####018003887####
FXAK02 KWNH 122330

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

729 PM EDT Fri Apr 12 2024



Valid 12Z Tue Apr 16 2024 - 12Z Sat Apr 20 2024



...Synoptic Overview, Guidance Evaluation, & Preferences...



An upper level ridge axis is expected to be in place across the

eastern mainland and into the Yukon Territory and southeast

panhandle region for the beginning to middle of next week. 

Meanwhile, a storm system over the North Pacific tracks in the

general direction of the AK Peninsula by late Wednesday and brings

a return to more rain and snow for southern coastal areas of the

state.  Meanwhile, a second low pressure system is forecast to

track across the Bering and weaken with time through midweek, and

some of the shortwave energy from this may interact with the low

moving north across the western Gulf. 



The 12Z model guidance suite features improvement overall in terms

of agreement compared to the unusually high differences noted

yesterday.  The CMC has trended more in line with the model

consensus across the Bering Sea region with a weakening surface

low even though it is depicted farther south, whereas its run

yesterday featured more surface high pressure over that region. 

Another big change from yesterday is the more northerly placement

of the main surface low in the ensemble means, compared to the

much more suppressed solutions from yesterday.  Upon examination

of the ML guidance from the ECMWF, there is more support for the

stronger GFS solution over the Bering early in the period, and the

ML guidance indicates a faster northward track of the low towards

Kodiak Island by 12Z Wednesday, which is also closer to the 12Z

GFS position.  The CMC and operational ECMWF support the idea of

the Gulf low moving on a more northeasterly path, with the low

south of the Aleutians becoming the dominant low by Thursday

morning.  The tricky part of the forecast is how much an

approaching weaker low south of the Aleutians and the stronger

Gulf low potentially phase, and this is where the model guidance

continues to struggle in resolving.  The fronts/pressures forecast

was based on a multi-model blend as a starting point through

Wednesday with more weighting towards the GFS given its solution

more in line with the ML guidance, and then increasing percentages

of the GEFS and EC means to close out the week and into Saturday.





...Weather/Hazards Highlights...



Coastal rain and mountain snow is likely to increase going into

the Wednesday-Thursday time period from Kodiak Island to the

Prince William Sound region as moist onshore flow increases ahead

of the Pacific low moving northward, there has been a slight

westward trend with the highest QPF from this event.  Strong

onshore flow over this region is expected to produce high waves

and gusty winds over 40 mph at times.  Light showers are possible

farther inland across southern mainland Alaska.  Temperatures are

generally expected to be in the 40s for highs across most Interior

locations, and some lower 50s for east-central portions of the

state.  The Brooks Range will be the demarcation for much colder

conditions across the North Slope and extending to the Arctic

Coast, with highs struggling to reach the freezing mark. 



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



$$