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FXAK02 KWNH 242356

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

756 PM EDT Wed Apr 24 2024



Valid 12Z Sun Apr 28 2024 - 12Z Thu May 02 2024



...Overview...



During this period an upper/surface low will drift east from the

the Aleutians/Alaska Peninsula on Friday, across the Northeast

Pacific ocean over the weekend into early next week before pushing

into Southeast Alaska and British Columbia. North and east of this

feature, upper ridging will stretch from Southeast Alaska

northwest into the northern part of the state late week but erode

with time. Another large trough upstream with one or two rounds of

passing energy will track through the Bering Sea with a course

toward the western Alaska coast; however there is a lot of

uncertainty with the details of this feature.



...Guidance Evaluation and Preferences...



The models continue to struggle with the timing, strength and

location of the large trough and embedded energy late in the

period although consensus has it tracking through the Bering

toward the Aleutians and west coast/Southwest Mainland. This

system has QPF trending up across the Aleutians, Southwest and

western Mainland Tuesday and beyond however the specifics are

uncertain given the large spread in timing and location of the

trough; which will also impact the strength of the winds for the

Aleutians and surrounding locations. At this time, wind and

precipitation seem to be below hazardous thresholds. There was a

small improvement with model clustering with the initial

trough/low that will track trough the Gulf of Alaska and slows

near Southeast Alaska/British Columbia. Previous runs ruled the

CMC out of the running for inclusion since it was out of phase

with the ECWMF. Although the GFS has consistently been further

east/faster with this feature than the ECWMF, it did slow for the

first couple of periods and were closer within the cluster. The

preferred model blend began with ECWMF/GFS/EC ensemble means/GEFS

means at 50/30/10/10 before transitioning to 50% weighting of the

means by hour 156, 70% by hour 180 and then to 100% beyond hour

204.



...Weather/Hazards Highlights...



Gusty winds and precipitation will accompany the upper and surface

lows this weekend for portions of the Aleutians to Alaska

Peninsula, into the southwest Mainland toward Kodiak Island and

the Kenai Peninsula. At this time the wind speeds will likely

remain below the hazardous threshold but will be dependent on the

position of the upper/surface low. Some precipitation is likely

over the weekend for Southeast Alaska as moist inflow increases

ahead of the low moving east. Generally light amounts are forecast

in northern parts of the Panhandle with more moderate amounts in

southern parts. As another system approaches the Bering, Aleutians

and western Alaska, precipitation chances will renew. The timing

and location of this feature will determine where the heavier

amounts will setup for the Aleutians, southwestern and

south-central Alaska. At this time guidance is suggesting areal

average of 0.50 to 1.25 inches by Wednesday for the Aleutians.

Meanwhile the northern half of the Mainland can expect generally

dry conditions.



Above normal temperatures are expected for much of the state into

the beginning of May with the highest anomalies likely positioned

over the Interior. To the north of a front settling over the

north-central mainland, cold high pressure over the Arctic may

keep temperatures near to somewhat below normal, especially across

the North Slope. Locations near the Southcentral coast and

northern Panhandle may also see near or slightly below normal

readings.



Campbell





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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