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Tropical Storm Henri


wxeyeNH
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And for the Sandy/1938/Carol etc thoughts, the pre-Sandy ones likely had big helps from the mid-latitude jet accelerating them and adding energy. Donna I can't say but likely the same story. Sandy essentially became the Perfect Storm 1991 literally doubled due to Sandy's own intensity, huge size, the trough phasing in and blocking high which drove it NW. This is nothing like that. Not to say this won't have significant impact somewhere but I think it's mostly rain related and over CT or 50 miles or so W and SW of where it tracks. 

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Strengthening now beginning

TCDAT3

Tropical Storm Henri Discussion Number  22
NWS National Hurricane Center Miami FL       AL082021
500 AM EDT Sat Aug 21 2021

An earlier GMI satellite microwave image continued to indicate that
Henri's low-level center was still located near the northwestern 
edge of the convective canopy.  However, more recent geostationary 
satellite imagery shows that the convection is beginning to wrap 
around the northeastern and eastern portions of the circulation 
suggesting that the anticipated decrease in shear is occuring, and 
that Henri may be on the verge of strengthening.  The latest 
subjective satellite intensity estimates from SAB and TAFB remained 
unchanged so the initial intensity remains 60 kt, in agreement with 
those estimates and the earlier aircraft data.  The next 
reconnaissance aircraft mission should be in the storm around 
1200 UTC this morning.

Henri is moving north-northeastward or 015/10 kt. A mid- to
upper-level low and associated trough over the Appalachians and
Ohio Valley should steer Henri north-northeastward at a faster
forward speed today.  As Henri moves around the eastern portion of
the upper-low, the storm is forecast to turn north-northwestward
tonight.  This motion will bring the center of Henri near or over
portions of Long Island and Southern New England on Sunday and into
the northeastern United States Sunday night.  After that time, the
cyclone should turn east-northeastward as it becomes caught in the
mid-latitude westerlies.  The latest dynamical model envelope
continues to narrow for the first 24 to 36 hours of the forecast
period and only small adjustments were needed to that portion of
the track.  After that time, the guidance has trended to taking
Henri farther inland over the Northeastern United States, and the
NHC forecast as been modified accordingly.

Decreasing shear, upper-level divergence associated with the trough
to Henri's west, and warm SSTs should allow the cyclone to
strengthen during the next 12-18 hours.  Although not explicitly
shown in the intensity forecast, Henri could still peak around 75 kt
later today or this evening.  After that time, cooler waters are
likely to cause a gradual reduction in intensity, however, Henri is
forecast to be at or near hurricane strength at landfall. Once the
center moves inland over the Northeast United States, a faster rate
of filling is anticipated.  The system is forecast to become
post-tropical in about 60 hours, and it will likely dissipate around
day 4, if not a little sooner.  The updated intensity forecast is
near the upper-end of the intensity guidance during the first 12-24
hours, and is close to the Decay-SHIPS model thereafter.

Users are reminded to not focus on the exact forecast of the
center of Henri since impacts will extend far from the center.

Key Messages:

1. Dangerous storm surge inundation is expected to begin late
tonight or Sunday in portions of Long Island, Connecticut,
Rhode Island, and southeastern Massachusetts, where a Storm Surge
Warning has been issued. Dangerous storm surge is possible
beginning late tonight or Sunday in western portions of Long
Island and Connecticut in the Storm Surge Watch area.  Residents in
these areas should follow any advice given by local officials.

2. Hurricane conditions are expected to begin late tonight or
Sunday in portions of Long Island and Connecticut, where a
Hurricane Warning has been issued.  Hurricane conditions are
possible late tonight or Sunday across portions of Rhode Island.

3. Heavy rainfall may lead to considerable flash, urban, and small
stream flooding, along with the potential for widespread minor and
isolated moderate river flooding, over portions of Long Island, New
England, southeast New York and northern New Jersey.

