We always look back at our previous forecasts to try to learn from episodes in which we believe we could have done better. The following satellite picture shows dry weather today in just the area that originally looked like it would have more rain.
In other words, while late summers in Phoenix have gotten wetter during the last few years, Boston has become drier. Is there anything more momentous or general that we can say about this?
This enhanced infrared satellite picture shows the cold front in the Northeast and the moisture wrapping around Odille on the southwest part of the map.
Across the Central and Northern states, thunderstorms are less common at this time of year than in late spring and summer. One area that has had more thunderstorms than usual recently is across the Desert Southwest.
Last week, I mentioned that longer range computer models were suggesting a major warmup by next weekend. More recent runs have backed off on the that idea. However, there is extreme uncertainty beyond the next 7-10 days. This can be seen by looking at the following map.
n the forecast office, we often track cold fronts with pressure maps like these. The examples are from 4AM and 10 AM today. You can see that the northern part of the front is moving more quickly than the southern end. The arrival of the front signals the start of the cooling trend that is spreading east.
The upper air flow over the East is from the west-southwest now, and some of the moisture associated with the cold front can be traced back to tropical storm activity off the Mexican west coast last week. The same moist air mass set the stage for recent flash floods in Arizona. By early next week, the upper-air flow will be coming to the Northeast region from well up in western Canada, as seen on this forecast map forecast map for next Tuesday:
As chilly air pours into the northern Plains and backs into the Rockies, snow can break out at higher elevations. Gillette, in northeastern Wyoming at an elevation of just over 4,000 feet, could have a close shave with snow on Thursday. This map shows the setup.
The main U.S. computer model shows very cool air coming into the Northeast this coming weekend. However, the same model shows a complete reversal by the following weekend.
Meanwhile, it is warm and humid in the Northeast corridor today but should be much more comfortable on Sunday. This map shows the pressure and temperature setup that existed at 7 a.m. ET. The cold front is associated with the rapid change of shape/direction in the pressure contours over the upper-left part of the map.