2:00 PM (Monday) | ***Strong-to-severe thunderstorm threat in the entire DC-to-Philly-to-NYC corridor through late tonight***

High-resolution model forecast for “updraft helicity” during this upcoming severe weather event. Map courtesy College of DuPage, NOAA

Overview

An unstable atmosphere and an approaching frontal system are raising the chances for strong-to-severe thunderstorm activity late today and tonight in the I-95 corridor region from DC-to-Philly-to-NYC.  There is already one line of strong storms pushing eastward into central PA and central NY and other lines are likely to develop during this threat time period which could continue until midnight or so.  The storms are moving quickly enough to reduce the chances of torrential rainfall amounts like we experienced last week; however, damaging wind gusts, hail and even isolated tornadoes are severe weather threats with this particular setup all the way from Washington, D.C. to New York City.

High-resolution forecast map of radar reflectivities at around 10pm. The threat for strong-to-severe thunderstorms will continue to midnight or so for much of the I-95 corridor from DC-to-Philly-to-NYC. Map courtesy NOAA, weathermodels.com

Details

Sunshine has helped to destabilize the atmosphere in the Mid-Atlantic region today and a frontal system is closing in from the northwest backed up by some upper-level support.  The combination of the surface front and upper-level trough is helping to produce strong storms at this time which are moving fairly rapidly across central PA and central NY.  High-resolution models suggest there will be some rotation in the atmosphere later today/tonight across the Mid-Atlantic region which raises the chance for isolated tornadoes.  The main severe weather threats from these storms will be damaging wind gusts and hail, but torrential rainfall amounts are somewhat less likely as with recent events which featured slow-moving storm cells. The threat for strong-to-severe storm activity in the entire DC-to-Philly-to-NYC corridor will begin in the late afternoon hours, but will be primarily focused during the mid-to-late evening hours and can run as late as midnight or so in some spots.  There will continue to be a threat for showers and storms on Tuesday, but much less in the way of severe weather.

Strong storms are pushing into central PA in the early afternoon hours and this is just the first line of many likely to form. Map courtesy College of DuPage, NOAA

Looking ahead, another very comfortable air mass will follow frontal passages for the mid-week in the Mid-Atlantic region.  In fact, temperatures in many suburban locations along the I-95 corridor will drop well down into the 50’s on Tuesday, Wednesday and Thursday for overnight lows. Daytime highs are quite likely to be in the very pleasant mid and upper 70’s during the mid-week time frame throughout the northeastern quadrant of the nation.  At the same time the Northeast US/Great Lakes enjoy comfortable weather, much of the western US will experience extreme heat.  Phoenix, Arizona, for example, will likely have high temperatures between 115 and 120 degrees in coming days and Death Valley, California can reach 125 degrees. One final note, tropical activity is quite likely to develop over the Gulf of Mexico by the late week and we could be dealing with a tropical storm closing in on Louisiana or Texas from the south by the early part of next week.

Meteorologist Paul Dorian
Peraton
peratonweather.com

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