Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
783 FXUS66 KPQR 250041 AFDPQR Area Forecast Discussion National Weather Service Portland OR 541 PM PDT Mon Jun 24 2024 .FOR TESTING PURPOSES.... && .SYNOPSIS... A transient shortwave ridge will bring dry and warm conditions to the area Monday and Tuesday, warmest on Tuesday. An upper level trough will then bring relatively cooler temperatures for Wednesday and Thursday with increasing chances for rain showers. Warm and dry conditions will return Friday and Saturday with near normal to slightly above normal temperatures. && .SHORT TERM...MONDAY NIGHT THROUGH THURSDAY...A transient shortwave ridge will bring warmer temperatures and dry conditions the rest of Monday and Tuesday. Temperatures today will peak in the upper 70s for the Willamette Valley, mid 60s at the coast. Tuesday is projected to be even warmer. For the Willamette Valley, NBM guidance shows a 60-80% chance of highs over 85 deg, and 20-40% chance of highs over 90 deg. The coast should remain cooler, closer to the upper 60s. Cloud cover will be fairly minimal during these two days. Tuesday night, the ridge begins to move eastward, accompanied by a shift to westerly onshore flow, and the following upper level trough begins to impact us. A few light showers may be possible Tuesday night and Wed morning, but the weak warm front passes through Wed afternoon, bringing a 10-20% chance of rain (mostly north of Salem). Accumulations look little to none. This will be followed by a cold front Wednesday night, with better chances for rain. PoPs at 40-70% for northern regions, decreasing south of Salem. Rain continues until Thursday evening, and chance of 0.25" of accumulation is below 10% everywhere but the WA Cascades. The northern Willamette Valley and northern coast can expect somewhere around 0.10-0.15" of rain, and areas south of Salem should see little accumulation at all except in the Cascades. .LONG TERM...FRIDAY THROUGH MONDAY...Friday shows the trough moving through, and we return to more of a ridge pattern. While uncertainty still exists as to when the ridge moves out of the area, Friday at least shows no real chance for rainfall, with a 60% chance of temperatures in the Willamette Valley above 80. Saturday sees much more uncertainty; WPC Cluster analysis shows 60% chance of weak ridging continuing, but there is the potential for a very weak and transitory shortwave trough. If this occurs, expect very weak showers and possibly cooler temperatures back into the low/mid 70s. Sunday sees better ensemble agreement (70-80%) on stronger ridging beginning to develop, continuing into early next week. /JLiu && AVIATION...High pressure remains over the region, with dry mild southwest flow aloft. This will maintain VFR under mostly clear skies through Tuesday at all inland sites although CAM guidance does suggest a 20-40% chance for MVFR low clouds to back build off the Cascades towards the I-5 corridor between roughly 12-16z. The coast likely sees MVFR to IFR low clouds building in overnight into Tuesday morning before slowly reverting to VFR by Tuesday afternoon. PDX AND APPROACHES...High pressure with mild dry southwest flow aloft will maintain VFR under clear skies. Will need to watch for SCT-BKN 1.5kft cloud deck back building off the Cascades 12-16z, otherwise, high confidence in VFR. -Schuldt && .MARINE... High pressure will remain over the offshore waters tonight and Tuesday. Meanwhile, thermal low pressure stays over northwest Calif into far sw Oregon. This will keep the northerly pressure gradient tight enough to support north winds gusting 20 to 25 kt into this evening far the waters south of Newport. Seas still running at 6 to 8 ft, but will fall back to 5 to 6 ft later tonight into Tue. Otherwise, not much change in the pattern for early this week, as high pressure remains anchored off the Pac NW. Low pressure will arrive mid-week, with a weakening front arriving. This will bring return of unsettled weather, with return of west to southwest winds, but still mostly 15 kt or less. /Higockey && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until midnight PDT tonight for PZZ252-253- 272-273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland