Oct 29, 2010: Cold Week, Then Major Nor’easter Possible

The 5-Day Forecast tonight was updated for the immedate NYC area only. An update tomorrow morning will add the rest of the area.

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The last few days were extremely active for most of the United States, with an unusually intense storm in the north central US bringing widespread high winds to that region, 72 tornadoes from the Ohio Valley to the Mid Atlantic and Southeast, nearly 500 strong wind reports, and a blizzard to the west of the storm center with over 6 inches of snow.

This storm, however, failed to bring anything to the area more than a few showers, despite the expectation of a strong cold front bringing a widespread 1/2 to 1.5 inches of rain. With the first storm on Tuesday, the heaviest rain was supposed to be over the area, but from the start it set up further north/west of NYC than expected, leading to the heaviest rain over central NY with only a few showers in the area. The cold front on Wednesday did bring the heavy rain it was capable of bringing as expected, producing rainfall amounts locally up to 1-2″ in some places, but the heavy rain failed to affect the area. The rain bands that were supposed to affect the area were at first too far west, then too far south/east, leaving a large dry area from NYC to Boston where less than 1/4 inch fell.

Yesterday was another mild day, however today was much cooler than yesterday, with highs back into the 50s. Things, however, are about to get much colder, as a colder pattern settles in for the region.

Tomorrow’s Outlook:

Tonight will be a very chilly night, with lows ranging from the upper 20s inland to the lower-mid 30s north and west of NYC, to the upper 30s to lower 40s in NYC. Frost is expected north and west of NYC.

Tomorrow will be another chilly day, but slightly warmer than today, with highs in the mid to upper 50s across the area. A SW wind is expected.

Sunday – Tuesday: Strong Trough, Very Cold

At first, it was thought that a strong warm up could take place around this time frame. Since then, however, it appeared that a 1030+ mb high pressure would move into the Northeast, with a strong trough moving into the region. Temperatures are expected to be at their coldest points yet, with lows in the mid 20s inland, upper 20s to mid 30s north and west of NYC, and in the upper 30s for NYC. High temperatures will be at their coldest on Monday, from the mid 40s to lower 50s across most of the area.

Longer Range: Storm Potential In The Late Week

Over the last few days, I mentioned a potential for a storm to affect the region during this time frame. While details have changed, especially the expected timing, the general idea remains that a storm is expected around this time frame. For the last 2 days, the models were all over the place with this storm, and still are, ranging from an intense low pressure moving through the Ohio Valley to a weak clipper moving through, redeveloping offshore and intensifying near Nova Scotia. Instead of trying to follow the models, I decided to look at the overall pattern, which shows a ridge in the west, a trough in the East, with an intensifying low pressure offshore.

There is uncertainty on some details such as the exact track of the low pressure, but with the details mentioned above, at this time I am expecting a coastal low to potentially intensify quickly off the coast on Thursday while interacting with a potential clipper to its northwest, ending up near or over the Northeast on Friday, where the most significant impact from the storm could be, with snow possible in the interior NE. The storm would then exit on Saturday, with a strong trough dropping into the region potentially bringing temperatures similar to those of the early week, if not slightly colder.

There is still some uncertainty at this time on the solution mentioned above, but as of now this is my understanding on the potential set up for the late week. Stay tuned for more details on this storm and how it may affect the area.

Tropics: Activity Quickly Picking Up, Season Approaching Historic Levels

When making my hurricane season outlook, I was mainly expecting the activity to focus through mid September, which it did, but I was not expecting a record active September like we had, where the 8 named storms tied the record for the most named storms in September. In addition, I did not think that the high activity would continue for this long, with this many hurricanes.

Last night, Tropical Storm Shary formed in the central Atlantic, and around this afternoon, just as Shary quickly strengthened and was nearly a hurricane aiming straight at Bermuda, attention quickly turned to the SE Caribbean, where Tropical Storm Tomas formed, being the 19th named storm this season and only the 3rd storm to have a name start with a “T”.

Tomas’ formation area is quite unusual for this time of the year, but it is well organied, and despite only forming several hours ago, it is already quickly intensifying and may be just below hurricane strength at this time. With clear waters, very warm SSTs and a very favorable environment, significant strengthening may be possible. If nothing disrupts Tomas’ intensification, it may become one of the strongest, if not the strongest storms this season, with a major hurricane a good possibility and Category 4 or even 5 not out of the question.

Regarding Tomas’ track, there is uncertainty on the longer range as it is expected to recurve north somewhere near the central Caribbean, but a recurve is expected, and Tomas will affect land directly while close to its peak strength, with landfall possibilities ranging from Cuba to Puerto Rico. Stay tuned for more details on Tomas.

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