textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

IR satellite imagery from early this morning shows the low that has been in the central Gulf the past two days has moved eastward along with its shower activity. There are a few showers still rotating around the low in the western Gulf that could move across Kodiak today, but other than that, this low is becoming less of a factor in the weather over Southcentral. Mid and high level clouds associated with a weak upper level low can be seen over southern Cook Inlet, but these clouds will dissipate as that low continues its journey westward. Other than that, weak ridging aloft is keeping most of Southcentral clear this morning. Most of Southcentral, but not all of it. Fog-fest 2025 is entering its third day for the Anchorage bowl and the big question is if today will be the day it finally dissipates and the fog party ends. What is different about today compared to the past two days is that there is definite colder and drier air finally moving far enough south down the Susitna Valley to begin eroding this persistent fog bank. Temperatures and dew points from Talkeetna to Wasilla are running 5 to 10 degrees colder than the same time last night. This is already eroding the western edge of the fog bank as can be seen on the nighttime microphysics satellite imagery. The fog bank remains over the Anchorage Bowl, but ends abruptly just west of the Anchorage airport. This is less widespread than last night, though it does extend southward past the Kenai and Soldotna areas this morning. The same thinking goes for the western Kenai Peninsula: The drier air should erode out most of the fog as the day progresses. We shall see.

The next front moves into the western Gulf later tomorrow with increasing easterly winds into Kodiak Island tonight. Current thinking is that these winds will expand in coverage across the Gulf, with small craft winds covering much of the Gulf by Tuesday morning. The strongest winds will be through the Barren Islands and into Kamishak Bay, with easterly gusts as high as 35 knots. This front over the western Gulf will push into the northern Gulf coast on Wednesday with precipitation chances returning to coastal mountains and Prince William Sound.

LONG TERM FORECAST (Days 4 through 7/Thursday through Sunday)

All attention in the long term should be paid to a likely atmospheric river event that could span from the Eastern Aleutians to as far east as the Cook Inlet region Friday and heading into the weekend.

Diving into the knowns and unknowns, the upper level pattern looks to become increasingly more amplified Friday morning as a deep, longwave trough takes shape over the Bering, Aleutians, and North Pacific with textbook difluent flow downstream over the western Gulf and interior Southwest Alaska. An anomalously strong 500 mb ridge over Southcentral Alaska, Gulf, and North Pacific becomes anchored over the weekend, forcing the storm track to become more north to south, which would track lows from the North Pacific to the Eastern Bering and northward up the western Alaska coastline.

Model agreement has decreased since yesterday, but guidance shows the semblance of a shortwave trough amid the mean upper flow rotating over the North Pacific as the longwave tries to take a negative tilt. This combination of forcing develops a surface low somewhere across the North Pacific and sends it northward towards the Aleutians and so on. However, location and timing of the low is poor as of the latest runs of the global models.

Along with being a wet system with periods of heavy precipitation, the possibility of strong winds are certainly there depending on the strength of the surface low and its associated front, though this parameter is of lower confidence. There is also a question of how much warm air advection the system may bring into Southwest Alaska, in which case rain and mixed p-types would likely make for hazardous conditions considering its current snow/ice cover.

Please stay tuned over the coming days as the forecast comes more into focus.

-AM

AVIATION

PANC...Fog and low stratus across the terminal, as with the last couple of mornings and days, continues to be the challenge. Unlike the last couple of days, there is more dry air just above the surface with the saturated layer near the surface not being as thick as the past two days. Therefore, fog could mix out at times today into low stratus or even a low scattered deck. With that, while IFR to LIFR conditions look to be predominant early this morning, later in the morning to the afternoon offers better chances for VFR. This evening into the overnight, an upper-level shortwave will approach from the north and potentially offer up some high-level clouds over the area which will help prevent further radiational cooling. Another ingredient against the fog case tonight would be greater dew point depressions of 4 to 6 degrees which indicates drier air at the surface. Thus, there are greater chances for maintaining VFR conditions this evening and overnight as opposed to this morning.