textproduct: Juneau

UPDATE

Updated aviation section following 18z TAF issuance.

LONG TERM

The active weather is expected to continue going into the long term period. A low moving into the Gulf Sunday will bring another round of precipitation and winds to the panhandle. The exact location of this low continues to remain uncertain both in deterministic and ensemble guidance. But the overall impacts look to still be seeing increased winds and another significant period of rain. Current thinking is that the strongest winds will be along the southern panhandle around the Clarence Strait area as the low moves up. The heaviest precipitation is also expected to be over the southern panhandle south of the Icy Strait area. 24 hour rain amounts in this area look to reach up to 2-3 inches of rain while the northern panhandle looks to see around 1-1.5 inches of rain during this time. With the warmer temperatures already in the area, most places will stay rain but snow is possible, especially for locations in the Northern Lynn canal area. Another concern with this low is where does it track. If the low tracks closer to land and then into Canada, a lot of locations could potentially see a surge of winds during the day on Monday.

Behind this low, the active weather is expected to continue into the middle of the week. Another atmospheric river looks to move into the area for Tuesday. This could potentially bring another shot of significant rain and strong winds to the area. Especially Tuesday evening headed into Wednesday morning as the low moves through the Gulf waters. Like the system on Sunday, there is still significant disagreements on the exact locations due to model uncertainty in ensembles as well as the NBM. This will need to be watched for any potential changes in track and intensity over the weekend.

AVIATION

For the northern panhandle, ongoing VFR to MVFR flight conditions with CIGS generally AoB 4000ft and VIS as low as 4SM within heavier showers particularly impacting the NE Gulf coastline. Conditions have begun to clear into this morning for parts of Icy Strait Corridor and up into northern Lynn Canal, however these clearer conditions will diminish again to MVFR with CIGs dropping to AoB 2000 ft and VIS dropping again to 4SM as the next round of precipitation moves up from the south. Chances for conditions to drop to IFR exist late tonight and into tomorrow morning as the heaviest precipitation moves through the northern panhandle, with CIGs AoB 800 ft possible as well as drops to VIS to below 3 SM at the heaviest rates.

For the southern panhandle, a system with moderate to heavy rain and elevated winds is pushing into the southern and central panhandle as of this morning, keeping flight conditions deteriorated down to MVFR with CIGS AoB 1500ft and VIS as low as 3SM. Conditions dropping to IFR from CIGS AoB 1000 ft at Metlakatla and Ketchikan are likely throughout the morning and into tonight as the heaviest rain pushes through. Worst flight conditions will remain across the southern panhandle TAF sites with likely drops to IFR VIS and CIGS as moderate to heavy rain rates move into the southern panhandle this morning through today.

Strongest sustained winds will remain across the S Panhandle through Sunday early afternoon as front pushes inland, with sustained winds up to 25 kts with gusts up to 45 kts likely for Ketchikan and Annette Island. In addition, strong S to SE-ly LLWS around 2000 ft will be a concern across the S Panhandle TAF sites through Sunday afternoon, with strongest LLWS up to 60kts expected near Ketchikan and Metlakatla as front pushes inland, gradually decreasing by 06z Sunday evening. Winds above the surface will shift from a SE-ly direction to S becoming SW into the end of the TAF period as the next system approaches around 15 to 18z tomorrow, however the LLWS will not be as strong as the system today. Surface winds will also begin to increase again into the end of the TAF period across the majority of the panhandle with this oncoming system.

MARINE

Inside waters: Winds diminished slightly overnight across the northern channels overnight into Sunday, but the southern channels will continue to increase to mid gale force of around 40 kt with gusts up to 50 kt, especially in Clarence Strait as another new short wave moves north behind the first one. Southerly winds of 25 to 35 kt will likely linger in the southern channels through at least Monday before diminishing. Seas will mostly be wind driven waves with the highest being up to 7 to 8 ft in Clarence Strait Sunday though some southerly swell will cause higher seas up to 18 ft near ocean entrances exposed to the south.

Gulf Waters: The first in a series of short wave features is moving inland over the northeast coast early Sunday morning. The next short wave will be moving north farther east spreading another area of gale force conditions to the SE gulf and Dixon Entrance area for Sunday, with winds already ramping up in the southeast gulf as of this discussion. Expect southerly winds of 25 to 35 kt to persist in that area through at least Monday before diminishing Monday night. Seas are rather high with 15 to 20 ft seas being rather common, driven by a 12 to 14 ft S swell with a 15 sec period. Seas overall are expected to remain rather high (in the 10 to 20 ft range with higher seas in the SE part of the gulf) through Monday at least with persistent high S swell through that entire period.

HYDROLOGY

Sunday sees another low pressure move up along the moisture feed, bringing an additional surge of rain primarily for the southern half of the panhandle. Expecting IVTs to be somewhat lower, less than 500 kg/ms, but with healthy divergence aloft, strong low level flow, and high freezing levels, rain to be fairly efficient. The southern and central panhandle could see 1.5 to 3.0 additional inches with higher amounts near Ketchikan and Metlakatla, and rainfall rates could exceed 0.2 inches per hour during the Sunday morning and early afternoon timeframe. Main concerns right now are ponding of water in low lying areas, along with rapid increases in creeks and streams. What is particularly uncertain at this time is the current state of the snowpack at higher elevations. As snow levels look to rise to above 4000 ft in the south, cold rain will fall on these higher snowpacks. If the snowpack is primed or near primed, additional runoff could be wrapped up into existing rainfall, adding to the fuel for any flooding in the area.

Additionally, Tuesday looks increasingly likely to have additional moisture move into the area. While IVT values look to exceed 500 kg/ms, details regarding location and magnitude of moisture are not fully clear at the moment. Stay tuned for details.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Flood Watch through Monday morning for AKZ326>332. Strong Wind until 6 PM AKST this evening for AKZ330. Strong Wind through this evening for AKZ332. MARINE...Gale Warning for PKZ036-641-661. Small Craft Advisory for PKZ022-031-033>035-053-642>644-651-652- 662>664-671-672.