textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

This afternoon has been mostly quiet across Southcentral Alaska with mostly to partly sunny skies and seasonable temperatures. This will be short lived, however, as a shortwave trough is progged to dig southeastward from the Interior tonight and into Tuesday morning. Increased cloud cover ahead of this feature will only allow temperatures to slowly cool tonight and most valley and lower elevation areas outside of the Copper River Basin are on track to see low temperatures 2 to 4 degrees F warmer than what was observed this morning. Along with precipitation chances increasing from Anchorage to the Susitna Valley, cold air advection working in aloft with this wave will lower snow levels to as low as 1800 to 2000 feet for the higher terrain of the Matanuska and Susitna Valleys, which will support a quick round of lower elevation rain showers and higher elevation snow before the wave lifts over the Copper River Basin. Gap winds up to small craft continue to gust around Kodiak Island as the remnants of Dujuan move east through the Gulf. Winds slowly diminish through mid-week as these final remnants dissipate.

For Wednesday, a longwave trough will move over the area with a quasi-stationary surface low developing south of Seward. Weak lift and weak winds aloft should help to bring steady precipitation to the Sound and the population centers from the southern Matanuska and Susitna Valleys and southward down into the Kenai Peninsula. Even colder air will wrap in around the low bringing 850 mb temperatures down to a range of -2 to -5 C depending on the model. This would yield steady snow for areas like Thompson Pass and even South Fork Eagle River and portions of the upper Hillside. The NAM is a significant cold outlier and drops snow as low as 800 ft, but we will continue to watch the progression of temperatures aloft as we get closer in time. Overall confidence is moderate (40-60%) that some of the upper elevations of Anchorage and Eagle River will see some snow on Wednesday. Though winds will remain sub-small craft, they will be elevated over gap regions around Kodiak Island as this trough passes through.

-AM/JAR

LONG TERM FORECAST (Days 4 through 7: Friday through Monday)

An active weather pattern will continue as we make our way into October. A cold upper level trough over the Interior on Friday will begin to move out of the region for the weekend. The departure of this low will bring a slight warming trend through the weekend.

There are signs of slight ridging over Southcentral for Friday, which will be the best chance to see some sun. This will be short lived since a Gulf low is expected to bring rain and wind for the weekend. Looking at integrated vapor transport from the GFS, the values are low, so the low is not expected to generate a notable amount of precipitation. Using the GEFS member spread, the pressure gradient is nothing note worthy. No significant winds are expected at this time Friday through Monday.

Another low from Kamchatka comes into the Bering Sea, then tracks over the Aleutian Chain through the weekend. There is growing model agreement of the low reaching peak intensity before going through the Bering Sea. There is low confidence of where the system goes after the weekend. Half of the members from the GEFS have the centers of the low track into the Gulf, crossing over the Alaska Peninsula. Other members have centers scattered around the Bering.

AVIATION

PANC...VFR conditions and light winds will persist for most of the TAF period. There will be a potential for rain showers and lower ceilings (possibly as low as MVFR) to return to the terminal late Tuesday morning.