WxWatcher007

Posting because this was actually alluded to a bit this morning and we did see some hints of a possible downshear reformation that looked to be ongoing from recon. Not saying RI is happening for those lurking, but rather highlighting a possible reason we see intensification once this starts paralleling the coast. Xiaomin is an atmospheric scientist for HRD (Hurricane Research Division) at NOAA.

That'd push big rains right into CT

Final VDM. Pressure drop of 2mb but no eye information. Center a little NW. Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 19th day of the month at 19:46ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF97-5304Storm Name: HenriStorm Number & Year: 08 in 2021 (flight in the North Atlantic basin)Mission Number: 1Observation Number: 13 ( See all messages of this type for this mission. )A. Time of Center Fix: 19th day of the month at 19:05:10ZB. Center Fix Coordinates: 29.63N 71.14WB. Center Fix Location: 420 statute miles (675 km) to the WSW (244°) from Hamilton, Bermuda (U.K.).C. Minimum Height at Standard Level: 1,439m (4,721ft) at 850mbD. Minimum Sea Level Pressure: 998mb (29.47 inHg)E. Dropsonde Surface Wind at Center: From 170° at 18kts (From the S at 21mph)F. Eye Character: Not AvailableG. Eye Shape: Not AvailableH. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 48kts (55.2mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 21 nautical miles (24 statute miles) to the NE (48°) of center fix at 18:58:30ZJ. Maximum Flight Level Wind Inbound: From 149° at 61kts (From the SSE at 70.2mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 46 nautical miles (53 statute miles) to the NE (49°) of center fix at 18:50:00ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 33kts (38.0mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 51 nautical miles (59 statute miles) to the SW (227°) of center fix at 19:21:30ZN. Maximum Flight Level Wind Outbound: From 303° at 39kts (From the WNW at 44.9mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 24 nautical miles (28 statute miles) to the SW (224°) of center fix at 19:13:00ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,525m (5,003ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 1,529m (5,016ft)R. Dewpoint Temp (collected at same location as temp inside eye): 13°C (55°F)R. Sea Surface Temp (collected at same location as temp inside eye): Not AvailableS. Fix Determined By: Penetration, Radar, Wind, Pressure and TemperatureS. Fix Level: 850mbT. Navigational Fix Accuracy: 0.02 nautical milesT. Meteorological Accuracy: 0.5 nautical milesRemarks Section: Maximum Flight Level Wind: 61kts (~ 70.2mph) which was observed 46 nautical miles (53 statute miles) to the NE (49°) from the flight level center at 18:50:00Z

Looks like the pressure is dropping. Here's the latest center dropsonde. Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)Transmitted: 19th day of the month at 19:20ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF97-5304Storm Name: HenriStorm Number: 08 (flight in the North Atlantic basin)Mission Number: 1Observation Number: 14 ( See all messages of this type for this mission. )Part A... Date: Near the closest hour of 19Z on the 19th day of the month Highest Mandatory Level For Which Wind Was Reported: 925mb Coordinates: 29.6N 71.1W Location: 419 statute miles (674 km) to the WSW (244°) from Hamilton, Bermuda (U.K.). Marsden Square: 080 ( About ) Surface and Standard Isobaric Surfaces Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed 1000mb -20m (-66 ft) This level does not exist in this area of the storm above the surface level. 998mb (29.47 inHg) Surface (Sea Level) 26.6°C (79.9°F) 25.2°C (77°F) 170° (from the S) 18 knots (21 mph) 925mb 667m (2,188 ft) 23.0°C (73.4°F) 22.6°C (73°F) 170° (from the S) 22 knots (25 mph) 850mb 1,408m (4,619 ft) 23.0°C (73.4°F) About 18°C (64°F) No Wind Report Available For This Level Information About Radiosonde: - Launch Time: 19:05Z - About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction. Remarks Section... Dropsonde Location: Dropped in center. Lowest altitude where wind was reported: - Location: 29.64N 71.14W - Time: 19:07:16Z Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding): - Wind Direction: 170° (from the S) - Wind Speed: 23 knots (26 mph) Deep Layer Mean Wind (average wind over the depth of the sounding): - Wind Direction: 180° (from the S) - Wind Speed: 18 knots (21 mph) - Depth of Sounding: From 844mb to 997mb 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: 170° (from the S) - Wind Speed: 21 knots (24 mph) Sounding Software Version: AEV 30404 Part B: Data for Significant Levels... Significant Temperature And Relative Humidity Levels Level Air Temperature Dew Point 998mb (Surface) 26.6°C (79.9°F) 25.2°C (77°F) 916mb 22.6°C (72.7°F) 22.1°C (72°F) 896mb 24.0°C (75.2°F) 19.1°C (66°F) 850mb 23.0°C (73.4°F) About 18°C (64°F) Significant Wind Levels Level Wind Direction Wind Speed 998mb (Surface) 170° (from the S) 18 knots (21 mph) 995mb 170° (from the S) 21 knots (24 mph) 947mb 170° (from the S) 24 knots (28 mph) 918mb 170° (from the S) 22 knots (25 mph) 889mb 200° (from the SSW) 18 knots (21 mph)

