textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key Messages:

- Flood Watch remains in effect for the Central Susitna Valley through Wednesday afternoon.

- Flood Warning remains in effect for the Petersville area through 5PM Wednesday.

- Flood Warning remains in effect for the Yentna River including Lake Creek through 1PM Friday.

Discussion:

The pattern will remain unsettled over the next few days as the upper low over the Bering Strait continues to wobble around before moving inland and weakening. Several impulses will rotate around the southern periphery of the low before lifting up across western Southcentral. The next of these waves will lift through this evening helping to reinvigorate some of the rain showers over areas along the Cook Inlet and up into the Susitna Valley. Overall rain chances will be trending downward, especially Thursday into Friday as ridging begins to build back over the Gulf, nudging into portions of Southcentral. For today, light rain showers are still lingering across the eastern Kenai Peninsula and the Susitna Valley, and will see these showers continue throughout the day. Heavy rainfall has ended over the Susitna Valley, but may be able to squeak out another 0.25-0.5 inches of rainfall through this evening. The previous few days heavy rainfall has resulted in several rivers in the northern and central Susitna Valley to rise to near of above flood stage once again. As such, Flood Warnings still remain in effect for the Petersville area through 5 PM today and for the Yentna River (and Lake Creek) through Friday. A Flood Watch also remains in effect for the Central Susitna Valley through this afternoon.

Looking ahead towards the end of the week and weekend... High pressure looks to build back over the Gulf and interior Alaska allowing for another period of warm and drier conditions.

- PP

LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)

An upper-level low situated over North-central Alaska will send shortwave energy southward across the Southern Mainland. The resulting weather will be diurnally-driven showers this weekend into next week. This pattern supports more of a scattered shower regime as opposed to widespread stratiform. The challenge will be to gauge instability each afternoon to determine whether or not lightning will be a threat with any robust showers that form. Right now, it looks like the Copper River Basin, along the Talkeetna Mountains, and along the Western Alaska Range feature the most instability through the long-term period.

Farther west, a system will drop south out of Upper Kamchatka and into the Bering Sea by Saturday morning. The point of uncertainty with this system is its progression. The GFS solution is the quickest with the system and places it near the Pribilofs Saturday morning. The Canadian and European guidance is slower with the progression and has the system in the north-central Bering near St. Matthew/St. Lawrence Islands Saturday morning. Regardless of the differences in speed/progression, this system does not look all that strong or impactful; just wet for the Pribilofs and perhaps the Central Aleutian Chain for this weekend. A separate front enters the western Bering on Monday and brings the Western Aleutians a round of rain Monday into Tuesday. A North Pacific low lifts towards the Alaska Peninsula by Tuesday morning. This system will bear further watching and interrogation as a tropical moisture plume may accompany this system.

AVIATION

PANC...Light southeasterly winds and VFR ceilings expected this morning through late this afternoon, however, brief clearing of cloud cover may allow a scattered 300-500 ft deck to develop this morning. Ceilings are expected to fall to the MVFR range this evening along with an increasing chance for a shower or two in the vicinity of the terminal.