Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Fri Aug 30 2019
Valid 12Z Tue Sep 03 2019 - 12Z Sat Sep 07 2019
Models and ensembles still agree that a potent short range low
pressure system slated to lift over the eastern Bering Sea will
gradually weaken early-mid next week. The system will offer a
lingering maritime hazard and heavy weather/precipitation threat
into western/southwestern Alaska and across southern/southeastern
Alaska with downtream energy/system transfer. There also remains a
decent upstrean early-midweek guidance signal for a second low
system to develop on the heels of the lead storm to mainly effect
maritime interests over the central and northern Bering Sea/Bering
Strait. A blend of the quite well clustered and reasonable 12 UTC
GFS and ECMWF was used in this period of above average forecast
confidence.
Upper trough amplification back into the Aleutians and southern
Bering Sea/AKpen still seems to support a pattern favorable for
additional organized low system developments and heavy
weather/rainfall potential into mid-later next week along with
lead southern stream low lift up into the Gulf of Alaska. Forecast
spread has improved some in this day 6-8 timeframe, so a composite
blend of the GFS/ECMWF and GEFS/ECMWF ensembles seems reasonable
in a period of at least average predictability.
Schichtel
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
- Heavy rain over portions of mainland Alaska, Mon, Sep 2.
- High winds over portions of mainland Alaska and the Aleutians,
Mon, Sep 2.
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