textproduct: Portland

SYNOPSIS

Temperatures will gradually cool each day Thursday through the weekend as onshore flow strengthens ahead of a low pressure system set to bring widespread rain to the area on Saturday. Showers dissipate on Sunday, with dry and mild conditions expected early next week.

LONG TERM...Sunday through Tuesday

The long term forecast is highlighted by mainly dry conditions and the continuation of below average temperatures, albeit a bit warmer than what is expected on Saturday. The vast majority (>90%) of ensemble guidance suggests the upper level low over the area on Saturday will push eastward and move towards the Northern Plains Sunday into early next week. A weaker secondary trough on the backside of this low looks to remain over Oregon and Washington, however it is unclear how deep this secondary trough will be. Total model spread for temperatures on the NBM 1D Viewer ranges is fairly low on Sunday, with highs most likely ranging between the mid 60s and lower 70s (80% chance). On Monday, spread ranges from the upper 60s to around 80 degrees, with low to mid 70s being the most likely outcome. Spread increases a bit on Tuesday, as highs could range anywhere from the mid 60s to the mid 80s. Overall, there are no signs of any high impact weather on the horizon. -23

AVIATION...Through 00z Friday

Widespread VFR conditions expected at inland terminals through this period while low cloud coverage will favor IFR/LIFR cigs along the coast. Reinvigorated moist onshore flow will see marine stratus coverage expand from north to south by 03-09z Thu, with 50-70% chances for LIFR cigs after 09z Thu. Chances for IFR vis are lower, 20-30%, after 09z Thu. Low cloud coverage inland is expected to remain low and MVFR cigs are very unlikely, 10% or lower chances. Any low clouds will tend to clear after 18z Thu, with VFR conditions again favored across the airspace by 21z Thu beneath increasing high cloud coverage.

North to northwest winds around 5 kt inland and 8-12 kt with gusts to 20 kt along the coast this afternoon will ease this evening, before rising to 5-10 kt inland and 10-15 kt with gusts of 20-25 kt along the coast by Thursday afternoon.

KPDX AND APPROACHES...VFR conditions expected throughout the period with increasing coverage of high clouds on Thursday. Northwest winds of less than 5 kt tonight will rise to near 10 kt by Thursday afternoon. -36

MARINE

High pressure offshore will maintain predominately northerly winds across all waters through at least Friday. Breezy north winds continue with gusts up to 30 kt from late tonight through Thursday evening. Therefore, have issued a Small Craft Advisory across all waters. Seas 5 to 8 ft through Friday with period of 9 to 11 seconds through at least Thursday night. 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 with this system. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Small Craft Advisory from 5 AM to 8 PM PDT Thursday for PZZ251>253-271>273.