2021 Tropical Season

weatherwatchermom wrote:Lonnie says needs to be watched, but tracking east
What is your take rb

Standing by the map I posted earlier in this thread for now. The ideas there have gotten us this far, so with 3.5 days to go, and only ~150 miles separating me from the current consensus, I’m standing firm right now, especially when this thing is showing potential of under-modeled intensity/corresponding feedbacks lol

#Henri's track forecast is tricky even in the short term. A stronger Henri will travel further south and west. As it enters a more favorable environment and turns north, faster restrengthening would also lead to a further west track. Track is highly dependant on intensity here. pic.twitter.com/2lrxLwJJ0O

— Nikhil Trivedi (@DCAreaWx) August 19, 2021

Many pro Mets as per our own rb honking on this

#Henri's track forecast is tricky even in the short term. A stronger Henri will travel further south and west. As it enters a more favorable environment and turns north, faster restrengthening would also lead to a further west track. Track is highly dependant on intensity here. pic.twitter.com/2lrxLwJJ0O

— Nikhil Trivedi (@DCAreaWx) August 19, 2021

Stronger he drifts more WSW and comes more west before heading N. If that were to occur there in no curve OTS.

50% of GFS Ensemble members verify my forecast verbatim, the other 50% essentially just go due north into southern New England, as do the latest UKMET and NAM. GEM looks like the ICON - my track just further East over southern New England. I’m not sold in the due north option, as it doesn’t make sense in my opinion. The storm would either go right, out to sea in response to being “booted” East from the wave spacing between it and the trough, or, go left in response to a capture. Based on the orientation of things, I don’t think the option to the right is likely, but I do think to the left makes more sense. Now, IF we see the current orientation/placement of the trough change, THEN that completely changes irrespective of what Henri does on its own. But if anything, I still anticipate further adjustments west right now.

In addition to the above, though not that I ever use them, the JMA and NAVGEM also support my idea. VERY interested to see the EURO tonight - does it finally trend toward other guidance, or, does it revert away from its 18z Ensemble and go back to its easterly solution?

Massive changes on the EURO Op through 48. I expect this to continue through the rest of the run. If these changes translate to the Ensemble, it’ll be……not good lol

And the EURO caved. It’s still a work in progress, but the evolution is now clearly similar to the rest of the multi-model ensemble, but like the rest of them, with details TBD.

Convection looks like it’s now rotating upshear, with evidence of transverse banding returning and a possible eye formation process. We *could* be entering a period of strengthening, if not RI, as the former are all signs of a strengthening system. This will have tremendous implications on the track for several reasons, some of which were explained nicely above in mugsy’s post.

00z EURO Ensemble:

06z hurricane models:

https://www.tropicaltidbits.com/storminfo/08L_tracks_latest.png

The operationals have npoticibly trended east but this always happens and I am still riding with rb. Yikes on some of the intensities some models show sub 960 even 950mb which would have a cat 4 barreling up the coast.....Are the models over doing it or is it really plausible we get a major hurricane status with henri? I may have to go check out the surf this weekend (no not swim) with henri passing unless he comes in then no dice.

rb924119 wrote:06z hurricane models:

https://www.tropicaltidbits.com/storminfo/08L_tracks_latest.png

Well the 06z there shows a strong consensus on the cape getting battered then a fast exit almost due east. We will see what today brings, Euro is basically a 50/50 shot right now.

Clearly Henri has been influenced by the NNEasterly shear overnight.  His appearance this morning is def not as "pretty" as he was last night.  On the IR imagery you can clearly see convection being knocked down esp on the western flanks and he has taken on a much more flattened elongated appearance east to west rather than that nice tight circular structure he had yesterday.  





https://www.tropicaltidbits.com/sat/satlooper.php?region=08L&product=ir


There certainly has not been any intensification overnight.  If anything it wouldn't surprise me if the 11am update has some weakening(minor if at all however).  The shear is not forecast to diminish for at least another 24hr, probably more like 36hrs.  Now keep this in mind.  Clearly this system has been an overachiever from the get go.  Honestly if it weren't for the shear I think he would have likely taken off already, but shear is def a player and should not be overlooked yet.  

