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FXAK02 KWNH 062317

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

716 PM EDT Sat Apr 06 2024



Valid 12Z Wed Apr 10 2024 - 12Z Sun Apr 14 2024



...Synoptic Overview...



A surface low is forecast to be in place over the northern Gulf as

the period begins Wednesday, and drift slowly south/southeast and

weaken as the parent shortwave moves inland next Friday. A period

of upper ridging should briefly build over the Mainland behind

this low later next week, but will shift east as the next system

enters the Bering Sea and approaches western Alaska next weekend.

These two systems should keep the Aleutians to Southern

Coast/Southeast unsettled with rain and mountain snows. Rainfall

may increase across Western Alaska as well later in the week.





...Guidance Evaluation and Preferences...



The 12z model guidance today shows a good overall depiction of the

synoptic scale pattern through about the first half of the period,

with the exception of the UKMET which wasn't as in line with the

rest of the guidance with both the Gulf low and the incoming

Bering Sea low. Was able to use an equal blend of the GFS, ECMWF,

and CMC for days 4-6 (Wednesday-Friday). By Friday and especially

next weekend, uncertainty increases with the evolution of the

Bering Sea low and an additional shortwave moving in towards the

western Aleutians. The GFS suggests more interaction with the

shortwave resulting in a totally phased and amplified trough

across the eastern Bering/Aleutians/AK Peninsula by next Sunday as

additional energy moves into the Gulf. Meanwhile, the ECMWF and

CMC show a slower progression of the shortwave and less phased

troughing, allowing the Bering Sea low to move closer to the West

Coast of the Mainland next weekend as the shortwave slides south

of the Aleutians, and ridging holds over the Gulf. Given the

uncertainty, the ensemble means are fairly washed out with the

details of these systems, but aren't as aggressive as the 12z GFS

seems to be right now. The WPC blend for today used the ECMWF/CMC

in conjunction with the ensemble means for the latter half of the

period, with a 70/30 ensemble mean/operational blend by Day

8/Sunday.





...Weather/Hazards Highlights...



Moderate precipitation over Southeast Alaska to start on Wednesday

should slide through the Panhandle on Thursday as the initial Gulf

storm weakens and the surface front moves inland. Rain and

mountain snow should continue into next weekend from the Aleutians

through the Southern Coast/Southeast as weak southerly flow

increases moisture across these regions ahead of the upper low

moving into the Bering and another weak surface front moves

through the Gulf. While amounts are not forecast to be all that

heavy/hazardous on any particular day, precipitation totals may

add up to several inches, especially from the Kenai Peninsula to

the Panhandle. Precipitation across Western Alaska may also

increase Thursday into the weekend, with some enhancement across

the higher elevations.



Temperatures may begin Wednesday moderately cool across the

southern half of Alaska, but should moderate into the weekend

across most areas. Temperatures across the northern half of Alaska

should see a warming trend through the period, with the Greatest

anomalies, on the order of 10-20 degrees above normal, likely

across the North Slope and northwest Alaska regions.



Santorelli





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



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