668 FXAK68 PAFC 111248 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 448 AM AKDT Thu Oct 11 2018 .ANALYSIS AND UPPER LEVELS... The pattern is signified by an upper level low anchored over the eastern Bering. Multiple shortwaves are rotating around the main low with the strongest pushing through the eastern Aleutians bringing rain to the islands. This setup is bringing southwest flow to the southern mainland with scattered showers over southwest Alaska and along the north Gulf coast. && .MODEL DISCUSSION... The models are in good agreement for the most part with the main synoptic features through the mid term. The 00Z runs were having some issues with a low approaching the western Aleutians Friday, but the 06Z runs seem to have a better handle on it. && .AVIATION... PANC...VFR conditions will persist. Winds will stay out of the south around 10 kt and gust into the mid teens through tonight. Turnagain Arm winds will increase overnight tonight but should remain south of the airport. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Rain showers will linger over the area today, mainly near the coast and along the Alaska Range and Talkeetna mountains. This is due to weakly unstable southwesterly flow. The next front will slowly make its way from west to east across the Gulf later today into Friday. It will briefly stall out in a north/south orientation stretching from Kodiak Island through the Kenai Peninsula and into the Susitna valley on Friday. Winds will once again ramp up through Turnagain Arm. Some gusty winds will also move into the Anchorage Bowl on Friday, but not as strong as those on Wednesday. Rain will be likely at some point Friday for much of Southcentral, though downsloping will limit precipitation from the western Kenai through Anchorage and the Matanuska valley. A system to the east of the front will move into the Gulf rapidly from the south on Friday night. This will bring strong winds and more rain to the northern Gulf beginning Saturday morning. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)... (Today through Saturday) Southwest winds and a cyclonic onshore flow is helping to maintain a decent amount of moisture across the region, with fairly widespread showers continuing to move across most locations. This looks to continue through at least the morning hours. By early afternoon, another deepening low will race northeastward towards the eastern Bering, before it turns more north. An associated weak warm front will loft north with the low, and a trailing weak cold front will slide east. Ahead of either of these features, winds will increase somewhat with widespread rainfall developing. This storm will have less of a tropical connection compared to the past few. That said, some of the rainfall will occasionally reach moderate intensity. As this low reaches Nunivak Island late Thursday night, it'll encounter the low from the former tropical system, and they'll rotate around one another in a Fujiwhara-like fashion near Saint Matthew Island. This will keep southwest Alaska in a continued broad cyclonic flow, conducive to maintaining a showery regime through Friday, before the lows consolidate/fill and edge eastward for Saturday, bringing a somewhat more steady rainfall to the coast. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)... (Today through Saturday) Another deepening low will lift from the east central Bering this morning, towards Nunivak Island by midnight tonight. This low will spread a weak cold front eastward, with widespread rainfall developing along and ahead of it. Winds will remain in small craft criteria, except south of the AKPEN, where sustained gales are likely through Friday morning, before gradually subsiding. Further west, cyclonic flow around a St. Matthew Island low will keep showers in the picture for all of the Bering and Aleutians, with sustained small craft criteria winds expected across the western half of the Bering and Aleutians. This looks to continue through late Friday, as models have slowed down the frontal timing of a cold front associated with a Kamchatka low. This system looks to bypass the western Aleutians to the west and south for Friday into the weekend. However, it'll pass close enough to bring widespread rainfall (some moderate to heavy at times) and sustained gales to the western portions of the Bering Sea and Aleutian chain, with rainfall spreading eastward along the chain through Saturday. && .LONG TERM FORECAST (Days 4 through 7: Saturday Night through Wednesday Night)... A strong low located south of Adak on Saturday night is forecast to make its way towards mainland Alaska, and will be the cause of much of the active weather across the area through the long-term. The long-term models are all in impressive agreement on the forecast behavior of the low, which adds confidence to the forecast that is not commonly there. The low center is expected to track eastward but remain well south of the Aleutians until it crosses the Alaska Peninsula near Cold Bay during the day Monday. The low will be a large one, and as such will impact many communities well away from the center. The front wrapping around the low pressure center is expected to approach and move in to Southwest Alaska on Sunday evening, despite the low center still located south of Cold Bay at that time. This is testament to the large area that will be affected by the low. Overnight Monday night into Tuesday, the low center will track northward to near Kuskokwim Bay, slowly weakening as it goes, then will remain nearly stationary over the Kuskokwim Delta through Wednesday night. Across Southcentral, rain ongoing from a low that will impact the area during the day Saturday will diminish Saturday night. High pressure briefly moves in during the day Sunday, which looks to be by far the nicer of the two weekend days. Winds will be on the increase through the gaps late in the day Sunday into the night, as a strong warm front lifts northward into the area. The rain, heavy at times will persist across much of Southcentral through the day on Monday, and continue into Monday night. With the stationary low over Southwest Alaska keeping the overall atmospheric flow out of the south to southwest Tuesday and Wednesday, a continuation of cloudy and showery conditions is likely to persist. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Gales...130 132 150 155. && $$ SYNOPSIS AND MODEL DISCUSSION...DK SOUTHCENTRAL ALASKA...BL SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD LONG TERM...JW