btangy wrote:The seeds to the weakness in the ridge that all the models seems to be latching onto are already planted:
Here's the height of the dynamic tropopause in potential temperature coordinates as analyzed by the 18Z GFS:
http://www.atmos.albany.edu/facstaff/rm ... 082118.jpg
If one is not familiar with PV/tropopause maps, the 200mb vorticity from CIMSS shows a similar feature:
http://cimss.ssec.wisc.edu/tropic/real- ... g8vor1.GIF
There's a large positively tilted 'PV tail' extended down from the mid-latitudes that is the source of all these upper level lows you see spinning around in the W Atlantic.
The 72 hour prog 18Z GFS shows the PV tail fragmenting which each magenta region representing an upper level low:
http://moe.met.fsu.edu/tcgengifs//gfs/2 ... 50PV12.png
The anomaly in the C Atlantic is projected to be quite strong and deep, so that its mid-level reflection will provide enough of a weakness in the ridge to eventually pull TD 4 north if it strengthens and becomes a deeper system. You can see this in the 500mb vorticity at 120hours for example @ ~55W,27N:
http://moe.met.fsu.edu/tcgengifs//gfs/2 ... vort20.png
All of the GFS ensemble members, even in the S portion of the ensemble envelope spread forecast recurvature:
http://wind.mit.edu/~btangy/TC/fig/storm1_18_ms3.png
This is a tremendous post and very, very insightful technical analysis.
Hard to argue against anything you've presented here...thanks for taking the time to put his out there...
MW
