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Invest 90L (Was Bahamas Disturbance)

Josh Morgerman

Josh Morgerman

EF4
Joined
Jan 8, 2006
Messages
444
Location
West Hollywood, CA
I don't want to drag the TS Karen thread off topic, so I thought I'd start a new one Re: the Bahamas disturbance that Jim Leonard first mentioned yesterday.

The NHC's 8:05 pm EDT TWD mentions a 1010-mb low near ~26N 74W. As y'all know-- and as Jim mentioned-- some of the models develop this low and track it generally W, across the Gulf. I'm getting mixed signals from forecasters as to whether the Gulf will be hospitable or not. Dr. Masters, on Weather Underground, seemed quite bullish about this disturbance this morning, and he mentioned the possibility of an upper-level anticyclone getting established.

It should be an interesting week!
 
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From the NHC's 10:30 pm EDT TWO:

A LARGE BUT DISORGANIZED AREA OF CLOUDINESS AND A FEW THUNDERSTORMS IS LOCATED OVER THE WESTERN ATLANTIC...BAHAMA ISLANDS...AND PORTIONS OF SOUTH FLORIDA. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER-LEVEL TROUGH AND A WEAK SURFACE LOW. SOME SLOW DEVELOPMENT...PERHAPS OF A SUBTROPICAL NATURE...IS POSSIBLE DURING THE NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES SLOWLY WESTWARD OR WEST-SOUTHWESTWARD.

I sure hope it's not another one of those annoying, hybrid systems. Ugh. The W or WSW motion is interesting in this respect, as it would give this low a lot more time over the Gulf than enjoyed by TD 10-- another initially subtropical system that "ran out of time", moving onto land just when it had made the transition to pure-tropical. (TD 10 could have become something if it had had a little more time over water.)
 
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Josh.
Im afraid so, this will probably be a slow process for development. First we need to get upper low to move to the SW of the surface low, this will allow a more anticyclonic flow to develop over the surface low. These subtropical formations usually take a few days to warm up. Most models are taking the system across the Gulf probably south of latitude 24N. The flow pattern across the U.S. this coming week should be somewhat zonal WSW which would allow a narrow ridge to stay along the Gulf coast so it would keep the low moving on a pretty much westward course across the Gulf. Watch it become a hurricane 12 hours before landfall.
 
Jim Leonard said:
Josh.
Im afraid so, this will probably be a slow process for development. First we need to get upper low to move to the SW of the surface low, this will allow a more anticyclonic flow to develop over the surface low. These subtropical formations usually take a few days to warm up. Most models are taking the system across the Gulf probably south of latitude 24N. The flow pattern across the U.S. this coming week should be somewhat zonal WSW which would allow a narrow ridge to stay along the Gulf coast so it would keep the low moving on a pretty much westward course across the Gulf. Watch it become a hurricane 12 hours before landfall.
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I belive it will, but i also belive it will intensify with a quickness( the GOM is a bowl of hurricane soup) and 12 hours is more than enough time to rapidly strenghthen into a major hurricane, you better start packin your bags jim.IMO
 
Jim Leonard said:
Josh.
Im afraid so, this will probably be a slow process for development. First we need to get upper low to move to the SW of the surface low, this will allow a more anticyclonic flow to develop over the surface low. These subtropical formations usually take a few days to warm up. Most models are taking the system across the Gulf probably south of latitude 24N. The flow pattern across the U.S. this coming week should be somewhat zonal WSW which would allow a narrow ridge to stay along the Gulf coast so it would keep the low moving on a pretty much westward course across the Gulf. Watch it become a hurricane 12 hours before landfall.
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Jim, I know what you mean Re: these last-minute hurricanes-- it's a bit frustrating. Humberto and Lorenzo could have been cool chases, but there was just no time with either. By the time I realized each was going to be a decent 'cane, it was too late to mobilize.

Re: the Bahamas thing... If a cyclone develops and stays on that W or WSW track, it would have at least a couple of days to transition to warm core (if it's not already) and deepen-- and given what happened this year with Humberto and Lorenzo, I'm wary of fast changes.

