Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
430 FXAK67 PAJK 202256 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 256 PM AKDT Thu Jun 20 2024 .SHORT TERM.../Through Friday night/...Passing trough tonight will increase clouds and give isolated rain showers to areas along the far northeastern gulf coast. As the trough moves north, wind speeds in the gulf will increase to around 15 to 20 knots. Inner channel speeds will increase to near 10 to 15 knots as the trough axis moves north, then decrease back to 5 to 10 knots. Friday into Friday night is when the next front will come near. The parent low will track west to east, way out in the gulf, towards Haida Gwaii. As this low marches east, it will swing a front north into the panhandle. This front will have minor impacts to the panhandle. The impact with the biggest concern is the marine winds along the front, where speeds could get up to 25 knots, with some evidence of near 30 knot wind speeds. As the front moves north, inner channel winds speeds will respond by increasing to near 15 to to 20 knots. Greater details for the marine forecast can be found in the Marine section. This front will also give the area passing light rain. Rain amounts aren`t anything too impressive with 24 hours amounts mainly less than 0.50 inches. Normally with increased cloud cover and rain in the forecast, temperatures would be expected to cool a bit. But with energy coming up from the south, overnight lows are still expected to bottom out near 50 and afternoon highs ranging from the low to mid 60s in the southern half to the upper 60s to low 70s in the north. Temperatures like this are a few degrees above normal. .LONG TERM.../Saturday through Tuesday/ A stacked low pressure center will slowly track eastward across the southern Gulf through Saturday then across Haida Gwaii and Hecate Strait Sunday. The low will be weakening some as it moves through, however bands of vorticity wrapped around the low will result in convective bands of showers, which tend to have some gusty winds. Those bands of showers will namely be over the southern panhandle closer to the low center. The lower latitude of the track will cause offshore flow across the northern half of the panhandle, which should reduce rainfall potential and amounts there. Models are indicating potential for an easterly wave on Sunday. There is disagreement on where said wave would cross from B.C. and extends over the panhandle. However, then central panhandle is looking most likely at this time. Through the first half on next week, another upper level low will track eastward across the southern gulf and give a repeat of offshore flow across the north and shower potential across the south. Additionally, there will be potential for convective development in Canada most days which could spill over the Coast Mountains. From mid-week onward, upper level flow will shift out of the NW as a ridge of high pressure pushes into the western gulf. This will push most lingering showers back out of the area...but bring back potential for marine layer clouds over the gulf coast. && .AVIATION...Marine layer has primarily moved offshore through the afternoon hours, with the lone holdout being Sitka which may break out briefly but then see a higher cloud deck move in later tonight. The rest of the panhandle will see continued relatively clear conditions with light winds aside from some local sea breezes through the evening hours, such as Skagway. A weak front will push into the panhandle tonight bringing lower ceilings and some light rain potential. By Friday morning a stronger low will move into the eastern gulf with higher shower potential spreading into the northern panhandle. Overall not expecting significant LLWS for the TAF period, though can expect ridge top winds to pick up out of the east heading into tomorrow afternoon for the southern and central panhandle with the approaching system. && .MARINE...For the Friday into Friday night time frame, marine wind speeds will be greatest along the front. In the gulf, speeds are expected to reach 20 to 25 knots with some evidence of up to 30 knots. These winds will first be seen in the far southern gulf and will track northward, reaching Cross Sound area late Friday morning. Speeds will decrease Friday night as the front more-or- less shears apart. For the inner channels, the winds will respond as the front moves north. But as the front gets farther away from the parent low, the forcing will be limited, so the speeds won`t respond quite as much the farther north it goes. Current timing has the front increasing wind speeds in the southern inner channels to around 20 to 25 knots Friday afternoon with those speeds lasting into Friday night. Farther north, mainly areas north of Frederick Sound, wind speeds will increase to around 10 to 15 knots beginning late Friday afternoon into Friday night. For the far northern inner channels, winds looks to stay out of the north at around 10 knots or less. && .AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-641-642-661>664-671-672. && $$ SHORT TERM...GJS LONG TERM...FERRIN AVIATION...STJ Visit us at http://www.weather.gov/Juneau