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FXAK02 KWNH 052328

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

728 PM EDT Fri Apr 5 2024



Valid 12Z Tue Apr 9 2024 - 12Z Sat Apr 13 2024



...Synoptic Overview...



A surface low is forecast to encompass much of the northern Gulf

region going into the middle of the work week, with an arctic

trough reinforcing this low and giving it some staying power

through late Wednesday.  Much colder temperatures arrive for the

western half of the mainland to begin the week behind a strong

cold front that will be aided by the arctic upper trough, followed

by a steady moderating trend through the end of the week.  Periods

of rain and mountain snow are expected for the southern coastal

areas owing to onshore flow.  The next organized storm system

crosses the Bering Sea mid to late week with increasing winds and

rain for the Aleutians.





...Guidance Evaluation and Preferences...



The 12Z model guidance suite has a good overall depiction of the

synoptic scale pattern on Tuesday across the Alaska domain with

only minor mesoscale differences noted, so a multi-deterministic

model blend works well as a starting point in the forecast

process.  There is more model spread with the next incoming storm

system across the Bering during the Wednesday-Thursday time

period, with the GFS continuing to depict a stronger triple point

low south of the Aleutians.  Model spread increases substantially

by next Friday and Saturday with shortwave energy pivoting around

the southern periphery of the main Bering Sea low, with ensemble

means increasing to about 50-60% of the forecast blend by that

time.





...Weather/Hazards Highlights...



The low pressure system over the Gulf through Wednesday will

result in moist Pacific onshore flow for precipitation from the

Kenai Peninsula to Southeast Alaska.  While amounts are not

forecast to be all that heavy on any particular day (no

atmospheric river events anticipated), rain and snow totals will

add up with multiple days of moderate rain/snow through next week,

generally on the order of 1 to 3 inches of QPF.  On the backside

of the Gulf low, northwesterly gap winds could be strong for the

Alaska Peninsula to Kodiak Island and to the western Kenai

Peninsula and surrounding waters, likely peaking in strength on

Monday into Monday night.



For the Monday-Tuesday time period, a pronounced cooling trend is

likely for much of the western and northern mainland, with

anomalies of 15-25 degrees below normal going into Tuesday.  This

equates to subzero overnight low temperatures for the normally

colder locations of the western Interior, and highs in the 0s over

the North Slope and 10s for the western Interior.  Gradual

moderation closer to normal is forecast for midweek and beyond,

possibly reaching above average for many areas by next weekend. 

Southeast Alaska should see near average lows but persistent below

normal highs next week given the increased cloud cover and

precipitation.



Hamrick





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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