Aug 21: The Good Stuff is Coming

Jonathan Carr
By Jonathan Carr August 21, 2019 10:24

Aug 21: The Good Stuff is Coming

Discussion: Another hot and humid day is expected across much of the region today. An area of organized low pressure is lifting to the NW in SE Canada. This is the driver of the warm and moist SW flow (the warm sector) that has dominated the region recently.

A Pre-Frontal Trough (PFT) will be the culprit for any thunderstorms that form later this evening and overnight. PFTs are typically generated when air moves across a mountain range such as the Appalachian Mountains. The air condenses over the peak of the range and then expands once on the other side. The expansion generates a pressure drop which in-turn generates a linear segment of lifting which is enough to spark thunderstorms. Typically PFT-enhanced storms do not feature high amounts of vertical wind shear and therefore run out of steam with the loss of diurnal surface heating. With that said my gut tells me that NWNJ is more favored for thunderstorms than SENJ with this round. I imagine NE PA will see the strongest storms this evening before the energy peters out somewhere over NNJ/CNJ.

The PFT is not the bringer of relief however. That will be the cold front’s job tomorrow (Thursday night). This cold front will be re-enforced by an area of high pressure diving down from Canada. Much of our region should be stabilized by the time the cold front moves through between Thursday night and Friday morning. Therefore I am not expecting much storm activity along the actual cold front aside from some scattered showers and isolated thunderstorms (non-severe) at most.

The weekend looks marvelous if you like late-September/early-October conditions. Dew points should drop into the 40s and 50s behind the cold front and hold through the entire weekend. The wildcard is cloud coverage as flow shifts out of the E (off the ocean). This onshore flow, in-theory, will be sending the year’s warmest ocean-driven surface air temps into very dry air. It could lead to overnight/AM fog and clouds during the day but we’ll have to see. Tomorrow evening’s weekend outlook will cover this in detail.

In English: Today will be another hot and humid day with showers and thunderstorms possible later this evening into the overnight. NWNJ is most favored for thunderstorms. SENJ is least favored. Areas between (along the I-95 corridor) will likely experience the fizzle. Tomorrow will also be hot and humid until the cold front arrives later Thursday night/early Friday morning. This cold front should bring magical weather for Friday through the entire weekend. IMO tonight’s storm activity (for NWNJ/NNJ) should be stronger than tomorrow’s cold front activity. The cold front could be mostly dry. Get ready to open the windows up. This weekend should be a beaut Clark. A beaut. Be safe! JC

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Jonathan Carr
By Jonathan Carr August 21, 2019 10:24