Tuesday, August 6, 2019

Unusual Low Pressure over the Eastern Pacific Brings Rain Back

The upper level (500 hPa) pattern is quite anomalous today, as illustrated by the height at 8 PM tonight.  A closed low is due Oregon, with another farther out in the Pacific.  Further to the north there is high pressure--producing an unusual, but highly stable "omega? pattern.



The offshore low will swing into northern CA and southern Oregon late Friday and early Saturday.    This is quite unusual for midsummer.


As the trough moves inland, precipitation will spread over Oregon, eastern Washington, and southeastern BC (see the 24 hr total precipitation ending 5 PM Friday)

The same for Saturday

 Sunday?  More rain, but mainly over Idaho, Montana, BC and Alberta.  Some light stuff over western WA.
 And another trough brings more showers on Tuesday.


 Temperatures will remain below normal.  The biggest concern is that some of the showers will be associated with thunderstorms and lightning, with the potential to start more fires.

15 comments:

  1. Cliff is there a way to send you a photo of a weird cloud thing over Rainier, not the typical lenticular? I would love to know what you think.

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  2. Here in BC we had nearly 500 lightning strikes over the Okanagan last Tuesday. Many of them were accompanied by small amounts of rain. It was just enough moisture to limit the number of fires started to under 10.

    It will be interesting to see the outcome of these moist but convective cells forecasted for this weekend.

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  3. NWS Seattle forecasting 50% chance of rain here on Saturday. Does that jibe with what you see in the forecast? Thanks.

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  4. Despite the way this summer has progressed, the only headlines I see locally are of the typical "Drought coming, forecasts of abnormally dry Fall season has local weather and wildfire experts worried." I wonder if they didn't actually have anything to worry about, would they still have their jobs? Has there ever been anytime over the past ten years where "experts" would pronounce things as normal?

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    1. A good question. I think this qualifies as a "normal" summer by traditional NW standards. A shot of rain every few weeks used to be normal. Until the last few years, anyway. And yes- it rather bugs me that the fire people are fond of talking about the "abnormally dry" but never give the "all clear" message when things are normal to wet. I suppose that if firefighting is your profession, you are fond of sensationalism- as is the media.

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    2. I'm sure that when they say 'unusual' they are speaking about what is normal for a longer period of time, not just the last decade.

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    3. Well, my weather station near Langley, WA is far below normal for current water year. Sure, the forecast area has had some rain this summer, but the totals aren't near enough to make up for the dry winter/spring. We're seeing tree mortality on Whidbey Island, so yeah, the drought is quite real.

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  5. How much rain should we expect over the weekend? I am planning on doing the ptarmigan traverse over 5 days, starting Saturday morning, and being camped in the alpine along the cascade crest. Was hoping to save some weight by leaving rain gear at home...

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  6. Cliff, Fortunately my small garden is recovering and doing well. I hope to have a good harvest this month.

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  7. Every so often we have summers like this. It's like a pendulum, swinging back and forth from one side to the other.

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  8. Please define what "real summer" is please, because this summer has been absolutely perfect.

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  9. The most recent NWS and Weather Channel/Wunderground forecasts seem real iffy on the precip totals for the lowlands. Would love an update as we get closer to read your take on it. Thanks for all the information you share.

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  10. Dang it, where's my drought emergency when I need it?

    Yours in global warming,

    Jay Inslee

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  11. Unfortunately, this omega block will worsen the extreme drought currently experienced in the SE Alaska/Juneau/Kenai Peninsula (what is otherwise classified as a rain forest):

    https://www.usda.gov/media/blog/2019/07/17/drought-worlds-largest-temperate-rainforest

    https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?wfo_ajk

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