Windspeed
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Everything posted by Windspeed
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This is not 93L but another wave behind it. 93L (a potential soon-to-be TC) moves NW somewhere west of the Verdes and dissipates. GFS wants to go gangbusters with the AEW behind it and grows a long-tracking deep MDR hurricane. Of note, the new GFS hasn't wanted to do jack squat with really any CV or MDR system up until now. Of course that is climatologically normal as typically this region doesn't start producing until mid August. Still...
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Uhm... This may get classified in short order. May not do anything crazy on a forecasted NW track into marginal waters and a more stable airmass. Still pretty suggestive ASCAT:
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The current AEW southeast of Cabo Verde has a vigorous and compact mid-level vortex. Though 92L was a larger and perhaps more impressive wave, it struggled maintaining any MCS with its mid level vort and failed to genesis before reaching a more hostile environment in the MDR. This wave on the other hand may do better entering the MDR if it can concentrate convection and close itself off at the surface. It certainly looks decent at the moment.
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Interestingly the new AEW near the CVs has decent model support for short-term TCG.
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In case anyone is curious, the next named "I" storm, Isaías, is pronounced "ee-sigh-ee-us". It's the Spanish name for Isaiah submitted by Argentina to the WMO.
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Our new Cape Verde disturbance has been designated Invest 92L.
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This is banter'ish, but is it really? lol...
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NHC isn't playing around with the large wave / disturbance near the Verdes. Developmental chances already up to 40%. We'll probably have a cherry tomorrow. ZCZC MIATWOAT ALL TTAA00 KNHC DDHHMM Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Fri Jul 24 2020 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on Tropical Storm Gonzalo, located less than 500 miles east of the southern Windward Islands. The National Hurricane Center is also issuing advisories on Tropical Storm Hanna, located over the western Gulf of Mexico a little more more than 200 miles east of Corpus Christi, Texas. 1. A tropical wave located about 300 miles south-southeast of the Cabo Verde Islands continues to produced an area of cloudiness and disorganized showers and thunderstorms. The disturbance is expected move westward across the tropical Atlantic during the next several days, and some gradual development of this system is possible by early next week when it reaches the western tropical Atlantic. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 5 days...medium...40 percent. Forecaster Stewart
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The next AEW exiting the coast already had a large wave breaking sharp axis, but now with deep convection associated with a strong MCS embedded within its inverted surface trough. This is the wave the EPS and ECMWF op runs have been consistently developing the past few days into a formidable TC. I'd say based on appearance, that's looking ever more likely. It will still have some dry air established to its north in pockets across the subtropical Atlantic, but the easterly SAL burst is way out ahead of it and may not be as much a factor. Also, the moisture envelope with this wave is quite large. If TCG occurs in the MDR this weekend into early next week, this would be Isaias. The "I" storms are frequently in the historical record as being Cape Verde or deep MDR systems east of the Antilles, but generally well into September. Here we may very well experience an "I" storm in July of 2020, yet it will not break the mold. As the Euro would have it, our next TC might end up being a powerful long-tracking Cape Verde hurricane. Obviously, not to count chickens before they hatch as even if a very advanced AEW, it's still just a low-embedded wave that could flop and not get named. Nah, who am I kidding? This thing is a beast...
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Interesting thread on MJO phase 1 and 2 inter-seasonal as it relates to Atlantic Basin hurricane seasons. Note 2020...lol:
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Invest91L has been designated. This has a decent chance of TCG in the central-to-NW GOM as conditions become more favorable. At this time there is still mid-to-upper level shear imparting over the western portion of the wave axis. But that should shift more easterly into the forecast period and allow some time for a potential low to stack. Not certain of any significant intensification but regardless, moisture fetch into very warm GOM SSTs could bring flash flooding rains into LA/Texas.
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We may still have some bouts with a PV streamer, possible TUTT and some shear dependant on timing and positioning during the onset of an uptick in activity, aside from whatever 99L does here in the coming week.
