Early week warmup in the Northeast to be replaced by winter from midweek on
December 04, 2017; 10:57 AM
1. The pressure analysis shows a high over the Northeast and a low off the west edge of the map. The southerly flow between the high and low will bring warmer air into the Northeast through tomorrow evening.
2. As cold air slices into the mild air, clouds, rain and even thunderstorms will break out. This map shows where the chance of thunderstorms is greatest today and tonight. The cold front will bring the heaviest rain in more than a month at Little Rock, Arkansas.
3. As shown on the following map, cold frontal clouds and rain are not well organized. With an influx of moisture from the Gulf of Mexico, a band of rain should develop along most of the length of the front by late tonight or tomorrow.
4. The following set of GFS maps shows flow aloft last night (first map), predicted flow (at 500 mb) on Wednesday afternoon (second map) and the prediction for Friday afternoon. In addition to the clear implication that cold air will advance into the Great Lakes, Ohio Valley and Northeast, we see that between Wednesday and Friday the trough should sharpen quite a bit. A low pressure area will form off the East Coast and a large area of precipitation will develop. However, it is still too early to tell how much of this will fall along and near the coast. This is not a trivial issue, because a storm like this can cause slippery travel in the busy I-95 corridor... or send all of its precipitation back into the sea. The fourth map in this set is te GFS ensemble mean for forecast for 1 a.m. Saturday. The large gray area in the Northeast reflects the fact that various members of the ensemble had different takes on where the precipitation would fall. If we see a compact area of green, we would conclude there was good agreement on where the heaviest precipitation would occur. Instead, we see a pattern resulting from lack of such agreement.
The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com