textproduct: Portland

SYNOPSIS

The overall weather pattern remains fairly progressive as we head into the middle of September with temperatures gradually cooling into the weekend. Saturday through the first half of Sunday a low pressure system ushers in a period of widespread rain shower activity and unsettled conditions. However, we'll quickly transition back into a sharp warming and drying trend by the early to middle portion of next week.

LONG TERM...Monday through Wednesday

Headed into the middle of next week conditions trend noticeably warmer as ensemble models begin to converge regarding the upper-level pattern. The vast majority (>90%) of ensemble guidance depicts the upper level low overhead ejecting eastward into the the Rockies and Northern Plains by Monday. A weaker secondary upper-level trough on the backside of this low looks to remain over Oregon and Washington through at least Tuesday albeit degrading day to day while a ridge of high pressure attempts to amplify over the eastern Pacific. This will allow temperatures to rebound, likely rising up into the mid 70s to low 80s across the inland valleys by Tuesday afternoon. Come Wednesday the ensemble space is now favoring (70-75% chance) the ridge of high pressure over the eastern Pacific nudging closer towards the region pushing temperatures even higher into the mid 80s across the lowlands - only 25-30% of ensembles leave weak troughing overhead by this point (thus lower temperatures than forecast). Given the average placement of the ridge, offshore easterly flow is also appearing more likely in the midweek timeframe as well - something to watch. -99/03

AVIATION...Through 18Z Friday

Current observations as of 20Z Thursday show widespread VFR conditions for inland locations with a mixture of MVFR/VFR conditions for coastal locations. Starting around 12Z-14Z Friday, inland locations will have increasing chances (10-25%) of MVFR/IFR conditions developing. IFR/LIFR conditions are expected to return to coastal locations starting around 03Z Friday with coastal locations expected to maintain these lowered flight conditions through the remainder of the TAF period.

Light north to northwest winds will build to 5-10 kt inland and 10-15 kt with gusts as high as 25 kt along the coast around 20Z Thursday. Winds become light after 04Z-06Z Friday.

KPDX AND APPROACHES...VFR conditions expected throughout the period with increasing high clouds. 10-20% chance for MVFR conditions to develop after 12Z Friday. Northwest winds of less than 5 kt will rise to near 10 kt by after 19Z Thursday, decreasing by 08Z Friday. /42

MARINE

High pressure will maintain northerly winds across all waters through at least Friday. Breezy north winds with gusts reaching 20-25 kt will continue through this evening. Marginally steep seas of 6-8 ft at 9 seconds will also continue to pose a hazard to small craft beyond 10 NM through tonight before easing. Therefore, Small Craft Advisories remain in effect through 8 PM PDT this evening across the inner water (within 10 NM) and across the outer waters (beyond 10 NM) through 8 AM PDT Friday.

Another weaker system is expected to approach the coastal waters from the north late Friday into Saturday. This will result in a southerly wind shift along with seas subsiding towards 4 to 6 ft and gusts below 20 kts. A more active pattern is expected to return next Tuesday. This system looks to bring northerly winds back into the forecast with gusts approaching 20 kt. Seas are also expected to build towards 5 to 7 ft. -42/03

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Small Craft Advisory until 8 PM PDT this evening for PZZ251>253.

Small Craft Advisory until 8 AM PDT Friday for PZZ271>273.