Sunday 5 PM
This is a video made late this afternoon showing where Sandy should go and what impacts to expect. The storm is still well out at sea, but it was supposed to be there according to previous forecasts. However, the various computer models have insisted the storm is about to hook to the left and head straight for the coast. The video shows where the storm should be at various times during the next couple of days. Keep in mind that dangerous wind and rain conditions will arrive long before the center reaches or passes you. In fact, the weather will slowly improve right after the center passes, but the damage will have been done. I'll write to you again tomorrow morning.
The current surface pattern clearly shows the flow that is bringing ocean-cooled air in from the east. If the high pressure area to the north expands southward as expected by tomorrow, this flow will be weakened and perhaps cut off.
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.