Glenn's Blog: Mother's Day Weekend Nor'Easter

Taking a look ahead at the weekend nor'easter that could put a damper on your Mother's Day plans.

11 photos
Cortesía Brandon Scneider/9news
We’ve been warning you about May’s nasty blocking pattern for quite a while. It was going to mean chilly weather with an occasional slow-moving storm. One of those storms hit this past weekend. Unfortunately for us, that blocking pattern will lead to another weekend storm-this time a nasty, wet, chilly, windy Nor’easter.
If you want to blame something on the weather map, don’t blame the LOW pressure-blame the HIGH. The map below shows the current upper-air pattern.
That area of deep purple in Canada represents pressures WAAAAY above normal. It is known as a “Blocking HIGH”, and it is more extreme than the upper LOW in Arizona. That forces the upper-air LOW (with the associated surface storms) to slow down and become more intense. Watch what happens three days later:
The “Blocking HIGH” is still in Eastern Canada, and the remnants of that Arizona upper-air LOW are now in the middle of the U.S. If the HIGH wasn’t there, the Arizona storm would be weak and move quickly into the Atlantic. But it won’t. Here is what the map will look like by Sunday morning:
Here we go again. The upper-air LOW is now just off the Jersey shore, and is much stronger. That upper-air pattern results in a strong, slow-moving storm at the surface:
The above is the computer forecast map for 8 p.m. Saturday. At this time, it should be raining all over our area, some of it heavy. It will be windy and chilly as well.
And the blocking pattern has caused that storm (the “Nor’easter”) to move less than 10 mph, making it affect Mother’s Day too. That means a cloudy, windy, chilly Sunday, with at least some rain, mainly in the morning. It will be less rain than Saturday, though.
NBC 5 News
Any differences with other computer models?nNot much. They have similar positioning, strength, speed, and rainfall. Here is a comparison of total rainfall predictions for the U.S. and Canadian models:
They look a lot alike.
Generally, around 2” to 3” over the weekend, with most of the rain falling during the day Saturday and Saturday night.
We’ll have updated forecasts on the details, such as temperatures, wind, and rain totals, but I’m afraid the verdict is pretty clear: a washout Saturday and Saturday night, with a less nasty day (but no picnic) Sunday.
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