Friday 9 AM
Sandy continues to threaten the Northeast, and in the area where is comes ashore, there will be damaging winds knocking down trees and cutting power, flooding rain and, at the coast, a dangerous storm surge. Time of that is crucial, because we will be close to the time of the full moon, and range between high tide and low tide is greatest then. This map shows the track forecasts of a wide variety of computer models. Why the differences? Each one has its own way of ingesting data and handling the intricate math associated with second order nonlinear differential equations. A big problem is we simply do not have data for every place in the atmosphere.
This video discusses where the storm is heading now, what should happen next, and what some of the effects will be. Unfortunately, this kind of storm can affect millions and cost billions.
This mornng, showers were moving across the lower Great Lakes region. A band of thunderstorms developed near Chicago before 6:30 a.m. CT and reached the southwest Michigan shoreline an hour later (8:30 a.m. ET). The following maps show the shower zone and Chicago area lightning.
The tropics have been more active recently. This map shows various entities that area being tracked and analyzed. Hurricane Gonzalo stands out clearly.
A couple of days ago, the storm entering the East had a stronger circulation than it does now. Here is the pressure analysis from earlier this morning. Several minor disturbance can be seen, and trough lines representing those have been sketched on the map. Note that there is little difference in temperature from western Pennsylvania to Wisconsin.
The rain band is only 100-200 miles wide, but it is moving slowly. This map shows its location at 10 a.m. today. Once the main rain band passes, it won't be quite as warm as it was when the rain started. However, by mid-October standard, it will still be mild.
On some days, there are so many "little things" that it is difficult to identify the players. Today, we see two systems dominating: the low pressure area on the left (west) and the high pressure area to the right (east). The cold front associated with the low pressure area is helping to support bands of rain.
One branch of the flow will go from Oregon and northern California eastward to the Plains, then it will go around the south side of the storm we have been talking about. A second branch of the flow will run from British Columbia northeastward to northern Hudson Bay. Cold air will be north of that current...which means it won't be anywhere near the eastern U.S. later this week.