Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
879 FXUS66 KPQR 270317 AAA AFDPQR Area Forecast Discussion UPDATED National Weather Service Portland OR 815 PM PDT Sun May 26 2024 ...EVENING UPDATE, for aviation weather... .SYNOPSIS...Decaying showers will give way to high pressure on Monday. Expecting warmer and drier conditions, but could still see some cloud cover and thus dampening any intense warming. Another round of rain on Tuesday through Wednesday, with slight chances for rain on Wednesday along the northern most portions of the forecast area. && .SHORT TERM...Now through Monday Night...Satellite shows generally clear skies with a swath of clouds over the north Oregon and south Washington coast. While the clouds are in place now, the clearing skies overnight will allow for ample radiational cooling overnight. Models are trying to bring in some patchy fog once again, but with a lack of moisture available, it will be difficult to get fog for anywhere east of the Coast Range. Monday will be warmer and drier, though temperatures will still be under seasonable normals. Inland temperatures will be in the 70s on Monday and in the 50s along the coast...minimal change from the last previous days. The range of possibilities though is much more narrow today so confidence is higher that tomorrow will be a typical springtime day. As the sun begins to set, yet another weak front will advance towards the coast from the Pacific bringing along clouds, rain, and cooler temperatures. At 850 mb around 0 degrees celsius temperatures will fill in behind the trough causing slow levels to drop and temperatures to cool at the surface. Overnight temperatures will stay fairly consistent with normals for this time of year. There are some chances for rain very early Tuesday morning, but they are isolated to the coast. -Muessle .LONG TERM...Tuesday through Saturday...Cool onshore flow through a majority of the week with rounds of light rain. The coast, Coast Range, and south Washington Cascades will see the bulk of the rain on Tuesday and Wednesday, while the Willamette Valley and Upper Hood River Valley will experience a bit of a rain shadow effect. Accumulations will be unimpressive. One shift from the previous forecast is the more widespread slight chances (15-20%) for thunderstorms on Wednesday. Soundings show ample convective energy available for some elevated storms, but unless these showers become more robust or the flow becomes more southwesterly, storms will be difficult to form. If they do, it would be isolated singular lightning strikes. Small hail is not as probable. Later in the week, conditions have the chance to start drying out, however, confidence is quite low. Ensemble clusters of the main long-term models are showing a variety of outcomes, especially on Saturday. Thursday there is consensus that we will be on the backside of the trough at 500 mb which will bring rain to an end and keep more of a neutral flow. Friday is taking on more of a ridging pattern, but it is looking a bit flatter than yesterday`s runs. Temperatures have the potentially to be a few degrees warmer though than what we will see on Monday. Saturday is a bit more of a mess though as around 25% of of members are showing ridging, and while the others are more zonal. Overall, not ready to hang a hat on a drier outcome, but there is still a chance. /Muessle && .AVIATION...Clear skies across the interiro this evening. But, a weak front offshore is approaching, with increasing mid clouds across the region overnight. System is quite weak, and as such, will just bring clouds. Increasing MVFR clouds along the coast tonight, with those clouds gradually breaking up and lifting to lower VFR by later Mon am. Farther inland, will remain VFR, with broken to clouds (5000 to 6000 ft) later tonight into mid-Mon am. But, those clouds generally from Salem northward into western WA. Areas to south and east of Salem likely to remain mostly clear. PDX AND APPROACHES...VFR with scattered to broken mid-level clouds rest of this evening. Will see broken to overcast deck at 5000 to 6000 ft from around 09Z to 16Z Monday. Later Mon am, clouds break apart with VFR and light north winds. && .MARINE...Winds gradually easing this evening, with winds mostly 10 kt. Not much change through Thursday. Then, another trough returns that brings some potential for gusts up to 20-25 kt again. Seas stay at 4 to 6 ft. /Liu && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland