LI under heat advisory as heat index breaks 100

Sweltering temperatures baked Long Island for a second day, previewing a possible weeklong heat wave expected to begin officially Tuesday.

A heat advisory was in effect for Long Island as temperatures hit the low 90s Monday, but it felt more like 100 degrees in parts of the region, according to the National Weather Service. With the humidity, it felt like 101 in East Hampton and Long Island MacArthur Airport in Ronkonkoma, and even 102 in Shirley, according to the service.

And there's more to come. Long Islanders can expect the intense heat to continue through Saturday, meteorologists say.

Tuesday might be a degree or so cooler at MacArthur Airport, and slightly less humid, said Mike Layer, NWS meteorologist based in Upton. But temperatures in the 90s are still expected, he said, resulting in the year's first official heat wave -- defined as three consecutive days of 90 degrees or above. Yesterday's high at MacArthur was 94 and Sunday's was 90, the weather service said.

The cause of the steamy weather is a high-pressure ridge that's "pretty much stalled" over the area, resulting in the same weather "day after day after day," said Bill Korbel, News 12 Long Island meteorologist.

If the forecast holds, there could be a seven-day heat wave for Long Island, before a Canadian cool front dips down, possibly bringing storms and finally relief, Layer said.

While heat waves are not unusual in summer, he said, one of this length would be, with the longest on record at the airport running from July 8 to 13 in 1993.

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Most Long Island towns announced special measures to deal with the heat, including extended pool hours and opening of cooling centers.

LIPA said yesterday's peak load was more than 5,000 megawatts. The all-time highest in its 15-year history was 5,915.

The utility said it had "adequate capacity" to meet the demand and expected peak demand to increase this week to between 5,200 megawatts and 5,500 megawatts by Friday.

The utility declined to provide Newsday with actual figures, but in a financial filing, it listed total 2011 capacity of 6,327 megawatts -- a reserve of almost 10 percent, or 556 megawatts. That cushion is well above the output of several large power plants contracted to LIPA, which are rated on average at around 350 megawatts. Despite the increased usage, LIPA said it has not enacted peak-load reduction programs such as LIPA Edge, which would allow the utility to remotely raise the thermostat setting on customers' air-conditioning systems. The program, which cost LIPA upwards of $33 million to install high-tech thermostats in 36,000 customer locations over the past decade, can trim around 50 megawatts from LIPA's peak usage.

Experts have long questioned LIPA's reluctance to use the system, particularly because it could help LIPA avoid future costs. LIPA's long-term forecasts and state-mandated capacity requirements are based on peak-use figures, and LIPA could reduce them, and costs, by showing lower peaks. Former LIPA chief Michael Hervey, explaining why he didn't enact the Edge program during the heavy-use 2011 period, said. "For me it's hard to force customers to conserve when we have plenty of margin," noting the nearly 1,000 megawatts of excess capacity on the LIPA system at the time. "I don't think we're in the business of trying to ration electricity on peak periods," he said then.

LIPA this week said it will continue to monitor system load and capacity levels "to determine whether activation of the LIPA Edge program is needed."

LIPA last week announced a new solar program that could help address the summer peaks by concentrating solar energy projects on the East End's South Shore, where mega-mansions outfitted with multiple central air conditioners draw large amounts of peak summer power. In the coming days, Long Islanders can expect the most discomfort -- heat indexes in the 95 to 100-or-above range -- in the midafternoon, from around 1 p.m. to 3 or 4 p.m. Korbel said.

Relief, apart from air conditioning, can be found on the ocean beaches, he said, which could be at least 10 to 15 degrees cooler with sea breezes.