Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
078 FXAK67 PAJK 032304 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 304 PM AKDT Fri May 3 2024 .SHORT TERM.../Through Saturday night/...The short range forecast will feature a changing weather pattern for Southeast Alaska. After a nice stretch of mostly dry and slightly warmer than normal Spring weather, a front will approach from the west on Saturday, spreading east and south through Saturday night. For some SEAK locations, this will be the first measurable precipitation in well over a week. Saturday`s daytime highs and overnight lows will likely be the warmest of this dry spell, but that will change with a return of the clouds and rain and heading into the medium range forecast period. Even so, overnight temps tonight still warrant a frost advisory for much of the northern Panhandle. .LONG TERM...An active weather pattern returns in full swing to SE AK as system after system moves into the panhandle, with each one bringing concurrent chances of rain and wind across the area. Aloft, the upper level pattern will sharply depart from its previous state of the past few weeks. The primary steering flow which was directing systems to the south and away from the panhandle will move directly overhead as a strong jet streak developing along the E flank of a deepening trough over the Bering Sea moves the primary area of upper level support over the panhandle. Closer to the surface, this will enable multiple waves to develop and enter the panhandle. The first wave, on Sunday, will be associated with an occluding system moving out of the NW which will cross the Gulf and dissipate over the panhandle, but not before bringing with it a return to more abundant precipitation. For more information on this system, refer to the short term forecast discussion. Lingering chances of precipitation associated with onshore flow will remain through Tuesday before another, stronger system arrives later on Tuesday or Wednesday. This second system will move up from the SW, moving around the broader area of upper level troughing. Expect a surge of more widespread precipitation to be possible with this system alongside the potential for small craft winds for many locations and gale force winds potentially in the gulf. Beyond this point operational guidance begins to falter as model spread grows, but ensembles are indicative of another system arriving immediately in the wake of the previous one, delivering another round of rain and wind to SE AK, with the active weather pattern likely to continue thereafter. This will bring temperatures more in lockstep with normal values as high temperatures return to the 50s, in departure of the 60s enjoyed during the previous week. The main changes to the forecast were significant increases in wind speeds and wave heights, along with some refinement to the QPF forecast, though exact timing for these remains difficult to precisely determine this far out. Likewise, increased PoP chances through the second half of the upcoming week given the growing agreement between operational models on at least two systems arriving after the Sunday system. Minor changes were made to temperatures and cloud cover. Minor adjustments made to temperatures to capture the diminished diurnal trends. && .AVIATION...Another day of VFR conditions today and tonight with some increasing cloud cover overnight and into late Saturday. CIG expected to be above 5k. Offshore and northerly flow with sea breeze activity continue with no LLWS issues expected. && .MARINE...Winds remain rather light and the northerly 15 to 20 kts experienced over Lynn Canal and Stephens Passage have already eased as of early this afternoon and are not expected to return tomorrow or tomorrow night. On the outside, pre-frontal winds expected to be 20 kts or less, even near the coast west of Icy Bay where barrier jet enhanced winds typically form. Based on present combined sea heights being reported by the offshore moored buoy network, the short term sea state forecast was diminished slightly to below small craft criteria, so no marine hazards have been included with the afternoon forecast issuance. && .AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...Frost Advisory from 1 AM to 9 AM AKDT Saturday for AKZ319>321- 325. MARINE...None. && $$ SHORT TERM/MARINE...Fritsch LONG TERM....GFS AVIATION...PRB Visit us at http://www.weather.gov/Juneau