WxWatcher007

Euro still wants to effectively kill it on Friday/Saturday. So that’ll be a whiff on this run. The other guidance (minus Euro and Canadian) have Henri intensify nicely based on the environment parallel to the SE/Mid-Atlantic coast, but it’s moving way too slow verbatim to hit stronger than a 1 IMO as it’s on final approach. This far north you can basically lock in a hostile environment for a strong tropical system. It needs to move faster north of the Gulf Stream through landfall to compensate for the increasing rate of structural decay that would happen.

It’s not where it needs to be, but the euro has initialized much better than prior runs. I personally don’t look at the SLP at initialization, but rather the level of organization at low levels.

Ukie is a strong hit over SE New England.

The GFS has been competitive, if not better than the Euro at various elements of tropical prediction, including track forecasting. Every system is different but the GFS is legit for tropical.

That was one hell of a run. That’s as anomalous as it gets with a loop like that over SNE (not out at sea). Also note that the GFS is consistent in showing weakening on final approach.

It just rots over SNE. Long duration tropical event

It would be a cycle or two after the mission is completed. I believe special soundings can be incorporated immediately.

Grace FINALLY meets expectations. Second hurricane of the Atlantic season.

Not much time to post but here’s the latest discussion. Track shifted left again we will have recon going out to sample the environment. That’s huge. Tropical Storm Henri Discussion Number 11 NWS National Hurricane Center Miami FL AL082021 1100 AM AST Wed Aug 18 2021 Deep convection has been increasing during the past several hours in association with Henri, and the cloud pattern mostly consists of a central dense overcast with some fragmented bands around it. The Dvorak estimates are steady at 3.5/55 kt from TAFB and SAB, and therefore, the initial intensity is held at that value. However, the latest automated Dvorak values from CIMSS at the University of Wisconsin are higher, so it is possible that Henri could be slightly stronger. An SSMIS pass from 1124 UTC showed some southward tilt of the vortex with height and revealed a small mid-level eye feature. Henri continues to move just south of due west at 7 kt. The storm is expected to move westward during the next day or so as it moves in the flow on the south or southeast side of a mid-level ridge. This ridge is expected to slide eastward by Friday as a mid- to upper-level low develops over the Ohio Valley and northeastern U.S. In response, Henri is expected to turn northward or north- northeastward on Friday and continue in that direction through the weekend. One complicating factor is that several of the models show a ridge building over the northwestern Atlantic and Atlantic Canada, which could cause the storm to stay on a more northward track closer to New England than currently forecast. The spread in the models for Henri's future track is quite large, with some guidance as far west as Long Island and as far east as 62W longitude. Overall, the models continue to walk left each cycle, and the NHC track forecast has again been shifted in that direction. NOAA Gulfstream IV missions and special weather balloon soundings have been scheduled, and it is hoped that this additional data will help the models handle the evolving steering pattern. Given the uncertainty in the longer range track forecasts, users should be prepared for additional adjustments to the NHC track forecast in future forecast cycles. The storm is currently in an environment of about 15-20 kt of northerly wind shear according to the SHIPS model and analyses from CIMSS at the University of Wisconsin. Since the shear is expected to persist or become a little stronger during the next couple of days, little change in strength is predicted during that time period. After that time, the shear is expected to lessen and that should allow Henri to strengthen to a hurricane by the weekend. Some weakening is shown by the end of the period when Henri is forecast to be moving over cooler waters. The NHC intensity forecast is largely an update of the previous one and is just a little lower than the consensus aids. Key Messages: 1. Swells from Henri could reach much of the east coast of the U.S. and Atlantic Canada by the end of the week and continue through the weekend. These swells could cause life-threatening surf and rip currents. 2. Uncertainty in the track forecast for Henri this weekend and early next week is larger than usual, and there is some risk of direct impacts from Henri in portions of the northeastern U.S. and Atlantic Canada during that time. Interests in these areas should follow updates to the forecast through the next several days. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 30.0N 66.6W 55 KT 65 MPH 12H 19/0000Z 29.9N 67.9W 60 KT 70 MPH 24H 19/1200Z 29.8N 69.8W 60 KT 70 MPH 36H 20/0000Z 30.1N 71.4W 60 KT 70 MPH 48H 20/1200Z 30.7N 72.4W 60 KT 70 MPH 60H 21/0000Z 32.1N 72.5W 65 KT 75 MPH 72H 21/1200Z 34.2N 71.5W 75 KT 85 MPH 96H 22/1200Z 38.0N 69.6W 75 KT 85 MPH 120H 23/1200Z 41.0N 67.0W 65 KT 75 MPH $$ Forecaster Cangialosi

Adding D26 for good measure

It just seems so off to me on intensity. Henri looks like it could hold its own when it runs into that shear later, and it should have a favorable environment for a while as it parallels the coast. I know though that small systems can really get torn apart when encountering significant shear.

