Alaska Extended Forecast Discussion
National Weather Service College Park MD
550 PM EDT Fri May 16 2025

Valid 12Z Tue 20 May 2025 - 12Z Sat 24 May 2025

...Overview...

Alaska will remain largely between anomaly centers next week, 
with upper ridging focused just south of the Aleutians and weak 
troughing over the mainland. A changeable and seasonable pattern 
is expected with no significant hazards expected. 

...Guidance Evaluation and Preferences...

The pattern will be generally progressive next week but with a 
trend toward higher amplitude -- ridge/trough couplet over the 
Bering/Gulf, respectively. As is typical, uncertainty is higher in
this quick-moving pattern due to differences in handling the 
incoming minor shortwaves upstream and through the quasi-zonal 
flow across the southern Bering/Aleutians early in the period. The
12Z GFS was unlike the ECMWF/Canadian and most ensembles in this 
regard over northeastern Russia before this medium range period, 
which resulted in an offset in timing between the larger cluster 
of solutions. However, by the end of the period, the GFS did align
better with consensus in forecasting digging troughing in the 
Gulf in response to building ridging upstream just west of 180. 

With the ECMWF showing inconsistency as well in the days 4-6 
period with the lead shortwave into the northwestern Gulf, opted 
to rely on a blend of the 00/12Z ECMWF with the 12Z Canadian and 
00Z ECMWF ensemble mean for most of the forecast. This did modify 
continuity (timing) and progression but the pattern suggests this 
may be the case for another day or two before things hopefully 
settle down. 


...Weather/Hazards Highlights...

Weak troughing over the mainland will promote near to below 
normal temperatures amidst mostly cloudy skies and widespread 
showers. More focused rainfall can be expected over the Aleutians 
with the passing systems and along the northern Gulf Coast as an 
area of low pressure settles into the region later in the week. 


Fracasso


Additional 3-7 Day Hazard Information can be found on the 
WPC medium range hazards outlook 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