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000 FXAK67 PAJK 231419 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 619 AM AKDT Mon Oct 23 2017 .SHORT TERM...
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/Through Tuesday night/Developing low will move NE across the central panhandle late this afternoon and evening. Another low will move NE across Dixon Entrance by Tue evening. Current forecast was handling these features well so did not need to make any significant changes. Main issues with first low will be heavy rain and strong winds. Most of this will be over the southern panhandle and SE gulf to the S of the low track. Have gales for much of that marine area with strong wind headlines for zones 27 and 28. Areas on N side of low track will have a mainly offshore wind but it will not be overly strong. Could see some locally heavy rain over the central panhandle as deformation zone moves in. Was a bit concerned that this heavy precip could cause a snowmelt cooling event in some areas over the N but it appears that the airmass will initially be too warm for that to occur. Once low moves inland tonight, precip should diminish. Along the NE gulf coast through tonight, a small low will remain offshore with a couple of mid-level vort maxima moving through. One of these vort features triggered a couple of TSTMS over the NE gulf, but this threat will diminish as temps aloft warm from the S. Otherwise will see mainly scattered showers for that area. Second low moving NE toward Dixon Entrance will bring more rain to the southern area Tue into Tue night, while the N sees precip threat diminish due to some offshore flow. Not expecting any strong winds in the southern panhandle as main wind threat will stay over Hecate Strait and Haida Gwaii on S side of low track. .LONG TERM.../Wednesday through Monday as of 10pm Sunday/The extended forecast begins with a low pressure system crossing from the southern panhandle into Canada. A drying trend is expected early in the extended forecast between Wednesday and Thursday with minimal shower activity as a weak ridge of high pressure builds. Between Thursday and Friday a low pressure system west of the Aleutians will send a front northward across the gulf. While confidence is lower with timing and location of this front, moisture associated with it is of tropical origin, which could set up another atmospheric river scenario for SE Alaska. This will pave the way for a wet weekend across SE alaska. Little change was made beyond Friday in the extended forecast. Ensemble forecast members and operational models still carry large discrepancies moving into the weekend. Tuesday`s forecast was altered to shift the low`s location over the southern panhandle which transitioned into the start of the extended forecast using the ECMWF. Winds were increased around this low; however, winds underneath the ridge on Thursday were decreased over the inner channels and panhandle. $$
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&& .AJK Watches/Warnings/Advisories...
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PUBLIC...Strong Wind from 1 PM AKDT this afternoon through this evening for AKZ027-028. MARINE...Gale Warning for PKZ035-036-041>043. Small Craft Advisory for PKZ012-022-031>034-052. Small Craft Advisory due to Seas for PKZ051.
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