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Henri: Moderate-Major impacts NYC subforum this weekend, possibly into Monday August 21-23, 2021


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504AM update on Friday (24 hours after initial issuance). Withdrew from the title INDIRECT.


333PM Friday about 33 hours after issuance.  Changed title to Moderate - MAJOR impacts,  tags changed from tropical weather to hurricane gusts,  heavy rain changed to flooding rains, RC and CF remain as they were

It is becoming more apparent via modeling through the 12z/20 cycle,  tho follow NHC, that this storm wants to turn northwest and make landfall anywhere between Block Island to Sandy Hook. Where and intensity? IFFFF Henri still passes east of Montauk,  that will be fortunate for LI/CT.  Follow NHC, and updated collaborated models and experienced statistical output of Tropical verification. 

Strongest gusts and largest waves & storm surge should be east of the center on the Atlantic side of the the storm,  but beware all the east and northeast facing inlets LI Sound.  RC obviously dangerous, and possibly even for experienced surfers. SHOULD BE ZERO casualties due to RC and high Surf.  There is enough info out there now that asks us be smart about living safely.  

Wind: potential from a combination of squall gusts 40 (to possibly ~ 65kt) and preceding heavy rains near and east of the center track,  to uproot and snap fully leaved trees, with 'potential' for long duration power outages.  Therefore east of the center track, charge your phones, have fuel ready for generators (outdoor exhaust only) and maybe rent a couple of movies since along and east of the center internet connectivity may be lost. 

TOR (s): maybe? mainly northeast quad of Henri Sunday morning. 

Rainfall: Looks like 3" near and west of the center of passage, but pockets of surprise amounts elsewhere in the interior?  Max by Tuesday in the lingering weakened remnant state??? Maybe isolated 10" somewhere???

Coastal Flooding: dependent on timing with the high of the tide cycles this weekend. 

This will be a pretty big storm, with varying impacts.  Worthy of monitoring updates and being cautious about outdoor activity late Saturday-Sunday. 


Below from Thursday 5AMish 8/19/21

Follow NHC and NWS collaborated guidance on the path and impacts of Henri upon our NYC subforum.

Astronomiically higher than normal tides combined with some onshore flow and building seas should result in pockets of significant coastal coastal flooding this weekend. Presuming the direct path of Henri remains e of LI, we are probably spared a tide cycle of major coastal flooding.  Vulnerable regions to typical minor coastal flooding should monitor NWS statements for an event that may be larger than the typical minor events encountered through the year 

Rip Current: Appears to me difficult to avoid the risk of dangerous rip currents this weekend. What might be good for surfers as exposed Atlantic shores coastal waves build to 6 feet, will be life threatening for most, if not all swimmers. Follow NWS and local official guidance including that of life guards.

Heavy rain: The combination of a trough(s) extending northwest of Henri and PWAT nearing 2" again, may develop pockets of intense slow moving showers well northwest of Henri's passage.  There could be isolated 3" amounts in our NYC subforum. 

Henri winds:  34 KT gusts probably remain east of our subforum but follow NHC guidance.   19/457AM

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  • Rjay featured, unfeatured and pinned this topic

It does look like the UKMET pressures are too low. But the NAM with higher pressures was west also. The GFS has been very volatile from run to run. The 0z Euro was more west than 12z but the pressures were too high. The stronger EPS members were further west than the OP.  So we’ll see what the 12z Euro and EPS comes up with. But this forecast may come down to the wire since these upper low capture scenarios are really complex.

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Several  variables for the models to decipher. How strong will Henri get? 12z Euro looks too weak again with forecast  while the UKMET is too strong. All models handle the upper low over the Delmarva differently. Some are closed and others more open. The CMC almost looks like a middle ground between the various guidance today. We may not know an exact track until we see how much deepening occurs east of the Carolinas and where the upper low ends up.






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52 minutes ago, David-LI said:

Not happening. Recon flight a few moments ago observed pressure of 1000mb and winds at around 55-60 kts. Ukie started at 985mb.

While it definitely initiated too strong there is a nice window for significant intensification while Henri is over high OHC and aligned with vertical shear. Pretty much anything is still on the table. The only certainty is in large swells and beach erosion regardless of track

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I know the ECM has been pretty accurate with how its initialized Henri, but im really quite skeptical about how much it has Henri intensifying over the next 36+ hours. The mere fact Henri has stayed as organized as it has (albeit a severely tilted vortex...but hey it didnt uncouple it) despite what would be enough sheer to rip apart PLENTY of tropical storms is alone impressive and is the main driver in my skepticism of the model forecasting relatively modest intensification. I guess well for sure know more after observing how it intensifies over the next 24 hours now that sheer is dropping significantly tonight, but I really do feel like the models that initialized it too low, may end up being the ones who are more accurate about the track and degree of intensification that occurs. I think what will happen is the track and strength of Henri will be something in between the UK and ECM/GFS, something like a landfall in the middle/east Suffolk maybe around 985-990mb. I dont think thats at all unrealistic at this point, those of us on LI need to be prepared and paying attention over the next 24 hours.

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  • wdrag changed the title to Henri: Moderate-Major impacts NYC subforum this weekend, possibly into Monday August 21-23, 2021
  • Rjay unpinned this topic

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