Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 628 PM EDT Thu Jun 08 2023 Valid 12Z Mon Jun 12 2023 - 12Z Fri Jun 16 2023 ...Overview... An upper low is forecast to remain nearly in place over the Bering Sea next week as the pattern over much of the Northern Hemisphere is anchored by several persistent anomaly centers; namely, upper ridging over western Europe and the northeast Pacific with cross-polar troughing from the Davis Strait to north central Siberia. Split-flow jet out of eastern Asia will maintain a mid-latitude storm track/frontogenesis zone after a lead-in day 3 system moves into the southwestern mainland. By the end of next week, current Typhoon Guchol will likely recurve east of Japan and across the mid-latitude north Pacific perhaps to the Dateline in about a week. ...Guidance Evaluation/Preferences... Overall synoptic agreement is better than average for the period as the ensembles have been rather consistent in their depiction of the trough axis across the Bering Sea. Deterministic runs of the GFS/ECMWF showed the best clustering with the ensembles and least amount of seemingly errant/overdeveloped system in and near the Gulf of Alaska compared to the UKMET/Canadian. Thus, a general blend of the guidance was utilized, with an increasing preference for the GFS/ECMWF with time at the expense of the UKMET/Canadian and in concert with the 12Z GEFS mean and 00Z ECMWF EPS. Highest uncertainty lies in the northern stream flow over the high latitudes, with a trend toward lifting one system to the northeast Wednesday while maintaining some semblance of weak ridging over northeastern Alaska. Over the Gulf, maintained the frontal boundary on the north side of the upper/sfc high in the mid-latitudes and south of the Gulf sfc high, but without much depiction of any coherent sfc wave. Farther upstream, JTWC track lied closer to the slower ECMWF rather than the quicker GFS in Guchol's recurvature, but the ECMWF and its ensembles were quicker to weaken the system than the GFS and its ensembles. With the system entering the westerlies beneath weak ridging, do not expect to see much downstream amplification of the flow, so the 12Z GFS deepening of the system as an extratropical low seems overdone. Again, relied mostly on the ensemble means by next Friday anyway, which results in a more modest system around 45N and just east of the Dateline for now. ...Sensible Weather and Potential Hazards... Short term (Sunday) system will weaken over the Seward Peninsula/western mainland on Monday with its surface reflection well into western Canada, leaving much of the area without strong forcing for precipitation. Some lingering rain is likely for the Panhandle early in the period. Precipitable water values are likely to remain near to below normal over most of the state, so mainly diurnal showers are expected. The exception may be across the Brooks Range where lingering moisture may help to promote more modest rain/snow. Temperatures will be near to well below normal over the state given the presence of the upper low. Some areas of the North Slope may see near to above normal temperatures with offshore flow. Fracasso Hazards: - Heavy rain across portions of the Alaska Peninsula and coastal Southcentral, Sun, Jun 11. 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