ATL: TROPICAL DEPRESSION ALEX - DISCUSSION

[Blown Away]

I see mid level rotation but closer to the convection just S of the DR not down where the models initiate?

[KWT]

CC rotation evident near 16.3N-72.5W this morning - probably a mid-level feature but the area to watch later on if it works its way down to the surface. Convection on the increase again this morning. By the way, the wave appears to be tracking very close to the GFDL solution so far.

http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

It does look like that, but I think I'll have to look at the high resolution images in that region first but yeah it looks like something is there.

That also would place the system closer to the jet axis with the upper high sitting close but with a tight gradient means shear quickly increases to the north of the system.

[ROCK]

got to learn to paste a image in here...

BAMMS for 06z....quite a shift left....but with nothing to track other than mid-level rotation and few t-storms, take it with a grain of salt



http://www.sfwmd.gov/portal/page/portal ... el%20plots

[cycloneye]

12 UTC Best Track

AL, 93, 2010062212, , BEST, 0, 153N, 723W, 25, 1010, WV

[Frank2]

Folks here who know me know that I usually won't post something like this, but when I heard the opening words to this song (after the intro - ahem), I had to laugh out loud:

http://www.youtube.com/watch?v=-6CAeDN9er8

P.S. NHC is down to 40 percent with their 8 a.m. TWO - now that's downcasting (LOL) - amazing at the decrease in convection from this time yesterday, but that's weather for you...

[ronjon]

You can really begin to see the upper level high building and fanning out toward the north this morning. If this wave doesn't develop, you can't blame it on the upper air environment. I still think inflow from the south is being disrupted by SA.

http://rammb.cira.colostate.edu/ramsdis/online/loop_640.asp?product=tropical_ge_4km_visir2_floater_1

[KWT]

I also think the fact it has a very broad slack region of convergence isn't helping either, no real central point to the convection and so the system hasn't been able to tighten up just yet.

I'd be surprised still if we don't get something, 95E though may well throw a spanner in the works down the line, esp if it moves NW/NNW towards Mexico, the outflow would induce shear.

[Frank2]

The wave axis is pretty easy to identify ATTM near 73W MOV W...

[Aquawind]

[quote="KWT"]I also think the fact it has a very broad slack region of convergence isn't helping either, no real central point to the convection and so the system hasn't been able to tighten up just yet.[quote]


Yes I think it's better off with the smaller convective blob because it needs to consolidate.. Granted it still needs to get further west as well.

[CourierPR]

You can really begin to see the upper level high building and fanning out toward the north this morning. If this wave doesn't develop, you can't blame it on the upper air environment. I still think inflow from the south is being disrupted by SA.

http://rammb.cira.colostate.edu/ramsdis/online/loop_640.asp?product=tropical_ge_4km_visir2_floater_1

Good call. That building upper high is evident on satellite.

[StormClouds63]

Even reaching tropical depression status is questionable after looking at this morning's satellite images. System also seems to have taken a northern jog overnight. I still think Alex is a July storm, but we'll see what happens in the next couple of days with 93AL.

[HURAKAN]

Latest

[Aquawind]

Wow look at the envelop of moisture this massive wave is pushing west.. Strong wave is right.

[hurricaneCW]

Even reaching tropical depression status is questionable after looking at this morning's satellite images. System also seems to have taken a northern jog overnight. I still think Alex is a July storm, but we'll see what happens in the next couple of days with 93AL.

I think it looks fine for a gradually developing system, convection is on the increase and wind shear is gradually decreasing. Its future looks bright with the upper high building in. Very warm waters too. If you loop it, you can almost see it developing a better structure.

[vacanechaser]

Even reaching tropical depression status is questionable after looking at this morning's satellite images. System also seems to have taken a northern jog overnight. I still think Alex is a July storm, but we'll see what happens in the next couple of days with 93AL.

I think it looks fine for a gradually developing system, convection is on the increase and wind shear is gradually decreasing. Its future looks bright with the upper high building in. Very warm waters too. If you loop it, you can almost see it developing a better structure.

i would agree with this, but the thing that is holding me back is we see no real maodel support... nothing of note in the globals.. to me, that is the sign... if they are now showing little of nothing, i think 93L may have a short future.. but we will see...



Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Reserach Team

[KWT]

Seems to be some turning with the convective mass just south of DR. Convective region may well induce flooding again in Haiti if it doesn't weaken. Quite a few of the GFDL runs form a system just to the south of Haiti weakly, so this feature maybe what the GFDL has been trying to form.

[cycloneye]

Below is a long analysis made this morning by Dr Jeff Masters from WeatherUnderground about 93L.