All of this having been said... Looking at the morning infrared, there's not a whole lot there just yet-- beyond a broad swath of very disorganized convection-- although I hear it's been very stormy in S FL overnight. I guess we'll have to wait for that cyclone. :)
 
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The upper low has begun to move WSW it is just about over KeyWest this morning. The surface system is beginning to flareup and is getting better organized just to the east of the central Bahamas. There improving upper flow over this convection so we should see some development today and tonight. The weather should get interesting here in south Florida in the coming days.
 
Jim Leonard said:
The upper low has begun to move WSW it is just about over KeyWest this morning. The surface system is beginning to flareup and is getting better organized just to the east of the central Bahamas. There improving upper flow over this convection so we should see some development today and tonight. The weather should get interesting here in south Florida in the coming days.
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Hi Jim, when you mention the surface system, do you mean the weak (1012-mb) low that the NHC puts near ~26N 75W? I notice there's some major convective flare-up this morning a little to the E-- from ~25-30N and 70-75W.
 
Mike Smith said:
What does "Invest" stand for?
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As I understand it, it's a term applied to any area of disturbed weather that may spawn a tropical cyclone-- i.e., an area that's being "investigated". If I understand correctly, there are no formal criteria for this label. Invests in the Atlantic are labeled 90-99L (when they get to 99, they start back at 90 again). Once the feature develops a closed circulation, it's designated a tropical cyclone-- usually starting off as a depression.

Anyone else with more expertise want to chime in here? :)

Re: 90L... It's pretty lame tonight-- definitely has not made any organizational progress today.
 
Im not too excited on the progged upper level evolution. The further west this storm goes the more hostile the environment. It looks like an upper level high will stay over or near florida as the upper low moves off to the SW, and the western GOM will be a bad place for the storm. Can we keep that convection firing offshore of the bahamas and get the surface low to form there and stay east?
 
MClarkson, I'm not terribly enthused by this system, either. It's going to be another one of these slowly-transitioning hybrid cyclones. <yawn>

The surface-low center is now in the SE Gulf, ~100 mi WSW of Key West, FL. Winds to near-gale force are occurring in the E Gulf, quite far from the low center.
 
Good day all,

Those same gale-forced gusts (~40 MPH) came ashore near Palm Beach last night / yesterday with heavy rain and thunderstorm (squalls). To me it was a GREAT Monday to work in my office.

If you look at the atlantic visible as a whole, and loop it, there are VERY FEW places where you have "trade winds" from the east anymore. There are westerly winds in many places.

If this (normally subborn) pattern does not change, The fat lady is singling indeed. She certainly is for "Cape Verde" storms, which that's done, obviously.

Funny that with all this shear, El Niño is no where to be found.

Hate to burst anyone's bubble (no, not your's Josh / MClarkson - You already know this is a dud) - I think we know what's GONNA happen with this one, again...

1). Take its sweet a-- time for the core to "warm up" as JL pointed out. I see "Subtropical Tease" TD #10 all over again.

2). Finally, after the agonizing subtropical to tropical transition, it should be moving NNW (although the NHC still says "WNW") and come ashore 2 hours after that at 37.9 MPH.

3). If it still moves W, then it will EXPLODE into a major hurricane, and make sure it make landfall in a non-english speaking country with thugs waiting to mug anyone who chases it.

"Season 2007 is to 2004 / 2005" as...

A: "Lunch with George Clinton is to lunch with Jenny Lopez"
B: "Winning the 'boobie' proze is to winning the lottery"
C: "Driving a Chevette is to driving a Ferrarri"
D: All of the above.

Sorry about this, TSDS (Tropical SDS) stinks and gets to my head when there's lots of shear ;-)
 
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Ha ha ha!! Nice one, Chris. The three scenarios are particularly accurate-- although of course there are many nice people and nice places in Mexico and Central America. But, otherwise, this is spot on-- pretty-much how I see things!! :) :D

Still... Re: the 2007 season overall, I've found it rich with interest. For me, hurricane landfalls are dramatic wherever they happen, and this season has had four really interesting ones so far: Dean, Felix, Humberto (in some ways the coolest one), and Lorenzo.

For me, a really dull season was 2006. Don't even get me started on that one. It wasn't actually that slow-- there were plenty of cyclones-- but talk about boring! Ugh!
 
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As 90L continues to bore, I should point out-- and some of y'all have probably seen this already-- that the GFS and Euro are suggesting development of a large, deep, W-moving cyclone in the Bahamas in a few days-- under a much-better upper-air pattern than what we have currently.

Now that could get interesting.
 
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