textproduct: Juneau

UPDATE...After 18z TAF issuance for the Aviation section

Cloud shield spreading over the forecast area with the lower deck across the southern two thirds of the panhandle. Ceilings of 1500 to 3000 feet. Spotty light rain this morning, but will see the rain become more widespread through late afternoon and overnight. Will see the cloud decks lowering, and visibility restrictions in the rain starting overnight.

PREV DISCUSSION......ISSUED AT 551 AM Sun Jul 5

SYNOPSIS...

Key Messages:

- A stronger low pressure system and front will impact the panhandle later Sunday into early next week. This system is expected to bring widespread rain, likely heavy across southern panhandle, and gusty winds.

- Outer coastal and inner channel winds and seas will also increase and become elevated with the strong low pushing through the Gulf.

- The active weather pattern to continue as another system looks to impact the region by late week.

SHORT TERM.../through Monday night/...Another mostly cloudy and cool day with pre-frontal showers increasing ahead of stronger low pushing through the Gulf. Afternoon temps will climb into the mid 50s to low 60s. A front extending from the low will lift northeast towards the panhandle late Sunday night, with rain becoming widespread over the panhandle by daybreak Monday. Moderate to heavy rain, along with breezy winds, will be possible, mainly across the southern panhandle. Multiple fronts and lows will rotate around the parent low in the eastern gulf and through the panhandle, bringing rounds of moderate to heavy rain and breezy to windy conditions, especially over the southern panhandle. Current rain totals through Monday night look to be around 2 to 3 inches for Annette Island and Ketchikan and 1 to 2 inches for Prince of Wales Island. Localized areas could see slightly more, or less, depending on the help of orographic lift. Other areas of the panhandle are less likely to receive as high of rain amounts. The central panhandle will generally see 0.5 to 1 inch, and northern panhandle will generally see around 0.25 to 0.5 inches. Southeasterly winds will increase out ahead of the initial front on Monday across the southern panhandle. Gusts could approach 40 mph from the late morning through early evening hours for locations across Prince of Wales Island, Annette Island and Ketchikan Borough. However confidence in this occurring is low at this point, so held off on a Wind Advisory issuance for this forecast package. Either way, expect breezy to windy conditions across the southern panhandle. Breezy east to southeast winds will also develop further north up to the Icy Strait corridor.

LONG TERM.../Tuesday through Thursday/...The main low in the eastern Gulf will sit offshore, slowly weakening after the stronger front on Monday evening/night moves northward through the early morning hours on Tuesday. Following this front is a dry slot at 700 mb that moves into the outer coastline and into PoW up to Baranof Island, ahead of one last band of precipitation rotating around the multivortex low before it fully weakens. This will keep some potential for thunderstorms, still largely offshore, overnight into the morning hours on Tuesday corresponding with a swath of higher CAPE values and PVA aloft just along the coast. This may bring potential for thunderstorm development into PoW and Baranof Island, but highest chances remain offshore in the eastern Gulf. The low itself is weakened by this point, as is the synoptic setup aside from lapse rates / CAPE / dry air aloft, so these may not end up being as impactful especially as heating still looks unlikely over the land areas from how early in the morning this will be. This next weak band of moisture will push into the southern panhandle and coastline, though it is uncertain as to how far inland it will even make it due to the weakening low and the upper level low gradually sliding SE to sit over the majority of the panhandle.

Either way, more uncertainty returns for Wednesday into Thursday as guidance begins to diverge on if a surface trough will push across from a weak low near Anchorage, ahead of another system beginning to develop in the western Gulf from a Bering Sea low. As of now, cloud cover and precipitation appears to last through the week with the chances for a longer break looking most possible on Wednesday, though the weak trough or remnants from the low may keep some shower activity over the area ahead of this end of week system.

AVIATION.../through 12z Monday/... Conditions this morning are generally borderline MVFR to VFR with the lowest CIGs at 2,000 ft. There are also a lot low hanging clouds that are scattered around TAF sites due to the dry slot moving out of the area and an upcoming frontal system moving in. The largest concern today is the rain that is associated with this incoming front. With rain comes reduced visibility and ceilings, however, guidance is not picking up on extremely deteriorated conditions associated with this system. CIGs are expected to drop to MVFR, but this would be at the end of the period, so confidence is not super high. TAFs do hint to deteriorating conditions, though. The confidence for rain begins to increase around 18-21Z, but high confidence for rain comes around 3-6Z on the 6th.

MARINE... Outside (Gulf and Coastal Waters): Winds in the gulf today are expected to build as a front moves into the area. There is high confidence in winds over 25kts associated with this front, but it is not highly likely that sustained winds will reach over 30kts. Winds are expected to peak early in the morning on Monday and are likely to decrease through the day. Waves are also expected to peak around this time, with wave heights reaching up to 11ft between Cape Fairweather and Cape Spencer as this is the location of the highest expected winds.

Inside (Inner Channels): As the incoming front moves across the inner channels, winds are expected to be gusty and shifty. Winds in the inner channels are expected to pick up Sunday evening, especially at ocean entrances and in Clarence Strait. Southeast winds are expected to be channeled up Dixon Entrance, so winds are expected to each 25-30kts. Winds from 15-20kts can be expected across the rest of the panhandle, except for Sumner Strait with winds expected to reach 20-25kts. Elevated winds are expected through the day Monday and are then likely to return to maximum speeds of 10-15kts on Tuesday.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ035-036-641>644-652-661>664-671-672.