Marion_NC_WX Posted August 5, 2012 Share Posted August 5, 2012 For all the pro Mets on here...any chance the current LLC dissolves and a new center forms under the convection? Link to comment Share on other sites More sharing options...
LakeEffectKing Posted August 5, 2012 Share Posted August 5, 2012 For all the pro Mets on here...any chance the current LLC dissolves and a new center forms under the convection? Not really. Usually as a storm decouples, the top half looses it's thermodynamic energy source and rains out, removed from the center. Generally the llc either will regenerate convection at it's location, or we have a system that opens to a wave. Edit: That said, if the "top half" of the storm maintain a "tilted" channel of convection from the surface and if shear relaxes, the centers can recouple. The stronger the system, the more forcing required to decouple... Link to comment Share on other sites More sharing options...
jhamps10 Posted August 5, 2012 Share Posted August 5, 2012 Living up to the curse of his name right now Ernesto is that's for sure Link to comment Share on other sites More sharing options...
Amped Posted August 5, 2012 Share Posted August 5, 2012 Its almost funny how loose the LLC is. One could make an argument that its pretty open right now. Open wave indeed. GFS and Euro kind of showed a vortex split. BOC Friday is all I have to say. Link to comment Share on other sites More sharing options...
carley5 Posted August 5, 2012 Share Posted August 5, 2012 problem is if it is an open wave then its going to fly straight west into central america. not sure it will even enter the BOC. Link to comment Share on other sites More sharing options...
tmagan Posted August 5, 2012 Share Posted August 5, 2012 Pretty telling you don't have any westerly winds along the northern South American coastline. Link to comment Share on other sites More sharing options...
Cheeznado Posted August 5, 2012 Share Posted August 5, 2012 Score a big win for the models so far- this is going to be a typical Ernesto, no big deal. Link to comment Share on other sites More sharing options...
Amped Posted August 5, 2012 Share Posted August 5, 2012 Haha NHC had 60mph @ 8pm. Recon pass almost insists they go final advisory @ 11pm. Link to comment Share on other sites More sharing options...
jhamps10 Posted August 5, 2012 Share Posted August 5, 2012 Score a big win for the models so far- this is going to be a typical Ernesto, no big deal. yep.... yawwnnnn so far... Almost wish the NHC would retire Ernesto so we could get something interesting out of this storm... Link to comment Share on other sites More sharing options...
Analog96 Posted August 5, 2012 Share Posted August 5, 2012 Haha NHC had 60mph @ 8pm. Recon pass almost insists they go final advisory @ 11pm. There is absolutely no way they would do that. Even if recon found no center whatsoever, they would probably wait until at least 11 AM tomorrow before writing it off, in case something of a center did reform. Link to comment Share on other sites More sharing options...
Eyewall2005 Posted August 5, 2012 Share Posted August 5, 2012 wow still in disbelief.. Link to comment Share on other sites More sharing options...
turtlehurricane Posted August 5, 2012 Share Posted August 5, 2012 This is classic for eastern Caribbean tropical cyclones, trucking along in those easterlies. The NHC would be foolish to declassify this since it is clearly a tropical cyclone in every sense besides the Earth relative circulation. There's is obviously a vigorous storm relative vortex, and plenty of sustained deep convection with spectacular outflow. Link to comment Share on other sites More sharing options...
sugaree Posted August 5, 2012 Share Posted August 5, 2012 how close to the center is that new burst of convection Link to comment Share on other sites More sharing options...
