textproduct: Juneau

UPDATE

06z Aviation update Scattered snow showers continue to be the primary threat overnight, with VFR diminishing to IFR/LIFR, and then going back to VFR. The heaviest of the snow showers currently look to be south of Frederick Sound, especially along Prince of Wales. Expect snow showers to slowly dissipate Wednesday afternoon starting in the Icy Strait Corridor first, with the southern Panhandle finally starting to dry out Wednesday night. However, there will be some persistent snow showers that remain along the coast of Prince of Wales.

Cold northerly outflow winds will continue in Lynn Canal and Taku Inlet, expecting to reach peak conditions Wednesday into Thursday.

PREV DISCUSSION......ISSUED AT 335 PM AKDT

SYNOPSIS...

Key Messages:

- Widespread convective showers continue into mid week, with chances of snow decreasing from north to south late week.

- Outflow conditions will continue to strengthen through the week and peaking on Wednesday. Outflow will bring colder, dryer weather for the northern half of the panhandle.

SHORT TERM.../ through Wednesday night / Satellite and radar imagery continue to show snows showers rotating around the nearly stationary low out in the eastern gulf and then pushing southwest to northeast into the central and southern panhandle. Stronger enhanced shower coverage and intensity are again expected this evening surface troughs continue to pivot around the low and into the panhandle. However, satellite snow fall products and area surface obs are generally indicating snowfall rates being a bit lighter than yesterday. A short wave moves into the southern panhandle are Wednesday morning and afternoon.

However, given the showery, convective nature of the snow, localized higher amounts are possible, especially along Baranof Island, and Prince of Wales Island to Ketchikan and Metlakatla into the afternoon.

Further north, high pressure continues to build into the Yukon with cold, drier northerly outflow increasing for Haines and Skagway.

LONG TERM...Few changes were made to the forecast for the mid to end of week as northerly winds and snow showers remain the main story. A change comes during this weekend as a low pressure system brings more organized precipitation. On Thursday, northerly flow continues across the panhandle with strongest winds located over Lynn Canal, Point Couverden, and Skagway. The strength of these winds will strong breezes to near gales (22 to 33 kts) through Lynn Canal with a 30% chance of low end gale force winds (34 to 40 kts) to continue into early Thursday. Point Couverden is the most likely area to continue to see the strongest winds. For Skagway. there continues to be a high chance for wind gusts to remain around 35 to 40 mph Thursday morning before decreasing through the evening.

Now for snow potential, showers will continue to be the main story for mid week. Strongest showers look to be over the southern panhandle as a band of vorticity moves northward Wednesday into Thursday. There is lower confidence on amounts, but there is higher confidence on the timing of these heaviest showers falling Wednesday. At this time, the northerly flow will bring drier air to north SE AK allowing for any showers to be very light.

A stronger system then arrives this weekend brining more organized precipitation. Currently, the focus of this system looks to bring moderate to heavy precipitation to the southern panhandle. With cold temperatures in place, precipitation will begin as snow. There is still uncertainly with where the low pressure system will track. It could be farther south bringing less precipitation, but allowing precipitation to remain as all snow. Or the low could track farther north allowing for more precipitation, but it could create a change over to rain for the far southern panhandle. We will continue to monitor for when the next low pressure system may arrive allowing for this change in pattern.

AVIATION.../through Thursday afternoon/...

Convective snow showers continue to be the primary hazard for aviation Tuesday afternoon, with VIS and CIG reductions down to IFR and briefly LIFR in some cases. As of this discussion, the outer coast of Prince of Wales Island including Craig and Klawock have been the primary recipient of particularly heavy snow showers, though training snow showers are also set up along Chatham Strait from around Point Gardner progressing northward over the Juneau Icefield. While northerly flow persists at the surface, a surface trough in the gulf will continue to bring moisture northward Tuesday into Wednesday, though snow showers are expected to gradually diminish from north to south Wednesday, with more consistent VFR conditions developing in their wake. From Frederick Sound southward, expect snow showers to continue to bring lowered conditions through most of the day Wednesday.

MARINE... Outside (Gulf and Coastal Waters): Somewhat stagnant pattern for the outside waters, with a vertically stacked low drifting southward through the next 24 hours. For the NE gulf coast, expect to see a gradual increase in NE gap flow winds to a strong breeze out of interior passes, including out of disenchantment bay. A gradual decrease in westerly swell from north to south will lead to a decrease in wave heights from 12-15 ft to 7-9 ft.

Inside (Inner Channels): Again, somewhat stagnant pattern for the inside waters, with a similar story of a slow transition into northerly winds in Chatham Strait, Stephens Passage, and Frederick Sound. Main uncertainty with the short term is how fast the transition from SE winds to NE, particularly near Five Finger, and when it transitions to NE, will the winds also collapse down to a gentle breeze. Otherwise, high confidence on the fresh to strong breezes for Lynn Canal, down to the convergence point of Point Couverden, with strengthening slowly through Wednesday.&&

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory from 10 AM to 10 PM AKDT Wednesday for AKZ318. Winter Weather Advisory from 4 AM to 4 PM AKDT Wednesday for AKZ323. Winter Weather Advisory from 3 AM to 6 PM AKDT Wednesday for AKZ328-330-332. MARINE...Gale Warning for PKZ012-013-651. Small Craft Advisory for PKZ011-021-022-031-032-053-641-643-644- 661>664-671-672.