Recon turning and heading toward a NE to SW pass. I must say it is more organized than I thought it would be. Winds don't really matter here, it's about how organized the center is and whether there is an inner core. So far, the answer to that seems to be yes, which makes it more likely to quickly reorganize and intensify when shear decreases. On this pass it'll also be interesting to see if there's a westward heading of the center or a continued south of due west motion. The latter would imply that it remains deep enough to verify further west.

Like I said, very interesting flight. VDM shows that there is still an inner core, with an eye open to the NW. At 1000mb! Recon starting to inspect the NE quadrant now. Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 19th day of the month at 18:14ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF97-5304Storm Name: HenriStorm Number & Year: 08 in 2021 (flight in the North Atlantic basin)Mission Number: 1Observation Number: 06 ( See all messages of this type for this mission. )A. Time of Center Fix: 19th day of the month at 17:30:40ZB. Center Fix Coordinates: 29.57N 70.97WB. Center Fix Location: 413 statute miles (664 km) to the WSW (243°) from Hamilton, Bermuda (U.K.).C. Minimum Height at Standard Level: 1,436m (4,711ft) at 850mbD. Minimum Sea Level Pressure: 1000mb (29.53 inHg)E. Dropsonde Surface Wind at Center: From 5° at 8kts (From the N at 9mph)F. Eye Character: Open in the northwestG. Eye Shape & Diameter: Circular with a diameter of 22 nautical miles (25 statute miles)H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 33kts (38.0mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 60 nautical miles (69 statute miles) to the WNW (303°) of center fix at 17:12:00ZJ. Maximum Flight Level Wind Inbound: From 25° at 38kts (From the NNE at 43.7mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 60 nautical miles (69 statute miles) to the WNW (303°) of center fix at 17:12:00ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 48kts (55.2mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 39 nautical miles (45 statute miles) to the SE (138°) of center fix at 17:46:00ZN. Maximum Flight Level Wind Outbound: From 230° at 61kts (From the SW at 70.2mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 28 nautical miles (32 statute miles) to the SE (142°) of center fix at 17:42:30ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,520m (4,987ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,522m (4,993ft)R. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)R. Sea Surface Temp (collected at same location as temp inside eye): Not AvailableS. Fix Determined By: Penetration, Radar, Wind, Pressure and TemperatureS. Fix Levels (surface & flight level centers within 5nm of each other): Surface and 850mbT. Navigational Fix Accuracy: 0.02 nautical milesT. Meteorological Accuracy: 6 nautical milesRemarks Section: Maximum Flight Level Wind: 61kts (~ 70.2mph) which was observed 28 nautical miles (32 statute miles) to the SE (142°) from the flight level center at 17:42:30Z Maximum Flight Level Temp: 23°C (73°F) which was observed 8 nautical miles to the NW (307°) from the flight level center

Really hope we can get multiple fixes to figure out what is going on with the center.

Data is a bit wonky by my eye, but there are FL winds between 55-60kts and some unflagged 47-48kt SFMR readings. Not bad given the shear.

Center dropsonde. Looks like the pressure is a touch lower than 1000mb. Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC) Transmitted: 19th day of the month at 17:41Z Agency: United States Air Force Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5304 Storm Name: Henri Storm Number: 08 (flight in the North Atlantic basin) Mission Number: 1 Observation Number: 07 ( See all messages of this type for this mission. ) Part A... Date: Near the closest hour of 18Z on the 19th day of the month Highest Mandatory Level For Which Wind Was Reported: 850mb Coordinates: 29.6N 70.9W Location: 408 statute miles (657 km) to the WSW (243°) from Hamilton, Bermuda (U.K.). Marsden Square: 080 ( About ) Surface and Standard Isobaric Surfaces Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed 1000mb -2m (-7 ft) Other data not available. 925mb 686m (2,251 ft) 22.8°C (73.0°F) 22.3°C (72°F) 360° (from the N) 7 knots (8 mph) 850mb 1,425m (4,675 ft) 22.8°C (73.0°F) About 16°C (61°F) 270° (from the W) 4 knots (5 mph) Information About Radiosonde: - Launch Time: 17:31Z - 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: 29.58N 70.94W - Time: 17:31:08Z Lowest altitude where wind was reported: - Location: 29.58N 70.94W - Time: 17:33:24Z Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding): - Wind Direction: 15° (from the NNE) - Wind Speed: 8 knots (9 mph) Deep Layer Mean Wind (average wind over the depth of the sounding): - Wind Direction: 345° (from the NNW) - Wind Speed: 7 knots (8 mph) - Depth of Sounding: From 844mb to 999mb Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding: - Lowest 150m: 160 gpm - 10 gpm (525 geo. feet - 33 geo. feet) - Wind Direction: 10° (from the N) - Wind Speed: 8 knots (9 mph) Sounding Software Version: AEV 30404 Part B: Data for Significant Levels... Significant Temperature And Relative Humidity Levels Level Air Temperature Dew Point 1000mb (Surface) 27.4°C (81.3°F) 25.2°C (77°F) 924mb 22.6°C (72.7°F) 22.1°C (72°F) 873mb 21.4°C (70.5°F) 18.9°C (66°F) 850mb 22.8°C (73.0°F) About 16°C (61°F) Significant Wind Levels Level Wind Direction Wind Speed 1000mb (Surface) 5° (from the N) 8 knots (9 mph) 905mb 340° (from the NNW) 7 knots (8 mph) 882mb 310° (from the NW) 11 knots (13 mph) 871mb 315° (from the NW) 12 knots (14 mph) 866mb 320° (from the NW) 10 knots (12 mph) 854mb 285° (from the WNW) 6 knots (7 mph) 844mb 205° (from the SSW) 3 knots (3 mph)