Marion_NC_WX Posted August 5, 2012 Share Posted August 5, 2012 The National Hurricane Center by reading the forecast discussion seems confused as to why the low levels of Ernesto has accelerated WNW throughout the evening. The next set of recon flights will be interesting to say the least. As far as the long term fate of Ernesto, I still would not rule out it coming as far north as the Northern tip of the Yucatan Pennisula, all along its been common knowledge that this storm may not truly develop until late tomorrow or Monday...if this storm does begin to take shape in the next 24-36 hours, it will be interesting to see how the global models respond shortly after a true center is established. Link to comment Share on other sites More sharing options...
sugaree Posted August 5, 2012 Share Posted August 5, 2012 at least the system is moving slightly slower right now Link to comment Share on other sites More sharing options...
jhamps10 Posted August 5, 2012 Share Posted August 5, 2012 at least the system is moving slightly slower right now no it's not.... it's zoomed to 22MPH as of the 11PM advisory Link to comment Share on other sites More sharing options...
carley5 Posted August 5, 2012 Share Posted August 5, 2012 at 22 mph the center, if there is one will be totally exposed tomorrow. Link to comment Share on other sites More sharing options...
Hurriplane Posted August 5, 2012 Share Posted August 5, 2012 Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 5, 2012 Share Posted August 5, 2012 Might be rain contaminated, not quite 50 knots, but some mid 40s... Low 40s unflagged and in lighter rain. Link to comment Share on other sites More sharing options...
Dunkman Posted August 5, 2012 Share Posted August 5, 2012 Somehow this pass is even worse. I guess it jumped SW but honestly there isn't much of a rotation. ENE to SE before and after the 1010mb "center." I don't understand what is going on with this storm but it's not good. Link to comment Share on other sites More sharing options...
CUmet Posted August 5, 2012 Share Posted August 5, 2012 This may very well be an open wave right now given the last couple recon passes. It's clear from the continued convective bursts on the east side of the LLC today that the vortex has become tilted, with the lower part accelerating ahead of the mid-level part. This is a classic example of a TC's convective structure telling you more than any shear diagnostics from global models. I think back of Erika of 2009 as a more extreme example. With that storm, most of the shear products suggested it was under low shear, but the massive convective blob that appeared to the east of the LLC was displaced for a reason: the shear was there and was tilting the vortex, but it was not captured by traditional shear measures. These examples serve as important reminders that the SHIPS/CIMSS area-averaged shear products that we all take for granted can be insufficient on rare occasions, and I'm talking about both the 850-200 mb shear product missing shallow layers of shear, and the 0-500 km averaging radius perhaps being too large in some instances. The ECMWF and GFS suggest that the vortex tilt should remain for at least another couple days, and since they have proven to handle this storm well, I don't expect much, if any, intensification at least until Tuesday as it nears the Yucatan. There is a decent chance this may degenerate temporarily into a wave (if it hasn't already), although I think it will come back Tuesday. In the meantime, expect continued periodic bursts of convection that gets everyone's hopes up, but if it looks like it's "sticking" in the same spot relative to the moving center instead of swinging around like a band, it's just fool's gold. Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 5, 2012 Share Posted August 5, 2012 Somehow this pass is even worse. I guess it jumped SW but honestly there isn't much of a rotation. ENE to SE before and after the 1010mb "center." I don't understand what is going on with this storm but it's not good. Glass half full optimistic, it probably won't get much weaker, from here on in until its hits the YP or CA, it will be getting farther from South America and convergence should be increasing. I am starting to get concerned it won't have enough time over the BoC to really redevelop. ETA: Speaking of convergence, perhaps, first signs of convection trying to fire well ahead of Ernesto. Link to comment Share on other sites More sharing options...
