July 15, 2011: Morning Update

Note: The 5-Day Forecast was updated this morning. Another discussion, focusing on Monday’s severe weather risk and the late week potential heat wave, will be posted tonight.

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With a high pressure over the region, yesterday brought mostly to partly sunny skies across the area with highs reaching the lower 80s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s across Long Island and southern Connecticut. Today will bring similar conditions as the high pressure stays over the region, but as the high pressure moves offshore, heat and humidity will return by Sunday. A cold front along with thunderstorms will bring a relief from the heat on Tuesday and Wednesday, but the potential is there for a major heat wave late next week that may challenge the June 6-8 heat wave for the hottest temperatures of the year.

Today’s Outlook:

Today will bring similar conditions to those of yesterday as a high pressure remains over the region. Mostly sunny skies are expected along with a light and variable wind. High temperatures will reach the lower to potentially mid 80s inland, mid 80s in the immediate NYC area, and the lower 80s across Long Island and southern Connecticut. Slightly cooler temperatures are expected along the immediate coast.

Weekend Outlook:

With the high pressure sliding offshore, winds will turn more towards the SSW/southwest during the weekend, allowing the warmth to slowly build in. A massive ridge is currently centered over the central United States, with widespread 500 mb heights over 594 dm expected, a clear signal for extreme heat. As we have seen most of this summer, the ridge has focused over the central US while a short lasting surge of heat spreads into the region, and at least for this weekend, this will be the case once again.

Warmer 850 mb temperatures will spread into the region, which will allow surface temperatures to warm up as well, reaching the mid to upper 80s from NYC and further west on Saturday and lower to mid 80s further east. Sunday will bring even warmer temperatures, with more widespread upper 80s from NYC and further west, and a few lower 90s are expected in the immediate NYC area, especially in NE NJ.

Monday – Wednesday: Cold Front Moves Through, Severe Storms?

So far this summer, the area has been mostly spared from major widespread severe weather outbreaks. We are not looking at a widespread major severe weather outbreak for Monday, but the risk of thunderstorms is higher than what we have recently seen. A cold front will approach the area on Monday, bringing warmer temperatures, reaching the lower to mid 90s in the immediate NYC area, but along with the heat comes a risk of severe thunderstorms. The latest models are showing high precipitable water values, decent LI/CAPE values, and supportive lapse rates as well, factors which are all supportive of severe weather. The best risk of severe weather should be in the Northeast, to the north of the area, but some thunderstorms are expected in the area as well, and the latest modeled parameters support at least a low risk of severe weather in the area. Stay tuned for more information on Monday’s severe weather risk.

The intensity of the cold front is the main question at this time. The ECMWF once again fails to bring any significant cool down with the front, while the GGEM brings a significant cool down for the middle of next week. Both solutions are likely extremes, and the most reasonable and least extreme solution at this time is the GFS, which shows a slight cool down for the middle of next week with temperatures cooling down into the mid to upper 80s across most of the area for Tuesday and Wednesday. At this time, I went along with a solution close to that of the GFS, with widespread mid to upper 80s behind the cold front on Tuesday, and a few lower 90s cannot be ruled out. Wednesday will bring slightly cooler temperatures.

Thursday And Beyond: Big Heat Possible

As previously mentioned, the center of the ridge for now will focus over the central US. It is possible, however, that this changes by late next week. Behind Wednesday’s brief cool down, there is a general model consensus for the center of the ridge to shift east, taking it closer to the area, and allowing more heat to make it into the region. Each model handles this differently, with some of them showing the possibility that a back door cold front drops through the Northeast during the peak of the heat, but should the heat spread in with no back door cold front, this has the potential to match, if not pass the hottest temperatures of the June 6-8 heat wave, when Teterboro in Bergen county (NE New Jersey) reached 100 degrees. The ECMWF is the hottest model, showing 850 mb temperatures which support high temperatures easily reaching the 100s, but was not used for today’s update especially when considering that it tends to have a warm bias with heat waves and is currently the most extreme solution.

This is still in the medium range and is subject to change, but at this time, given the potential set up during this time frame, temperatures are likely to significantly warm up around Thursday/Friday, and if no back door cold front comes through, the heat should last through next weekend. Temperatures may be capable of surging well into the 90s with this type of set up, and parts of the region may even reach the 100s. Stay tuned for more information on the potential heat wave with tonight’s update.

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