textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

Areas of fog developed overnight along the northwest Kenai Peninsula and central Cook Inlet and along the Knik Arm and Palmer Hay Flats. Initially, these areas of fog were fairly transient with visibilities varying as these areas of fog drifted around. One blob moved north along the Parks Highway towards Talkeetna where visibilities dropped to under a half mile. By early this morning, fog and low stratus was starting to fill in across the northern Cook Inlet, the Anchorage Bowl, and the Wasilla/Palmer area. And while conditions are starting to improve as mid and higher level cloud cover works in from the west, pockets of dense fog may linger for several more hours this morning.

Quasi-zonal flow will turn more longitudinal today as an upper ridge starts to amplify over the Northern Pacific and Bering Sea. This amplification will continue into Monday as a strong low drops southwards across the Panhandle and eastern Gulf, and another strong low lifts up towards the Gulf of Anadyr in the western Bering Sea. For today, a shortwave trough translating eastwards just south of Norton Sound will bring increased cloud cover and a chance for light snow showers along the western slopes of the Talkeetna and Chugach Mountains, and the some lower end snow chances for the Mat Valley by early to mid afternoon then moving into the Copper Basin with increased snow chances for the western slopes of the Wrangells and the eastern Alaska Range. Any snowfall amounts look light as this system will move through quickly and have limited moisture to work with.

The bigger story for the next few days will be colder temperatures and strong gap winds along the coast. A series of low amplitude short-waves embedded in the fast westerly flow will cross Southcentral today, reinforcing the Arctic air and maintaining gap winds.The aforementioned ridge will further amplify tonight and Monday as it shifts eastward toward western Alaska. As a result, a cold trough up over northwest AK, will be forced southward and across Southcentral tonight and Monday, bringing even colder air with it. This will once again cause gap winds along the coast to strengthen. The track of the short-wave (and area of strongest cold air advection) will be across the Copper River Basin. This will bring the strongest winds to Valdez/Thompson Pass and the Copper River Delta on Monday. The lack of a deep surface low in the Gulf is the one piece missing to make this a high end wind event. Still, expect strong and gusty winds. The bottom line for coastal areas: winds will remain elevated through at least Monday, with some fluctuations in strength as various short-waves and surges of cold air move through. Meanwhile, much colder temperatures will settle over the region, with each day colder than the previous.

- PP/SEB

AVIATION

PANC...Low end MVFR to IFR visibility and IFR to LIFR ceilings will most likely prevail through most of the morning hours of the TAF period. Areas of fog can be seen this morning on satellite along the Knik Arm, across Anchorage, and farther south down the Cook Inlet. Expect fog to begin to scatter out around 18z to 20z. Winds will generally be light and southerly this morning, though will turn more southeasterly after 00z with occasional gusts over 10 knots possible.