Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
179 FXUS66 KSEW 222220 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 320 PM PDT Wed May 22 2024 .SYNOPSIS...Weak high pressure will build aloft for drier and somewhat warmer conditions on Thursday. Another upper trough will move across Washington Friday into Saturday for cooler and unsettled conditions. Ridging will begin to build into the interior West next week for warming temperatures, but continued troughing offshore will allow for chance of precipitation. && .SHORT TERM /TONIGHT THROUGH SATURDAY/...An upper low located across eastern Washington will continue to move southeastward tonight allowing for lingering showers over the Cascades to dissipate during this period. Weak high pressure aloft will briefly build in Thursday for slightly warming temperatures, generally drier conditions, and some sunshine. Troughing will develop Friday into Saturday for a return of unsettled conditions. Rain showers will increase into Friday morning for the coast, and then slowly move eastward through the day, but expected to remain generally light. Weak convergence may occur Friday night into early Saturday across central Puget Sound. Otherwise, temperatures will generally range in the upper 50s to low 60s Friday and Saturday. .LONG TERM /SUNDAY THROUGH WEDNESDAY/...Ridging will begin to nudge into western Washington later Sunday into Monday, allowing for warming temperatures into next week. However, continued troughing offshore will allow for southwesterly flow aloft, leading to continued precipitation chances, mainly for the Olympic Peninsula and areas near the border during this period. Uncertainty increases in ensembles Tuesday in regards to the extent ridging builds into western Washington with troughing offshore. However, at least some troughing is expected to move across the Pacific Northwest later Tuesday into Wednesday, increasing precipitation potential. Normal to slightly above normal temperatures Monday into Tuesday, with perhaps some cooling for Wednesday. JD && .AVIATION...Mostly VFR across area terminals this afternoon. But, low clouds look to fill and become more widespread overnight between 08-12z Thursday for most interior terminals. For these airfields, confidence is leaning towards MVFR cigs but can`t rule out a 20-30% chance of IFR for locations such as KPWT. Northerly winds 5-10 kt will switch out of the south to southwest this evening around 03- 06z. Any lingering low clouds should scatter around 18-20z Thursday back to VFR criteria. KSEA...VFR conditions this afternoon. However, MVFR stratus is expected to redevelop overnight around 08-10z Thursday. These cigs are to hang around before scattering back to VFR conditions by 18- 20z Thursday. Northerly winds look to switch out of the SSW by 04- 06z tonight between 8-12 kt and remain into Thursday. McMillian && .MARINE...Seas around 10-12 ft offshore are maintaining SCA headlines before they ease into the evening. Afterwards, conditions should trend more benign into the remainder of the night and Thursday. However, the next frontal system is expected to pass through area waters on Friday. This will likely bring another round of elevated seas and breezy winds. Seas decreasing to 6 to 8 ft overnight before settling around 3 to 5 for both Thursday and during the day on Friday. Then, a NW wave train looks to arrive Friday night helping to increase seas to around 8-10 ft through early Saturday morning. McMillian && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 6 PM PDT this evening for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm- Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-Grays Harbor Bar. Small Craft Advisory until 9 PM PDT this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. && $$