Maybe, but depending on the track I think you'd see areas that are already fairly saturated that could see trees go down easier. Of course, if it's a CT hit expect us to be knocked back to the 18th century

No update from the NHC at 8am, but Grace is clearly on its way to hurricane status, if it isn't there already. Recon is impressive so far and the northern side hasn't been sampled. It has a closed eye on recon! Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 18th day of the month at 11:54ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF98-5307Storm Name: GraceStorm Number & Year: 07 in 2021 (flight in the North Atlantic basin)Mission Number: 13Observation Number: 05A. Time of Center Fix: 18th day of the month at 11:29:30ZB. Center Fix Coordinates: 19.10N 81.30WB. Center Fix Location: 14 statute miles (22 km) to the SSE (161°) from George Town, Cayman Islands (U.K.).C. Minimum Height at Standard Level: 1,375m (4,511ft) at 850mbD. Minimum Sea Level Pressure: 994mb (29.36 inHg)E. Dropsonde Surface Wind at Center: From 255° at 8kts (From the WSW at 9mph)F. Eye Character: ClosedG. Eye Shape: Elliptical (oval shaped)G. Orientation of Major Axis in Elliptical Eye: 20° to 200° (NNE to SSW)G. Length of Major Axis in Elliptical Eye: 20 nautical miles (23 statute miles)G. Length of Minor Axis in Elliptical Eye: 12 nautical miles (14 statute miles)H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 40kts (46.0mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 52 nautical miles (60 statute miles) to the WNW (295°) of center fix at 11:06:00ZJ. Maximum Flight Level Wind Inbound: From 283° at 60kts (From the WNW at 69.0mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 4 nautical miles to the S (190°) of center fix at 11:24:30ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 56kts (64.4mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 4 nautical miles to the ESE (117°) of center fix at 11:31:00ZN. Maximum Flight Level Wind Outbound: From 240° at 64kts (From the WSW at 73.6mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 6 nautical miles to the ESE (122°) of center fix at 11:31:30ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,538m (5,046ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 1,522m (4,993ft)R. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°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: 1.5 nautical milesRemarks Section: Maximum Flight Level Wind: 64kts (~ 73.6mph) which was observed 6 nautical miles to the ESE (122°) from the flight level center at 11:31:30Z

Probably too in the weeds this far out but even a weaker system could be rough given the slow (relative to climo) motion projected on the guidance would bring prolonged rain and wind, not to mention terrible timing with regard to tides this weekend.

I can't post the tweet, but it looks like 70mph sustained was measured at a CWOP site on Grand Cayman.

Trend west continues from what I've seen so far this morning. Definitely become less of a long shot and more of a legitimate threat to the northeast given the 500mb look. A long way to go though.

Just one more addition, here's the reanalysis by Eric Webb of 500mb anomalies for NE hurricanes since 1900. Image courtesy of his Twitter. Note the dates at the bottom, and compare/contrast with the 500mb pattern being shown even on the Euro.

I love it when a TC makes my forecast look good. That Monday post looks pretty good right now for Henri lol. Still a long way to go, but that 500mb look is how we get our tropical up here. Last 8 GEFS runs Euro operational trend at 500mb

The story of Henri in two gifs GEFS last 8 runs Operational GFS last 8 runs It's easy to see the 500h changes here, and it's been similar across the guidance--even the Euro/EPS which tries its hardest to effectively kill Henri as it's making its turn to the west has been adjusting a bit to a steering pattern where we see a trough try to capture rather than kick Henri as it ends its westward jog and turns northward as ridging over eastern Canada seals off an escape route to the NE. In fact, the guidance has been playing catch up IMO from forecasting TC genesis to now, with Henri consistently more organized and further south/west than forecasts. Doesn't mean it'll stay that way, but it can have significant downstream implications. Although the location of Henri's development and potential northward swing is almost totally outside climatology from what I've seen with regard to how we get our storms (they're usually deeper in the tropics and CVs), the potential steering pattern fits the method of how we tend to see our TC impacts with ridging over SE Canada and troughing in the Great Lakes/Mid Atlantic. Again, even the operational Euro (note the EPS were the first to hint at a East Coast threat days ago before pulling back) in its last four 00z runs have trended toward a similar 500h look that lends itself to a close call or direct impact. The signal looks legit to me, but 5 days out I know a lot can change. I'm watching 1) whether the south/west trend continues as Henri runs into a more favorable environment the next 12 hours that will make it more resilient when it encounters more northerly shear later tonight, 2) whether the trough continues to be oriented in a way that creates a capture rather than a kick, and 3) whether the ridge continues to become more pronounced on guidance.

For the few EPS members that don’t kill off Henri, the trend is west as well.

Euro is not even in the same ballpark as the other guidance. It could be right, as shear should increase again in the next 24 hours or so per NHC, but it’s curious that it has no interest in intensifying Henri when it’s actually in a favorable environment and quite frankly has done well in the face of prior shear in a less organized state. We’ll see what the ensembles say and what Henri looks like later this morning but the presentation is excellent on IR and radar once again tonight with a nice convective blowup over the center and at least a mid level eye on radar.

Yeah, it’s a bit west from 12z. All the major global guidance so far and the GEFS shifted west tonight. Doesn’t mean it’ll stay that way, but it’s definitely intriguing.

Ukie is west and an eastern NE hit on the crude maps.

There’s obvious spread among the GEFS but there’s a definitive shift west this cycle through hour 102.

Very first thing I noticed. It seems like a sensitive forecast to be based on intensity, and the next 24-48 hours are really tricky because moderate shear could increase Wednesday/Thursday and small storms can be more impacted by that.