Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
733 FXAK67 PAJK 241759 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 959 AM AKDT Mon Jun 24 2024 .UPDATE...Update to aviation section to account for 18z TAF issuance. && .SHORT TERM...Minor changes to the ongoing forecast. For winds, large scale thermal gradients from clearing skies in British Columbia and the Yukon yesterday and again today will cause enhanced wind speeds in the inner channels, particularly for Icy Strait/Point Couverden area, northern Stephens Passage, and northern Lynn Canal. Expect wind speeds to maximize during the afternoon around 20 knots for any area mentioned. For precipitation, made edits to PoPs to bring up chances around Petersburg and Juneau during the early morning, and continuing the trend westward across to Pelican through early afternoon. This is due to some vorticity advection making its way westward, providing some minor upward motion in a very moist atmospheric profile. .LONG TERM...Continuing from the short range, the extended forecast once again remains relatively unchanged with lingering showers diminishing into Tuesday, followed by a warming and drying trend. Models continue to come into agreement for a surface ridge to build in over the gulf which will bring clearing skies to the inner channels and overall warmer surface temperatures due to abundant summer sunshine and warmer temperatures at 850 mb. High temperatures in general are set to reach the upper 60s and low to mid 70s for a majority of the panhandle in the latter half of the week. This will also lead to generally light winds overall throughout the panhandle. With low pressure developing during daytime over BC, there remains a slight chance for showers to develop but are expected to struggle to make it past the Coast Mountains. Expect the highest winds with the usual sea breeze circulations in the afternoon and evening hours, such as Taku Inlet. Being on the downstream side of the ridge, the exception to otherwise clearer skies would be any marine layer potentially moving into coastal communities which in turn could limit daytime warming. As is often the case, model guidance is not in full agreement on the longevity of the blocking ridge in the upper levels and subsequent surface high in the northern gulf. The strength and position of this high pressure over the northern gulf will strongly influence when more organized unsettled weather will make its way back into the panhandle. Ensemble guidance is leaning towards bringing a system into the southern gulf sometime Friday/Saturday. Depending upon its strength and track, this could cause easterly showers to develop and propagate over the southern panhandle during this time. && .AVIATION...../For 18z TAF issuance/...Aviation concerns this morning are the low clouds. Surface stations are reporting cloud decks around 1500 to 3000 feet with a few stations (Yakutat, Elfin Cove, Juneau, Klawock as I write this) reporting ceilings of 600 to 1200 feet. Poking around the webcams over the marine inner channels, estimate cloud decks are around 1500 to 2500 feet. Visibility has been reduced mainly because of a few rain showers and drizzle, down to around 3 miles with conditions improving over the last few hours. Wind speeds aren`t too high, mainly around 5 to 10 knots. Going forward, not a lot...but some improvement is expected today. IFR conditions are expected to improve to MVFR. Those with MVFR conditions should see conditions improve to low-end VFR. Some spots of low-end VFR this morning will more-or-less remain low-end VFR. Later today into today, weak trough tracking north would lower conditions tonight. So overall, expecting IFR to low-end MVFR again tonight. For the northern half of the panhandle, isolated and temporary LIFR cloud decks can`t be completely ruled out with LIFR probabilities around 10 to 30% during the overnight hours. && .HYDROLOGY...The Chilkat River continues to run right around minor flood stage today and is expected to continue to fluctuate right around minor flood stage into the early part of the week. Temperatures aloft are expected to remain mostly high and are even expected to increase later in the week as clouds depart the area leading to more runoff from high elevation snow melt. As such the river is expected to remain near or above minor flood stage for the next few days at least. The result is that the Flood Advisory has been extended again for the Chilkat. It now ends at 7 pm Wednesday and may be extended further in the coming days depending on how much snow is left to melt in the upper reaches of the basin. && .AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...None. && $$ SHORT TERM...NC LONG TERM....STJ AVIATION...GJS Visit us at http://www.weather.gov/Juneau