June 3, 2013: Seasonable Week, Then Rain Returns

Forecast Highlights:

A slow moving cold front moved off the coast today after producing several rounds of thunderstorms, including localized heavy storms in NYC last night, heavy rain this morning, and additional scattered storms in the afternoon. Behind this front, temperatures slightly cooler than average will return along with mostly sunny skies will return for Tuesday and Wednesday, with increasing clouds on Thursday ahead of a potential tropical storm expected to move up the coast, producing widespread rain for Friday and Saturday.

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Tonight - Thursday: Drier, More Seasonable

As of this evening, the cold front is located over eastern Long Island, slowly moving to the east. The cold front will continue to move offshore, with clearing skies expected tonight as a trough settles in and a surface high pressure builds into the region. This high pressure will provide the area with mostly sunny skies for Tuesday and Wednesday with temperatures slightly cooler than average. A light NW wind is expected on Tuesday with highs reaching the low to mid 70s inland and the mid to upper 70s across the rest of the area, with chilly overnight lows falling into the mid to upper 40s inland, low to mid 50s in NYC, and the upper 40s to low 50s elsewhere. A light SW wind is expected for Wednesday with slightly warmer temperatures, reaching the mid to upper 70s across the area. Cloud cover will gradually increase on Thursday with a light south wind and highs reaching the low to mid 70s across most of the area along with a slight risk of showers for western NJ and Orange county in NY.


Friday - Weekend: Widespread Rain, Possibly Heavy

Currently, a weak disorganized tropical disturbance is located in the southern Gulf of Mexico near the Yucatan Peninsula and western Cuba. Currently, conditions are not very favorable for significant development, including wind shear of 30-35 knots, although this disturbance may potentially develop into the first tropical or subtropical storm of the Atlantic hurricane season as it continues to gradually track north/NE, reaching Florida by Thursday. Should this develop into a tropical/subtropical storm, it will be named Andrea. Meanwhile, a trough will drop into the central US with a surface cold front slowly moving east; the tropical disturbance is expected to phase with the central US trough and track up the coast, losing its tropical characteristics in the process, which along with a SW-SSW flow aloft over the region, will bring a moist tropical air mass up the East Coast with widespread rain, potentially heavy.

There remains some uncertainty regarding the exact track and timing of the storm, with the GFS currently showing a drier and further east system while the ECM supports a more organized and much wetter low pressure. Regardless of these differences, with the moisture in place and precipitable water values approaching 2 inches, widespread rain is expected across the region, with the potential for heavy rain over 1.5 to 2 inches. Most of the rain is currently likely to focus between Friday afternoon and Saturday afternoon, although the timing is still subject to change. At this time, the timing is likely to be fast enough for the system to clear the region by Saturday night, with a drier Sunday and Monday. Stay tuned for more information on the outlook for Friday and Saturday and the potential tropical system.