textproduct: Portland

SYNOPSIS

Cool and wet to hot and dry. This is a simple, concise and accurate summation of the weather conditions as we progresses through the next 7-9 days. Tonight will remain rather soggy and cool, with a very slow warming and drying trend expected through the remainder of the week. Confidence continues to increase for a multi-day heat event in the June 12th through June 16th timeframe. Don't get caught off guard and start preparing for heat related impacts, you'll thank yourself later.

LONG TERM...Thursday through Monday

Now that the cooler part of the week has been discussed, lets look at the warm and dry conditions of the long term forecast. As mentioned above, and upper level ridge looks to slowly build over the region for the latter part of the week and remain over the Pac NW through the weekend and into the start of next week. This synoptic pattern is resulting in moderate to high confidence in a prolonged multi-day heat wave beginning on Saturday.

However, before the heat kicks in, expect rather pleasant weather on Thursday with mostly sunny skies and high temperatures in the mid to upper 70s for inland locations and , upper 60s to mid 70s for the coast and Cascades. Friday through early next week, models and their ensembles show an upper level ridge amplifying over the far northeastern Pacific, with some lingering uncertainty regarding exactly how far east the ridge axis will move. Despite the uncertainty with the location of the ridge axis, confidence is high temperatures will be heating up significantly June 13-16. For Saturday, June 13th, the NBM probabilities for daytime highs above 90 degrees F is 45-75% for the Willamette Valley. NBM probabilities for daytime highs at or above 100 degrees F on June 14th are 30-60% and 20-70% on June 15th, with the highest probabilities each day towards the northern portions (Portland/Vancouver Metro) of the Willamette Valley. Also, there is a 10-20% chance for daytime highs on the 14th and 15th of 105 degrees F or higher for locations between Salem, OR and Kalama, WA.

For reference, HeatRisk levels are as follows: Little to None, Minor, Moderate, High and Extreme.

Given the likely record breaking daytime highs, probabilities for a Moderate HeatRisk or higher on June 13th is 70-85%, on June 14th and 15th is 85-99%. For Major HeatRisk or higher, there is a 40-75% probability on June 14th and 25-70% on June 15th. The probability for Extreme HeatRisk across the CWA is 10% or less through June 13th through June 15th. Anyone who is sensitive to heat or those who have outdoor plans should pay attention to the forecast over the coming days and be prepared for potential extreme heat. Those planning on swimming in rivers or lakes to cool off should be mindful of cold water temperatures and swift currents, which can become life threatening.

Typically with this upper level pattern, a thermally induced surface trough also looks to establish itself somewhere west of the Cascade Crest, which could result in gusty winds within the Cascades and Willamette Valley. As daytime highs increase, relative humidities will also decrease. Therefore, with conditions drying out AND the potential for gusty winds, there are increasing fire weather concerns for the latter part of this week through the start of next week. So, be aware of potential ignition sources such as chains dragging on the pavement, hot vehicle components, as well as cigarette butts as these could easily result in the ignition of dry, fine fuels. Larger fuels may not have the time to dry out, but this is a variable that is being closely monitored by State and Federal Fire Partners. /42

AVIATION

Steady rain continues as a frontal system traverses the airspace through the period. Flying conditions are currently mixed, but vis/cigs are expected to be restricted to at least IFR along the coast and to MVFR at inland terminals. Chances for IFR cigs inland reach 15-35% tonight at inland terminals, while LIFR chances increase to the south along the coast from 25% at KAST to 75% at KONP. Vis restrictions to MVFR are most likely, but periods of IFR during heavier rain rates are possible at all terminals. Vis/cigs will tend to improve behind the frontal passage, after 09-15z Tue.

South to southwest winds continue to build this afternoon. Peak gusts are expected to reach 25-30 kt at most terminals this evening (through 03z Tue) along the coast and this evening into tonight (through 09z Tue) inland. Periods of low-level wind shear exceeding 30 kt in the lowest 2 kft are most likely at KONP through 03z Tue. Wind speeds will tend to ease behind the frontal boundary while turning out of the southwest to west after 09-15z Tue.

KPDX AND APPROACHES...Deteriorating flying conditions are expected as cigs fall below 2 kft this afternoon. Chances for IFR cigs remain at 25-35% through 03z Tue. MVFR conditions are otherwise favored to persist through 12-15z Tue while cigs slowly lift behind the front. Southerly wind gusts reaching 20-25 kt continue through 12-15z Tue, before winds ease and begin to turn out of the southwest late in the period. -36

MARINE

A robust frontal system continues to traverse the coastal waters this afternoon, bringing a period of gale-force gusts reaching 30-40 kt south of Cape Falcon through 7 PM this evening. Otherwise, relatively steep seas of 7-10 ft at 8-9 seconds with a dominant westerly swell are expected, while southerly wind gusts of 20-30 kt turn out of the west behind the front this evening. Conditions across the waters and including the Columbia River Bar will therefore remain hazardous to small craft through much of Tuesday.

As high pressure builds offshore through the remainder of the week, west winds of 5-10 kt on Wednesday will steadily shift out of the north. Typical summertime northerlies will reach diurnal peaks of 15-25 kt each afternoon and evening from Thursday through the weekend, which may necessitate daily Small Craft Advisories, especially beyond 10 NM south of Cape Falcon. Seas will persist at 4-7 ft at 9-11 seconds with a continued westerly swell. -36

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 11 PM PDT Tuesday for PZZ210-251-271.

Gale Warning until 7 PM PDT this evening for PZZ252-253-272-273.

Small Craft Advisory from 7 PM this evening to 11 PM PDT Tuesday for PZZ252-253-272-273.