Glenn's Blog: Rain Then an Arctic Blast - NBC 10 Philadelphia

Glenn's Blog: Rain Then an Arctic Blast

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    NEWSLETTERS

    Could we see slippery conditions in our region? NBC10 First Alert Weather Meteorologist Sheena Parveen has the update. (Published Tuesday, Dec. 6, 2016)

    FIRST CAME THE RAIN

    There was a lot of rain in the Southern U.S. and much of it came our way. The rain hit us Tuesday afternoon and night. It was a nice, solid, soaking rain-just the type to help ease the drought. But it also wasn't heavy enough to cause a flood threat. 

    Here’s the radar showing the big rain area (zoom out to find it).

    And here’s what one of our computer models showe for 8pm Tuesday (around the peak of the event):

    Photo credit: TropicalTidbits

    The yellow and reddish colors represent heavier rain and there was a brief period of downpours. 

    The area in blue is snow, and you’ll notice some of it is dark blue. That represents heavy snow, but it’s mostly confined to the northern part of PA. So, the Poconos saw accumulating snow. Just a bit farther south, and at lower elevations, it was about all rain. 

    THE ARCTIC BLAST

    I first had the dramatic drop in temperatures in my forecast from last Tuesday, Nov. 29th. That was Day 10 of our 10-Day forecast. The next day, I had a forecast high of only 39 degrees for Friday, Dec. 9th-a full 10 degrees below normal. See, we can sometimes be precise in a forecast even TEN days in advance. That’s why we are the only ones to do a 10-day forecast every day. 

    Here is what the Arctic air mass looked like Monday night. The coldest air moved down into Montana from western Canada, with temperatures near zero:

    Photo credit: TropicalTidbits

    By the time the arctic air gets here on Friday, it won’t be as severe. Here are the temperatures predicted by one model for first thing Saturday morning:

    Photo credit: TropicalTidbits

    Those are low temperatures in the 20s. But the wind at the time will probably make it feel like the teens. That’s quite a change from our mild November. 

    The unseasonably cold weather should last through the weekend, but it won’t be long-lasting….this time. Here’s the forecast from the “Best of the Best” that I’ve described in the past: Ensembles of the European model (the model is run 51 times, and the results averaged):

    Those blue and purple colors represent temperatures way below normal on December 15th. It sure looks like December is going to turn out to be a much different type of month than November.

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