788 FXAK68 PAFC 161244 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 444 AM AKDT Sun Oct 16 2022 .ANALYSIS AND UPPER LEVELS... Broad low pressure system sits nearly stationary near the Kuskokwim Delta today and tomorrow before dropping south to merge with a low in the North Pacific. Associated longwave troughing extends into the central Bering and the Gulf of Alaska. Upper level riding over Canada clips into the Copper River Basin today, getting shoved off to the northeast as troughing moves north from the Gulf of Alaska. Another high pressure ridge sets up over the western Bering and will linger through Monday evening. Radar shows rain filling in across portions of Southcentral and Southwest Alaska tonight. Other observations show freezing precipitation further inland for places like the Kuskokwim Valley and Kuskokwim Delta near Bethel, as well as in the Copper River Basin. Two larger systems are developing, one over Russia and one in the North Pacific. Both will have some impact over Southern Alaska towards mid-week. && .MODEL DISCUSSION... Models are in good overall synoptic agreement through the short term. Which the general consensus at the surface is better, there are still some minute issues, mainly with precipitation and tracking of the shortwaves. Models seem to have a pretty good handle on the two larger systems, one over Russia and one over the North Pacific, as they work their way towards the Bering Sea and Gulf of Alaska respectively. && .AVIATION... PANC...Light rain will continue. Expect periods of MVFR-IFR conditions throughout much of the day today. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3; Today through Tuesday night)... A surface low south of Cordova this morning will move over Prince William Sound then weaken rapidly as it moves inland by Sunday afternoon. A widespread area of precipitation stretching from Prince William Sound and the southern Copper River Basin to the Susitna Valley will lift northeast across the region today as the aforementioned low and associated upper-level shortwave move toward the Copper River Basin. Along the coast and over the Mat- Su Valleys and Anchorage Bowl, the precipitation is falling mainly as rain. For the Copper River Basin, however, the precipitation continues to fall as wintry mix, with snow in the western half of the basin and a mix of snow, sleet, and freezing rain from the Richardson Highway east. The frozen precipitation over this area will wind down by late morning as southerly winds increase and temperatures finally climb above freezing. A series of shortwaves and surface troughs will continue to move north across the Gulf of Alaska in the wake of this initial system. These features will keep conditions unsettled late Sunday through Monday. with a steady rain along the coast and periodic waves of showers inland. With the persistent southerly flow aloft, temperatures across much of Southcentral will stay above the freezing mark. This will mean much of the precipitation that falls from Sunday night through Monday is expected to fall as rain, with the exception of locations along the northern Susitna Valley and Copper River Basin as well as higher elevations. Attention then shifts back to the southern Gulf for Tuesday as a potent storm system lifts north from the Pacific. A front will swing out ahead of the center of circulation, likely bringing strong winds and heavy rain to Kodiak Island by Tuesday afternoon. The front is expected to continue north to the Southcentral coast by Tuesday night. There remains a bit of uncertainty as to how far inland the front advances for Wednesday as the northern extent of precipitation. Right now, this system looks to weaken quickly as it takes a more eastward track toward Yakutat for Wednesday afternoon. &&.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Tuesday)... A broad low pressure system extends across the eastern Aleutians and southern Alaska Peninsula. Upper level shortwaves rotating on the eastern side of the low is moving northward with rain across Bristol Bay. A surge of warm, moist air has slowly changed the precipitation type from wintry mix to all rain in the Kuskokwim Delta. Not much changes are expected with precipitation continuing through Monday afternoon/evening as the broad low remains quasi- stationary. By Monday night, the low will weaken and lift northward in response to a Bering Sea high pressure system shifting eastward. Precipitation will then taper off as the high builds overhead with cool, dry conditions returning on Tuesday. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... A broad low pressure system extends across the eastern Aleutians and southern Alaska Peninsula. Small craft northerly winds along with scattered rain/snow showers continues across the Bering Sea and Aleutian Chain as cold air streams over the relatively warm sea waters on the back side of the low. Winds are expected to diminish along with precipitation tapering off by Monday night as a ridge of high pressure builds overhead. Meanwhile, a front extending ahead of a strong low in the Sea of Okhotsk will advance eastward. This front has the potential to bring storm force southerly winds into the western Aleutians and Bering Sea between Monday and Tuesday. && .LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)... There is reasonably good consensus with the models most of this forecast period. Confidence continues to increase regarding the low tracking into the Gulf Of Alaska Tuesday-Wednesday. This low contains the remnants of a former tropical system. All the global models have a tight pressure gradient, expect strong (gale to hurricane force) winds and enhanced seas with this low. Heavy precipitation is anticipated along the northern Gulf coast. There is a second system that will sweep across the Bering and Aleutians with the front near Cold Bay Wednesday morning. Expect gale force winds and precipitation. This front will weaken as it approaches the Southwest Alaska coast. Cyclonic flow will impact the Bering through day 6 and by Saturday the models are out of phase. It is also worth mentioning that temperatures will be warmer than normal. A number of locations in Southcentral, including Anchorage and Palmer will see afternoon temperatures in the mid to upper 40s. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Winter Weather Advisory 141 MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...KM SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MF LONG TERM...PJS