Forecasts

PinPoint Alert: Record high temps today, widespread storms expected Wednesday

WASHINGTON — Happy Tuesday! We still have a little moisture closure to the Canadian Border this morning with mostly cloudy skies for most of the area. We’ll continue to dry out and see some increasing sunbreaks and much warmer weather. In fact, today will be the warmest day of the year with record high temps possible in Seattle, Forks, Hoquiam, Olympia and Bellingham! Expect some patchy fog early and then partly cloudy to mostly cloudy skies with highs in the upper-60s and lower-70s.

The warm, humid conditions remain in place for Wednesday as a potent disturbance approaches the Pacific Northwest. Early in the day Wednesday through early afternoon, there will be a few spotty showers with a slight chance of a thunderstorm, but the greater instability for thunderstorms arrives late Wednesday afternoon across southern parts of the area through Wednesday evening for the rest of the area.

The ingredients for strong storms look to be there in abundance for Wednesday afternoon into Wednesday night, possibly similar to thunderstorms we experienced last August 17, when thousands of lightning strikes occurred in Western Washington!

In fact, lightning will be the greatest hazard to people during Wednesday afternoon and Wednesday night as fast-moving storms from south to north pass through the region. Outdoor activities planned for Wednesday afternoon and Wednesday evening should be reconsidered due to the threat of frequent and deadly cloud-to-ground lightning.

I’m looking at the greatest risk starting well south of the Seattle area by 3-6 p.m., spreading north through Puget Sound from 5-11 p.m., and moving north of the Canadian border after midnight. This timing will be fine-tuned as we get closer to the event, but it’s looking more probable that the evening hours will be “prime time” for storms.

There will also be a chance of hailstones growing to half inch to one inch in diameter and isolated thunderstorm wind gusts over 55 mph. The Storm Prediction Center has placed much of Western Washington in a “marginal” risk of severe thunderstorms (hail to one inch or larger in diameter and wind gusts 58 miles per hour or greater). While this is the lowest on their scale of severe weather risk — a one out of five — a “marginal” risk means the potential is greater than five percent of these severe conditions for any given point. That is greater than we usually experience!

The tornado threat is low in the lowlands but overall, a greater chance than we typically see. Storms that do begin rotating will need to be watched closely for the chance for an isolated tornado. Of particular interest will be any rotating storms nearer the Cascades, as wind currents and rotation could be “tightened up” as storms enter foothill and mountain locations.

Torrential rainfall will occur with these storms as well, posing a risk for drivers especially after dark Wednesday.

Thunderstorms will be moving northward at a rapid clip, so it will be important to keep abreast of conditions using the KIRO 7 Pinpoint Weather App. It might appear calm one minute, but then storms will quickly move in.

Storms look to clear the region by early Thursday morning as colder air moves into the area. We’ll be back in the 50s for highs with rain showers Thursday through Friday.

Rainfall from the thunderstorms Wednesday could push the Skokomish and Snoqualmie rivers back to flood stage by Thursday.

This weekend looks calmer with more dry vs wet weather in the mid-50s.

-Nick Allard



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