Tag Archives: noaa

NYC Weather Update – May 27, 2014

What fantastic weather for the Memorial Day weekend! We topped off in the mid-80s across the area yesterday, and we’re likely to see another day with temperatures in the mid-upper 80s across the region (esp in interior portions of New Jersey).

Sadly, our stretch of summer-like temperatures is about to come to an end as a backdoor cold front (a front that does not approach from the west like most fronts do over this area) approaches the area from the north. Ahead of this cold front, temperatures are in the mid-80s and there is robust moisture in the atmosphere. This will provide the right ingredients for the possibility of severe thunderstorms later this afternoon and evening.

Possibility of Severe Thunderstorms This Afternoon

 

Current thinking is that these storms approach the NYC metro around 4-7PM during the evening rush hour. The Storm Prediction Center has placed NYC, western Long Island, Northern New Jersey, and much of the Hudson Valley under a slight risk area for severe weather this afternoon. By the way, slight risk in this context does not indicate that storms which occur will not be that severe, rather, it is denoting that the probability for severe storms is on the low side, and that coverage is not expected to be widespread. Just so you all are clear, the National Weather Service defines a severe thunderstorm as producing one or more of the following:

  1. Wind gusts greater than 58mph
  2. Hail greater than 3/4″ in diameter
  3. A funnel cloud or tornado

A severe thunderstorm or tornado watch means that conditions are favorable over an area for the development of these types of weather hazards, however, no immediate threat has yet been identified. A warning means that a severe thunderstorm or tornado is imminent or already ongoing, which is understandably a much more dangerous situation. Anyway, the most likely threat for our immediate area are damaging wind gusts and hail, although a few isolated tornadic supercells cannot be ruled out.

Storm Prediction Center Day 1 Convective Outlook
Storm Prediction Center Day 1 Convective Outlook – we are in the slight risk area highlighted in yellow

Wednesday – by tomorrow, the cold front responsible for the possible thunderstorms later today will have moved through our area, however, there is still a chance for lingering showers on the backside of this frontal boundary. Also, since this is a backdoor cold front, temperatures will be significantly cooler tomorrow than today with an onshore easterly wind keeping high temperatures only in the mid 60s (about 20 degrees cooler than today).

Thursday – an area of high pressure will build into the area, but due to its position to our northeast, it will also continue to usher in onshore easterly/northeasterly winds that will keep our high temperatures below normal in the upper 60s. Otherwise, it will be a nice, sunny day.

Friday – another cold front will approach the region from the west and bring in the possibility for afternoon showers and thunderstorms. Slightly warmer with cloudy conditions and a high temperature near 70.

Saturday – high pressure will once again build in across the region and remain in place through the weekend. Therefore, am expecting pleasant, sunny conditions with about average temperatures in the mid-70s.

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About that meteor shower… so as it turned out, the Camelopardalis meteor showers were a dud. Astronomers may have miscalculated the timing and/or amount of debris accumulated. Hey, it was the first time this particular shower was supposed to go down, so I guess you can’t blame them for not getting it right.

NYC Nowcast – Afternoon Tstorms – May 22, 2014

The Storm Prediction Center in Norman, OK has placed western portions of our region under a slight risk for severe weather this afternoon, with the primary threat being damaging winds and hail.

UntitledMid-upper level conditions are favorable for the development of thunderstorms with some rotating updrafts. Unidirectional winds at various levels, as well as wind speed shear, could impart enough rotation on storm cells to cause marginally severe wind damage and some hail. The highest potential will be over Eastern Pennsylvania and New Jersey where sufficient solar heating could produce CAPE (Convective Available Potential Energy, measured in joules per cubic kilogram) values of between 1000-1500 J/kg^3.

Storm Prediction Center in Norman, OK has placed western portions of our region in a slight risk area for severe weather this afternoon
Storm Prediction Center in Norman, OK has placed western portions of our region in a slight risk area for severe weather this afternoon

A small cluster of thunderstorms is already initiating along the western New York/Pennsylvania border ahead of a weak cold front. These storms should expand in coverage and increase in intensity as skies are clear ahead of the frontal boundary, allowing for a good influx of energy for storms to feed off of. The current thinking is that isolated severe thunderstorms reach our region by around the 4-6PM time frame. The chances of these storms remaining severe over NYC and coastal areas is low, since there will be a stabilizing influence from the cool marine layer offshore.
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