Well now that i've had a bit more time to look at the downstream upper air, I kinda noticed something a bit odd. While looking at the 18Z GFS 500mb charts, if you look closely you will notice that between about 102hr's and 108 hr's, that the mid level center appears to be easily 8 degrees farther west than the low level center. So, here I am thinking that perhaps the system is experiencing some NE'rly shear thus "shunting" the upper/mid levels back a bit while the low to mid level gets pulled into the trough. So then as I continue to looking at the 500mb flow, it seems quite appearant that a fairly strong ridge is building over time and slowly sliding east over the S.E. Conus. So to me, now it would appear that any vertically stacked sytem, would possibly drift north and if anything bend back to the WNW or NW under the building ridge. I suppose if 99L were to develope quite quickly, than this might best allow a developing LLC to slip NNE into whatever weakness that may still be there in 48-72 hr"s. Than for good measure, I'm looking at the 200mb flow and the upper air seems difluent enough, but at about 48 hr's from now, there are 20-30 knot westerlies tearing across the N. Caribbean at about 18N with no appearant anticyclone to be seen, with exception to a small one south of E. Dominican Republic. Contrary to the maps, a very prominent anticyclone seems to be presently established over a developing 99L, already further west than that point. Looking at the most recent Rapid Update (RUC) model which only goes out to 18 hours, it seemed fairly clear that the upper level energy caused by a deep low over the Great Lakes, suddenly seems to lift up and out.
It looks to me that the entire steering flow seems to be shifting, at least by 60 hours from now. So my guess is that the dynamic models, along with the UK and CMC are anticipating 99L to develop a bit slower but then trek north, only to possibly get caught under a building ridge, thus bending a system back "ala" Hurricane King. Must have been a similar setup for that to happen then. Here is yet one more though on eventual motion. Perhaps at some point 3-4 days from now - and assumsing that 99L is developing under a decent upper high, than perhaps at that point it simply makes a hard "left turn" when nearing Cuba and continues west or even WSW?
My guess is that it continues to develop while moving slowly NW tonight & tomorrow and if nearly a depression by Monday morning somewhere near or just east of Jamaica, than the whole mess will continue to move NE under strong shear, but eventualy be named given the forward motion negating the shear slightly. If 99L can remain south and continue to progress west to about 80W for 48 to 60 hours, than things look to get even more interesting. -
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