***Biggest rain event in several months...thunderstorms may mix in...powerful winds are possible; especially, along coastal sections...cold blast to follow and perhaps a touch of snow***
Paul Dorian
An intense low-level jet will develop later Wednesday along the eastern seaboard from the Carolinas to New England. As a result, winds can easily gust past 50 mph along the coastal sections of New Jersey and the Delmarva Peninsula and past 60 mph across eastern New England (e.g., Boston, Cap Cod). Map courtesy NOAA, tropicaltidbits.com
Overview
There was some rainfall in the DC-to-Philly-to-NYC corridor on Monday which was certainly a welcome happening; however, overall totals were on the low side due to the quick movement of the low pressure system. The rain event coming from late Tuesday night through Wednesday will be quite a different story, however, and likely the biggest single rainstorm in this area since early June. Rainfall amounts can exceed 2 inches all along the I-95 corridor and a few thunderstorms can mix into the picture. The combination of a strong surface cold front, plenty of available moisture, and a deep upper-level trough that becomes “negatively-tilted” will lead to this heavy rain event
In addition to the rain, the winds will become an important factor; especially, along coastal sections of the eastern seaboard from the Carolinas to New England where a low-level jet is going to become very intense. In fact, there is the potential for winds to gusts to 60 mph late Wednesday across portions of eastern New England where the low-level jet will reach its greatest strength.
In terms of temperatures, it’ll be unseasonably mild through much of the day on Wednesday - ahead of the strong cold front - temperatures will drop sharply late in the day or early tonight on the heels of its passage. This cold air intrusion can lead to a brief period of snow in some of the N/W suburbs along the I-95 corridor where small accumulations cannot be ruled out this evening. Finally, this cold blast will result in yet another “Great Lakes snow event” for those areas just downstream of Lakes Erie and Ontario (e.g., Erie, PA, Watertown, NY).
A “negatively-tilted” trough axis will develop on Wednesday leading to enhanced “lift” in the atmosphere over the Mid-Atlantic region and strong cyclogenesis over the Appalachian Mountains. Map courtesy NOAA, tropicaltidbits.com
Details
Some welcome rain fell in the Mid-Atlantic region on Monday, but overall amounts were on the low side due to the quick movement of the low pressure system (e.g., “trace” at PHL, 0.05” at DCA). This current event is going to be quite a different story and likely ends up as the biggest single rainstorm in this region since early June with 2+ inches on the table all along the DC-to-Philly-to-NYC corridor.
This current weather event is likely to end up being the single biggest rainstorm in much of the Mid-Atlantic region since early June with 2+ inches of rainfall on the table in the DC-to-Philly-to-NYC corridor. Map courtesy NOAA, tropicaltidbits.com
An upper-level trough of low pressure centered over south-central Canada today will develop a “negatively-tilted” trough axis by later Wednesday. Specifically, the trough axis extending from the low pressure center will become oriented from northwest-to-southeast and should extend all the way to the Mid-Atlantic’s coastline. As such, upward motion will become significantly enhanced across the region by Wednesday afternoon increasing the likelihood for a rapidly intensifying low pressure system to develop over the Appalachian Mountains and this will, in turn, will help to generate heavy rainfall and possibly a few strong thunderstorms into the evening hours.
In addition, winds will become quite an increasingly important factor later today/early tonight; especially, along coastal sections along the eastern seaboard from the Carolinas to New England. Specifically, winds can gust past 50 mph along coastal sections of New Jersey and the Delmarva Peninsula, and can gust past 60 mph across eastern New England (e.g., Boston, Cape Cod) where the low-level jet likely reaches its peak intensity level.
A cold blast will follow the passage of a strong cold front into the Mid-Atlantic region on Wednesday night and temperatures on Thursday and Friday will be well below-normal for this time of year. Map courtesy NOAA, tropicaltidbits.com
Once the strong cold front slides through the region on Wednesday evening, temperatures will drop sharply and there is a chance that rain changes to snow for a brief time in the N/W suburbs along the Mid-Atlantic’s I-95 corridor where small accumulations cannot be ruled out. More significant snow will fall during this storm across interior, higher elevation locations of the Mid-Atlantic region/Northeast US all the way from West Virginia to interior New England. Winds will remain strong on the back side of the front from a northwesterly direction during Wednesday night and Thursday and they will funnel into the area much colder-than-normal air for the last two days of the work week and wind chills will make it feel even colder than the actual ambient temperatures. Moderation in temperatures begins early this weekend in the Mid-Atlantic region and rain will be possible by Sunday in parts of the area.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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