Two points Id like to make.  First Like I said yesterday with the shear involved until at least tomorrow I dont think we see any strengthening today.   Again with Henri's overachieving powers I certainly wont rule out small amt of strengthening, but; if anything some weakening over the next 24hrs is more likely than strengthening.  In addition, with the shear still involved the details on the track  after the nnorthen turn wont really come into focus until Mid day Friday the earliest.  I dont care what models do today.  Positioning and strength of Henri as he begins his ascent in latitude are important to its track thereafter, and both of these factors are still uncertain as seen in the differences among models.  

Second, and maybe Im wrong here, but Ray last night you mentioned the injection of the mid lat energy from the trough enhancing strengthening.  I think this is a non factor here.  Henri isnt forecast to interact with the mean mid lat trough at all.  It is forecast to be captured by the ULL which is forecast to cut off from the departing mean trough over the next 36-48hrs.  This will do nothing more than slow it's northerly momentum down a bit rather than inject energy into it.  Any strengthening during its northern ascent in lat will be derived from the overly warm SST of the Guld stream, and the fact that come mid day Friday and beyond the shear environment becomes much more favorable again.  I think once he gets north of the gulf stream, esp if its slowing, he weakens again before any potential landfall.  

Regarding the euro soln,   It always walks itself into the correct soln when its been struggling with the details.  It almost NEVER makes any major adjustments run to run.  Like we very often see in winter, it would not surprise me to see all modeling over correct one way, in this case west, only to adjust back the other way, in this case east, as we start to focus on the detals.  So my official forecast takes Henri to the right with a scrape to the cape of his out edges, leaving the majority of our coverage with only minor indirect impacts.  Obv that is a first call, as there is no way I'm writing off the more western track yet,l because as I mentioned above final track details still have a ways to go.

One final note. I believe recon planes are set to go out and sample conditions along the EC and I think directly into Henri early this afternoon, so maybe 18z runs today, more likely 00z, models should have this data incorporated into its soln.

12Z NAM looks interesting, shows Henri turning west at the end and heading inshore around MA...end of range and not a hurricane model, but just fwiw

jmanley32 wrote:The operationals have npoticibly trended east but this always happens and I am still riding with rb.  Yikes on some of the intensities some models show sub 960 even 950mb which would have a cat 4 barreling up the coast.....Are the models over doing it or is it really plausible we get a major hurricane status with henri? I may have to go check out the surf this weekend (no not swim) with henri passing unless he comes in then no dice.

Do so at your own risk (both the riding with me and the checking of the surf)!! haha jk

I don't think we see Henri get that strong, honestly. Mid-high grade category seems reasonable to me. Maybe, maybe getting lower end category 2 if we see RI. That said, a storm of that magnitude would still be destructive, regardless of where it goes. And IF it comes in from the east, that just exacerbates the issues.

06z EURO Ensemble:



Still adjusting IMO, but notable decrease in members that don't see some sort of curvature back toward the coast.

sroc4 wrote:One final note.  I believe recon planes are set to go out and sample conditions along the EC and I think directly into Henri early this afternoon, so maybe 18z runs today, more likely 00z, models should have this data incorporated into its soln.  

You are correct, good sir!!

rb924119 wrote:

sroc4 wrote:One final note.  I believe recon planes are set to go out and sample conditions along the EC and I think directly into Henri early this afternoon, so maybe 18z runs today, more likely 00z, models should have this data incorporated into its soln.  

You are correct, good sir!!

Looks like they are En route!

