May 20, 2012: Showers, Storms This Week

Forecast Highlights:

– Showers, Storms This Week
– Temperatures Staying In 70s
– Prolonged Heat Appears Less Likely For Long Range


Today’s Observations:

As a cutoff low pressure to the south slowly approached, today was the last sunny and warm day before clouds and showers return. Temperatures inland were similar to those of yesterday, slightly warmer in some areas, peaking in the upper 70s to lower 80s from NYC and further north/west. The immediate NYC area was slightly cooler than yesterday, with Long Island and southern Connecticut reaching the lower to upper 70s for highs.

With the cutoff low to the south, not related to Alberto, drifting towards the region, clouds will increase tonight, with more clouds and scattered showers/thunderstorms through most of the week. Beyond the late week, a brief surge of warmth is still possible, although the probability of a significant warm spell is much lower than previously thought due to a strong east based -NAO block developing.

Week Overview:

Mainly cloudy skies are expected for Monday with highs in the mid to upper 60s from NYC and further north/west and the lower to mid 60s further east. Scattered showers are expected throughout the day as well. Some models, including the NAM, are inconsistent with the rain forecast, noticeably moving the axis of heavy rain around with each run, making it harder to determine exactly where the heavier rain totals end up, although at this time the eastern half of the area appears to be more favored for locally heavier rain totals over 1/2 inch. Temperatures on Tuesday and Wednesday will gradually warm up, reaching the 70s in parts of the area on Tuesday and most of the area on Wednesday, getting close to 80 degrees near NYC on Wednesday. Scattered showers and thunderstorms are expected on both days with partly to mostly cloudy skies. Partly cloudy skies and a risk of isolated thunderstorms will continue through Friday with high temperatures in the 70s except for coastal areas.

Next Weekend – Next Week: Warm At Times

Slightly Edited on 5/21 Morning

Over the last few days, there has been a strong signal for heat on the models for the Memorial Day Weekend time period and beyond. The latest trends, however, point to an east based -NAO developing along with a polar vortex near SE and/or central Canada. With the core of the ridge in the central US, this supports the potential for a back door cold front to move through the region. A brief surge of warmth is expected around Saturday and/or Sunday, with highs well into the 80s for parts of the area possible, with somewhat cooler temperatures for Sunday and parts of early next week. The back door cold front potential will not stick around the entire time, however, as another surge of heat may be possible later on next week. The possibility for thunderstorms is also in place for the late weekend/early week; this type of set up supports a NW flow aloft, which results in a potential for strong to severe thunderstorms in parts of the region, although there is not enough confidence on the weekend set up at this time to go into more detail regarding precipitation chances. Stay tuned for more information.

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