Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
758 PM EDT Mon Apr 6 2020
Valid 12Z Fri Apr 10 2020 - 12Z Tue Apr 14 2020
...Overview and model guidance...
The latest suite of 12Z Guidance is in good agreement on the upper
level ridge axis extending northward across the Gulf of Alaska and
inland towards the Interior for the beginning of the forecast
period. A closed low is situated north of the Arctic coast and
this drifts slowly eastward through the upcoming weekend. Model
differences are most apparent with a low situated over the Bering
Sea, with the 12Z UKMET considerably more progressive than the
other solutions through Saturday. More model uncertainty exists
with the shortwave trough tracking across the Aleutians this
weekend, with the GFS and CMC indicating a slower and more
amplified system, whilst the ECMWF and the ensemble means are more
progressive and a bit weaker. This has implications on the
eventual break-down on the ridge over the Gulf region by early
next week. An even larger storm system is expected to arrive by
Monday across the western Aleutians, with wide latitudinal spread
in the solutions regarding the position of the surface low. The
12Z GFS was farther south than the model consensus and the ECMWF
is indicating more of a dual-low type structure across the Bering
Sea. Given the high level of uncertainty in the later portion of
the forecast period, a greater weighting of the forecast blend for
fronts and pressures was given to the 12Z GEFS mean and the 00Z EC
mean, with some of the operational 00/12Z ECMWF added in, with
below average confidence beyond Sunday.
...Weather/Threats Highlights...
Locations along the Panhandle and southeast corner of the mainland
will trend drier late this week and into the weekend with the
departure of the short-range midweek Gulf system. By Saturday a
wavy front near western Alaska should bring a period of light to
occasionally moderate precipitation to parts of the western and
northern/central Interior. The storm systems affecting the
Aleutians will bring episodes of moisture and periods of gusty
winds depending on system strength. From late this week into the
weekend expect the North Slope region to see above normal
temperatures with more modest positive anomalies over the extreme
western part of the mainland. Chilly high pressure settling over
the southern-southeastern mainland will support below normal
temperatures elsewhere. Pattern evolution aloft by late weekend
and early next week should favor a warmer trend over most of the
state even if surface high pressure may persist over the southeast
portions of the state.
Hamrick
Hazards:
- Much above normal temperatures across portions of mainland
Alaska, Sun-Mon, Apr 12-Apr 13.
- Much below normal temperatures across portions of mainland
Alaska, Thu-Fri, Apr 9-Apr 10.
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
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