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FXAK02 KWNH 082300

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

700 PM EDT Mon Apr 08 2024



Valid 12Z Fri Apr 12 2024 - 12Z Tue Apr 16 2024



...Major winter storm likely late this week across much of western

Alaska...



...Synoptic Overview...



A major winter storm will be ongoing as the period begins Friday

across western Alaska with an amplified trough moving through the

state bringing gusty winds, maritime impacts, and moderate to

heavy snowfall - especially in the higher elevations. Shortwave

energy rounding the base of this trough may briefly close off

another upper low in the Gulf this weekend, keeping conditions

unsettled for Southeast Alaska. Upper ridging will build over the

state Sunday-Monday before another potentially strong trough moves

towards northwest Alaska with some indications for another strong

storm system to impact the state.





...Guidance Evaluation and Preferences...



The 12z model guidance today continues to show a good overall

depiction of the synoptic scale pattern especially regarding the

high impact storm across Western Alaska late this week. The CMC

was slightly slower with this system than the better consensus so

it was not used in todays blend. There remain some differences in

the details of this system, but increasing confidence for an

impactful weather event. Increasing agreement for shortwave energy

rounding the base of the system allowing for brief surface low

development in the Gulf, which should quickly translate

southeastward, with some timing inconsistencies still as well.

Compared to previous days, the guidance has also trended stronger

with a compact system that slides south of the Aleutians this

weekend with some uncertainty still in eventual phasing of this

with a larger system lifting northward from around Hawaii early

next week. There is some indication from the models for another

round of amplified troughing to edge towards western Alaska, but

some significant timing questions. 12z ECMWF was much slower than

the GFS/CMC with this and so was not used in the late period. The

WPC blend for today used the GFS/ECMWF/UKMET for the first half of

the period, increasing the ensemble means the second half, along

with the GFS.





...Weather/Hazards Highlights...



For Thursday-Friday, a system moving into the western Mainland

will bring likely moderate to heavy snow across much of the West,

along with gusty winds and maritime impacts. Heavy snow is

especially possible in the higher terrain. Farther South general

troughing should keep the Southern Coast/Southeast/Panhandle

generally unsettled through at least the weekend. The West may dry

out this weekend, but an additional cold front from the north may

bring another round of rain/snow to parts of northwest Alaska

early next week, with some locally heavy precipitation in spots.

Temperatures across the southern half of the state should stay

cool much of the period, trending warmer at times, with rounds of

troughing. The highest anomalies are likely across the Southeast.

Northern Alaska should stay warmer than normal the entire period,

but moderating somewhat this weekend as additional shortwave

energy slides through the region.



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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