Oct 30, 2010: Storm Potential Late Next Week

Today was another chilly and windy day for the area, with high temperatures in the mid to upper 50s across most of the area. Low temperatures were in the lower to mid 30s inland, mid 30s to lower 40s north and west of NYC and in the lower 40s in NYC, which was slightly warmer than expected due to more cloud cover.

The next few days will be cold and dry, with widespread frost expected on Sunday/Monday night being why I issued a Freeze Watch for most of the area, however uncertainty returns to the forecast for the late week, when there is the potential for a storm to affect the region.

Tomorrow’s Outlook:

Tomorrow will be a partly to mostly sunny day with a WNW wind. High temperatures will be in the lower 50s inland, mid 50s in the immediate NYC area, and mid to upper 50s in Long Island/S CT as a cold front moves through in the morning.

Overnight temperatures will be cold, in the mid to upper 20s inland, upper 20s to mid 30s for the areas north and west of NYC, and in the upper 30s for NYC. Widespread frost is possible, being why a freeze watch is in effect for most of the area.

This cold front will be related to a weak storm moving out of the region, which should produce accumulating snow in central Maine tonight through tomorrow morning, with a general 1 to 3 inches of snow. Widespread rain/snow showers will be observed in the Northeast tomorrow, but the NYC area will stay dry.

Monday And Tuesday: Dry, Cold
Mainly sunny weather will persist for Monday and Tuesday, with mostly sunny skies expected. High temperatures on Monday will be in the mid 40s inland, upper 40s to lower 50s for Long Island/S CT, and in the mid 40s to lower 50s in the immediate NYC area. Low temperatures on Monday night should be slightly colder than those of Sunday night, with Tuesday night’s lows also cold. Tuesday’s highs should be slightly warmer than those of Monday.

Longer Range: Storm Potential, Then Cold Again

For the longer range, it is nearly certain that a storm will develop and potentially affect the region, but how it develops, where and when is still a question. Up to Wednesday, the models are in good agreement with a low pressure in the Gulf of Mexico and a high pressure near the area. Afterwards, however, there are significant differences with the models, even the ensemble means, with solutions ranging from the GGEM showing an intense storm covering all of the East Coast with heavy rain, to the ECMWF which develops the southern low pressure and has it going inland into the Great Lakes, or the GFS that barely develops the storm but instead develops another one around November 6-7.

The main uncertainty with the models seems to be with which low pressure to develop, one near the North Carolina coast which would lead to a scenario like the one I mentioned yesterday, or the southern one in the Gulf of Mexico, which would lead to a solution closer to the ECMWF or GGEM, which are much further inland. It is possible that the first storm fails to become anything significant and a potential second storm that the GFS and DGEX are showing is the main storm.

At this time, in my 5-Day Forecast, I mentioned a chance of rain on Thursday afternoon, but this is just a general forecast which doesn’t exactly follow these potential storm tracks. The ensemble means still show a coastal storm, but have trended much further west than yesterday. As uncertainty decreases on the models, I will discuss the scenario in more details. Stay tuned for more details on this storm.

After the storm, however, one thing that is likely again is that a strong cold air mass could affect the area. There is uncertainty on how strong this cold air mass is, or whether a second storm like the GFS/DGEX show has any effect on it, but if the latest models verify, temperatures could be even colder than those of Monday/Tuesday.

Tropics: Tomas Now A Hurricane

Last night, Tomas continued to quickly strengthen, and is now a 90 mph Category 1 hurricane, which passed through the southern Lesser Antilles earlier today causing damage. Tomas has an eye that formed not too long ago, though the eye is not well organized yet. Tomas will likely continue strengthening tonight, reaching Category 2 intensity by tomorrow.

Afterwards, due to increasing shear that the models are forecasting, Tomas may slightly weaken, but the shear is then expected to relax, and with a very favorable environment, Tomas may rapidly intensify. The peak intensity is uncertain, however at this time I put the potential for Tomas to reach Category 4 intensity in my forecast map, posted above.

Tomas’ Track: For the short range, there is agreement with the models, showing a general WNW movement for the next 2 days. Afterwards, however, it appears that the steering currents should collapse, with Tomas significantly slowing down, then starting to move more north. There is uncertainty on where Tomas could so do, and at this time, while the latest models show landfall near Hispaniola/Haiti, there is a large range of potential landfall areas, ranging from Puerto Rico to Jamaica/Cuba. Regardless of the track, Tomas will likely be a dangerous hurricane, and people from Puerto Rico to Cuba should pay close attention to Tomas over the next few days.

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