Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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809 FXAK02 KWNH 192342 PMDAK Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 741 PM EDT Wed Jun 19 2024 Valid 12Z Sun Jun 23 2024 - 12Z Thu Jun 27 2024 ...Overview and Guidance Evaluation/Preferences... During the extended period there will be three main low pressure systems of interest. One will be a slowly retrograding polar upper low moving across eastern Siberia, another with be a surface low/upper low tracking in the general direction of the southern Southeast Panhandle this weekend, and finally a third system tracking south of the Aleutians. The guidance is hinting that there may be a fourth system that approaches the western Aleutians by middle of next week, although details are uncertain. Meanwhile, most of mainland Alaska will be between these Pacific storm systems and an arctic upper trough north of the state, with pleasant early summer weather expected south of the Brooks Range. In general, there was fair agreement will the large scale pattern through most of the extended period. Opted to begin with a multi-model blend of the ECWMF, GFS, CMC and UKMET for the first couple of days before dropping the UKMET, reducing inclusion of the CMC while adding in the ECWMF and GEFS ensemble means for the later period. As previously noted, the spread in guidance increases a fair amount for the last couple of days of the extended which lowers confidence on the exact track of the last system near the Aleutians. This approach provided decent forecast continuity. ...Weather/Hazards Highlights... Increasing chances for light to moderate rain is expected for much of the southern tier of the state and in the vicinity of the Brooks Range through the extended period. Some showers are also likely across the central and eastern Aleutians as the next low pressure system passes by to the south. For the Interior, the possibility for thunderstorms and dry lightning strikes during the afternoons and evenings may increase the risk for fire weather concerns given the dry fuels across the region. Areas north of the Brooks Range will likely remain dry through the week. Weak ridging across the Mainland will lead to near normal or slightly warmer than normal temperatures. Afternoon maximums are expected to climb into the 70s for many areas across the Interior, perhaps reaching 80 degrees for the Yukon Flats, and also just north of the Alaska Range. Overnight lows here should also be rather mild with readings bottoming out from the upper 40s to upper 50s. The Arctic Coast will likely remain chilly with onshore flow from the Arctic Ocean, with highs generally from the upper 30s to upper 40s. Campbell/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 $$