Report by Paula Antolini, August 22, 2021, 6:51AM EDT
National Weather Service Updates:
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Situation Overview
Current Headlines
–Hurricane Warning continues for Eastern LI and SE CT.
–Tropical Storm Warning continues for NYC/NJ Metros, Nassau, SW CT, and Westchester.
–Storm Surge Warnings continue for N Queens and Bronx and northern and eastern portions of Long Island, S. Westchester, and S. Ct.
— Storm Surge Watch continues for S bays of W LI.
–Damaging to destructive winds, major (life threatening) storm surge and flooding rains likely for LI
and CT.
What has changed?
–Henri track has been shifted east slightly.
–Landfall still likely to be at or near Cat 1 hurricane strength
–Henri has increased slightly in forward speed, but expected to slow as it makes landfall.
–No changes to headlines, as the forecast track/intensity changes are within the noise
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Situation Overview
–Hurricane Henri is likely to strengthen a bit tonight as it tracks north.
–It is expected to make landfall at or near Cat 1 hurricane strength over or just east of eastern LI early Sunday afternoon, and continue northeast into CT while weakening Sunday evening.
–Dangerous marine, rip current, and high surf conditions build through Sunday.
–Damaging to destructive winds, life threatening storm surge and heavy rainfall impacts are likely tonight into Sunday Night for LI and CT.
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Damaging to Destructive Wind Threat
Eastern LI and SE coastal CT
–Winds – 75 mph sustained and gusts 90-100mph.
–Likely Timing – Sunday morning into afternoon.
–Impacts – Extensive damage and uprooting of trees, power lines and poles. Damage to roofs and siding. Significant damage to mobile homes.
—Note: The area hasn’t seen a landfalling hurricane since Gloria in 1985, which at that time caused extensive and long duration tree damage and power outages.
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Strong to Damaging Wind Threat
Nassau County, coastal SW CT,
southern Westchester, and interior
coastal CT
—Winds – Moderate potential for 50-60 mph sustained winds with 70-80 mph gusts.
—Likely Timing – Sunday morning into afternoon.
— Impacts – Widespread tree damage and power line damage likely. Wind impacts could be on the same level of Isaias.
NYC/NJ metro counties-
— Winds– Moderate potential for 30-40 mph sustained winds with 50-60 mph gusts.
–Likely Timing – Sunday morning into afternoon.
— Impacts – Scattered tree damage and power line damage possible.
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Most Likely Time of Arrival of Tropical Storm Force Winds
–The most likely arrival time of tropical storm force winds across the Tri-State area is early Sunday
morning (7-10 am)
–However, the region could see tropical storm force winds as early as late tonight (after 2-4am)
— Peak winds will be from late Sun morning through Sun afternoon.
— Winds gradually subside Sunday evening into Sunday Night.
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Life Threatening Storm Surge Flooding Threat
Along E LI bays/Twin Forks, LI Sound and ocean beachfront
—Major inundation (Life threatening) threat – 3 to 4, locally 5 ft (AGL) in vulnerable spots.
East end of Long Island and coastal SE CT have the highest threat of widespread major (life threatening) inundation
Along the southern bays of W LI and Queens
• Moderate to locally major inundation threat – 2 to 3 ft, locally 4 ft (Great South Bay) Along NY/NJ Harbor
• Minor inundation threat- 1 to 2 ft
Timing of greatest concern-
• During the Sunday morning and Sunday Night high tides Forecast Challenges
• Exact magnitude and hardest hit locations will be based on track. Hardest hit locations may be north facing shorelines to west of the track and south facing shorelines to the east of track due to wave action.
• Storm surge, particularly in the bays areas, may not fully recede after the Sunday morning/early afternoon high tide, before the Sunday evening/nigh high tide.
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Potential Storm Surge Water Levels Values
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Dangerous Marine and Shoreline Impacts
Battering Surf at Ocean beachfront
• Timing – Tonight into Sunday Night
• Surf Height – 8-12 ft western LI beaches, 12-18 ft eastern LI beaches
• Impacts – Widespread dune erosion and overwash issues are likely, particularly E LI and Orient point.
Potential for isolated dune breaches for vulnerable E LI barrier islands.
Marine
• Tropical storm conditions developing tonight, with Hurricane conditions likely for eastern waters on Sunday.
• Ocean seas building to 15 to 20 ft on the ocean on Sunday, particularly east of Moriches Inlet.
• Seas on Long Island Sound building to 4 to 7 ft on Sunday.
Dangerous rip currents this weekend through Monday!
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Flash Flood Threat
Storm Total Rainfall forecast tonight
through Monday.
–4 to 8” with locally higher for much of CT and LI.
–2 to 4” with locally higher amounts for rest of area.
Max rainfall rates-
–1-2”/hr
Timing-
–Most widespread and torrential rainfall likely late tonight thru Sunday Night.
–Scattered heavy downpours could linger into Monday
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Flash Flood Threat
Flood Watch in Effect for Entire Area
Timing–
–Tonight through early Monday morning.
Impacts-
–Scattered to numerous areas of urban and poor drainage flash flooding
–Highest threat for LI and CT. Potentially rising to considerable severity level.
— Flash flooding of numerous small streams and creeks, particularly in S CT.
— Minor to locally moderate flooding on S CT main stem rivers possible
Forecast Challenges-
–Heavy rainfall axis could linger across the NYC/NJ metro and points N & NW well into Sunday night.
–Urban and poor drainage flooding will be exacerbated during the times of high tide Sunday morning and night in coastal communities, including tidally affected riverine communities.
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Tornado Potential
Threat for isolated tornadoes along and to the east of the path of Henri Sun morning into afternoon. Mainly E LI and much of CT.
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Key Take-Aways
–Damaging to Destructive winds likely across Long Island and coastal Connecticut, highest threat for E LI and SE CT. Extensive tree and power line damage is expected.
–Major (life threatening) inundation threat across vulnerable coastal locales along eastern LI bays/Twin Forks, most of LI Sound and ocean beachfront. Dangerous rip currents and high surf building today, continuing through Sunday Night.
–Widespread dune erosion and overwashes along ocean beach front. Isolated dune breaches possible. Widespread urban and small stream flash flooding threat for LI and CT tonight into Sunday Night. Minor to moderate flooding possible along large stem rivers likely.
–Dangerous marine conditions expected across the coastal waters tonight thru Sunday Night.
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