Interesting so far. Like I was saying earlier, it looked like it was decoupling under the shear but that process stopped on visible. Recon is finding the center deeper within the convection. It'll probably have a strong tilt, but it's not separated from the data we have so far. Center is a little weaker than estimates though. Not sure what they'll find deeper within the convection.

Recon looks like it is approaching the center. Lowest extrapolated pressure so far is 1000.1mb at ~5k ft.

I knew it wouldn't be long before the model slander began Recon has just started sampling the storm. https://www.tropicaltidbits.com/recon/

Here’s the actual data.

Recon starting its descent into the system now. The first thing to watch for will be how tilted the vortex is. It looked like decoupling was close on visible but the last few frames look like that has halted, at least for now.

Tropical tracking ain't for the faint of heart lol

It's pretty straightforward. The track is very sensitive to intensity and that's across guidance. Been that way for days. Weaker solutions mean a further east track, and when you have globals trying to resolve TC intensity in a steering environment that's highly sensitive to it you'll get waffling. I wouldn't be locking onto anything strong or weak yet. Next 24 hours are critical.

I'm not that far out yet, but the GFS could be looking at a longer recovery from the current shear.

You have to download it, but here's a good powerpoint on it https://www.wpc.ncep.noaa.gov/hmt/seminar_files/PRE_NWS_Teletraining.ppt

Yeah, there's a tradeoff. Wind for rain and coastal flooding depending on the heading. We actually had a significant flash flood event this morning here due to Fred. Shades of 1955.

The first recon flight is wheels up and en route to Henri. Looks like it's the low level recon flight.

Yeah I haven't come across anything like that. I just look at deep layer shear and maybe wind vectors at different heights on the Euro and GFS.

Shear vector and height matter a lot. Last year, Isaias went from unfavorable to favorable environment as it was paralleling the FL/Carolina coast because of the heading change. I believe that also was the case for Dorian as it started going up the same region. For Fred, we saw less deep layer shear near the FL panhandle that allowed it to organize (though not fully) despite decent shear at higher levels.

A couple of important points from that 11am disco 1) despite the shear, objective analysis still has a strong TS to low end hurricane currently. Recon will sort that out but given the shear we're seeing Henri is hanging tough so far. 2) It's still moving south of due west. Seems like a small thing, but that probably increases the likelihood of a more westward track as it parallels the coast, which puts it in a better TCHP/SST environment. 3) NHC hasn't latched onto the stall/loop idea, but it has discussed acceleration more as it comes north. Definitely worth watching because that's how we'd get better winds up here. Slowing with rapid decay won't get it done. 4) Note the language when talking about shear. Henri should find a favorable environment for intensification if shear is very low, especially if it is able to continue with at least a strong mid level vortex and deep convection. 5) They also note the expansion of the wind field as it heads north.

NHC has it analyzed at 25kts per their discussion fwiw. I got 32kts from CMISS. Looks like it decreases significantly in about 24 hours. From the NHC discussion: The current north-northeasterly shear over Henri is forecast to continue for about another day, and given the degraded structure of the system it seems unlikely that the storm will strengthen during that time period. However, the shear is expected to decrease on Friday and it will remain quite low through the weekend. Therefore, strengthening to a hurricane is expected during that time period. Once Henri crosses the north wall of the Gulf Stream in a few days, steady weakening is predicted. The NHC intensity forecast is just an update of the previous one and lies near the middle of the guidance envelope.