Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 750 PM EDT Fri Jun 09 2023 Valid 12Z Tue Jun 13 2023 - 12Z Sat Jun 17 2023 ...Overview... Overall a stalled and blocky pattern is likely to remain in place next week across much of the Northern Hemisphere. This will include a northeast Pacific ridge/high (though its magnitude may weaken with time), while to the west troughing is likely to prevail across the Bering Sea into at least western Alaska as high latitude energy drops south to reinforce energy already in place. The troughing should keep much of Alaska cooler than normal while also directing moisture into the state for widespread rain chances, but light to modest amounts. The overall storm track including recurving current Typhoon Guchol should stay south of Alaska over the midlatitudes. ...Guidance Evaluation/Preferences... Model guidance is at least generally agreeable that troughing will persist across the Bering Sea. But there are some notable differences first with the timing and placement of mid-upper energy spilling south from the Arctic Ocean and how it interacts with the preexisting lows/energy across the Bering. GFS runs generally show a southward trend of the energy earlier than other guidance for a phasing north-south oriented trough by Wednesday or so. The other guidance, after holding the northern energy farther north for longer, show troughing edging into northwestern Alaska by Thursday (farther east than GFS runs). The eastern side of the trough and the northern extent of the northern Pacific ridge are uncertainties with the Alaska pattern. There has been a trend toward some energy coming farther east into the Gulf of Alaska/northeast Pacific by the latter part of next week amongst most models, suppressing that Pacific ridge. This potentially allows surface low pressure to form in the vicinity, and GFS runs are deepest with the surface low. Farther west, the Joint Typhoon Warning Center forecast is for what is currently Typhoon Guchol to recurve east of Japan and across the mid-latitude north Pacific as it transitions to post-tropical. There is reasonable agreement in the models with its track and it reaching the Dateline around Thursday. It appears most likely to stay well south of Alaska, though the 12Z CMC curved it northward enough to approach the Aleutians late week, so something to watch, but this is not favored for now. The depth of its low remains in question at this point as well. Broadly, there is lower predictability than has been seen recently as the pattern shifts somewhat, but model agreement could be worse. The WPC forecast started with a deterministic model blend of the ECMWF/GFS/CMC/UKMET runs, but transitioned to a blend consisting of half GEFS and EC ensemble means by day 7 and more by the end of the period given the increasing uncertainty with multiple features, but the fairly agreeable ensemble means for the overall pattern. ...Sensible Weather and Potential Hazards... The persistent troughing over the Bering Sea (and beyond) will allow for some moist inflow into the state, but not too high in terms of precipitable water anomalies. Thus mainly diurnal showers are likely, with broad coverage of rain chances but with amounts generally staying light. The exception may be across the Brooks Range where lingering moisture may help to promote more modest rain/snow. Meanwhile temperatures will be near to well below normal over the bulk of the state given the presence of the upper trough. Some areas of the North Slope may see near to above normal temperatures with offshore flow, especially through Tuesday-Wednesday. Tate No significant hazards are expected over Alaska during this forecast period. 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