Nov 30: Tornado Watch Discussion

Jonathan Carr
By Jonathan Carr November 30, 2020 13:36

Nov 30: Tornado Watch Discussion

Dan Mueller Financial Advisor

Discussion: The heaviest precipitation slug has passed through New Jersey from S/SW to N/NE. Some of those downpours were intense. I know because I was in one. Remaining precipitation today will be of an isolated-to-scattered nature, no longer widespread.

We now shift our attention to some of the wild dynamics that I mentioned in my discussion last week. The surface low is currently over W/C PA and tracking to the N/NE. All surface level air flow is racing towards the center of this low in a cyclonic flow. This puts the strong surface flow over NJ out of the SE.

The mid and upper level flow however (850mb and above) are all in alignment with the mid and upper level lows that are forming the approaching upper level low/trough. That means that from about 5,000 feet and up, the flow is out of the SW.

Therefore, we have SE flow at the surface underneath SW flow aloft which is obviously producing a difference in wind direction over altitude (vertical wind shear). That should create several areas of horizontal roll in the atmosphere. If convective currents (downdraft from rainfall/updraft from correlating lifting) can turn the horizontal roll into a vertical structure then a tornado would form and touchdown. This is likely what the National Weather Service is seeing and the reason why they have issued a tornado watch until 7pm today for portions of NJ, with the greatest chance in SNJ.

While the tornado watch is justified in expressing a small possibility of such happening for safety awareness, it is not a guarantee. Such an occurrence would likely be very isolated. I do recommend keeping your finger on the pulse of your favorite weather source just in case.

In English: The widespread rain is over. Isolated, perhaps scattered, pockets of rain should remain until ~sunset today. Winds should continue to whip with a small chance of an isolated tornado in this period. This will all end around or just after sunset this evening and we’ll be left with stiff, cold, but stable and aligned W, maybe W/NW, winds to chill us down for the next few days. Have a great rest of your Monday and please be safe! JC

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Jonathan Carr
By Jonathan Carr November 30, 2020 13:36