4. Swells from Henri will continue to affect much of the east coast
of the U.S. through the weekend. These swells could cause
life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 33.1N  73.2W   60 KT  70 MPH
 12H  21/1800Z 35.6N  72.3W   70 KT  80 MPH
 24H  22/0600Z 38.8N  72.0W   70 KT  80 MPH
 36H  22/1800Z 40.9N  72.7W   60 KT  70 MPH...INLAND
 48H  23/0600Z 42.1N  73.6W   35 KT  40 MPH...INLAND
 60H  23/1800Z 42.8N  73.3W   25 KT  30 MPH...POST-TROP/INLAND
 72H  24/0600Z 43.3N  71.5W   25 KT  30 MPH...POST-TROP/INLAND
 96H  25/0600Z 44.5N  62.5W   25 KT  30 MPH...POST-TROPICAL
120H  26/0600Z...DISSIPATED

$$
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Yeah let me get in before the flood of storm cancel posts that we know are coming...

IR can be deceiving, as I hope we've all seen the last few days. Despite what you think you see on first glance this morning on visible and IR, under the hood microwave imagery shows a more organized storm, with much less tilt and another attempt to form an inner core.

Henri has been trying to do this the entire time, but the difference now is that with lessening shear, the attempt is more likely (though not guaranteed) to be successful. 

Yesterday

D6oWsbD.jpg

nRgxyD5.jpg

 

This morning

l1rPROx.jpg

pyo4Rp7.jpg

 

it's still very fragile just based on this imagery. You don't see the deepest convection fully wrapped around and until that happens this attempt at organization could all still collapse, but it looks ok at the moment.  

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First recon flight of the day descending into the storm now. I'm watching 1) has the tilt been eliminated 2) has the wind field contracted and organized into an inner core and 3) are the FL winds that were impressive last night starting to translate to the surface as a result. 

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2 minutes ago, WxWatcher007 said:

First recon flight of the day descending into the storm now. I'm watching 1) has the tilt been eliminated 2) has the wind field contracted and organized into an inner core and 3) are the FL winds that were impressive last night starting to translate to the surface as a result. 

Any good links?

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5 minutes ago, MarkO said:

Also lol'd at the NAVGEM. Just checked it for shit's and giggles. Still, lot more model spread this AM between the two camps. NAM taking it just northeast of NYC and GFS is almost into Newport, RI.

RGEM is east as well. 

I think the Euro tickles a bit more east and this ends up a BID landfall

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This is really where recon earns their keep. IR and microwave can only tell us so much. It's the real time observations from recon that can tell us what's really happening. Really interested to see how much tilt there still is and whether the features we see are working their way down to the surface. 

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The model spread seems like it has increased overnight. Definitely an east trend but you still have guidance over central/western LI but now instead of BID being near the eastern envelope, some other eastward guidance is near UUU. 

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1 minute ago, ORH_wxman said:

The model spread seems like it has increased overnight. Definitely an east trend but you still have guidance over central/western LI but now instead of BID being near the eastern envelope, some other eastward guidance is near UUU. 

Give me UUU----having spent too much time following this, I hopeI can at least score some good rains .

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4 minutes ago, WxWatcher007 said:

This is really where recon earns their keep. IR and microwave can only tell us so much. It's the real time observations from recon that can tell us what's really happening. Really interested to see how much tilt there still is and whether the features we see are working their way down to the surface. 

This doesn't get said enough: thank you for all your input here.

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Interesting to note that while there are some hints of an eastward trend, a loop of the Northeast radar composite nicely shows showers across central & western NY heading west/northwest; strongly implying the modeled tug or bend back to the northwest as Henri is likely as it approaches LI. 

Aug 21 Henri.png

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We have the center dropsonde from the early recon flight (Mission 9). Pressure looks more or less steady from last night, maybe a few mb lower given the wind at the surface. That flight is now heading for a NW to SE pass. 

