textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

As of this afternoon, a broad/weak vertically stacked area of low pressure is tracking eastward across the north-central Gulf. Radar returns show rain showers, and at times moderate rain showers, rounding the coast and pivoting northeast to southwest amidst the cyclonic flow. Elsewhere, easterly waves aloft moving along the northern fringe of this low have helped convection to form this afternoon across the Copper River Basin, which will persist through the evening hours.

As this low continues eastward towards the Alaska Panhandle through Thursday morning, there is high confidence in rain showers clearing from west to east along the Gulf coast. In the wake of the low, while surface high pressure establishes itself across the Mainland, upper level high pressure also noses in from the AlCan border, continuing easterly wave activity for the Copper River Basin and Susitna Valley on Thursday. Less cloud cover in the area will also allow Southcentral to continue its warming trend through the first part of the weekend. Diurnally driven showers and isolated thunderstorms (similar to this afternoon) will most likely develop once again for Thursday afternoon. Model guidance shows that the highest CAPE values/most convective activity will form across the Susitna Valley.

Looking into Friday to Friday afternoon, the upper level flow reorients as ridging situates itself over the Gulf and interacts with a large upper level system moving over/near Nunivak Island. This flow regime will begin to send southerly waves over the Mainland. With models showing daytime high temperatures warming well into the mid to upper 70s to flirting with 80 degrees Friday afternoon, this timeframe looks especially conducive for widely scattered showers and thunderstorms for the Susitna Valley and Copper River Basin - with higher confidence for the Susitna Valley seeing the bulk of activity with less coverage for the Copper River Basin. There is also medium confidence in convection (including isolated thunderstorms) forming across the Kenai Peninsula Friday afternoon. The global models show that upper level southerly flow and very warm temperatures continue into Saturday, where the chances of thunderstorms will stay with us - especially near terrain.

-AM

LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)

Sunday will see unsettled weather for Southwest and Southcentral Alaska due to a low moving into the western Gulf south of Kodiak Island. This low will push moisture into the Southwest Mainland and coastal Southcentral Alaska including Kodiak Island. Widespread rainfall over the aforementioned regions will result. Easterly waves moving into Southcentral will allow for shower activity over the Copper River Basin and the Mat-Su through Wednesday. The Bering will be in-between lows and will be relatively calm through Monday. The Gulf low will begin to progress eastward on Monday, which will decrease rain chances for the Alaska Peninsula and coastal Southcentral while the Aleutian ridge erodes during that time frame. The Bering low will slowly move eastward through Wednesday due to a blocking high over the Bering Strait.

A front from the Bering low will track across the Aleutians, bringing a period of rain and gusty winds before the front stalls and weakens between the Pribilof Islands and Unalaska by Wednesday. For Southcentral, the Gulf Low continues moving east through Wednesday, but rainfall will linger over coastal Southcentral and Kodiak Island. An upper level ridge will begin to build over the interior Monday night. There is higher confidence for continued scattered showers and thunderstorms for the Alaska Peninsula and Southwest Alaska from the anticyclonic flow and easterly waves.

-SS/JAR

AVIATION

PANC...VFR conditions are expected to prevail through at least tonight. Guidance is hinting at some low stratus and fog developing along Cook Inlet and possibly nudging into the terminal after 08-10Z as high pressure moves in for Thursday. Any fog or stratus that does develop should erode by mid to late morning Thursday as daytime mixing increases.