textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

A shortwave trough moving over Kodiak this morning will phase with an upper level low over the western Interior through the day and into tomorrow. At the surface, a lee-sde trough has developed south of the Kenai Peninsula, which will remain fairly stationary/redevelop with the westerly flow aloft. Precipitation, mostly in the form of showers due to widespread instability, has begun to develop along the eastern Kenai Peninsula and will spread inland through the day as the southern shortwave lifts into the area. Yesterday there was some model disagreement as to the location of the surface trough and speed of the shortwave moving east, but generally speaking guidance has trended towards the GFS solution, which means more precipitation for Anchorage and the southern Mat-Su Valleys. Showers will also develop over the eastern Sound and move over the Chugach into the southern Copper Valley.

By Thursday morning the southern shortwave will move into the Panhandle and Yukon Territory, while an arm of the cold upper low moves south over the western Alaska Range and greater Bristol Bay area. This will continue to provide lift for showers along the Chugach and Kenai Mountains, with some precipitation possible for Anchorage and the Mat Valley. By this time the airmass aloft will be quite cold, dropping snow levels as low as 800 ft or so. It's not out of the realm of possibility for some near sea level areas from Anchorage north to Palmer to see some snowflakes Thursday morning if a heavier shower moves overhead. Areas along the upper Hillside and South Fork Eagle River are likely to get a dusting up to 3 inches depending on the elevation and intensity of the showers. Should showers train over the higher elevation areas like Glen Alps or South Fork tonight, up to 5" may be possible.

Moving into Thursday evening and Friday there is some uncertainty as to when the trough axis will finally move through, thus leading to the end of precipitation. Overall model consensus is Thursday evening, but the GFS lingers the trough for a longer period of time, thus leading to a longer period of potential precipitation. By Friday morning precipitation should be out of the area, and with clearing skies the first hard freeze with temperatures less than 30 degrees is likely for many of the population centers.

CJ

LONG TERM FORECAST (Days 4 through 7)

Looking ahead toward this weekend, models are synoptically in good agreement in the midrange forecast, featuring a low moving toward Kodiak Island from the North Pacific and another low into the Bering Sea from the west. Precipitation with east to southeast winds will be more than likely for Southcentral, especially closer to the Northern Gulf coast and Kodiak Island. By Sunday, the front extending from the Bering Sea low reaches Southwest Alaska and the Alaska Peninsula bringing rain, snow, and southerly flow across the area. As the low sinks southward Monday, models diverge on how far south the low will dip. Generally, the low appears to pass through the Alaska Peninsula and near Kodiak Island/Western Gulf. As this pattern sets up through the first half of next week, cold air advection and northerly winds will become enhanced through gaps along the Aleutians. If the low sinks south farther east, the Alaska Peninsula would see more cold air advection and those northerly winds. While temperatures overall for southern Mainland are trending cooler in the short term, some moderation of that trend is expected toward more seasonable norms, but will remain on the cooler side.

AVIATION

PANC...VFR ceilings are expected to lower to MVFR late this morning as precipitation chances increase through the morning hours. Ceilings improve back to VFR as rainfall tapers off this evening.