Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 261058
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
258 AM AKDT Tue Sep 26 2017

.DISCUSSION...
The 00z model suite initialized well against the 00z surface
analysis and verified well against the 06z surface analysis. Model
spread remains reasonable with the 00z run in the short range
however significant differences appear in the model suite in the
timing, track and intensity of a low pressures system progged to
move over the northwest coast by Thursday and the large
differences continue through the weekend. Small differences in
timing, track, and strength will have significant impacts on
sensible weather and potential coastal impacts for the western
north slope.

Aloft at 500 hpa, a 500 dam low near 80N and 155W with a shortwave
trough extending southeast to demarcation point and then southwest
to near Fairbanks and Nunivak Island will continue to sweep east
into the central interior this morning and through eastern
interior this evening. A stalled out and weakening front that
currently extends from Eagle to McGrath will be further weaken
as strong shortwave passes into the eastern interior and as a
ridge of high pressure builds in aloft over the eastern Bering
Sea, the west coast and the western interior today and Wednesday.

Another shortwave moves east out of the Chukotsk Peninsula into
the Bering Strait Wednesday evening and into Norton Sound and the
west coast Thursday morning. A much stronger shortwave rotating
around another strong upper level low 300 nm north of Wrangel
Island Wednesday night will approach the northwest coast and
stretch from near Barrow through the Bering Strait Thursday
morning. The model suite continues to display significant
differences in the time track and strength of both the parent low
and the shortwave rotating around the low in the vicinity of the
northwest coast as early as Thursday. An upper level low near
Kodiak Island will have a shortwave rotate north and west into the
southeastern and south central interior Thursday morning and will
bring another round of mostly rain showers as snow levels will
remain near 5000 to 6000 feet over the southern interior.

On the surface, weak high pressure over the north slope will drift
east today. A weak ridge of high pressure will build north and
east out of the eastern Bering Sea into the western interior
Wednesday ahead of a weak trough extending to the south of a
surface low 350 nm north of Wrangel Island. The trough sweeps
east into the Bering Strait and western north Slope Wednesday
night and Thursday morning. The GFS places the surface low nearly
200 nm north and west of where the ECMWF and Canadian model place
the low which is 250 nm north of Wrangel Island Thursday morning.
The Canadian and ECMWF continue to track a 992 mb low approximately
300 nm north and west of Barrow Friday morning and bring much
stronger on shore winds to the western north slope than does the
GFS solution which tracks a 999 mb low 500 nm northwest of Barrow
Friday morning. Friday evening the GFS tracks a 999 mb low 250 nm
northwest of Barrow which only produces a brief period of along
shore winds while at the same time both the Canadian and ECMWF
models track a 999 mb low 250 nm northeast of Barrow which keeps
stronger on shore winds impacting the northwest coast. A weak
front rotating around a 1004 mb low in the Gulf of Alaska will
produce scattered rain showers over the central and eastern
interior while ridging continues to build over the west coast and
western interior.


Coastal Hazard Potential Days 3 and 4...
The 00z model suite as well as previous model runs continue to
display significant differences in the time track and strength of
both the parent low and the shortwave rotating around the low in
the vicinity of the northwest coast as early as Thursday. Small
differences in timing, track, and strength will have significant
impacts on sensible weather and potential coastal impacts for the
western north slope. Continue to monitor.

&&

.HYDROLOGY...None.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ210-PKZ220-PKZ245.
&&

$$

CCC SEP 17


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