first, a couple thoughts on gustav. folks in la got the message from the 2005 assault, and this time they're heading for higher ground. coastal louisiana is a deathtrap in a major hurricane. the eastern wards of new orleans are likely to be inundated again if the forecast track verifies, and a bit more deviation to the east and the chances that the city turns into a fishbowl again are enough to get people moving, hopefully. i don't think many people are dumb enough to stick around for that... the whole mass casualty event/humanitarian crisis from katrina made an impression on even the thickest holdouts. gustav should sputter for a bit while its inner core recovers from that knot of hills in western cuba it just ripped across. the whole category five peak over the central gulf is as likely as not to occur, followed by a slow spin-down as the thermodynamic profiles for the storm decrease near the coast. the nhc is definitely on the ball with this one... the devil is in the smaller scale track and intensity details. hope and pray that deviation to the left occurs in the track sooner than forecast, and that the storm moves ashore obliquely over less densely populated areas. i'm sure lafayette, new iberia, morgan city, houma, abbeville and the like have no reason to wish this on themselves... but the scale of the coming disaster can be governed by just 20 miles or so... or maybe one rung on the saffir-simpson scale.
further east hanna is plodding westward, making one of the more inconspicuous approaches that could be expected. gustav hype is letting this system slowly sneak up on the southeast coast... as forecast models have it slowly approaching throughout the new week. hanna probably won't change much in basic profile or location for the next three days... shear will keep shifting around, keeping the storm in check through mon-tue or so.. and forecast models are now showing a more amplified, less influential ridge, with a huge cut-off low off the canadian maritimes poised to set up shop early next week and slow hanna's approach. thereafter the ridge is shown breaking down more quickly, with the model solutions now edging hanna much further north than guidance had the storm just yesterday. what looked like an east florida threat now looks like a more typical jab at wilmington or cape lookout, then out to sea.. if the trends are to be bought. i'm not ready to buy anything... gustav is simple compared to hanna, in terms of forecasting. the exact evolution of the cut-off to the northeast (which will entrain energy from the active tropical waves further east), i'm suspicious about. if it amplifies that much, dips to new jersey latitude.. the sucker might just try a tropical transition. is it really going to eat away at the subtropical ridge north of hanna that much, or snatch harder at the sheared system trying to develop to the southeast? does hanna keep edging along westward or go quasi-stationary for two days near the east-central bahamas? this one is much harder to peg.
systems to the east--the feature tagged invest on the nhc imagery, with no number... that one looks much better than the one just passing the cape verdes. shear or no shear, it has more going for it right now. there's an obvious surface center, which it seems fond of ejecting/reforming.. or reabsorbing.. and the shear is wheeling around more and appears to be slackening. when this thing gets to the edge of the subtropical ridge fracture, don't be surprised if it develops in earnest as it lifts out.
further east invest 97L is a large, sprawling wave... moving over marginal waters and unlikely to develop quickly. i'm not sure which model camp to buy into--some lift it through the ridge fracture just like the others... others, notably the euro, take it pretty much straight wnw for days. there are obvious disagreements on just how amplified the blocky pattern in the atlantic will get.
gfs is turning the faucet off after the following wave or two, indicating a lull, not seeing activity in the longer ranges. the atlantic goes back to a flatter ridge with no obvious breaks. scratching my head on that one--this time of year you need widespread westerly shear to stop development on that scale. guess we'll have to see.
HF 0553z31august