Tuesday, September 28, 2010

Sept 28: Changes In Forecast For TD16

Note: today only has a brief update, and the pages were not updated. Expect a full update tomorrow, with the final forecast for Tropical Depression 16/potential Nicole.


Today's Storm Review: Why Did It Fail?



Unlike what the models have been consistently showing, and the radar appearance of the storm before the rain fell apart last night, the rain event that affected the area has busted too low, with some places seeing totals as low as 1/4 inch, when it appeared for days that this would likely be a solid 1/2+ inch event. The heaviest rain totals ended up in western Long Island, however these amounts aren't too high, and are generally below 2 inches.

The small severe weather risk that was also in effect for today did not verify, as the parameters and the radar appearance did not support widespread severe weather activity for today, being why I kept the Severe Weather Alert in place instead of a watch, indicating a less than 70% chance of severe weather. There were some locally heavy storms, but they were not severe.

Forecasts For Tropical Depression 16: Too Far West?



Yesterday's forecasts mentioned that the models have trended west with the forecast for 96L, which is now Tropical Depression 16, however today's models have trended much further west, now bringing the heavy rain to central VA into central Pennsylvania, where 3-6 inches of rain are likely, but have decreased rainfall amounts in the area to barely 1 to 2.5 inches. Despite this, the forecast winds have increased, with sustained winds up to 40-50 mph and gusts up to 60 mph now possible for Long Island, S CT and potentially the immediate NYC area if the current scenario was to verify.



Despite the impact timing only being 2 days from now, there is still significant uncertainty, which could continue until the last minute. Tropical Depression 16 is currently disorganized, and may not be able to get its act together into a tropical storm before becoming extra-tropical, and at this time, its pressure of 997 mb is much lower than that of a typical Tropical Depression. While it is likely to intensify as it becomes extra-tropical and moves up the East Coast, we can still end up with a different scenario.

The track forecast is currently the most uncertain. The models today have significantly trended west from yesterday's models, however TD16 has yet to have an organized center, and according to NHC's 8 PM update, TD16's center shifted a little to the east, which may have an impact on the overall track. The further west it goes, less rain and stronger winds can be expected for the area, and the further east it goes, more rain and less wind can be expected.

Stay tuned for more details with tomorrow's full update, including final maps, and updated alerts and 5-Day Forecasts.

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