Wednesday 10 a.m.
Temperatures a mile overhead in the Northeast today would support afternoon ground-level temperatures well up in the 80s today... if this were July. In July, the sun climbs high in the sky. Mornings warm quickly; soon it is very warm or hot. Not so fast in October, though. The longer nights allow more time for the temperature to drop to the saturation point, and soon fog forms.
The fog prevents much solar energy from the reaching the ground to cause warming. If there are higher clouds around like there are at many places today. the warming process is delayed further... and before we know it the sun is sinking back toward the horizon. The changing amounts of clouds and fog can wreak havoc on temperature forecasts. Despite this, we can say confidently that temperatures in Middle and North Atlantic states will run higher than the long-term averages for this time of year.
Fog may redevelop late tonight and longer tomorrow morning. On Friday, however, slightly drier air will advance from the west and southwest... and with the breeze picking up, it could turn out to be the warmest day of the week. A cold front will arrive and be followed by noticeably cooler air for the weekend. The cold front is associated with a low pressure area that will cause heavy snow across parts of the far North Central states and adjacent Canada. This video shows the expected progression of events:
Dense fog has often proven to be very challenging for painters and photographers. You can see why with this image from a webcam overlooking the area between the Statue of Liberty and the buildings of Manhattan.
The NWS Storm Prediction Center issued this outlook for today and tomorrow: A preliminary area of showers may advance from the Carolinas as far as southeastern Pennsylvania and southern New Jersey by tonight.
For the almost 24 hours between 10 a.m. ET Tuesday and 9:20 a.m. ET today, here is a the lightning recap. The dry pattern from the Midwest will now advance across New York and New England.
Cooling aloft and heating moist air closer to the ground should trigger strong thunderstorms from eastern New York and much of New England southwest through parts of the Middle Atlantic states.
The front will move into a region with high humidity as it approaches the I95 corridor tomorrow. This is the basis for SPC's forecast of thunderstorms approaching severe limits tomorrow.
Tropical Storm Colin is caught in the southern stream while the northern stream is helping to send unseasonably cool air out of central Canada.
Then, as the cold front arrives, there may be violent thunderstorms. This map shows the early morning SPC assessment of the severe weather risk on Sunday: