textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

The first half of this week will see two significant upper level waves, both anchored to the upper level low in the northern Bering Sea, move through southern Alaska. These upper level disturbances will bring some windier and wetter conditions as they pass through the region. The first system currently has a weak surface low centered near Bristol Bay with a front extending across southern Cook Inlet and into the Gulf of Alaska. This front is weakening as it slowly moves northward through tonight and into Monday morning. This system expected to bring light rain to most of the region overnight. Southeasterly winds along the Kenai Mountains and western Chugach Mountains will provide a downslope component for Anchorage and portions of inland and western Kenai Peninsula, but it will not be enough to shut off the rain, but should keep it light. The southerly winds along the Copper River this afternoon through the evening should be more effective in keeping the lower elevations of the Copper River Basin dry. However, as these winds diminish overnight some light rainfall is expected to develop in this area as well.

The second system is stronger in general and has a surface low centered in the Western Aleutians this afternoon. This surface low will also weaken some as it tracks eastwards and moves onshore in the Kuskokwim Delta , but the upper level wave will track over Southcentral Alaska late Monday night. However, the upper level trough will continue to move eastward over Southcentral Alaska through Tuesday. This will bring another round of widespread rain to the region. Turnagain Arm winds will bend into Anchorage Monday evening, with wind gusts expected to range from 15 to 30 mph. Copper River winds will also increase again for Monday afternoon into Tuesday morning, but as they diminish, rainfall should increase for the Copper River Basin as well on Tuesday.

LONG TERM FORECAST (Days 4 through 7)

The upper level pattern becomes increasingly amplified to begin the long term period as a strong upper level Kamchatka low opens to a trough in the western Bering while a strengthening upper ridge slides east across the Mainland. Ensemble model guidance remains in fairly good agreement for the associated surface low over Kamchatka to track northeast across far eastern Siberia and eventually into the Arctic Ocean by Friday. Its associated small- craft to gale-force front moves east across the Bering through midweek with gusty southwesterly winds and moderate to heavy rainfall across the Aleutians and Pribilof Islands.

The front is set to reach the Southwest Alaska coast Thursday into Friday, spreading the gusty winds and moderate to heavy rainfall across the western Mainland. The long fetch of strong, southwesterly onshore winds could bring the possibility of high surf and minor coastal flooding and erosion along the Kuskokwim Delta coast as the front progresses through the region. Additionally, widespread moderate to potentially heavy rainfall across Southwest Alaska will accompany this system as it taps into a robust stream of subtropical Pacific moisture. Elevated water levels in the Kuskokwim River due to preceding rainfall across the Interior, combined with strong southwesterly winds up Kuskokwim Bay and additional rainfall, could lead to minor river flooding for communities along the river from Bethel southwards. Details will continue to become clearer in the coming days on the exact timing and potential impacts of this upcoming late-week storm.

By the weekend, weaker, more zonal flow takes over the Bering while the weakening frontal system and rainfall continues east into Southcentral and the Gulf. Expect unsettled, showery weather to continue across the Bering, Southwest, and Southcentral through the weekend into early next week as weak upper level perturbations move through the region.

AVIATION

PANC...Light rainfall is expected this afternoon through early Monday morning. Exact timing for rainfall will depend on the strength of downslope drying. Highest probabilities for precipitation will be 02Z to 10Z. VFR ceilings will likely hover around between 4000 to 6000 feet with intermittent drops to 3500 feet during steadier rainfall and towards Monday morning. Surface winds at the terminal will be light and generally between the north to southeast. Relatively stronger southeast winds through Turnagain Arm are expected to bend down-Inlet away from the terminal.