textproduct: Portland

SYNOPSIS

Hot and increasingly humid conditions will continue today, with another round of very warm overnight temperatures limiting recovery across the interior. Highs this afternoon will again reach the 90s for most inland locations, and a few spots may touch 100 degrees before cloud cover and convection begin to temper heating. Monsoonal moisture spreading northward will bring a rising chance of showers and thunderstorms today, especially from afternoon into evening, with the greatest risk over the Cascades. Cooler weather is then expected Thursday and beyond as onshore flow strengthens.

LONG TERM...Thursday Night through Tuesday

By late Thursday into Friday, upper ridging will weaken while a broader trough moves toward the Pacific Northwest. This will allow onshore flow to re-establish itself and bring a more noticeable cooling trend late this week, along with a return to more marine influence and night/morning cloud cover. Confidence is moderate to high in the overall cooling trend, though lower in the exact day-to-day temperatures. Temperatures should remain somewhat above seasonal averages Thursday and Friday, but well below the temperatures reached earlier in the week, with improved overnight recovery as well. Looking into the weekend and early next week, temperatures appear likely to settle back into the upper 70s to lower 80s inland, with no strong signal for meaningful precipitation after Friday, though light shower chances may linger Saturday along the north Oregon coast and south Washington coast. ~12

AVIATION...Through 12Z Thursday

VFR conditions with sct/bkn high clouds inland will continue through most of the TAF period, with the exception of marine stratus potentially pushing inland late Wednesday, bringing a 20-30% chance of MVFR conditions after 06Z Thu. Periods of haze from elevated smoke may restrict vis to 5-6 SM in the afternoon at inland terminals. As for coastal terminals, current LIFR conditions will likely improve back to VFR conditions by 16-18Z Wed. Marine stratus will then likely creep back in from south to north, returning KONP to LIFR/IFR conditions around 00Z Thu, then to KTMK around 06Z Thu, and to KAST by 09Z Thu. There is less confidence for these conditions at KAST compared to KONP, with a 30-40% chance of IFR at KAST but a 80-90% chance at KONP. Additionally, there is a 20-40% chance of LIFR at KAST but 50-70% chance at KONP.

Otherwise, winds will be calm to light and variable early this morning, building out of the west to northwest at 5-10 kt inland and 9-14 kt along the coast after 18-21Z Wed. KEUG and KSLE are an exception, with winds around 9-14 kt expected. Coastal terminals and KEUG/KSLE may see gusts up to 20 kt during the afternoon. Winds will begin to shift more west to southwesterly after 03Z Thu.

Afternoon temperatures are forecast to approach 100 degrees at many inland terminals this afternoon; be aware of high density altitude which may reduce aircraft performance. Showers and isolated thunderstorms are expected to develop this afternoon, tracking northward through the remainder of the period. Confidence in the occurrence of thunder is too low to include in TAFs at this time, but heavy showers may briefly result in MVFR/IFR vis if they pass over a terminal. Showers may also produce gusty or erratic winds nearby. Late in the period, winds will begin to turn out of the southwest to south as showers wane.

KPDX AND APPROACHES...VFR conditions and sct/bkn high clouds through most of the TAF period. There is a 20-30% chance of MVFR CIGs after 06Z Thu. Smoke aloft may yield surface vis of 5-6 SM this afternoon, although vis aloft can often be lower. Chances for showers or an isolated thunderstorm increase after 00z Thu; the most likely terminal impacts are gusty/erratic winds and locally heavy downpours which may briefly restrict vis to IFR/MVFR levels. Northwest winds continue through the period at 5 kt or less overnight, building to 5-10 kt by this afternoon. Winds will shift more west to southwesterly after 03Z Thu. ~12/36

MARINE

North to northwest winds over the coastal waters will shift to west to southwesterly late today and through the weekend as weak low pressure develops over the waters. Winds will remain light less than 10-15 kts. Seas will be 3-6 ft at 8-9 seconds through the weekend.

Today, there is a chance for showers and thunderstorms across all of the waters through the majority of the day and overnight hours. There could be frequent lightning and gusty and erratic winds with any thunderstorm that forms. ~12/03

CLIMATE

Daily record high minimum temperatures for July 22 Astoria 62 (2007) Vancouver, WA 74 (2006) Portland Int'l 74 (2006) Hillsboro 73 (2006) McMinnville 73 (2006) Salem 74 (2006) Eugene 71 (2006)

Daily record high maximum temperatures for July 22 Astoria 88 (1891) Vancouver, WA 98 (1928) Portland Int'l 98 (1978, 2004) Hillsboro103 (1938) McMinnville102 (1928) Salem102 (1928, 1978) Eugene101 (2006)

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory until 11 PM PDT this evening for ORZ108>115- 120>122. WA...Heat Advisory until 11 PM PDT this evening for WAZ204>210. PZ...None.