Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
321 PM EDT Tue Mar 26 2019
Valid 12Z Sat Mar 30 2019 - 12Z Wed Apr 03 2019
There remains very good agreement in models and ensembles for a
strong ridge/upper high building over the mainland during the
weekend and persisting into next week which would keep
temperatures above normal for this time of the year, with a
handful of record daily highs possible. There is some question
towards the end of the period on if/how much undercutting of the
ridge happens which may bring in southerly flow and a slight
increase in precipitation chances by the end of the period to
parts of the Peninsula and Southern Coast.
Elsewhere, things continue to look a bit more chaotic farther west
across the North Pacific, Aleutians, and the Bering Sea. Most of
the guidance continues to show an initial regime of strong flow
around an upper level low well to the west of the island chain,
pushing a surface front through the Western Bering on day 4. After
this, there should be gradual elongation of upper troughing over
the North Pacific and one or more surface lows tracking south of
the Aleutians. There is fairly good agreement overall on the
synoptic setup, but the details and timing start to diverge more
by mid-period. By day 8 (Wed), the ensemble means generally
suggest that the strongest low pressure over the North Pacific
should track into the western Aleutians.
The WPC progs started with a majority blend of the deterministic
models (06z GFS/00z ECMWF), with smaller contributions from
ensemble mean guidance (namely the GEFS/ECENS/NAEFS). For day 5
and beyond, began increasing the weighting of the ensemble means
to try and mitigate the smaller scale unpredictable features and
differences. This maintains good continuity with yesterdays
forecast as well.
Santorelli
Bullet points from the WPC Days 3-7 Hazards chart can be found at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
-No significant hazards are expected over Alaska during this
forecast period
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