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Posts posted by Windspeed

  1. The wave I posted above when it rolled off Africa is still making its way across the western MDR at a low latitude. It's nothing special, there may be some weak mid-level vorticity. It also isn't the sharpest of wave axii. But it has a favorable upper environment and if convection can coalesce to tighten vorticity or close off a surface low, could be interesting in the southern Antilles and deep Caribbean later this week.7b742327f0e9c2d3fbef23305b2e4702.gif&key=0e4e2ed9628d1f333f3dd539a1aa7d511b16ca08d0b3d536e835cda725768175



  2. It's ran out of time to get named. Environment is too hostile. Will be ET soon.


    [/b]Edit:[/b] Figures I call this dead to rights and yet convection comes back with a vengeance this evening, though perhaps due to some baroclinic forcing with the low. ATCF has analyzed 35 kt winds. l I'm not sure if the NHC will pull the trigger on Edouard. It may be a very short-lived NS if so.





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  3. The MCV accociated with the old boundary draped off the ECONUS might be forming an LLC under the current MCS complex that went up this evening. Note the circular pattern of the lightning near the highest cloud tops. Possible curved banding forming might be the beginnings of an LLC and we may get a named system out of this sooner than later if it holds together.4bd3817e4e5a9bb69579898d905b2486.gif

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  4. Fairly healthy wave axis with an MCS mid-level vort max south of the Verdes. Who knows if it will persist long with the SAL locked in to its NW. But interesting nonetheless. 12Z ECMWF does have a solution or two that closes off a surface low but there's negligible model support beyond that.a8a4fe7f78857b375370977ed7b9c448.gif

  5. What does that show? The azores high seems to keep anything in the MDR on a due west track until the western Caribbean. But, it is still too early for much in that region base don climatology. This would be great in Aug/Sept. Unless there is something I am missing. Such as the area of lower pressures moving west. Not sure if that is pointing out development potential.

    That particular model animation shows Azore's ridging below the 700 hPa layer of the atmosphere backing down over the eastern subtropical Atlantic. Surface-to-mid level pressures weaken slightly, retreating poleward. This eases low-level easterlies off Africa, which, in turn, limits SAL propagation westward off Africa. Additionally the ITCZ would become less suppressed south and gain some latitude within that pressure regime. This would help increase instability along the MDR, with better low-level convergence for convection, especially if the MJO is in a favorable phase aloft. Tropical wave tracks would also gain some latitude with the decrease in pressure heights, and be able to tap into moisture feed from the ITCZ.



    We generally see this pattern of strong Azores ridging back down in August, not early July. Typically a beefy late Spring to middle Summer eastern Atlantic Azores ridge is why we generally see SAL and too amped a low-level easterly jet to favor any MDR development. That, and upper level shear and vorticity is not yet favorable. At any rate, the pattern in the animation above may coincide with a favorable MJO [see below] and a relaxation of upper level wind shear across the Caribbean and lower MDR as well. 44da54f287ccfb1bb24ba08fe3a07146.jpg&key=c3d46da7c848de703330f30a437cf778a6f95f2f2a789f7fafd73ab0ff5bc06a7c53dc374add7ad5369d8f64b77cc2eb.jpg&key=5169f1b149672cc48fc73b2b2b3a2326b7de87f4be39cdf5511e74811456f26149a3566a09627574a8f8326c6522b170.jpg&key=debedfa44a8b70bfc2f4855646b4260c605546624a16b095c74ef90a16400718







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  6. I guess I meant more specifically, how will the upcoming favorable MJO wave influence the SAL. Would the strong SAL we have seen this week be more likely to subside during this period? I’m not familiar with how all this things interact.
    If SAL plumes continue to be lifted and break away into the easterly jet during the potential favorable MJO phase over the Atlantic, I am sure it would still have a negative effect on environmental conditions for cyclogenesis. But we have seen cyclogenesis occur with waves that were interacting with SAL in the past. It really just depends on location of a hypothetical wave axis versus the most hostile dry airmass and propagation of moisture flux out of the ITCZ. That's a remains to be seen kind of thing. Who knows...
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  7. How will the current SAL outbreak influence this otherwise favorable period? Is it expected to subside soon?
    Plumes of SAL dry airmass and aerosols riding the easterly jet should suppress activity for a few weeks at least. It will moderate with time as the ITCZ and individual waves begin to gain some latitude July-August.

