Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
423 PM EDT Wed Oct 09 2019
Valid 12Z Sun Oct 13 2019 - 12Z Thu Oct 17 2019
Relatively benign weather is expected to start out the
medium-range period in Alaska on Sunday before a deep cyclone, the
extratropical transformation of super typhoon Hagibis, moves
across the Aleutians by Monday. The model guidance today
indicates a higher degree of uncertainty regarding the track of
the cyclone through the Aleutians early next week. The ECMWF is
now taking the cyclone more on a easterly track along the
Aleutians on Monday in pretty good agreement with the GFS and GEFS
track. However, this easterly track is contrary to the 00Z EC
mean which takes the cyclone into the Bering Sea. In addition,
the 00Z Canadian mean also takes Hagibis on a track into the
Bering Sea. Thus, the decision was to use a blend of the 00Z EC
mean with the 00Z NAEFS for Days 6, 7 and 8. This yielded a
cyclone track that was fairly close to continuity. For Days 4 and
5, a general compromise of the 00Z EC mean, 06Z GEFS mean, the 12Z
GFS and the 00Z ECMWF was used.
High winds and significant waves along with heavy rain can be
expected with the arrival of the extratropical cyclone/Hagibis
across the Aleutians on Monday. Meanwhile, another occluded
cyclone is forecast to edge closer to the south coast of Alaska
and the Alaska Panhandle with gusty winds and periods of heavy
precipitation possibly lasting into Wednesday. Uncertainty
increases as to whether the circulation of Hagibis will eventually
merge with this occluded cyclone. However, the trend is for the
stormy conditions over the Aleutians to slowly subside during the
middle of the week.
Kong
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
Alaska Hazards...
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Mon-Wed, Oct 14-Oct 16.
- High winds across portions of the Aleutians, Sun-Tue, Oct 13-Oct
15.
- Significant wave heights for coastal portions of the Aleutians,
Mon-Wed, Oct 14-Oct 16.
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