Shell Mound wrote:The strength and persistence of the mid-level circulation may play a key role in the survival and intensity of DORIAN down the road, should it manage to survive the next day and a half. By days two and three, the large-scale TUTT to the east of Bermuda will retrograde and fill, allowing northerly mid-level shear to weaken and veer, thereby advecting a more unstable air mass from the ITCZ, while anticyclonic (divergent) flow begins to take hold near Puerto Rico. If the MLC remains vigorous and compact by then, as seems probable, then DORIAN could certainly reorganise and couple (a new) low-level and mid-level centres, even if a LLC is very weak or nonexistent at the moment. High environmental pressures seem to favour DORIAN remaining a small system as it nears the Greater Antilles and then passes beyond into the Bahamas. Then the only real inhibitor to further, potentially rapid deepening would be the degree of interaction with either PR or the Dominican Republic or both. Currently, the TUTT to the east of Bermuda seems to be more cut-off than originally forecast, suggesting a high degree of anticyclonic wave breaking, which would favour a faster retrogression, allowing more favourable conditions over DORIAN in two or three days (probably the former vs. the latter). This would also potentially favour convection on the northern and eastern sides of DORIAN by then, which would imply that any LLC/MLC coupling would take place farther northeast, increasing the likelihood that DORIAN would miss the DR, quite possibly "splitting the gap" between the DR and PR, i.e., over the Mona Passage. IF this takes place, then the combination of a rebuilding mid-level ridge to the north and very favourable (low) vertical shear levels, PLUS extremely warm SSTs and deep oceanic heat content over the Bahamas/FL Straits, along with improving humidity levels, could very well set the stage for an ANDREW- or 1935-type scenario. Of course, this is highly uncertain, but if everything goes just right, then the potential ceiling for DORIAN is, in my estimation, extremely high, with steering favouring a likely possible threat, beyond the south-central Bahamas, the southernmost FL peninsula and the Keys. DO NOT discount farther SW/stronger shifts in terms of track and intensity on the EPS/GEFS. A FL Straits/Keys/Gulf threat, potentially VERY strong, is well within the realm of possibility, with further threats to the W/C Gulf Coast (TX/LA) possible down the line.
One last thing: compare current CIMSS data to the 850-250 mb U-anomalies for ANDREW on 20-23 August 1992. VIRTUALLY IDENTICAL placement of features.
Edit: I apologise for not uploading images from ESRL, but I don't like all the cookies on image-hosting sites. Just click on the latter link and put in the options.
