Oct 14, 2010: Final Storm Forecast

Note: The graphics and information for most of this post were created around 5-6 PM, but I was unable to post it over the last 2 hours, so some information here is not up to the latest radar observations.

***Due to a computer error, no second update will be posted tonight. An update on the longer range will be posted tomorrow, with details about the wind lasting through Saturday, a storm for Monday-Tuesday, and a cold, much more fall-like pattern that may set up afterwards.***


8:26 PM: Moderate rain has been falling over most of the area for the last several hours, with heavy rain now moving into Long Island. This storm will start to end over western New Jersey over the next 1/2 to 1 hour, with the end of the rain moving from SW to NE.

Rainfall amounts so far are generally between 1/2 to 1 inch from central New Jersey and further east, with at least another 1/4 to 1/2 inch of rain possible before the rain ends for central NJ. Further east, a round of heavy rain will move in for tonight, with more on that below.

Tonight’s Forecast:

As the low pressure deepens off the coast, it will continue to become negatively tilted, meaning that the precipitation will run from ESE to WNW, instead of south to north as we’ve seen earlier today. The low pressure is currently near 1004 mb and is off the coast of Delaware, moving northeast. As it is expected to move NE, then NNE late tonight, it will continue to quickly intensify, reaching 995 mb after midnight, with the rain becoming more widespread and heavier. The models did in fact end up trending east from yesterday’s solutions, and this is the direction I followed for this forecast.

By that time, however, most of the rain will have already passed the area, with generally light rain remaining for places outside of Long Island/Connecticut. As the rain map in the bottom of this post shows, the storm will have its greatest impact on New England in terms of rain. Heavy rain, however, will continue to affect Long Island and Connecticut through most of the overnight hours, and a few thunderstorms are also possible.

Tomorrow’s Forecast:

The storm is expected to have peaked in intensity by the early afternoon hours, near 975 mb. It will become vertically stacked around then, meaning it can no longer intensify, and will stall until the evening hours, when it will start to slowly move to the NE. Precipitation will be the heaviest and most widespread around the early afternoon, with heavy rain affecting most of New England and Maine. As a colder air mass will also enter New England, wet snow will fall in the higher elevations. Throughout the evening hours, precipitation will weaken throughout the Northeast.

The rain will be northeast of the area, with a cloudy and windy day expected due to the low pressure northeast of the area. Winds will be sustained between 25 and 35 mph, with gusts up to 50 mph possible in the immediate NYC area and Long Island/S CT, being why I have a Wind Alert in effect, which was issued 2 days ago. The central/southern Mid Atlantic will see some light rain due to a weak disturbance moving into these areas, south of the main storm. High temperatures will be in the mid 50s to lower 60s across the area.

Friday Night – Saturday: Chilly, And Windy

As the storm moves out on Friday night, lows will be in the lower 40s inland, lower to mid 40s north/west of NYC, and in the upper 40s for NYC and closer to the coast, with Saturday’s highs in the mid 50s to lower 60s across the area. The windy conditions will continue until Saturday afternoon, then start to calm down.

Overall Storm Forecast:

By the time that the storm ends, totals will be similar to where they are now in the interior, slightly higher in the immediate NYC area, and between 1 and 2 inches for Long Island/S CT. To the left, I posted my rain map for the storm from 2 PM today, and I also included a snow map for the interior Northeast, as snow will begin to fall in the higher elevations tomorrow afternoon and last through Saturday, bringing the first flakes of the season to many places.

As this is a high elevation snow event, some places will see less snow than the map shows, with the higher elevations potentially seeing more snow than the forecast shows. Snow totals will generally be in the 1 to 3 inch range in places where snow does accumulate, and it will be wet snow.

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