Feb 24, 2013: Stormy Tuesday Night, Wednesday

Forecast Highlights:

The system that has affected the region over the last two days is currently moving out, with scattered snow showers observed north/east of NYC this evening. Dry conditions will briefly return for Monday with highs in the 40s, followed by another storm on Tuesday night into early Wednesday expected to produce heavy rain, wind, and snow/ice for interior locations. Behind this storm, seasonable to slightly cooler than average temperatures will continue through the weekend.



Short Range Update: As the radar image posted above shows, snow showers have been affecting Long Island and southern CT this evening. Most locations have generally received a dusting of snow, although isolated accumulations as high as 1/2 to 1 inch have been reported under the heavier bands. These snow showers will gradually end tonight as the storm departs and skies clear. Mostly sunny skies are expected for Monday with highs generally seasonable, in the low to mid 40s inland and mid to upper 40s for the rest of the area.

Tuesday – Wednesday: Heavy Rain, Wind, Snow And Ice

The next storm to affect the region is currently developing in the south central US, and will track towards the Great Lakes on Monday and Tuesday, producing a widespread significant snowstorm in the central US region. Unlike this weekend’s storm, this storm will have more significant impacts on the region as the primary low persists over the Great Lakes while a secondary low pressure develops near North Carolina, tracking north into New Jersey and New England. This secondary low will remain attached to the primary low in the Great Lakes and will not escape east and offshore like this weekend’s storm.

Widespread moderate to heavy precipitation is expected to affect the region, although the main question at this time is the precipitation types. The model guidance is currently split between the warmer GFS and NAM models and the colder ECM and UKMET models. The GFS and NAM show some interior snow/ice to start followed by a quick changeover to rain, especially on the NAM which shows a quick changeover to ice and rain through central-northern New York state as well. The ECM and UKMET, however, suggest a longer duration snow/ice event in southeastern NY and far NW NJ as temperatures fail to quickly warm up, with central-northern New York state staying with plain snow. The last time there was such a split with the models was with the 12/26/12 storm, when the ECM was colder, supporting widespread snow accumulations followed by a changeover to rain, while the GFS and especially the NAM showed mostly, if not plain rain across the area. In the end, the GFS and NAM were too warm as widespread snow did fall initially, but the ECM was a bit too cold. At this time, I am leaning closer to the ECM solution but with slightly warmer temperatures and a faster changeover to rain, although this aspect of the forecast is still subject to some changes.

Latest forecast: At this time, precipitation is expected to develop across the area on Tuesday evening, towards 6-10 PM from southwest to northeast. Precipitation is initially expected to fall as snow and sleet in NW and north central NJ, SE NY, and parts of western CT, while the rest of the area starts out with rain. Precipitation will steadily intensify through the evening and overnight hours, with the snow/mix changing over to rain except for interior SE NY, which is expected to hold on to sleet and freezing rain for a longer period of time. Windy conditions are also expected during this time frame, with east/ENE winds of 15-30 mph, gusting up to or over 40 mph across the area. The steady rain will end from south to north on Wednesday morning, with mostly cloudy skies expected afterwards and highs generally in the 40s.

Heavy rain totals of at least 3/4 to 1.5 inch are likely across most of the area, with light snow and ice accumulations likely for interior parts of the area, especially towards interior SE NY where freezing rain is a concern. Stay tuned for more information over the next few days.

Longer Range Update:

A deep trough is expected to cover east and central US for the late week into the weekend as the primary low over the Great Lakes slowly drifts east through the region, moving offshore by Friday. Despite the magnitude of the trough, with 850mb temperatures below freezing extending as far south as Florida, the core of the cold air mass is focused west of the region, with the greatest negative temperature anomalies over the southern US due to the significant southward extent of the trough. With a stale cool air mass over the region, temperatures will remain close to average through Thursday and Friday, peaking in the low to mid 40s inland and the mid to upper 40s for the rest of the area. Partly to mostly cloudy skies are expected to persist with scattered showers possible at times.

Towards next weekend into the start of the following week, stronger transient ridging is expected over the western US, with the colder temperatures slowly shifting east towards the region; highs on Sunday and Monday are likely to gradually cool down into the 30s, ending up below average, with less cloud cover expected compared to the late week time frame. Yesterday, some of the models were hinting at a storm potential around this time frame, although today’s runs have lost this signal, with cold and dry conditions continuing until later next week. This is still in the longer range, however, and the potential for a storm remains, whether it’s over the region or offshore. More information will be posted on this time period as details become clearer.

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