July 5, 2012: 100 Degrees Possible Saturday

Forecast Highlights:


- Heat to peak Saturday; 100 degrees possible for NE NJ
- Cooler temperatures to return next week
- More warmth, potential storms towards late next week


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Today's Observations:

Today was another partly sunny and hot day across the area, with most of the immediate NYC area starting another heat wave with the 3rd consecutive 90+ degree day; the two heat waves were separated by one day of upper 80s, although Newark extended the heat wave through that day, resulting in a single heat wave which so far is up to 8 days. Temperatures reached the lower 90s inland, mid 90s in the immediate NYC area, and the upper 80s to lower 90s in Long Island/S CT, ending up very slightly warmer than expected but still close to the forecast.

The heat wave will peak on Saturday, when temperatures have the potential to reach 100 degrees in parts of NE NJ with heat index values up to 105 degrees. Following an overnight cold front with scattered thunderstorms, the heat will break across the region, with temperatures returning back to average for early-mid next week, although temperatures may warm up with more rain chances in the longer range.


Friday - Saturday: Final Days Of Heat Wave


Temperatures similar to those of today are expected for Friday, with highs reaching the lower to mid 90s from NYC and further north/west. More sea breeze influence is expected in Long Island/S CT, however, with highs reaching the mid 80s to lower 90s, staying below 85 degrees in the immediate coast, especially further east.

The peak of the heat will take place on Saturday, when the warmest air mass moves through with 850mb temperatures up to 22-24C, along with WSW winds and mostly sunny skies. Since yesterday, the cold front has trended slower than previously expected so that any widespread cloud cover/scattered storm activity should not move into the area until at least the evening/early overnight hours, ahead of a severe weather outbreak in New England that will weaken before reaching the area. With the conditions mentioned above, temperatures will easily surge into the mid to upper 90s inland and the upper 90s in the immediate NYC area.

Forecasting potential 100+ degree days this year was complicated as the NAM was usually the only model showing such a scenario, and ended up busting too low with dew points which resulted in slightly cooler temperatures than it modeled. In this case, however, the ECMWF also supports 100+ degree heat for parts of NE NJ. To stay closer to previous trends, I am expecting most of the immediate NYC area to reach the upper 90s, except for JFK that may end up a bit cooler, but the potential is there for parts of NE NJ, specifically near Newark and possibly into Teterboro, to reach and/or slightly exceed 100 degrees. A weak sea breeze will develop in the afternoon hours for Long Island/S CT, but not before temperatures can reach the mid 90s away from the immediate coast, with some upper 90s possible as well. Stay tuned for more information on Saturday's temperature outlook.


Saturday Night - Next Week: Not As Hot


A cold front will move through on Saturday night, producing some thunderstorms, but due to poor timing a widespread severe weather event is unlikely. The front will then shift south for Sunday, resulting in severe weather in the Mid Atlantic while temperatures in the area cool down as a trough moves into the region. Sunday will still be warmer than average, however, with highs in the upper 80s to lower 90s from NYC and further north/west and the mid 80s to 90 degrees in Long Island/S CT. Partly cloudy skies are expected for Sunday, although it is not out of the question that the north end of the storms makes it into the southern end of the area, resulting in slightly cooler temperatures than expected with a little more cloud cover.

For early-mid next week, a trough will be in place across the region, resulting in temperatures generally close to average, peaking in the mid to upper 80s for most of the area, slightly cooler further east. Despite a trough moving into the region, there is still no significant cool air mass in place anywhere in the US through the foreseeable range. By late next week and the longer range, a strong ridge is expected to build over the central Atlantic before gradually shifting west towards the region. While this is not expected to result in any extreme heat wave like the central US recently observed under the strong ridge, this may bring the potential for increased storm activity along the East Coast for the longer range. More information will be posted on this time period as details become clearer.