Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
552 PM EST Sat Jan 09 2021
Valid 12Z Wed Jan 13 2021 - 12Z Sun Jan 17 2021
...Active Pattern Continues Across Gulf of Alaska Next Week...
...Guidance/Uncertainty Assessment...
A pair of shortwave troughs and/or closed lows are forecast over
the Gulf of Alaska during the period with an increasingly
amplified upper level pattern. The first system has reasonable
agreement on day 4 but the 12Z GFS quickly falls out of favor in
the preferred blend as it becomes too amplified and fast with the
upper level energy. This becomes even more apparent for the second
system, as the GFS takes it well east/south compared to the other
deterministic guidance. As such, the WPC blend incorporated little
of the 12Z GFS and instead focused on the better agreement seen in
the 12Z ECMWF/CMC. By day 7-8, with the typical model biases
coming into play, the blend used more of the ECENS/GEFS.
...Weather/Hazards Highlights...
A pair of storm systems are forecast to impact the
southern/southeast coasts next week, the first should be
ongoing/weakening on day 4 with low pressure over the eastern
Aleutians. A brief lull with some ridging in place for day 5 will
be quickly followed by another deepening low pressure lifting
toward the southern coast and is likely to bring significant
precipitation, high winds, and significant waves. For much of the
interior regions, above normal temperatures and below normal
precipitation is expected.
Taylor
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Mon, Jan 11.
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html