Latest 24 Hour WV imagery reveal that the TUTT type ULL has moved west towards the Western Caribbean, leaving in its wake a shortwave upper level ridge in its place... convection has remarkedly increased in the region in the last 24-48 hours ...
http://orca.rsmas.miami.edu/wximages/jet/1_05/anis.html
The CMC and its ensemble members are quite insistent on the idea of a development scenario (now making the 5th consecutive day for such a depiction and 9 runs of the operational and 5 for the ensemble member spread) ...
A good spread of CMC ensemble members now depict that something comes from this ... with a couple of members depicting stronger development ... CMC5 develops quite a healthy system and PHASES it with the extratropical low for later in the period and DEEPENS the PHASED low down to 940 MB!!!!!! moving NW past Hudson Bay and winding down (a VERY extreme and an outlier scenario ... not likely) ... ALL the member spread and the operational CMC do not make this a US threat ... so don't worry about that ...
http://www.stormsfury1.com/Weather/Mode ... mbles.html
The GFS 00z run deepened the system somewhat (down to 1007 mb), but the 12z run splits the energy more pronouncely and takes the majority of it NNE after passing by PR and keeping it a weaker low scenario ...
GFS 00z 950mb Vort.
http://met.psu.edu/trop-cgi/avntc2.cgi? ... =Animation
12z
http://met.psu.edu/trop-cgi/avntc2.cgi? ... =Animation
The CMC operational model guidance at 00z depicts quite a system developing at the surface and also like some of the CMC ensembles, shows a phasing of the tropical system down the road with an extratropical system exiting off the coast of the NE US and becoming quite a maritime low.
CMC 00z run MSLP
http://met.psu.edu/trop-cgi/cmctc2.cgi? ... =Animation
CMC 00z run 925mb Vort (clearly shows the phasing in the N. Atlantic) and would pose quite an issue for Newfoundland in the MR ...
http://met.psu.edu/trop-cgi/cmctc2.cgi? ... =Animation
CMC 12z run 925mb Vort (showing a transfer of energy from the Eastern Caribbean into a strong reflectivity north of between Hispanola and PR).
http://met.psu.edu/trop-cgi/cmctc2.cgi? ... =Animation
CMC 12z run MSLP
http://met.psu.edu/trop-cgi/cmctc2.cgi? ... =Animation
Just WHY doesn't the UKMET show much of anything ... Hmmm, well it does show SOMETHING ... the vorticity, albeit weak, and correctly assuming the energy gets TRAPPED right over Hispanola ...
UKMET 12z 925mb Vorticity
http://met.psu.edu/trop-cgi/ukmettc2.cg ... =Animation
The NOGAPS ... is NOW ON BOARD AS WELL ... and quite striking ... as it takes a developed system WNW! ... however, right now, IMHO, the movement is the model bias showing up being much too progressive further south, despite showing quite an amplified extratropical system at the 500mb level in the NE states/Eastern Canada.
NOGAPS 96 hour Surface Isotechs/Wind Barbs and MSLP

NOGAPS 120 hour Surface Isotechs/Wind Barbs and MSLP

NOGAPS 96 hour Streamlines

Even the ETA showing a 1008mb low between Hispanola and PR.

There's a bit of potential down in the region ... be on guard ... at the least, expect very heavy rains in that region (some already have been experiencing such weather conditions) ...
SF