textproduct: Portland

SYNOPSIS

Warm temperatures feed into an evening of showers and thunderstorms. Thunderstorm activity will be highest this evening over the Cascades and Cascade foothills, then will progress westward impacting the north coast by early Thursday morning. Around a 20-30% chance of thunderstorms throughout the area though this afternoon they have initiated a bit earlier than previously forecast. Cooler on Thursday, then heating up and drying out over the weekend into Tuesday.

LONG TERM...Saturday through Wednesday

Ridging over the central CONUS is expected to rebuild into the PacNW, supporting a warming trend Saturday and into early next week. The interior lowlands can expect highs in the mid to upper 80s on Saturday, building into the low 90s for Sunday and Monday. In this pattern, marine stratus is likely, especially along the coast though it could transition down the Columbia River into the interior lowlands. If cloud cover becomes pervasive, it will have an impact on high temperatures and minimum humidity. There is some spread among the NBM in exact high temperatures, ranging from the mid 80s to upper 90s in the 10th-90th percentiles so could see adjustments moving forward. Moderate HeatRisk is currently forecast across the interior lowlands, including the Cascade foothills, for both of these days. Chances for major HeatRisk are generally 10-30% for the Portland metro and Columbia River Gorge. Warm temperatures are expected to continue into the middle of next week as models continue to anchor the ridge over the CONUS. -19/27

AVIATION

Southerly flow aloft will continue as an upper level low spins offshore through Thursday. Marine stratus has returned to the coast this evening with at least low-end MVFR CIGs. The highest chances (40-60%) for IFR conditions at the coast are between 06-12z Thu. A stronger marine push tonight is bringing a 30-50% chance of MVFR CIGs at most inland terminals, except around 60-80% at KEUG after 12z Thu. Any lowered CIGs inland should improve to VFR by 19-21z Thu.

The upper low will approach the coast tonight through Thursday, bringing increasing chances for showers or elevated thunderstorms north of Salem. Showers are expected to spread west from the Cascades to the coast, along with a 15-30% chance of thunderstorms through 21z Thu, with best chances along the Coast Range and Coast between 12-18z. Main impact with any thunderstorms is abundant lightning along with brief erratic and gusty winds.

Smoke aloft is moving north into NW OR and SW WA from a wildfire in southern OR north of KMFR. This may at times produce a BKN layer around 15-25 kft.

KPDX AND APPROACHES...VFR expected through at least 12z Thu. Chances for MVFR stratus increase to around 40-50% between 14-19z Thu morning as a deepening marine layer pushes inland. There is also a 15-20% chance of elevated showers or thunderstorms between 12-18z Thu. Conditions are expected to improve back to VFR Thu afternoon. Northwest winds are expected to become southerly by 12-14z Thu. /DH

MARINE

Benign conditions with a typical summertime pattern expected through the week. Northerly winds 10-15 kt expected with afternoon gusts reaching to around 20 kt each day. Seas could be choppy at times with heights 4-6 feet but could see some 7 foot seas at 8-10 seconds. There is a 30-60% chance for Small Craft Advisory (SCA) criteria winds for all waters Saturday afternoon into Sunday.

A SCA is in effect until 9AM for rough seas within the Columbia River Bar due to a very strong ebb current leading to seas of 6 to 7 ft. Another SCA for strong ebb current and choppy seas Thursday morning from 4 AM to 10 AM. -19

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 4 AM to 10 AM PDT Thursday for PZZ210.