Windspeed Posted September 23, 2023 Share Posted September 23, 2023 Tropical Depression 17 has formed in the MDR of the Atlantic. It is not yet forecast by the NHC to become a hurricane. This is due to a future that includes westerly shear at the 20°N latitude stretching from just WNW of the TC to along the northern Leewards. There, however, is some uncertainty bearing on the location and timing of a WATL trough versus ridge strength west of the Azores. A fast turn north with a deepening upper trough to the west might eventually place the system in a more favorable environment in the N Central Atlantic. The TC should have a recurving track and sheared while doing so until late next week. 2 1 Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted September 23, 2023 Share Posted September 23, 2023 How many depressions form E of 50W after September 21? Link to comment Share on other sites More sharing options...
MattPetrulli Posted September 27, 2023 Share Posted September 27, 2023 00z Euro brings it pretty far west and redevelops it a little. It's the vorticity over the Bahamas, the other concentrated vorticity is 91L. GFS kinda does this too. Something to watch over the next few days. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 28, 2023 Share Posted September 28, 2023 The model guidance for this system has become comical Link to comment Share on other sites More sharing options...
Windspeed Posted September 28, 2023 Author Share Posted September 28, 2023 Too much chaos to simulate between the globals due to the close proximity of both Philippe and Rina's vort maximums. Additionally, we have a hybrid low (remnents of Ophelia) and an upper trough that will split off the ECONUS with uncertainty between 500 hPa ridging and weakness.I think it's a very low confidence forecast between either TC and their eventual tracks right now. If Philippe were more intense, I would consider Rina being absorbed or dissipating. But if Philippe drives SW due to the synoptic setup and Fujiwara effect, it should remain sheared just NE of the Leewards.Haven't said much since the initial post, as nothing much has changed in idea here. If Philippe can shake off Rina and lift north, it could find a more favorable environment and intensify. That was a potential outcome with the original recurve guidance, though that is now more uncertain. Likewise, if Philippe were to remain sheared, get decapitated, or outright dissipate, then Rina could possibly become the dominant TC and intensify.I don't really think anyone can accurately know the outcome of these systems at present. It's going to take a few days to watch unfold and iron out. Furthermore, modeling will continue to struggle with this setup and spit out some ridiculous solutions.Updating thread to cover both systems since they're so closely tied together right now. There is no need to make a separate TC thread for Rina. 2 Link to comment Share on other sites More sharing options...
Windspeed Posted September 28, 2023 Author Share Posted September 28, 2023 Should also add that shear is really taking its toll on Philippe. I mentioned in the previous post the outcome of Rina becoming the dominant TC. That might actually unfold. The low-level circulation flow of Philippe looks very broad now on visible. Forget TS status. It might even open up tonight if degradation of the low-level circulation continues. 1 Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 28, 2023 Share Posted September 28, 2023 41 minutes ago, Windspeed said: Should also add that shear is really taking its toll on Philippe. I mentioned in the previous post the outcome of Rina becoming the dominant TC. That might actually unfold. The low-level circulation flow of Philippe looks very broad now on visible. Forget TS status. It might even open up tonight if degradation of the low-level circulation continues. I cannot find a closed circulation center on visible Link to comment Share on other sites More sharing options...
Windspeed Posted September 28, 2023 Author Share Posted September 28, 2023 I cannot find a closed circulation center on visible Looks more like a broad surface trough now. Rina, OTOH, does have a vigorous surface vortex, though currently exposed. It's a fairly unimpressive mess at present for both systems. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 29, 2023 Share Posted September 29, 2023 18z GFS has Philippe literally absorb the other storm whilst interacting with Rina in a textbook perfect Fujiwhara effect and then absorbing Rinas remnants and becoming a monster hurricane. Almost 0 threat to land but i hope people are paying attention to this over the next several days as this is possibly the beginning of an incredibly rare meteorological event with two cyclones interacting in this manner 4 2 Link to comment Share on other sites More sharing options...
olafminesaw Posted September 29, 2023 Share Posted September 29, 2023 Nom nom 2 Link to comment Share on other sites More sharing options...
Boston Bulldog Posted September 29, 2023 Share Posted September 29, 2023 Can anyone guess the direction of the shear over the western MDR this morning? 2 Link to comment Share on other sites More sharing options...
Chrisrotary12 Posted September 30, 2023 Share Posted September 30, 2023 Wait…. How close together are these two? Can’t recall something like this. Link to comment Share on other sites More sharing options...
Windspeed Posted September 30, 2023 Author Share Posted September 30, 2023 Wait…. How close together are these two? Can’t recall something like this.Around 500nm between the two circulation centers. Link to comment Share on other sites More sharing options...
Windspeed Posted September 30, 2023 Author Share Posted September 30, 2023 Philippe is now forecast to eventually turn into the N Central Atlantic and become a hurricane. Rina is forecast to continue weakening and remnant low to get absorbed. This is more or less following recent runs of the GFS. 1 Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted September 30, 2023 Share Posted September 30, 2023 I'm all in on a hybrid 977 mb storm NW of Spain in 10 days. Link to comment Share on other sites More sharing options...
