Feb 26, 2011: Uncertainty With Monday's Storm

Today started out with mostly to partly sunny skies across the area, however cloud cover has increased as the next storm is moving into the Northeast. This storm will stay mostly to the north of the area, bringing a few rain/snow showers especially north and east of New York City, with temperatures tomorrow warming up well into the 40s. The return to dry conditions will be brief as another storm affects the region on Monday, but how it affects the region is still uncertain.


Monday's Storm: Uncertainty Increases

This winter, we have seen many cases where even the day before a storm hit, there was not a high confidence on what the storm would exactly do as the models trended to a different direction in the short range. This storm is no exception, as the latest models are trending in a different direction with this storm.

Yesterday, the models showed this as a single, strong low pressure moving northeast through the western Northeast into Canada, bringing a warm front through in the early afternoon with high temperatures reaching well into the 50s in NYC, followed by a cold front with heavy rain and strong thunderstorms in the early overnight hours. While some models continue to support this solution, especially the GGEM and the UKMET, and for now it remains a possibility, the NAM and GFS models have trended towards a different solution, where we see a weaker storm coming in two waves.

In the two wave scenario, there is a relatively high confidence with the first wave, which would track through the western Northeast in the afternoon hours, bringing moderate to potentially locally heavy rain across the area between the early morning and early to mid afternoon hours with temperatures steadily rising. There is uncertainty with when high temperatures peak and how warm they get, which could range from high temperatures peaking in the mid afternoon to the early overnight hours, with the high temperature range in NYC from the lower 50s to the upper 50s. There is still expected to be a break in the precipitation sometime around the late afternoon hours.

The second wave would come in the overnight hours and would be south of the first wave, ranging from the GFS focusing the heaviest rain in Virginia to the NAM focusing the heaviest rain just south of NYC. In this scenario, there would likely not be a strong thunderstorm risk, though there would be a heavy rain potential. This is the more uncertain part of the two wave scenario.

There is still a lot of uncertainty with which scenario verifies, though especially with the NAM and GFS having first correctly trended southeast for yesterday's storm, with the other models catching on afterwards, this two wave scenario needs to be watched. Regardless of which scenario verifies, heavy rain is possible for the area again which may lead to additional flooding. Stay tuned for more information on this storm tomorrow.


Longer Range:

Behind this storm, Tuesday will bring a return to more seasonable temperatures and drier conditions, with Wednesday warming up into the upper 40s to potentially the mid 50s across the area ahead of a weak storm in Canada that will bring down much colder air into the region. While the coldest conditions will stay north of the area, high temperatures will cool down into the mid 30s to lower 40s, with low temperatures in the 20s and potentially 10s inland. The next storm will then affect the area around March 5-7.