Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
537 PM EST Fri Jan 08 2021
Valid 12Z Tue Jan 12 2021 - 12Z Sat Jan 16 2021
...Deep lows to bring heavy precipitation and wind/waves from the
Gulf of Alaska to Southern/Southeast Alaska Early Next Week...
...Guidance/Uncertainty Assessment...
The large scale pattern was reasonably clustered through the
period with the WPC blend initially blended with the 12Z
ECMWF/CMC/UKMET/GFS and is expected to feature closed lows and/or
troughing confined to the Gulf of Alaska west across the
Aleutians. A pair of stronger/deeper lows is forecast during the
period. The first will be ongoing at the start of the period and
has decent clustering between the various models. Over time,
typical model spread increases but by day 7/8, guidance suggests
another shortwave trough will swing through. At the surface, low
pressure is forecast to track across the Gulf and could bring
hazardous weather by the end of the forecast period. But because
of the higher model uncertainty, the WPC blend favored the
ECENS/GEFS at this time.
...Weather/Hazards Highlights...
The latest guidance continues to suggest a deep cyclone / closed
upper trough over the Gulf of Alaska late this weekend into the
early part of next week. This anomalous moisture fetch will favor
heavy precipitation and high winds/waves from the Gulf toward the
southern/southeast Alaska with the threat transitioning mainly to
southeast Alaska by mid-week as the low weakens/occludes. After a
brief break, another deep low is forecast to lift into the
northern Gulf of Alaska and potentially could bring another round
of heavy precipitation, significant waves, and high winds. Though
given the lower than average model agreement and higher forecast
uncertainty, there is still quite a bit of details left to
discern. This pattern should also favor some much above normal
temperatures into the Interior next week.
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