General Synoptic Overview: A northern stream shortwave trough with an associated surface cold front amplifies (strengthens) as it digs across the upper-Midwest interacts with shortwave energy and an associated frontal system lifting northeast out of the southern Plains overnight Tuesday:
As these two systems interact the result will be a rapidly developing and deepening area of low pressure at the surface along a strengthening cold front. Low pressure begins developing within the mid-Atlantic early Wednesday morning and strengthens as it lifts northeast towards New England late in the afternoon:
With surface low pressure passing to the west of southern New England and strengthening while doing so, this should propel a warm front through much of the region yielding a surge of unseasonably strong theta-e characterized by surface temperatures climbing into the upper 50's to lower 60's and dew points into the mid-to-upper 50's across much of the region Wednesday afternoon:
With an intensifying system the response will be an increase in jet stream dynamics aloft, characterized by a potent 50-60 knot jet at 925mb (about 2,500 feet above the ground) overspreading much of southern New England through the day Wednesday with as much as 70-80 knots overspreading costal Connecticut and eastern southern New England:
What to Expect: Heavy rain is expected across the entire region Wednesday with a widespread 2-4 inches of rain and locally higher amounts. While this is great news for the drought situation there will be concern for flash flooding, particularly within typical flood prone areas and northern portions of the region where the is snow cover and some frozen ground.
In addition to heavy rain, strong winds are expected, both sustained and potential gusts. A strengthening pressure gradient from the deepening low pressure and strong pressure falls should result in sustained winds of 20-30 mph within the region. Winds will be less in more sheltered areas, however, towards the coast (but just a bit inland) and towards eastern sections of New England winds could become sustained as high as 30-35 mph.
There is also potential for widespread damaging wind gusts of 50-60 mph which could yield downed tree limbs and scattered power outages. As usual with these setups, the wind gust potential will be contingent on the strength of a temperature inversion just above the surface. Given the potential for temperatures to push 60 with dew points well into the 50's this may limit any inversion; increasing potential for damaging wind gusts. Another factor which could inhibit the max gust potential is stability produced by rainfall.
With such a vigorous weather system, combined with the anomalously warm temperatures and higher dew points, there atmosphere will also become weakly unstable. Some forecast model guidance suggests a fine line of intense rainfall, potentially accompanied by thunder/lighting will develop across eastern Pennsylvania, northwest New Jersey, and southeast New York and strengthen as it progresses across southern New England during the late afternoon and evening. Should this materialize, this would increase the potential for wind gusts as high as 55-65 mph on the leading edge of it as it crosses the region.
The worst of the weather conditions are expected to be from about noon to midnight Wednesday with improving conditions from western southern New England during the evening and eastern southern New England around midnight.
