For most summers, during July or August there is an intrusion of "monsoon" moisture from the southwest into our region, resulting in showers and thunderstorms...and this year will be no different.
Such thunderstorms can be both good and bad. Good at providing needed rain and lessening fire risk, but bad if lightning starts fires.
The predicted totals through Friday morning (seen below) range from a few tenths to a half inch, with higher values along the coast.
The wet fun will begin later this afternoon and evening as convection and thunderstorms build near the crest of the Cascades (see forecast for 5 PM below).
Why this wet bounty?
Two things are occurring together. The upper-level pattern includes an approaching upper-level trough (500 hPa, about 18,000 ft shown for tomorrow morning). Such troughs produce upward motion (which helps initiate cumulus clouds) and bring in moisture from the south.
Such "monsoon" moisture and unstable air from the southwest are evident in the forecast below.
Total water vapor content of the atmosphere this evening.
Blue and red are higher values
Enjoy the show overnight!
I remember really impressive thunderstorms that happened in mid July of 1999. My family went on a camping trip up the mountain loop highway, and I can remember encountering rain and thunder - what northwest camping trip would be complete without at least one of those things? Not long after we returned home to Lake Stevens, an intense thunderstorm rolled right through our neighborhood. It's one of the only times I can remember witnessing incredibly localized lightning strikes. It looked like the lightning was striking trees in the nearby forest, and the sound of the thunder was unimaginably loud.
ReplyDeleteI've actually been trying to pinpoint the day when this occurred, but I haven't been successful. The weather records for Everett and Seattle aren't localized enough to offer much confirmation. The only real timestamp I can go off is that all this happened right around the time (then) Safeco Field opened.
I remember this thunderstorm. I was watching the Blair Witch Project at a theater in the U District while it was happening. I initially thought it was part of the movie. It was still going strong by the time we got out of the theater
DeleteI remember this storm. I was watching The Blair Witch Project at a theater in the U District. At first I thought it was party of the movie but it was still going strong after the movie ended. I got to see some really nice lightning strikes that day.
DeleteI was in Chehalis, and that 'green sky' loomed to the southwest, as a night of lightning and thunder began- wasn't intense, but flashing in all directions for the whole night.
DeleteAlthough there have already been some large grass/range fires in Eastern Washington, the incoming storm will likely bring the first real fire threat to the forest areas. There has been a prolonged warm, dry period, especially in the east slopes and Okanogan forests and this storm does not look like it will produce significant rain amounts. Then another warm, dry period, probably with initial wind, is forecast to follow shortly after the storm moves out. These situations in the past have often produced some of the largest forest and range fires in Eastern Washington.
ReplyDeleteWhen I left work this afternoon, noted the sun was filtered (yellowish) at 3:30 PM in the Kent Valley where I work and just now seeing some patchy clouds, but still mostly sunny. True, it's now 8:22PM, but the sun is now very much orange in Tacoma as if filtering through some smoke.
ReplyDeleteIt'll be interesting to see what transpires to night. Have memories of dry lightning at night around this time of the summer in the past. Not often, but we can get them. One memorable one was in the mid to late 70's, around midnight, dry lightning occurred, and a dear family friend (now deceased) showed me how beautiful they are, and I've loved thunderstorms since. That sudden clap and flash from 2019 was so unexpected, but once that initial clap went off, I was hooked, even if my lights went out.
Nothing like a couple of years back when the smoke was awful and we got little to no circulation in the upper atmosphere for a couple of days before it finally did so.
The evening of August 18, 2024 was the last time I recall thunder and lightning at my location in Mason County. It came with some wind and enough rain and 1/2”+ hail to trigger a brief flash flood on my property, soaking the first few feet of my garage floor. No atmospheric river from the last 15 years has been able to achieve that.
ReplyDeleteOn Sinclair Inlet - starting about 10am, almost continuous thunder.
ReplyDeleteBeen raining off and on all morning 7/16/26 here in South Bellevue. Nearly constant thunder for a couple hours still. Getting more rain than I expected. One of my birdbaths was dry, so will check accumulation later, but look like 1/8” already as of 10:21 this Thursday morning. Hopefully the Cascades on both sides get a good soaking too.
ReplyDeleteIt's 11:35 AM here in NE Seattle and flashing and booming. Rain Barrels are refilling quite nicely.
ReplyDeleteAnother month and a half and summer is over. Where is the suffocating drought? I'm looking under my bird bath I don't see it. Maybe it's in the tool shed
ReplyDelete