Sept 6: Thunderstorms Expected!

Jonathan Carr
By September 6, 2014 09:54

Sept 6: Thunderstorms Expected!

All ingredients are on the table for a stormy Saturday night. Instability will be high, wind shear should be sufficient, dew points will be jungle-like, and we have a trigger (cold front) rolling through from the NW. As far as timing goes, most of New Jersey should luck out until after sunset. Isolated pop-up showers and thunderstorms are possible as early as the afternoon but the main cluster of storms along the cold front should pass through between ~8PM and midnight. The storms should hit NWNJ first and SENJ last over a period of 3-4 hours. Here’s the high-res 4km NAM indicating precipitation intensity at 11PM:

high resolution NAM weather model indicates thunderstorms moving through new jersery between 8PM and midnight

Today should flirt, if not break, 90 degrees and feature relentless humidity. Any time you have dew points breaking 70, it’s a good indicator (not the only ingredient however) for thunderstorms. While wind shear is marginal, there will be plenty of instability to grow towering cumulonimbus clouds as we approach the afternoon-evening. The sun should have all day to diurnally heat the surface and destabilize the region. Check out the surface-based CAPE (Convective Available Potential Energy). That’s 3,000 j/kg (joules per kilogram) throughout most of the coverage area during the afternoon. Higher levels of the atmosphere feature plenty of instability as well (MLCAPE) which tells me light-show potential is high tonight:

surface based convective available potential energy will increase as the sun diurnally heats the new jersey

In English: Expect a warm and humid day with isolated showers and thunderstorms in the afternoon followed by higher concentrations of storms after sunset. While most storms will be of strong nature, some could easily reach severe criteria so pay attention. I’m thinking lightning and tropical-like downpours will be the headline however. Everything should clear out by the early AM hours of tomorrow as a cold front moves through transforms the region from July to October. Be safe! JC

Jonathan Carr
By September 6, 2014 09:54