light by Tuesday morning.
Current GFS and European model (ecmwf) agree in the development of a moderately
strong low to be near or northwest of Shemya by 12z Tuesday. For Tuesday
and beyond...operational GFS/European model (ecmwf) runs diverge over the Bering
Sea. GFS/European model (ecmwf) means show a mean low center over the far western
Bering with a trough extending eastward to Bristol Bay by Thursday.
There is a possibility of minimum brisk winds over St Lawrence
Island and marine zone pkz210 Tuesday into Thursday...but the probability
of gale force winds appears to be low.
Near the end of next week...GFS/ECMWF differ on the details
but allude to a more active weather pattern over the
Bering Sea with gale force winds possible.
In the short term...areas of stratus likely persisting over
the eastern and northeastern interior...and the central and
eastern Arctic slope. GOES infrared and nighttime rgb microphysics from
polar satellites showing widespread stratus over zone
224...patches of stratus elsewhere over the eastern and northeast
interior...widespread stratus over the central/eastern Arctic
Coastal hazard potential days 3 and 4...none
heavy freezing spray warning for pkz210.
Small Craft Advisory for pkz210.
Brisk Wind Advisory for pkz220.