AF304 Mission #1 into HENRI
Type: Unknown | Status: En Route

As of 15:19 UTC Aug 19, 2021:
Aircraft Position: 25.55°N 78.72°W
Bearing: 27° at 263 kt
Altitude: 7467 gpm
Peak 10-second Wind: 22 kt at 81°
Extrapolated Sea-level Pressure: N/A

12z NAM has a landfall on LI, still some models and NHC has put a bit of a westward curve back in the cone b4 heading very close to the cape. Hopefully the recon will be in the 18z or 00z tonight, i bet we see potentially big changes in track maybe intensity. Scott I just saw Henri on sattelite and he actually looks a bit more symetrical than this morning, might be fighting off some of that shear. Or maybe I am not seeing it right.

rb924119 wrote:06z EURO Ensemble:



Still adjusting IMO, but notable decrease in members that don't see some sort of curvature back toward the coast.

interesting the ones that do curve and are closer to clast are the strongest, any reason why the ones more east are so weak?

sroc4 wrote:Clearly Henri has been influenced by the NNEasterly shear overnight.  His appearance this morning is def not as "pretty" as he was last night.  On the IR imagery you can clearly see convection being knocked down esp on the western flanks and he has taken on a much more flattened elongated appearance east to west rather than that nice tight circular structure he had yesterday.  





https://www.tropicaltidbits.com/sat/satlooper.php?region=08L&product=ir


There certainly has not been any intensification overnight.  If anything it wouldn't surprise me if the 11am update has some weakening(minor if at all however).  The shear is not forecast to diminish for at least another 24hr, probably more like 36hrs.  Now keep this in mind.  Clearly this system has been an overachiever from the get go.  Honestly if it weren't for the shear I think he would have likely taken off already, but shear is def a player and should not be overlooked yet.  

Two points Id like to make.  First Like I said yesterday with the shear involved until at least tomorrow I dont think we see any strengthening today.   Again with Henri's overachieving powers I certainly wont rule out small amt of strengthening, but; if anything some weakening over the next 24hrs is more likely than strengthening.  In addition, with the shear still involved the details on the track  after the nnorthen turn wont really come into focus until Mid day Friday the earliest.  I dont care what models do today.  Positioning and strength of Henri as he begins his ascent in latitude are important to its track thereafter, and both of these factors are still uncertain as seen in the differences among models.  

Second, and maybe Im wrong here, but Ray last night you mentioned the injection of the mid lat energy from the trough enhancing strengthening.  I think this is a non factor here.  Henri isnt forecast to interact with the mean mid lat trough at all.  It is forecast to be captured by the ULL which is forecast to cut off from the departing mean trough over the next 36-48hrs.  This will do nothing more than slow it's northerly momentum down a bit rather than inject energy into it.  Any strengthening during its northern ascent in lat will be derived from the overly warm SST of the Guld stream, and the fact that come mid day Friday and beyond the shear environment becomes much more favorable again.  I think once he gets north of the gulf stream, esp if its slowing, he weakens again before any potential landfall.  

Regarding the euro soln,   It always walks itself into the correct soln when its been struggling with the details.  It almost NEVER makes any major adjustments run to run.  Like we very often see in winter, it would not surprise me to see all modeling over correct one way, in this case west, only to adjust back the other way, in this case east, as we start to focus on the detals.  So my official forecast takes Henri to the right with a scrape to the cape of his out edges, leaving the majority of our coverage with only minor indirect impacts.  Obv that is a first call, as there is no way I'm writing off the more western track yet,l because as I mentioned above final track details still have a ways to go.

The shear has definitely flattened the system's appearance a bit, and it doesn't appear to have undergone the incremental organization that I was expecting to see when I woke up. However, the CDO/stronger convection remains solidly in tact over and near the center of circulation - this is huge. Henri is still fairly successfully fending itself off, and is continuing to try to organize it's convection wholly around the center. There were instances where the convection was able to rotate upshear, but it wasn't sustained. I'm curious to see what the dropsonde data show later today, as I think this system may be a bit stronger than what is currently being indicated. We shall see. Either way, the longer Henri continues these trends, the better it bodes for the system to undergo a period of RI down the road, as it's internal "combustion" (so to speak) will be allowed to more efficiently fire on its single cylinder (.......sorry, I couldn't resist - it's basically like an oversized one-lunger lmao). It should also be noted that the center is CLEARLY significantly further south than much of the guidance was previously indicating, which, as has been stated several times, should lend itself to a more impactful evolution for the Northeast, and yes, us (to what extent is still uncertain, more on this in a following comment).

