Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
127 FXUS66 KSEW 132045 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 145 PM PDT Mon May 13 2024 .SYNOPSIS...Building high pressure will allow for temperatures to rebound upward Tuesday and Wednesday. Weak systems will bring temperatures back down by Friday into the weekend and may bring with them chances for precipitation across the region. && .SHORT TERM /TONIGHT THROUGH THURSDAY/...As of 145pm this afternoon temperatures we still in the upper 50s to low 60s across western Washington, a marked change from yesterday. Onshore flow will continue to persist today with clouds perhaps thinning out a little more before the end of the day. The exception will be across the central Puget Sound where a very weak convergence boundary is still forecast to develop this afternoon through this evening. The sensible weather with this feature may be nothing more than a wind shift and enhanced clouds, but there is still a slight (10-20%) chance of precipitation. Upper level ridging will nose into the region Tuesday and build through Wednesday allowing for temperatures to rebound up both days. Slight cooling is expected Thursday as a wave flattens the ridge. HeatRisk levels will remain in the green and yellow categories through the period. .LONG TERM /FRIDAY THROUGH MONDAY/...Forecast confidence wanes somewhat Friday through the weekend as ensemble guidance continues to struggle with the synoptic flow. The general consensus is for additional waves to move through the area keeping temperatures mild and precipitation chances in the forecast. That said, even at the extremes of the ensemble envelope there doesn`t currently appear to be a signal for any significant weather hazards during the extended period. -Wolcott- && .AVIATION...An upper-level trough will is still on track to pass over the region this afternoon. Westerly flow aloft will turn northwesterly going into the evening. Ceilings remain MVFR for a majority of terminals (except KBLI and vicinity with higher CIGs). A couple areas are seeing improvements into VFR, but with ceilings still hovering around 3,500 ft (topping out around 4,500 ft going into tonight). There appears to be widespread MVFR ceilings behind the trough going into the first part of Tuesday, before clearing out the remainder of the day. Additionally, hi-res guidance still shows possible convergence zone showers developing mid afternoon over Kitsap/Snohomish Counties and traveling southeastward into King/Pierce Counties. Will keep the mention of vicinity showers and variable winds in the affected terminals. Southwest winds at 5 to 10 kt inland will switch to the northwest late this afternoon/evening. Expect 8 to 12 kt winds with gusts to 20 kt at terminals close to the Strait of Juan de Fuca/coast. KSEA...Still watching the potential for a convergence zone with light/vicinity showers from 22Z-02Z. This may cause sudden wind shifts around the terminal from any showers that do develop. Once the convergence zone passes, the southwest winds will solidify to northwest winds at 5 to 8 kt. MVFR ceilings will likely hold at MVFR until after the convergence zone passes early this evening, then look for some improvements to low-end VFR until early Tuesday morning, as MVFR returns for the first part of the day. HPR && .MARINE...An upper-level trough will pass through the region today. Gusty winds affecting small craft continue in the Central/East Strait of Juan de Fuca and the Admiralty Inlet - expected to last through late evening. High pressure will build off the coast during the week, with troughing to the east. With strong northwesterlies translating downward towards the surface, a couple periods of gusty winds are possible in the outer coastal waters Tuesday evening into Wednesday, as well as the central Strait of Juan de Fuca. A stronger push looks probable Wednesday into Thursday for these areas, and again Friday for the coast. Seas will hold around 6 to 8 ft through Friday before increasing 8 to 12 ft from Friday into the weekend. HPR && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 3 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until midnight PDT tonight for Admiralty Inlet. && $$