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Well 10-14 days is when I thought things would kick up. The current surprise MDR system is just an example of how you can still get activity in a mediocre and typically unfavorable environment. Yes, the timing convectively-coupled Kelvin moving out of the EPAC into GOM/WCARIB next week could be critical to 99L (potential Gonzo), etc.; however, the middle-to-upper MDR is still quite hostile. 99L just got lucky with its very low latitude with TCG here. We'll see how it all plays out.
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New ASCAT. Vortex signature looks even better than last night. At this point, I'd be surprised TAFB didn't pull the trigger in the next hour.
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Looks like a depression to me. Especially with that ASCAT pass last night confirming the closed low. All it needed was sustained convection and a bit more organization. Interesting how even a quiet stretch with most meh environmental conditions can still produce surprises. But 99L is an especially strong wave born out of a favorable environmental bubble thanks to the WAM and ITCZ boundary. Looks like if things continue, we'll get a NS. Questions remain if it can become anything substantial in the long term / Caribbean. It still has to deal with a lot of unfavorable possibilities.
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Well then...
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Considering that ASCAT pass, if we get any sustainable convection over that center, we'll probably get a classification. Clearly there is a closed low. Perhaps it doesn't survive the potential hostile environment in a few days, but it may still get named. Interestingly, this feature might spell trouble with the Western Caribbean next week. The favorable coupled Kelvin may be timing just right off to extend east off of Central America by then.
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New paper by NOAA/OAR/AOML on the relationship between the Madden-Julian oscillation (MJO) and rapid intensification of tropical cyclones. Important Conclusions: 1. Rapid intensification events and the MJO tend to move with each other from west to east across the hemisphere suggesting a relationship between the two. 2. Rapid intensification is most likely to occur when the MJO is neither stormy and wet nor sunny and dry near the tropical cyclone. 3. The addition of information about the MJO does not improve forecasts of rapid intensification. This is likely because the information about the MJO is already available in the forecast models in a different form. Klotzbach (2012), in their seminal study on the relationship between RI in the Atlantic and the MJO, found that RI is four times more likely during the active MJO phase than during the inactive phase. The current study extends this work to the Central and East Pacific and tests whether the MJO may have predictive capability in current forecast schemes. All RI events in the north/western hemisphere along with the two commensurate RMM modes (Wheeler and Hendon 2014) are compiled from 1974 to 2015. The events are compiled into 20-degree-wide bins, and the mean values in each bin show that RI events and MJO events tend to move in tandem with each other from west to east across the hemisphere. Unlike in the Klotzbach (2012) study, the MJO is not generally in the most active convective phase in the region when RI occurs. Though the mean magnitudes are small, the differences between many bins are statistically significant. However, the addition of this information to statistical RI forecasting schemes does not significantly improve forecasts from SHIPS-RII, possibly because the MJO is not related to RI itself, but instead to cyclogenesis, a necessary precursor to RI, or due to the large scatter in the RMM values. Though the results here show a relationship between the MJO and RI events in the hemisphere, they do not show improvements to current operational RI-prediction models. Despite this, other techniques, such as those based upon machine learning or other artificial intelligence algorithms, might be useful to pursue in the future. Paper can be obtained here. Some additional thoughts of my own. Though clearly a favorable MJO or strong coupled Kelvin can help induce tropical cyclone genesis via an existing MCS, disturbace, wave, etc., there is clearly other factors at play with respect to an existing strong convectively coupled Kelvin and an already established TC going through RI. It may even be possible that a strong coupled Kelvin could create too much surrounding convection and competing micro regions of convergence that might limit low-level feed or interfere with the main vortex of an established TC. Also, since this paper focused on how currently existing RI models do not seem to benefit from additional MJO- Kelvin data, though an unfavorable MJO phase might deter RI, a favorable coupled-Kelvin doesn't necessarily increase existing parameters for RI of a potential TC. Essentially, though a convectively-coupled 200 hPa vorticity wave does greatly establish much better support of TCGs, it does not necessarily help in their RI phase if already mature, and that a neutral phase of the MJO might be the most conducive for RI of an existing TCG.- 46 replies
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