Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
607 PM EST Tue Nov 19 2019
Valid 12Z Sat Nov 23 2019 - 12Z Wed Nov 27 2019
Upper pattern will transition toward a flatter flow next week with
troughing generally remaining in the Bering Sea. Models and
ensembles showed good agreement on the pattern unfolding over the
high latitudes with less agreement in the mid-latitudes of the
Pacific. Less-predictable smaller-scale waves show little
consistency in the models and were smoothed out via a blend.
12Z GFS/ECMWF/Canadian/UKMET offered a reasonably-clustered
solution to start with the weakening system over the interior/SW
Alaska Saturday with a lead-in heavy precipitation threat. Next
two systems of interest were from the west through the Bering and
to the south heading toward Hadai Gwaii and maybe the southern
Panhandle. For the Bering system, the Canadian and ECMWF and its
ensembles were generally quicker than the GFS and its ensembles
with this system that flattens out and likely redevelops its
triple point low into the Gulf by next Wed. Flattening of the
pattern and a quicker trend in the guidance suggested a majority
weighting of the ECMWF/Canadian/ECMWF ensembles. To the south, GFS
has wavered on whether or not to detach an upper/sfc low in the
mid-latitudes or keep it progressive toward the ENE. 12Z GFS went
back to the detached solution but the other guidance favored a
progressive sfc low. Depicted this scenario in the progs which
still seems to be supported by the 12Z ECMWF ensemble mean.
Wet period for the Panhandle will slacken after Saturday as the
front departs the area. Bering system will bring wind/rain to the
Aleutians but will be progressive. Snow is likely on the north
side of the frontal zone (warm front ahead of the main system) in
warm advection. Temperatures will likely be above average over
most of the state but trending cooler around Bristol Bay with the
approaching Bering system with increasing easterly flow.
Fracasso
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,
Fri, Nov 22.
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