Temperatures will be back on the rise in the Northeast Monday after a brief period of comfortable weather made for a perfect July weekend. Fortunately, a cold front and upper-level influences from intensifying Tropical Storm Chris will prevent this heat from achieving the longevity or record-breaking intensity as that of the July 4 holiday weekend.
Modest heat will initially build Monday as a high pressure system centered over the Deep South directs warmer air towards the Northeast US. Temperatures will be slightly above average, with middle 80s in the interior Northeast and upper 80s to low 90s along the Atlantic Seaboard and in the Mohawk, Hudson, and Champlain Valleys. Humidity will be in check, so outdoor conditions will not be oppressive.
Things kick up a notch Tuesday ahead of an upper-level trough. Hot, moist air will surge northeastward as it is squeezed by Tropical Storm Chris to the east and a cold front to the west. Temperatures will climb into the mid 90s along the I-95 Corridor from Washington, D.C. to Boston and the upper 80s to around 90 F at the shore, along the Appalachian Mountains and in the Hudson and Champlain Valleys. The cold front will arrive just in time to keep temperatures in the mid 80s further west in cities like State College, Buffalo, and Syracuse. But Boston, Albany, New York, and Washington, D.C. will have to wait for the evening frontal passage for relief.
In addition to the heat, humidity will be more oppressive Tuesday than Monday. Dew points in the low 70s will make temperatures actually feel like 95 F to 100 F ahead of the cold front. But this discomfort will not last. Comfortable humidity levels will follow the frontal passage from west to east between Tuesday afternoon and early Wednesday morning.
Scattered thunderstorms will accompany the frontal passage and lower humidity levels late Tuesday morning through Tuesday evening. Isolated storms will develop around midday mainly in New York north of I-90 and increase in coverage as they spread southeast through the afternoon. Some strong wind gusts are possible with these storms, especially east of I-81 in New York and north of I-80 in New Jersey and northeast Pennsylvania. The storms will not approach the I-95 corridor until the evening rush hour, but will likely be less widespread given the weakening of the front, loss of daytime heating, and decreasing mid-level moisture.
Behind the storms Wednesday, wall-to-wall sunshine will return. In the interior, seasonal temperatures in the mid 70s in high elevations to low 80s in the valleys alongside dew points in the 40s and low 50s will make for refreshing conditions after Tuesday’s steamy airmass. Temperatures will only drop a few degrees Wednesday for the I-95 corridor given the weakening of the cold front but crashing dew points and breezy winds from Tropical Storm Chris passing offshore will eliminate much of the discomfort.
The heat and humidity will be on the rise again this weekend, with low 90s returning to the I-95 corridor by Sunday and possibly persisting through next week. How hot it gets this weekend ultimately depends on the tracks of Tropical Storms Chris and Beryl. A further west track of Chris would delay the development of ridging of high pressure in the east until at least early next week. Currently, Chris is poised to take a track just east of Nova Scotia, which would permit heat and upper-level high pressure to build eastward starting Saturday. A track closer to the New England coast would keep upper-level low pressure over the Northeast coast through at least the first half of the weekend. Likewise, if Beryl tracks further west early next week, her circulation could disrupt the building heat in the east. As of Sunday afternoon, Chris was an intensifying tropical storm east of the Carolina coast and Beryl was a weakening tropical storm over the eastern Caribbean.