Posted by: JeffMasters, 1:50 PM GMT on June 22, 2010

A modest region of intense thunderstorms (Invest 93L) is over the central Caribbean, a few hundred miles south of Hispaniola. This disturbance has the best chance to become Tropical Storm Alex of any system we've seen so far this year. We don't have any buoys near 93L, but pressures at the ground stations surrounding the storm are not falling. A pass of the ASCAT satellite over the Central Caribbean at 9:45 pm EDT last night revealed a modest wind shift associated with 93L, but nothing at all close to a surface circulation. Top surface winds seen by ASCAT were 15 - 20 mph. Water vapor satellite loops show that 93L is embedded in a large region of moist air. The atmosphere over the Caribbean has moistened over the past day, which should aid development of 93L. Wind shear is a low 5 - 10 knots. The high wind shear associated with the strong winds of the subtropical jet stream are over the northern Caribbean, too far north to interfere with development, but close enough to provide good upper-level outflow for the storm. Visible satellite loops show high level cirrus clouds streaming away from 93L to the northeast, evidence of the upper-level outflow channel that is developing to the storm's north. Sea Surface Temperatures are plenty warm, a record 29 - 30°C. The Madden-Julian oscillation (MJO) currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The main negative for 93L continues to be lack of spin. The University of Wisconsin 850 mb relative vorticity analysis is showing that spin at 850 mb (roughly 5,000 feet in altitude) has increased over the past day, but 93L needs to acquire additional spin before it can grow more organized. I speculate that it is this lack of spin that contributed to the loss of much of 93L's heavy thunderstorm activity last night. The storm is now going through a cycle where it is building another respectable mass of heavy thunderstorms, and the increased inflow of low-level air that will feed these thunderstorms will likely enhance 93L's spin today. The Hurricane Hunters are on call to investigate 93L on Wednesday afternoon.

Forecast for 93L

NHC is giving 93L a 40% chance of developing into a tropical depression by Thursday morning, which is a reasonable forecast. Given the storm's current lack of spin and relatively modest amount of heavy thunderstorms, the earliest I'd expect 93L to become a tropical depression would be Wednesday afternoon, with Thursday more likely. Wind shear is expected to be low, less than 10 knots, over the central and western Caribbean this week. Water temperatures will be warm, dry air absent, and the MJO favorable. I don't see any major impediments to the storm becoming a tropical depression by Thursday, and it is a bit of a surprise to me that the computer models have been reluctant to develop 93L. The GFS, NOGAPS, and UKMET models do not develop 93L, and the ECMWF model doesn't develop 93L until after it crosses the Yucatan Peninsula and enters the Gulf of Mexico in a about a week. The current (2am EDT) run of the GFDL model predicts 93L will be a weak tropical storm in the Gulf of Mexico in five days; its previous run had 93L as a major hurricane in the Gulf. Given all this model reluctance and the current disorganization of 93L, I give the storm a low (less than 20% chance) of becoming a hurricane in the Caribbean. Expect 93L to bring flooding rains of 3 - 6 inches to Jamaica, eastern Cuba, and southwestern Haiti today through Wednesday. These rains will spread to the Cayman Islands and central Cuba by Thursday, and western Cuba and Mexico's Yucatan Peninsula on Friday. The current run of the SHIPS model has 93L slowing down late this week to a forward speed of just 6 knots (7 mph) from its current speed of about 10 mph, in response to a weakening in the steering currents. A trough of low pressure is expected to swing down over the Eastern U.S. early next week. If this trough is strong enough and 93L develops significantly, the storm could get pulled northwards and make landfall along the northern Gulf of Mexico coast in the oil spill region. This is the solution of the Canadian GEM model. If 93L stays weak and/or the trough is not so strong, the storm would get pushed west-northwestwards towards the Texas coast. This is the solution of the ECMWF model. The amount of wind shear in the Gulf of Mexico next week is highly uncertain. There is currently a band of high shear near 30 knots over the Gulf, and some of the models predict this shear will remain over the Gulf over the next 7 - 10 days. However, other models predict that this band of high shear will retreat northwards and leave the Gulf nearly shear-free. The long-term fate of 93L remains very murky. My main concerns at this point are the potential for 3 - 6 inches of rain in Haiti over the next two days, and the possibility 93L could become a hurricane in the Gulf of Mexico next week.

[canes101]

[KWT]

Certainly an interesting little curve to the convection on that image there...

Wouldn't surprise me if a MLC tries to form on the SW part of that convection.

[ConvergenceZone]

I"m not ready to throw in the towel yet with this sytem, but if it does develop, it probably won't be for several days.