Product: NOAA Temp Drop (Dropsonde) Message (UZNT13 KWBC)
Transmitted: 21st day of the month at 10:29Z
Agency: National Oceanic and Atmospheric Administration (NOAA)
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Name: Henri
Storm Number: 08 (flight in the North Atlantic basin)
Mission Number: 9
Observation Number: 03 ( See all messages of this type for this mission. )

Part A...
 

Date: Near the closest hour of 10Z on the 21st day of the month
Highest Mandatory Level For Which Wind Was Reported: 700mb
Coordinates: 33.3N 72.7W
Location: 211 statute miles (339 km) to the SE (130°) from Cape Hatteras, NC, USA.
Marsden Square: 116 ( About )
 
Surface and Standard Isobaric Surfaces
Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1000mb -37m (-121 ft) This level does not exist in this area of the storm above the surface level.
996mb (29.42 inHg) Surface (Sea Level) 27.4°C (81.3°F) 25.7°C (78°F) 230° (from the SW) 31 knots (36 mph)
925mb 652m (2,139 ft) 24.0°C (75.2°F) 21.6°C (71°F) 225° (from the SW) 19 knots (22 mph)
850mb 1,391m (4,564 ft) 19.8°C (67.6°F) 18.4°C (65°F) 285° (from the WNW) 15 knots (17 mph)
700mb 3,053m (10,016 ft) 14.0°C (57.2°F) About 8°C (46°F) 65° (from the ENE) 8 knots (9 mph)

Information About Radiosonde:
- Launch Time: 10:06Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 
Dropsonde Location: Dropped in center.

Highest altitude where wind was reported:
- Location: 33.26N 72.72W
- Time: 10:06:33Z

Lowest altitude where wind was reported:
- Location: 33.26N 72.70W
- Time: 10:11:11Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 230° (from the SW)
- Wind Speed: 32 knots (37 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 255° (from the WSW)
- Wind Speed: 14 knots (16 mph)
- Depth of Sounding: From 695mb to 995mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 155 gpm - 5 gpm (509 geo. feet - 16 geo. feet)
- Wind Direction: 230° (from the SW)
- Wind Speed: 31 knots (36 mph)

Sounding Software Version: AEV 30406
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
996mb (Surface) 27.4°C (81.3°F) 25.7°C (78°F)
949mb 24.2°C (75.6°F) 23.1°C (74°F)
917mb 24.4°C (75.9°F) 20.8°C (69°F)
850mb 19.8°C (67.6°F) 18.4°C (65°F)
773mb 15.8°C (60.4°F) 14.8°C (59°F)
750mb 17.2°C (63.0°F) About 11°C (52°F)
695mb 13.2°C (55.8°F) About 8°C (46°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
996mb (Surface) 230° (from the SW) 31 knots (36 mph)
953mb 230° (from the SW) 32 knots (37 mph)
943mb 235° (from the SW) 28 knots (32 mph)
931mb 225° (from the SW) 17 knots (20 mph)
892mb 250° (from the WSW) 18 knots (21 mph)
865mb 265° (from the W) 13 knots (15 mph)
850mb 285° (from the WNW) 15 knots (17 mph)
799mb 285° (from the WNW) 24 knots (28 mph)
787mb 275° (from the W) 15 knots (17 mph)
779mb 285° (from the WNW) 10 knots (12 mph)
763mb 265° (from the W) 4 knots (5 mph)
695mb 65° (from the ENE) 8 knots (9 mph)
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8 minutes ago, jbenedet said:

I like the NHC’s track. Risk vs guidance is still skewed west—the recent trends East have been due to much less phasing with the UL trough, and not less ridging to the east. 

I still find it hard to believe in 2021 models could be that far off with the track this close in.  Their cone seems somewhat absurd to me at 2pm tomorrow of NYC or Cape Cod.  It’s probably 98% it ends up within 10-20 miles of their current position forecast at that time 

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  • dendrite changed the title to Tropical Storm Henri
  • dendrite unpinned this topic

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