Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
167 FXUS66 KPQR 061043 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 343 AM PDT Sun Oct 6 2024 Updated PQR WATCHES/WARNINGS/ADVISORIES. .SYNOPSIS...High pressure will result in areas of patchy morning fog in valleys with mostly sunny afternoons and pleasant temperatures for the next several days. A series of weakening fronts will bring increasing chance for light rain later this work week, with the highest chance for widespread rain on Friday. && .DISCUSSION...Now through Saturday night...Clear skies and calm winds will result in another round of fog development early Sunday morning, albeit less widespread and less dense than what was observed across much of the interior lowlands early Saturday morning. Aside from early morning patchy fog, Sunday will be another sunny day with temps warming into the mid 70s over the Willamette Valley and Clark County lowlands, except upper 70s in the Eugene-Springfield area and near 80 degrees around Oakridge and Creswell. Winds will be light, making for a beautiful fall day. Even warmer temps are in store on Monday. Models and their ensembles remain honed in on high pressure over the area and another day of sunshine, with high temps warming into the upper 70s to lower 80s from Kelso to Portland to Eugene. The coast will be a bit cooler with highs in the mid 60s to lower 70s. Models continue showing southwest flow aloft Tuesday through Thursday with a gradual cooling trend and mainly dry conditions, aside from a round of light rain at the coast with a decaying Pacific cold front that is set to move inland Monday night into Tuesday morning. Models show another decaying front moving inland on Wednesday with slighter higher chances for at least some light rain inland (NBM PoPs are at 25-45%, except 50-60% in Astoria and on the Long Beach Peninsula). PoPs increase close to 50% on Friday across all of northwest OR and southwest WA, as this is when most ensemble guidance is showing at least some rain over the area. That being said, there are still some ensemble members from the GEFS/ENS/GEPS showing no rain at all and overall model spread remains high. The NBM is showing a 35-50% chance for 24-hr rain amounts in excess of 0.25" from 5am Friday-5am Saturday. -TK && .AVIATION...VFR conditions prevailing as of 09Z Sun, but IFR/LIFR stratus at the coast as far north as KONP. Fog/stratus forecast to spread north to around KTMK by 12Z Sun then dissipate over land area 18-20Z Sun, but could linger just offshore through the afternoon. North of KTMK there is lower chances 30-40% for IFR conditions to reach KAST 12-18Z Sun. Under clear skies and light winds comes the potential for low stratus and fog for the Willamette Valley. As of 09Z Sun RH values in the 85-95%, and there is already fog at KCVO & K775. Satellite fog products not picking the fog yet (too small an area.) HREF forecasting up to 20% chance for IFR between KUAO and KEUG through 18Z Sun. Overall pattern suggests higher chances for fog this morning and current forecast looks reasonable with fog at most sites through 18Z Sun. Surface winds are generally variable less than 5 kts, becoming north to northwest after 18z. Similar fog potential inland late tonight into Monday morning with HREF showing up to 20% chance for low stratus/fog. Coastal fog/low stratus chances are lower tonight as weak offshore component to the low level flow should keep mainly VFR conditions. With that said fog/stratus may lurk just offshore. PDX APPROACHES...Light winds and clear skies 10-15% probability of fog development 12-18z Sunday. Winds mainly less than 5 kts, variable then turning northwesterly after 18z. /mh && .MARINE...Weak high pressure resides over the coastal waters with a thermal low pressure along the south Oregon coast and a trough offshore for the next couple days. By Tuesday the trough offshore nudges to the coastal waters, followed by a stronger system Wednesday. Right now winds look to remain below 20 kt through at least mid-week. Seas 4 to 5 feet will increase to around 6 to 7 feet on Monday as a system moves well to our north. Seas subside a foot or two into the latter part of next week. /mh -Batz && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Dense Fog Advisory until 9 AM PDT this morning for ORZ103. WA...None. PZ...Dense Fog Advisory until 11 AM PDT this morning for PZZ252-253. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland