WxWatcher007

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.

There’s your weenie GFS run of the season. Basically a perfect “capture” to slingshot it into eastern NE as ridging over the top closes the escape route. Interesting, but show me the ensembles.

Newest VDM now has an eye that’s open to the north and northwest. Clearly still organizing per recon.

Based on the vortex data message (VDM) from 30 minutes ago, it’s not an eye. Definitely more organized than its ever been as a system though.

Tropical Storm Henri Discussion Number 8 NWS National Hurricane Center Miami FL AL082021 500 PM AST Tue Aug 17 2021 Henri appears to be gaining strength. Satellite images show banding features becoming increasingly curved, especially on the east side of the system, and an eye feature has been occasionally seen in radar images from Bermuda. The upper-level outflow is also well established to the north and east of the center. The center itself is estimated to be located near the western edge of the convection, but it is possible that a new center is forming farther east. The initial intensity is raised to 55 kt following the Dvorak classification from TAFB. The initial wind radii has been expanded outward based on an earlier ASCAT pass. The tropical storm appears to have slowed down, and the latest initial motion estimate is 255/2 kt. A subtropical ridge over the western Atlantic is building eastward to the north of Henri, and this feature should steer the storm westward at a slightly faster pace during the next two to three days. After that time, the ridge is expected to weaken and shift farther east as a cut off low or negatively-tilted trough develops over the northeast U.S. This change in the steering pattern should cause Henri to turn northeastward between Bermuda and the east coast of the U.S in the 72-120 h period. There is a fair amount of spread in exactly when and where Henri makes this turn and the GFS and EC ensembles have some members not far offshore of New England and Atlantic Canada. Overall, the guidance has shifted westward again this cycle, and the NHC track forecast has been adjusted accordingly from days 3 to 5. The northwesterly shear currently affecting Henri is subsiding, which should allow the storm to gain a little more strength tonight. However, a round of moderate northerly shear is expected to setup over Henri on Wednesday and Thursday and that will likely temporarily end the opportunity for strengthening. Although this shear would typically cause some weakening, the combination of warm SSTs and increasing mid-level moisture could offset the negative influences of the shear. By Friday and over the weekend, the shear is expected to lessen again and since the other environmental factors are predicted to remain favorable for the storm, strengthening is shown from days 3-5. This forecast is above the previous one, and lies fairly close to the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 30.4N 64.2W 55 KT 65 MPH 12H 18/0600Z 30.3N 65.5W 60 KT 70 MPH 24H 18/1800Z 30.2N 67.0W 60 KT 70 MPH 36H 19/0600Z 30.2N 68.6W 60 KT 70 MPH 48H 19/1800Z 30.3N 70.0W 60 KT 70 MPH 60H 20/0600Z 31.0N 71.1W 60 KT 70 MPH 72H 20/1800Z 32.0N 71.5W 65 KT 75 MPH 96H 21/1800Z 35.5N 69.6W 70 KT 80 MPH 120H 22/1800Z 39.1N 65.2W 70 KT 80 MPH $$ Forecaster Cangialosi

65mph/997mb at 5pm Now expected to become a hurricane by the NHC

I know I know I’m asking a lot

Henri has an excellent presentation on both visible and radar. Radar shows a nearly fully developed eyewall, though it's hard to be 100% sure without recon confirming it's not a mid level feature.

I can’t see anything yet with the EPS but a quick glance of the Euro showed perhaps a less pronounced PRE signal as Henri passes SE?

I know…you riled me up. That comment was more with regard to winter wx threats lol. In all seriousness, I always appreciate hearing your tropical thoughts. I know I sometimes come off as waffling with my tropical posts but I have two good reasons it: 1) I’ve been burned too many times making declarations, especially during my early tropical tracking days 2) I’m a lawyer and I’m trained to think and write that way

And this post makes that kind of discussion impossible.

I just meant not worth discussing in terms of verbatim impacts here in SNE. That’s a prickly response to my post, but that’s alright. I’m simply stating that the steering environment as currently modeled is more conducive for casual tracking and discussion than straight flushing it. I’m not calling for play by play of cherry picked operational guidance or weenie IR hallucinations. I know it’s usually HECS or bust for you but there’s a lot of marginal stuff that may not bring exciting conditions to your backyard in between that’s worth a little discussion.

Let me just be clear. I’m less concerned with what the models show and more intrigued by the broader trend so far, which has been more west/strong in the presence of a ridge/trough pairing that if positioned and timed right could make things more interesting. Given the environment, while highly unlikely at the moment, there is a window for something more interesting if things align. Obviously two different setups but Grace went from a S FL 5 day NHC forecast to a Bay of Campeche forecast in 48 hours. That’s the exception to the rule but it’s a reminder that track and intensity forecasting in tropical is still really hard in complex setups when models are playing catch up to the actual environmental conditions.

You’ll get your 1938 redux from a Bermuda low the models couldn’t sniff out until it developed and like it

That site is good for quick panels but use pivotal or another site for higher resolution. It’s a heck of a low off the coast verbatim.

Not really worth discussing more since the Ukie has been bad with tropical this season IMO (though all the models have had their bad moments), but Henri is far stronger on the higher resolution Ukmet. I really do think OTS is most likely, but I wouldn’t say it’s a lock. Everything would really need to come into place fairly quickly for any type of impact here. The models have really struggled this season as a whole.

Tropical Storm Henri Discussion Number 7 NWS National Hurricane Center Miami FL AL082021 1100 AM AST Tue Aug 17 2021 Henri remains a sheared tropical storm. Geostationary satellite images and microwave data show a relatively large area of deep convection (~200 miles across), but the center of the storm is located near the western edge of the thunderstorms due to ongoing northwesterly vertical wind shear. The latest Dvorak estimates have been steady at 3.0/45 kt from TAFB and SAB, and based on that data, the initial intensity is held at 45 kt. The center of Henri is located roughly 130 miles south-southeast of Bermuda currently, and this will likely be as close as the storm gets to the island. The tropical storm is gradually turning to the west, as expected, and the initial motion is estimated to be 255/5 kt. A subtropical ridge over the western Atlantic is building eastward to the north of Henri, and this feature should steer the storm westward at a slightly faster pace during the next two or three days. After that time, the ridge is expected to weaken and shift farther east as a cut off low or negatively-tilted trough develops over the northeast U.S. This change in the steering pattern should cause Henri to turn northeastward between Bermuda and the east coast of the U.S in the 72-120 h period. The NHC track forecast is a little faster than the previous one in the short term and farther west than the previous one from days 3-5, trending toward the latest consensus models. The northwesterly shear currently affecting Henri is expected to subside later today, and that should allow the storm to gain strength during the next 12-24 hours. However, a round of moderate northerly shear is expected to setup over Henri during the 24-96 hour period. Although this shear would typically cause some weakening, the combination of warm SSTs and increasing mid-level moisture could offset the negative influences of the shear. Therefore, no change in strength is predicted beyond the 24 h period. Some of the models suggest that the shear could lessen again this weekend, so although not explicitly forecast, some strengthening is possible then. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 30.4N 64.3W 45 KT 50 MPH 12H 18/0000Z 30.4N 65.1W 50 KT 60 MPH 24H 18/1200Z 30.3N 66.5W 55 KT 65 MPH 36H 19/0000Z 30.3N 68.2W 55 KT 65 MPH 48H 19/1200Z 30.4N 69.7W 55 KT 65 MPH 60H 20/0000Z 30.7N 70.6W 55 KT 65 MPH 72H 20/1200Z 31.6N 71.3W 55 KT 65 MPH 96H 21/1200Z 34.1N 69.6W 55 KT 65 MPH 120H 22/1200Z 37.4N 66.0W 55 KT 65 MPH $$ Forecaster Cangialosi