cieldumort
Moderator
Reged: Mon
Posts: 1635
Loc: Austin, Tx 30.40N 97.80W
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A weak area of low pressure has developed along a surface trough in the western Atlantic, centered near 27.5N 65.5W, or roughly just less than halfway between Julia and Karl today. Movement has been a slow drift to the northwest, and this feature presents no immediate risk to any land, but could be a player, especially with regard to TS Karl's future steering currents, next week.
Of the global models this morning, only the has really latched on to this, being a model that runs hot. spins it up into a low-end gale-force storm by mid-week as it ejects it northeast out to sea.
Scatterometer data has been lacking in this region but it appears that a closed circulation exists - at least down to about 1000' above the surface. Buoy 41049 located 300 NM SSE of Bermuda near 27.5N 63W has been seeing winds there increase to about 20 knots out of the SSE this afternoon.
This feature does not yet have an Invest tag, but the title will be updated should it be given one.
Edited by cieldumort (Mon Sep 19 2016 12:39 PM)
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cieldumort
Moderator
Reged: Mon
Posts: 1635
Loc: Austin, Tx 30.40N 97.80W
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This low has not gotten any better organized today, traveling through a zone of 20-30 knots of northwesterly shear.
There have been a few informative scatt passes, and judging by these, if there is a surface circulation, it is fleeting at best. However, this feature is producing increasingly strong winds. Recently, a ship at 0600z located 27.60N 64.50W reported winds out of the due south at almost 30 knots, and had logged a pressure rising from 29.91 (the low is to its north, moving north).
As can be seen in the image below, this trof and its associated (probable) 925mb level circulation (aloft) have already set up an escape route for Karl to follow (note the indents shown in the isobars of the High in the vicinity of this trof).
In relation to this above-surface circulation/surace trof, shear is decreasing and now under 10 knots just to its north. The circulation is now traveling more due north than northwest, and so it may have a small window to pull a hat trick sometime in the next 36 hours.
Something to watch for with regards to both systems - if his trof's circulation develops and ejects rapidly, leaving this region to fill back in with high pressure faster than Karl can get to it (unlikely, but possible .. more probable that trofiness will remain and Karl will ride that river out to sea)...
Just in relation to Karl: Should Karl stay weaker and further south, he may not feel the tug of this trof at all, regardless of how strong it is at the time.
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cieldumort
Moderator
Reged: Mon
Posts: 1635
Loc: Austin, Tx 30.40N 97.80W
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CMC is basically the only model to develop this west Atlantic low, now doing so after it has passed to the north of Bermuda.
Normally it is not worth putting much stock in this model, but because it tends to run hot, sometimes it accurately catches and/or forecast systems that the others initially miss, and has done a better job than others with this feature so far.
The image below (base model run map courtesy TropicalTidbits.com) from 12Z today shows this low finally closing off at the surface well north of Bermuda by 0z Wednesday as a 30 knot depression. Also shown here are the this model's forecast intensity and location of PTC Julia's remnant circulation, and also Tropical Storm Karl.
The primary significance of this west Atlantic low/trof is going to be its ability to offer an assist to the eventual recurving of Karl. Otherwise, a likely weak fish spinner.
Edited by cieldumort (Mon Sep 19 2016 01:05 PM)
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