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Tropical Storm Warning for Long Island! Flash flooding, strong winds, and strong thunderstorms:

The center of Tropical Storm Elsa is expected to pass near Montauk tomorrow morning. Flash Flood Watch for Nassau and Tropical Storm Warning for the south shore and from Port Jeff eastward on the north shore. Most of the action will be from midnight tonight to 10:00 tomorrow morning with torrential downpours at times. The strongest winds will be for eastern Suffolk with gusts as high as 55 mph. Gusts for most of Long Island will be in the 35 to 45 mph range with higher gusts along the south shore. Rainfall totals generally 1 to 2 inches in Suffolk and 2 to 3 inches in Nassau with amounts up to 4 inches possible. Also, a tornado cannot be ruled out tomorrow morning. As I was expecting, the National Weather Service did increase their wind gust projections for Long Island.


From the National Hurricane Center: Rawinsonde data and GOES-16 RGB airmass imagery show an upper-level shortwave trough over the southeastern United States to the west of Elsa, and the global models forecast this system to follow the cyclone northeastward and take on a negative tilt. This should result in increasing upper-level divergence over Elsa, which in turn should lead to some strengthening as the storm moves near or over the east coast of the United States. The 00Z ECMWF model is not as bullish on intensification as its previous run, but it and the 00Z UKMET still call for strengthening, and even the weaker GFS forecasts the favorable upper-air pattern. Based on this, the new intensity forecast shows a little more strengthening than the previous forecast.


LONG ISLAND FORECAST:

*A Flash Flood Watch is in effect for Nassau County for tomorrow (Friday) from 12 AM to 12 PM: Heavy rainfall ahead of tropical system Elsa will move into portions of the Tri-State area late Thursday night, with periods of heavy rainfall possible through Friday morning. Although heavy rainfall will be possible as early as Thursday afternoon, the greater chances for this will begin Thursday night. Total rainfall from Thursday afternoon through Friday is expected to range mostly 2 to 3 inches, with locally higher amounts possible.**

** A Tropical Storm Warning is now in effect for the coast of Long Island from East Rockaway Inlet to the eastern tip along the south shore and from Port Jefferson Harbor eastward on the north shore**

Today: Partly to mostly cloudy and humid with a chance of a shower or thunderstorm in the late afternoon and evening and becoming breezy with highs mostly in the low to mid 80's, but cooler for the south shore and east end. Wind out of the SSE to S at 10 to 20 mph in the afternoon with higher gusts along the south shore.

Tonight: Breezy and humid with heavy showers and thunderstorms, mostly after 11 PM. Lows in the low 70's. Wind out of the SSE at 10 to 20 mph with higher gusts late.

Tomorrow: Humid and windy with heavy showers and thunderstorms in the morning, and a tornado cannot be ruled out, then cloudy with some lingering showers possible in the afternoon. Highs mostly in the low 80's. Wind gusts in the morning up to 40 mph in Nassau, 45 mph in central Suffolk, and up to 50 to possibly 55 mph mph possible in extreme eastern Suffolk. The wind will be mostly out of the SSE and then shifting to NW behind the storm. Total rainfall amounts of 2 to 4 inches in Nassau and 1 to 2 inches in Suffolk.

Saturday: Partly cloudy and moderately humid with only a slight chance of a passing shower with highs in the low 80's. Light and variable wind.

Sunday: Partly to mostly cloudy and humid with a 30% chance of a shower in the afternoon and evening with highs around 80 degrees. Wind less than 5 mph in the morning and then around 10 mph out of the SSE in the afternoon.

Monday: Mostly cloudy and humid with a 30% chance of some showers and thunderstorms. Highs in the low to mid 80's. Wind out of the SE at 5 to 10 mph.


- 1st image: Tropical Storm Elsa official map from the NHC

- 2nd image: My 5 day outlook for Long Island

- 3rd image: Radar for 8 AM tomorrow from the HRRR model

- 4th to 6th images: Projected rainfall from the HRRR, HREF ensemble mean, and National Weather Service

- 7th and 9th images: Maximum projected wind gusts from the National Weather Service, HRRR model, and Euro, respectively, and the Euro is in knots.

- 10th image: Flash flood potential

- 11th image: Projected temperatures for Long Island

















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