phil882 Posted August 5, 2012 Author Share Posted August 5, 2012 This may very well be an open wave right now given the last couple recon passes. It's clear from the continued convective bursts on the east side of the LLC today that the vortex has become tilted, with the lower part accelerating ahead of the mid-level part. This is a classic example of a TC's convective structure telling you more than any shear diagnostics from global models. I think back of Erika of 2009 as a more extreme example. With that storm, most of the shear products suggested it was under low shear, but the massive convective blob that appeared to the east of the LLC was displaced for a reason: the shear was there and was tilting the vortex, but it was not captured by traditional shear measures. These examples serve as important reminders that the SHIPS/CIMSS area-averaged shear products that we all take for granted can be insufficient on rare occasions, and I'm talking about both the 850-200 mb shear product missing shallow layers of shear, and the 0-500 km averaging radius perhaps being too large in some instances. The ECMWF and GFS suggest that the vortex tilt should remain for at least another couple days, and since they have proven to handle this storm well, I don't expect much, if any, intensification at least until Tuesday as it nears the Yucatan. There is a decent chance this may degenerate temporarily into a wave (if it hasn't already), although I think it will come back Tuesday. In the meantime, expect continued periodic bursts of convection that gets everyone's hopes up, but if it looks like it's "sticking" in the same spot relative to the moving center instead of swinging around like a band, it's just fool's gold. Agree completely. I even admit that I was fooled by the satellite presentation this morning, and even a few microwave passes indicated a better organized system than what we witnessed in reality. If this current presentation continues, we may have an open wave by tomorrow. I do want to ask one question though. Is a better organized mid-level vortex in a shear pattern actually a deterrent for intensification? The system had a weak mid-level reflection the first two days of its life and the low level circulation remained in-tact because the convective forcing wasn't competing with a mid-level vortex. However, last night and today when the mid-level vortex became much more established through a strong convective burst (as suggested by the GFS and ECMWF) we saw the surface circulation actually lose definition as it now appears to be opening up this evening. I have to give credit to the GFS and ECMWF, they really scores a coup in a difficult forecast with this one. Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 5, 2012 Share Posted August 5, 2012 On a postive note, last couple of HDOBs showing smaller T/Td spread, and a little earlier had some flight level winds mid/uuper 40s. It may technically be an open wave, but I suspect it will closeoff a center again fairly soon. As I mentioned before, it is definitely now firing convection West of the center. Link to comment Share on other sites More sharing options...
CUmet Posted August 5, 2012 Share Posted August 5, 2012 Agree completely. I even admit that I was fooled by the satellite presentation this morning, and even a few microwave passes indicated a better organized system than what we witnessed in reality. If this current presentation continues, we may have an open wave by tomorrow. I do want to ask one question though. Is a better organized mid-level vortex in a shear pattern actually a deterrent for intensification? The system had a weak mid-level reflection the first two days of its life and the low level circulation remained in-tact because the convective forcing wasn't competing with a mid-level vortex. However, last night and today when the mid-level vortex became much more established through a strong convective burst (as suggested by the GFS and ECMWF) we saw the surface circulation actually lose definition as it now appears to be opening up this evening. I have to give credit to the GFS and ECMWF, they really scores a coup in a difficult forecast with this one. Good questions. While I don't have any definitive answers (this storm has knowledgeable, experienced people stumped), I'll offer some speculation. I'm not sure if I see it as a competition between the low-level vortex and the mid-level vortex per se; I view them both as part of the same vortex tube, but tilted over. When you tilt the vortex over by vertical wind shear, you induce a circulation that forces inflow towards the downtilt side of the vortex (towards the east in this case) and strong vertical motion there. You often see these huge convective bursts that appear displaced from the LLC, but in the same spot relative to that LLC as a result of this strong, persistent forcing. Now, why these huge bursts seem to preferentially occur in strongly sheared/tilted storms is unclear to me, but perhaps these bursts have a much larger stratiform precip region that the more "bubbly" or popcorn type convection that you see in other cases. Stratiform diabatic heating tends to spin up vorticity in the mid levels, while convective heating (presumably associated with the bubbly convection) favors spinup in the lower levels. I'm speculating here, but perhaps once the vortex tilts over (to the east with height, for example) and you get that burst to initiate, the burst ends up producing a large, persistent stratiform region that spins up the mid-level vorticity to the east. This reinforces the tilt, which produces more forcing for vertical motion in that spot, and so on...a positive feedback if you will. This begs the question: why didn't Ernesto do this bursting thing when it was sheared east of the Lesser Antilles? Perhaps the vortex wasn't deep enough then to feel the shear as much? Or maybe the shallow, mid-level shear that it might be experiencing now is that much more harmful? Or is there something else we're not thinking about? I do find the difference in the nature of the convection between when Ernesto was east of the islands (popcorn) vs. now (massive bursts) to be fascinating, and my feeling is that it's really important, but I don't fully grasp why. Link to comment Share on other sites More sharing options...
