May 8, 2012: More Rain Tomorrow

Forecast Highlights:


- Uncertainty for tomorrow's outlook
- Gradual warm up throughout late week, weekend


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Forecast for tonight and tomorrow:


A coastal low is expected to develop tomorrow south of the area, moving NE towards New England. Until now, most models kept this coastal low mostly to the east of NYC. The latest 18z GFS run, however, significantly shifted west, bringing well over an inch of rain for Wednesday evening/night for NYC and over 2 inches further east. Currently, the GFS is the westernmost model, although the other models have been gradually shifting slightly more west. This increases the uncertainty with tomorrow's forecast even more; the coastal low is barely 24 hours away, and should the storm end up well to the west of where most models have it, this would reflect a large bust with the models, which haven't done too well recently in several cases including the failed thunderstorm potential on Friday and the weekend, originally supposed to be partly sunny but instead ending up mostly cloudy and colder.

At this time, I think that the 18z GFS may have taken this too far west, although based on the scenario I expect at least some moderate rain to affect the area. Confidence is not high for tomorrow's outlook, although based on the latest information, I am siding with the western outcomes but not to the extent of the 18z GFS, with periods of light-moderate rain and possibly some thunder developing late in the afternoon hours for most of the area, with locally heavy rain possible east of NYC. The rain is mostly expected to end late on Wednesday night, with mostly cloudy skies and a few showers on Thursday. Rainfall amounts are the most uncertain, depending on the low pressure track, although at this time I expect 1/4 to 1/2 inch inland, 1/2 to 3/4 inch in the immediate NYC area, and near 1 inch, higher in some areas, in Long Island/S CT. Amounts may end up locally higher, especially further east, although depending on the development of the heavier rain, western parts of the area may see less rain than currently expected. High temperatures will reach the mid 60s to lower 70s across the area, with the warmest temperatures north/west of NYC.

Stay tuned for an update on the forecast on Wednesday afternoon.


Late Week - Weekend Outlook: Mostly Cloudy, Few Showers


With the low pressure cutting off near New England, mostly cloudy skies will stick around through Thursday and Friday along with scattered showers, especially north of NYC, with highs in the mid 60s inland and the mid 60s to lower 70s across the rest of the area. Less cloud cover and warmer temperatures will return for the weekend, with highs likely warming back up well into the 70s.

As the pattern continues to gradually transition with time to a summer-like one, ridging in the Atlantic may extend closer to the region, with a weak trough persisting near the eastern US. While this still supports near-above average temperatures, this pattern doesn't support any persisting warmth, and more scattered rain may be possible at some point early-mid next week. Stay tuned for more information.