July 16, 2013

The Unusual May Happen: Summer Showers and Thunderstorms Later Today

It has been dry so long around here that many of you have forgotten what precipitation is like.  But according to our models...and particularly new technology "rapid refresh" models...we might see some showers and thunderstorms before the day is up.

And the threat of lightning-caused fires is real.

The U.S. is probably the world leader in something called rapid-update, intermittent data assimilation....a fancy way of saying a version of numerical weather prediction where every hour new weather observations are brought in and a new (generally short term) forecast is made.  Every hour a new forecast!   Such systems take advantage of all data sources (surface data, radar, aircraft data, satellite data, etc).  The folks at the NOAA Earth Systems Research Lab (ESRL) have been working hard on this technology for several decades and during the last year or so the predictions have improved rapidly.

The top-of-the line system run by NOAA is the HRRR (High Resolution Rapid Refresh), which has a resolution of 3 km (1.8 miles).   The runs started this morning indicate a band of showers and thunderstorms moving northward this afternoon and evening.  Here are the forecasts of reflectivity...what a weather radar would see.. at 9 AM, 5 PM and 7 PM.  Heavier rain is associated with warmer colors (yellow, orange, red).  If true, we will see showers over Washington later this afternoon.

Some of these showers will be thunderstorms.  The forecast line is not particularly vigorous and many of the thunderstorms will be "high-based"  meaning that the rain will be falling for great distances through dry air.  Thus, only limited precipitation may reach the ground.  Lightning might hit relatively dry ground...with the clear threat of fire initiation.

A visible satellite photo this morning at 11 AM (see below) shows a line of showers developing over Oregon...and they are now moving northward into Washington.

The showers in eastern Washington are the most significant right now and they are accompanied by some lightning.  Anyway,  today will be a good test of some of our new tools.

Seattle School Board Race

I strongly support Sue Peters for school board and I hope you will too.  She has been a strong advocate of better math in Seattle Public Schools and I have been extraordinarily impressed during my interactions with her.  She has a very impressive educational resume, including serving on a number of district committees and task forces, has a respected education blog, has been an active volunteer in local schools, and was a founding member of the Seattle Math Coalition. Sue is supported by FOUR of the current school board members and has a long list of endorsements by local organizations.  The Seattle Times, the supporter of corporate education philosophy, endorsed her opponent...another sign that Sue is on the right track.

Check out her web site at: http://suepeters4schoolboard.org/http://suepeters4schoolboard.org/
Please vote for her in the primary and support her campaign.   


  1. Hi Cliff,

    Looking at Weather Underground temperature reports, it looks like parts of Whatcom County will see 40+ degree diurnal swings today. The Eldridge site in Bellingham looked to have a low of 55 and is now at 89, and we still have several hours of warming to come.

    This feels like some unusual weather!

  2. Hi Cliff. The Medford sounding this morning wss the inverted V type; there may be a risk of dry microbursts to confound the potential lightning problem

  3. It has already been unusual weather here on Sinclair Island. I live on the water and a gusty northwest wind blew all night across miles of cold Salish Sea water. But the temperature stayed in the mid-sixties. It was 67 degrees here at 5:30AM. Now that almost never happens.

  4. Somewhat rare certainly, that the more monsoonal type moisture south is making it further up north, and then to the west of the greater Sierra / Cascades divide.

    .. Much more frequent, and occurring pretty much annually to some degree here more south where I live in CA. — I attribute the broader idea mainly and if more generally, to a slower movement of colder air mass east from out over the Pacific.

  5. Well, you nailed it! Definitely raining here at SeaTac at 5pm! Now it's 5:45 and no rain but still ahve clouds and that lovely "Florida" feeling... :)

  6. The weather in Quincy has been hot and heavy. There has been some wind today, but that doesn't help a lot.

    Why does the heat/air feel heavy at times and not so bad at others? It's not a humid heat, where you feel sweaty and miserable no matter what. It just feels..heavy. I am not very good at describing.

    I've been watching the Pendleton radar today, last year on July 19th or 20th, we had a severe thunderstorm go over us. I think two of them merged south of us and became one long line from Quincy to Moses Lake. This day feels like that did, BUT the radar has been much quieter. We watched those storms coming towards us for hours before they hit. The alert from the cell phone scared the heck out of me. That was a first!


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