Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
081 FXAK68 PAFC 031250 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 450 AM AKDT Wed Jul 3 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Friday)... An upper level ridge that has been sagging gradually south from the Interior is beginning to move overhead this morning. This is helping to keep just about everywhere precipitation free, but a mid level cloud deck associated with moisture trapped under the ridge has stubbornly held on across a good chunk of the Copper Basin, as well as parts of the Mat-Su and Anchorage areas. It`s unclear just how much this deck will erode as the day progresses given the weak to nonexistent flow in place, and this uncertainty will affect how far into the 60s we will manage to get over lower elevations as the weakening ridge slowly drifts towards the Gulf coast. A weak shortwave will also dive down past the Talkeetnas and Alaska Range today, and this will help set off scattered showers progressing from the far northern Susitna Valley into parts of the Copper Basin by this evening. Looking towards the July 4th holiday, the overall shift to a wetter pattern we`ve been advertising still looks on track, but confidence regarding the exact timing of rain moving in for various locations is still in flux. Models have struggled to ascertain how quickly a strong shortwave and trailing front over Southwest will progress south across the Alaska Range, making it difficult to say exactly when conditions will deteriorate towards the latter half of the day on Thursday. Newer guidance has moved back the timing of rainfall spreading in ahead of the trough just a touch. Thus, have opted to update the forecast with this package to reflect a slightly more optimistic outlook through Thursday evening for all but the Susitna Valley where rain will arrive first. In general, the farther south the later the arrival of any rain threat will be, possibly holding off until after 10 pm from Anchorage south to the Kenai Peninsula. By Friday, an overall break in the rain is expected for all but the Prince William Sound area as the shortwave continues southeast into the northern Gulf and weak ridging momentarily tries to rebound behind it. Unfortunately, the break doesn`t look like it will last long. A much deeper upper level trough will begin to dig into Southwest late on Friday, setting up a belt of convergence and southwest flow extending from the mid to upper levels between this next approaching system and the ridge sinking into the Gulf. A more widespread and significant rainfall event looks increasingly possible with this setup heading into the first half of the upcoming weekend. Suffice to say, the endless stretch of sunshine back in June is not coming back anytime soon. -AS && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)... High pressure ridging extends over Southwest Alaska, promoting dry conditions for the rest of today. A front extending off a Kamchatka low stretches across the Central Aleutians and central Bering sea that will eventually feed into a shortwave dropping south into Southwest Alaska early Thursday morning. There is a decent moisture feed that will pull into Southwest, bringing a round of wetting rain showers on Thursday. && .LONG TERM FORECAST (Days 4 through 7)... The long range models are in more agreement today with the pattern change mentioned in previous discussions. The areas of high pressure that have been persistent over the Bering Sea and the Gulf of Alaska in the early part of the period will start to break down allowing a North Pacific low to track northward into the Gulf. This combined with troughs of low pressure transiting across the Bering Sea and Kuskokwim Delta will track eastward across the region through the end of the period. As a result, expect scattered precipitation and cooler temperatures across the much of the forecast area. Additionally, gusty winds and possible small craft conditions are expected in Cook Inlet and coastal regions of the Kenai Peninsula Saturday afternoon and into Sunday. -DD .AVIATION... PANC...VFR conditions and light winds persist through Wednesday evening. Westerly winds this afternoon will shift southerly overnight, before becoming westerly again tomorrow afternoon. && $$