Regarding your second point, I (respectfully, of course lol) think it would be unwise to watch the evolution of the larger synoptic environment. Yes, Henri's position will play a very large role in the outcome, BUT so too will the positioning and orientation of the mid-latitude trough over the eastern CONUS. There has been a notable trend southward with this feature over the last several days, which is something that I was banking on from the get-go given the hemispheric pattern in play, so this trend, to me, is completely real. It's overall retrogression (with respect to positioning) in successive runs is also something that makes physical sense based on the same drivers. While I think there is still room for further correction, which in and of itself would lead to a more impactful solution, the orientation of the energy associated with this feature is HUGELY important in interplay between it and Henri's circulation. A highly concerning trend on the guidance has not only been to back the trough and sink it south, but to also increase the negative tilt of the axis of energy in relation to the pivot point between the two systems. The more negative this tilt is (southeast-northwest oriented, coupled with a further south/west starting point of the trough), the more efficient the "slingshot effect" on Henri will be. It's basically the control arm/fulcrum for the whole setup. If the tilt of the energy is more neutral (north-south oriented) coupled with a further north/east starting point, then the less efficient the "slingshot effect" on Henri will be, and the broader the sweep of the bend. this is why yesterday we were seeing a straight north track into southern New England. If the trends continue, though, that particular solution will end up on the eastern side of the guidance envelope.

To your final few points: the ULL (upper-level low) that you are referencing is still a "trough", it's just a shorter wavelength than the mean trough over the western U.S. Semantics, admittedly, but a good point of clarification for those who may not be as well versed Secondly, as the "squeeze play" goes on between the Atlantic ridge to the east and the incoming ULL to the west/northwest, you have the corresponding steering currents working constructively (or at least some of their directional components), which will add forward momentum to Henri, increasing its forward speed with latitude. In order for the ULL to capture Henri's circulation, it has to phase with it. Whenever a phase occurs, there is always an injection of energy, and this goes back to my conversation with jman: The phase by itself may not ACTUALLY increase the strength of the storm, but it will work to offset the weakening by allowing mid-latitude dynamics to at least partially compensate for the decreasing oceanic thermal input (i.e. being downstream of a trough axis, vorticity advection, jet structure, etc. all leading to an area of general upper-level venting). That said, it would not surprise me to see some strengthening depending on the evolution of any extra-tropical transition. Lastly, your "windshield wiper" prognostication of the adjustments of guidance is spot on, and should always be considered. And, your first call is certainly reasonable

WE TRACK!!!

GFS suite now trending away from the NAM with respect to the ULL/trough over eastern CONUS - NAM is trending deeper with it, GFS trending shallower. This is why it's gone further east at 12z. Classic divergence in the short range now commencing......

jmanley32 wrote:

rb924119 wrote:06z EURO Ensemble:



Still adjusting IMO, but notable decrease in members that don't see some sort of curvature back toward the coast.

interesting the ones that do curve and are closer to clast are the strongest, any reason why the ones more east are so weak?

Differences in how they handle evolution of Henri's convection and correlated intensity changes/impacts on the surrounding environment.

Hey Scott, take a look at the 12z UKMET……..Henri stops by your place to say hello lol

Very concerning trends on the shorter range guidance today. Globals so far are a mishmosh. GFS suite deamplified a little bit, GEM looks to have amplified a little bit. EURO Op on deck in 48 minutes.

rb924119 wrote:Hey Scott, take a look at the 12z UKMET……..Henri stops by your place to say hello lol

OH MY