  8. Notice in long-range modeling, the region of above median precipitation shifts from interior western Africa to off of the western coastal region of Africa, just south of the Cape Verdes, into the Atlantic MDR. The ITCZ and WAM becomes focused there. As such, this suggests that easterly intertropical waves that continue forming over deep interior and eastern Africa, if their energy holds together, will move off the African coast, and should reach a favorable environment for tropical development somewhere within the MDR:68d428fa19523e925b8959abbf6d7307.jpg&key=4fed78a607d7f5f560b7238e7cd7e5a89b17d92c3e4e5dbda7a367367955f4be

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  9. So is the rain that has already fallen in Africa going to impact peak season?  In other words, if it totally stops raining right now, are the pieces already in place for an active MDR during peak season?

    That precip anomaly map only matters to show that the pattern from the Indian Ocean to West Africa has favored stronger intertropical frontal troughs to support wave formation in the interior of central Africa. This has coincided with an amped West African Monsoon, resulting in a much wetter pattern than normal the past few months. The pattern could, of course, change. At any rate, the N. African anticyclone / SAL typically breaks off aerosol-laden dry airmasses during this stretch of Summer when typical strong Azores ridging below the 700 hpa layer begins cranking the ENE and easterly jet off of NW Africa. But by mid-July to mid-August, the Azores SPHP generally shifts west into a SER/WAR regime, especially during a +AMO/+NAO/-ENSO setup, allowing WAM to expand west of the Cape Verdes and ITCZ to gain latitude. If that occurs, increased numbers of tropical waves and MCSs exiting Africa into the Atlantic MDR would seem to favor the MDR being active this year. I believe it will even be hyperactive based on earlier discussions in this thread, but we shall see.

  10. I'm puzzled, the prior posting by Windspeed shows much above average rainfall in the same area that this unusual amount of dust is coming from. Can someone please help explain?

    The dust is coming from the Saharan and portions of the sub-Saharan that is not within the above normal precipitation regions discussed earlier. Yes, Morocco and Northern Algeria has seen above normal precipitation due to cutoffs and the previous -NAO pattern, which tracked extra tropical cyclones into the Mediterranean off of the Eastern Atlantic. This had little influence on the main desert regions though. In the image below, the two red Xs have remained normal (dry, low precip) over Saharan and sub-Saharan. The blue X has seen above normal, but that is still mostly an arid region. The point of the original post above was to show the extreme above normal precipitation amounts for already generally moist grasslands and forest regions of the interior and west-central African continent, south of the sub-Saharan region. This suggests increased numbers of multi-convective systems and tropical waves advancing through the West African Monsoon (WAM), which should increase activity out into the Atlantic ITCZ and MDR through the heart of the Cape Verde stretch of the season.


    As for the dust, the Azores ridge is cranking below the 700 hpa level of the atmosphere seen in purple below. This is inducing strong easterly trades off the Sub-Saharan region pulling desert dust along with it. The low-level easterly jet burst will push all the way across the Atlantic over the next 10 days.9b5a3fca7fa76d356a1343238b3826fe.jpg&key=5115f4f813e18ca7f6fca278d503c48b7919ac35ad67110cac835a4196eb4c2d

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  11. The previous TCHP maps may have been showing old data. This does seem to make sense based on the Gulf Stream data from last week being virtually non-existant for heat content on previous maps. There should be noticeable kinetic energy in the GS off of Florida by this time frame, yet last week's maps were showing zilch there.

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