Higher Winds Approaching

Jonathan Carr
By December 11, 2021 14:35

Higher Winds Approaching

Discussion: I’m seeing a lot of speculation and fear about the frontal system expected for New Jersey later this evening. Yes, it’s true that this frontal system was part of the tornadic outbreak in the South-Central US last night. But that does not mean we are going to see the same.

Yesterday, the area hardest hit by tornadoes reached surface temperatures of 80+ which allowed significant instability to build ahead of the cold front. Also, there were much more intense shear parameters and other severe red flags in place. Today we are cloudy in New Jersey and therefore diurnal instability is thwarted. We do have a strong upper jet overhead however our shear profile is nowhere near yesterday in the S-C US. I do think we’re in for a windy/stormy evening/overnight in New Jersey however we’re not going to see an EF-5 tornado.

Higher winds in New Jersey this evening/overnight are possible from two sources. First there are synoptic scale winds (the S/SW rip ahead of the cold front in the warm sector + the NW winds that will ensue after the frontal passage from cold air advection in the cold sector. When I say warm and cold sector, I am referring to the standard Norwegian Cyclone Model. The synoptic scale winds are of high confidence in occurring. We’re talking sustained 15-25 with gusts of 40-50mph possible. These winds should occur from afternoon through early evening (warm sector out of S/SW) and then midnight through Sunday morning (cold sector out of the NW).

The second wind source are mesoscale winds. These will be the short-lived and localized instances of the stronger winds aloft making it down to the surface along and under the actual front. This will be reflected by a thin linear strip of precipitation on radar which will correlate with the thin frontal boundary. The only mechanism I can think of that would bring these winds down are worthy rain columns. So if your rain is lighter, your winds will be lighter. If the rain downpours then you have a better chance of the 50+ mph winds hitting you. And this should vary along the front. There is no way to even try to predict where this would occur but everyone along the cold front is subject to the chance of it happening. Most should not experience it due to a strongly modeled temperature capping inversion near the 850mb layer. This is a layer where temperatures are increasing while ascending in altitude and can therefore thwart upward motion associated with heat and rising. This in-turn inhibits the chance of downward reciprocating motion which could also bring the higher winds aloft down. So again, if anything is going to bring the higher winds aloft (50+ mph gusts) down it will likely be isolated/ instances associated with heavy downpours. This entire mesoscale wind source should only last about 30 minutes or so on either side of the passing front. The front should push through NJ between early evening and midnight.

So we have increasing synoptic winds from this afternoon (now) through this evening out of the S/SW, mesoscale frontal winds along the passing cold front later this evening/tonight, then synoptic winds overnight into tomorrow out of the NW or W/NW. Throughout the entire wind event, NJ should generally expect sustained winds of 15-25mph with gusts of 40-50mph possible. If you get nailed with the mesoscale wind scenario, gusts of 50+ mph are possible but again this would not be everywhere, only localized/isolated along the front. Most rainfall should fall just ahead of the front this evening and is modeled pretty light IMO (under a quarter inch for most areas). Just want to emphasize once more that NJ will not be seeing an EF2+ tornado outbreak this evening. Let’s allow an ultra-small chance of a weaker EF-0/1 along the front but I am not thrilled about the possibility of it.

In English: We’ll see a decent wind event tonight but nothing like what the South-Central US saw yesterday/last night. Expect winds to pick up out of the S/SW from now (Saturday afternoon) through early evening. Eventually winds should transition from breezy to gusty. Then expect periods of moderate-to-heavy rainfall with gusty winds this evening/tonight as the cold front moves through. Lastly, expect strong/gusty winds out of the NW or W/NW overnight into tomorrow once the cold front moves through. This should dry out and cool down NJ for tomorrow but a very mild week is then expected. I’ll have the full weekly outlook posted tomorrow evening. Have a great rest of your Saturday and please be safe! JC

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Jonathan Carr
By December 11, 2021 14:35