Normandy Posted September 30, 2023 Share Posted September 30, 2023 Seems like this is going to be less of a Fujiwhara and absorption and more of a send Rina north first and the Philippe follows Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted October 2, 2023 Share Posted October 2, 2023 Pretty amazing naked swirl ejected from the convection currently. One of the best examples of shear you will see! Link to comment Share on other sites More sharing options...
hlcater Posted October 2, 2023 Share Posted October 2, 2023 Kinda wonder if we start impinging on length records depending on eventual track. There is potential that Phillippe is still around in 10 days. 1 Link to comment Share on other sites More sharing options...
Windspeed Posted October 3, 2023 Author Share Posted October 3, 2023 TS Philippe, a storm I never thought had a chance to affect the Lesser Antilles, is doing that and more. Persistent convection is remaining nearly stationary in the SE quadrant of the cyclone as strong low-level convergence lifts rapidly, feeding into robust westerly mid-level flow. Significant flooding may occur into Wednesday for the islands with this setup.As for track, due to Philippe's motion WNW, the door is opening for a more W. Atlantic track. It should still turn north but may combine into a large ET cyclone that could even affect maritime Canada. 1 Link to comment Share on other sites More sharing options...
Normandy Posted October 3, 2023 Share Posted October 3, 2023 Totally agree I’m shocked it’s slammed the Antilles like it is with so much rain. thought for sure this would turn north further east. Any thoughts on why it’s got so much further west? Link to comment Share on other sites More sharing options...
Windspeed Posted October 3, 2023 Author Share Posted October 3, 2023 Totally agree I’m shocked it’s slammed the Antilles like it is with so much rain. thought for sure this would turn north further east. Any thoughts on why it’s got so much further west?The low-level easterly steering flow in Philippe's locale isn't that strong. Due in part to Rina moving north in a pseudo-Fujiwara motion and also weakening ridge and trades. This has allowed for two critical developments. 1) Though mid-to-upper westerly flow has kept shear in place, the LLC has never been allowed to fully outrun and dissipate. Convection has built back repeatedly or just close enough to sustain the surface vorticity maximum. But the vortex has never aligned or stacked. So the weak low-level steering flow keeps the LLC moving west albeit slowly. 2) Time. The longer it takes for the TC to remain weak, the longer it will take to feel a deeper southerly flow and weakness in the ridge. This allows the downstream pattern to evolve longer, which ultimately can have consequences on eventual track. Essentially, shear vs steering flow isn't enough to kill Philippe, but is keeping it weak enough to let other steering features or synoptic players have more time to develop, which, in turn, could change the eventual track.I should also add that modeling has been poor. But that isn't surprising given the more chaotic nature of what evolved between the two TCs and steering currents. All of the above made the official NHC forecast take a right beating. It is hard to be critical about that given the nature of how the pattern and systems evolved. 4 1 Link to comment Share on other sites More sharing options...
WxWatcher007 Posted October 3, 2023 Share Posted October 3, 2023 Really significant flooding images coming out of the islands. I’m just starting to look at this one again. Really interested to see how track and intensity guidance continues to adjust today. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted October 3, 2023 Share Posted October 3, 2023 Per recon, radar, and sat, I’m not sure Philippe still has a closed center or meets criteria to still be a storm. Looks to have opened up Link to comment Share on other sites More sharing options...
olafminesaw Posted October 3, 2023 Share Posted October 3, 2023 3 minutes ago, NorthHillsWx said: Per recon, radar, and sat, I’m not sure Philippe still has a closed center or meets criteria to still be a storm. Looks to have opened up A hot mess indeed. CNN is currently running a story with the headline "an unusually hot Atlantic Ocean is neutralizing El Nino. That could be bad news for the rest of hurricane season." Right on cue, the Atlantic seems to have flipped a switch to it's usual hostile El Nino state. Shear all over the place and little signs of development. 2 Link to comment Share on other sites More sharing options...
jbenedet Posted October 3, 2023 Share Posted October 3, 2023 54 minutes ago, NorthHillsWx said: Per recon, radar, and sat, I’m not sure Philippe still has a closed center or meets criteria to still be a storm. Looks to have opened up It’s that or it redeveloped LLC further south/west under the deep convection. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted October 3, 2023 Share Posted October 3, 2023 Per the GFS, the system opens up into a wave before being absorbed and combining with a large, non-tropical low over GL and Canada. Pretty wild to see what’s left of a tropical cyclone go from the Virgin Islands to Ontario without ever touching the US 1 Link to comment Share on other sites More sharing options...
MattPetrulli Posted October 3, 2023 Share Posted October 3, 2023 Link to comment Share on other sites More sharing options...
Normandy Posted October 4, 2023 Share Posted October 4, 2023 Radar out of San Juan would suggest this is reforming just ENE of the PR. The prior circulation seems to have ejected north and dissipated 1 Link to comment Share on other sites More sharing options...
Windspeed Posted October 5, 2023 Author Share Posted October 5, 2023 Forecast looks a lot more confident since last night. Not really much to add. Bermuda may get some nastiness, but nothing they can't handle. Phasing with the low could impact Maine, however. Link to comment Share on other sites More sharing options...
olafminesaw Posted October 5, 2023 Share Posted October 5, 2023 The cone vs ensemble spread is kinda wild Link to comment Share on other sites More sharing options...
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