CUmet Posted August 5, 2012 Share Posted August 5, 2012 Also, this 00z sounding SSE of Ernesto seems to support the idea that the mid-level part of the vortex is a lot better developed than the low-level part. Note the westerlies between 400-600 mb: Link to comment Share on other sites More sharing options...
U_Thant Posted August 5, 2012 Share Posted August 5, 2012 Some light W-NW winds showing up in the latest set HDOBs. However, the winds are generally light in a large area near the center and the windshift puts the center somewhere around 14.9N (The 03Z advisory position was up at 15.4N). Link to comment Share on other sites More sharing options...
U_Thant Posted August 5, 2012 Share Posted August 5, 2012 Hideous looking M/I pass from a few hours ago...look how far ahead of the convective mass the LLC is. Link to comment Share on other sites More sharing options...
yoda Posted August 5, 2012 Share Posted August 5, 2012 60 mph and 1009 mb at 2am.... think that looks weird Link to comment Share on other sites More sharing options...
Hurriplane Posted August 5, 2012 Share Posted August 5, 2012 Well, whoever said on here they wanted a storm with 1010 mb or more, here it is... WHILE SOME SPREAD REMAINS...THE GUIDANCE HAS COME INTO BETTER AGREEMENT THAT ERNESTO WILL TURN WEST-NORTHWESTWARD AT A REDUCED FORWARD SPEED AFTER 36 HR...MOVING OVER THE YUCATAN PENINSULA OF MEXICO BETWEEN 72-96 HR AND REACHING THE SOUTHERN OR SOUTHWESTERN GULF OF MEXICO BY THE END OF THE FORECAST PERIOD. THE NEW FORECAST TRACK IS SHIFTED A LITTLE NORTH OF THE PREVIOUS TRACK THROUGH 24 HR DUE TO THE INITIAL MOTION. HOWEVER...IT HAS BEEN SHIFTED SOUTHWARD AFTER THAT TIME TO LIE NEAR THE VARIOUS CONSENSUS MODELS. OVERALL...THE NEW FORECAST TRACK IS FASTER THAN THE PREVIOUS TRACK. IT IS ALSO UNCLEAR WHY ERNESTO HAS LOST ORGANIZATION SINCE THE OUTFLOW IS GOOD IN ALL DIRECTIONS...THE VERTICAL WIND SHEAR IS LIGHT...AND THE SEA SURFACE TEMPERATURES ARE WARM. ONE POSSIBLE CAUSE MIGHT BE DRY AIR SEEN IN WATER VAPOR IMAGERY WEST OF THE CYCLONE. THE DYNAMICAL GUIDANCE CONTINUES TO SUGGEST THAT ERNESTO WILL NOT STRENGTHEN MUCH BEFORE REACHING THE NORTHWESTERN CARIBBEAN...WHILE THE STATISTICAL-DYNAMICAL MODELS CONTINUE TO FORECAST STEADY STRENGTHENING THROUGH THE FORECAST PERIOD. GIVEN THE TRENDS DURING THE PAST 24 HR...THE NEW INTENSITY FORECAST CALLS FOR A LOWER INTENSIFICATION RATE THAN THE PREVIOUS ADVISORY...WITH ERNESTO BECOMING A HURRICANE IN 48 HR. GIVE THE DIVERGENT GUIDANCE...THE INTENSITY FORECAST REMAINS OF LOW CONFIDENCE. Link to comment Share on other sites More sharing options...
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