Dec 22: Wind Event Detected

Jonathan Carr
By Jonathan Carr December 22, 2020 14:38

Dec 22: Wind Event Detected

Dan Mueller Financial Advisor

Discussion: If Christmas is going to experience any kind of weather, please, for goodness sake, let it snow. Not a wind event! Are you serious Clark? </rant>

A strong mid-latitude cyclone will track to the NW of NJ up into SE Canada. At the same time a strong area of high pressure is tracking from NW US into Texas. This flow combination and feature positioning should allow colder Arctic air to spill S into the E US for this Thursday into the weekend.  

But since the low will track to the NW of NJ, it places us in the warm sector during most precipitation. So as far as rain vs snow goes, this will be a mostly rain event that may finish as tail-end snow. About 1-2 inches of rainfall are modeled from the precipitation just ahead of the cold front. I’d allow an extra inch for the areas who see the most concentrated storm banding. So again, a warm miss in terms of winter weather but we’re still subject to the aggressive dynamics of a negative-tilting trough and cold front passage. Also, there should be various attempts of low pressure organization along/just ahead of the front. They likely won’t mature into low centers but should provide additional lifting for precip generation and possibly more shear.  

Models are seeing very impressive jet streams in the mid-to-upper levels. The flow at many layers will be cyclonically aligned within the overall deep trough. This will produce higher levels of vertical wind shear along the front (sfc layer) and could lead to damaging wind gusts possibly making it to the surface at times. The convective nature of the precipitation could also bring that higher winds of the LLJ down to the surface. With that said, we’re dealing with a period when damaging winds (more than 60mph) could occur between this Thursday night and Friday morning.  

The actual band of rain should move across NJ from W to E between about 8PM Thursday night and 6AM Friday morning. The rainfall could be heavy enough at times to produce localized flash flooding. But since the precip band is not expected to be very wide geographically, the rain should come and go relatively fast. Winds should gradually build throughout the day on Thursday and then reach peak intensity overnight into daybreak on Friday. The main wind direction should be S or S/SE ahead of the front. Once the front is through, temperatures should drastically fall for Friday through the weekend. We’ll be under the deep trough. I’m still seeing a very active pattern to close out December and at least start January. The next synoptic signal is Dec 28-29.  

In English: Christmas Eve looks very mild and windy. Christmas Day looks cold and breezy. The Santa Clause cold front is coming to town. Expect periods of heavy rain, possibly thunderstorms, and gusty/potentially damaging winds from about 8pm Thursday night until 6am Friday morning. It won’t be that way the whole night for everyone but rather a near-vertical strip of those conditions that slowly moves from W to E over NJ overnight. Once the strip of higher-impact weather (the front) is through (by Friday morning), temperatures should then plummet to a more legitimate late-December feel. I’ll probably provide another update before the event but just in case I don’t, everyone please have a Merry Christmas. Be safe! JC

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Jonathan Carr
By Jonathan Carr December 22, 2020 14:38