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FXAK02 KWNH 092355

PMDAK 



Alaska Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

754 PM EDT Thu May 09 2024



Valid 12Z Mon May 13 2024 - 12Z Fri May 17 2024



...Overview...



Upper troughing will generally prevail across Alaska next week in

a broad sense, as a trough stretching into the Aleutians/Alaska

Peninsula and the northern Pacific tracks energy into the Gulf

during the first half of the week, and then another upper

low/trough affects at least the western part of the state later

into next week. The pattern will favor multiple rounds of

precipitation across the Panhandle and light precipitation

stretching into the Interior, while there is more uncertainty in

precipitation and wind potential from the Aleutians to the western

Mainland.





...Guidance Evaluation and Preferences...



Model guidance continues to indicate broad troughing over Mainland

Alaska as the period begins Monday, with energy across the Alaska

Peninsula southwest into the northern Pacific creating a positive

tilt to that southern part of the trough. This energy and possible

upper low is forecast to pivot east and then northeast toward the

Gulf by midweek, though with some timing uncertainty--the CMC

seems to be a slow outlier as other guidance is faster, while the

ECMWF is faster than the GFS runs. Naturally the associated

surface low follows a similar pattern in the models. The depth of

the surface low varies a bit as well but recent models do not show

it to be very deep.



Farther west, models continue to advertise the likelihood of

energy tracking from Siberia across the Kamchatka Peninsula and

likely forming a closed low in the Bering Sea. While

Tuesday-Wednesday has become more agreeable for the timing of this

to move into the Bering, the placement varies where the sensible

weather across the western part of the state is affected. Into

Wednesday, the ECMWF shows the upper and surface lows moving east

toward and into the western Mainland, while the GFS and CMC runs

track farther south and cross the Aleutians into the northern

Pacific by Thursday. While the ensemble means are much flatter,

the GEFS mean is more like the GFS/CMC while the EC mean is more

like the ECMWF. The differences in the model suites yield low

confidence in which solution may play out.



A mainly deterministic model blend favoring the ECMWF and GFS was

used for the early medium range period. As the period progressed,

increased the proportion of the GEFS and EC ensemble means to over

half by Days 7-8 amid the increasing uncertainty. This seemed to

provide a reasonable middle ground, though changes to the forecast

could certainly be needed if models converge.





...Weather/Hazards Highlights...



A weakening surface low and shortwave aloft could help direct

moisture into the Panhandle early in the week, and by

Tuesday-Wednesday, another low system shifting into the Gulf

should renew precipitation chances. Precipitation amounts will

likely be on the moderate side but perhaps locally heavy. Some

lighter precipitation in the form of rain showers and higher

elevation snow showers should extend into the Interior as well.

Then there is considerable uncertainty with precipitation and

winds that may affect the western Mainland and/or Aleutians by

midweek depending on how the pattern evolves. Low confidence in

the sensible weather persists into the latter part of next week,

but generally some light to moderate precipitation seems possible

for the southern coast.



On average, temperatures should not be too far from average next

week. Highs look to be cooler than normal across the southern

coast to the Panhandle as well as Brooks Range, and near to

slightly above normal by late next week across portions of the

Interior and the North Slope. Meanwhile lows may be a bit above

average in many areas, for a smaller than normal diurnal range.





Tate





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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