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 cold front is embedded in a large area of clouds, showers and thunderstorms covering the middle of the country. It will advance past the Northeast coast by the end of the day Sunday. The frontal zone is shown on this picture from late morning Friday.
When weather systems are relatively weak, small scale variations cause forecast uncertainty because several different weather types (such as showers, sunshine, cloudiness, etc.) can coexist in the same region and change constantly. This map shows such a pattern:
Some of the thunderstorms can become severe, with damaging wind and brief cloudbursts of rain. The greatest chance for locally severe storms should be in the "S" areas highlighted on this map (based on the NWS Storm Prediction Center's guidance).
There is a slight risk for severe thunderstorms later today from north-central Tennessee up across Indiana and Ohio to Michigan and eastern Wisconsin (shown by the "S" area on the map below. Thunderstorms are not predicted for areas near the coast from Delaware to New England.
It is not going to snow any time soon, but in any type of weather the flag is a symbol of freedom. This holiday weekend we celebrate the contributions of those who were there to defend the freedoms we enjoy in these times.
Once again, the rain will miss much of central and northern New England. The region has been in a dry spell, as evidenced by its appearance on this U.S Drought Monitor map.