93L slow to develop, but bringing heavy rains to Haiti

By: Dr. Jeff Masters , 1:50 PM GMT on June 22, 2010

Share this Blog
5
+

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.


Figure 1. Morning visible satellite image of the central Caribbean disturbance 93L.

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.

Elsewhere in the tropics
None of the reliable computer models is calling for tropical cyclone formation elsewhere in the Atlantic over the next seven days.

Floods in China and Burma kill over 250
The deadliest and most destructive weather-related disaster on the planet so far this year is occurring in southern China and northern Burma, where a week of heavy rains has caused flooding that has claimed over 250 lives. The heavy rains and floods ravaging 10 southern Chinese provinces had killed 199 and left 123 missing as of 11:00 a.m. Tuesday, a Ministry of Civil Affairs statement said. Damage is estimated at $6.2 billion. Floods and landslides in neighboring areas of Myanmar (Burma) have claimed at least 63 lives in the past week.


Figure 2. Paramilitary policemen help evacuate residents from Wanjia village of Fuzhou City, East China's Jiangxi province, June 22, 2010. Days of heavy rain burst the Changkai Dike of Fu River on June 21, threatening the lives of 145,000 local people. Local authorities have ordered immediate evacuation, and the army and paramilitary police have begun conducting rescue operations. Image credit: Xinhua.

Wind and ocean current forecast for the BP oil disaster
Southeast to east winds less than 10 knots will blow in the northern Gulf of Mexico today through Saturday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook is uncertain, and will depend upon what 93L does.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) The latest on 93L
2) Which model is the most reliable?

Today's show will be 30 - 40 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 996 - 946

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75Blog Index

Quoting DestinJeff:
12Z Euro and 12Z GFS both show a north to NE movement at end of runs.
Yep. keep yours eyes on that trough.
Member Since: December 1, 2006 Posts: 2 Comments: 3616
Quoting BioChemist:
Seems to me that it would be a relatively good thing for a weak hurricane to strike the Cape San Blas to Cedar Key area, this would disperse the Oil away from the coast? Or am I wrong?


That would bring it ashore around St. Marks where I fish and "reconfigure" the oyster bars I have spent the last several months learning where the Redfish are holding......Not a good example..... :)
Member Since: Posts: Comments:
Quoting jasoniscoolman09:
look like 71.5 west 17.5 noth look like the low is..this storm look like is moving move north to me.
I think that is temporary. It will start moving west pretty soon....I think..:)
Member Since: Posts: Comments:
Okay, now on this visible loop, I can see a bit of rotation. Looks to me like it's going NNW straight into Haite though.

http://www.esl.lsu.edu/animate/goes/index.php?region=tropics&channel=vis
Member Since: Posts: Comments:
93L has a taranchula appearance in that sat pic VA.
Member Since: Posts: Comments:
Paint's still sloppy wet, seems like.


Member Since: Posts: Comments:
Quoting staggalee:
How can you determine wind speed in the euro model?


You can't really determine an actual wind speed, but you can look at the pressure that the model is showing. Generally, a storm with less that 990mb or so (give or take) will be a hurricane.
Member Since: Posts: Comments:
Quoting jasoniscoolman09:
look like 71.5 west 17.5 noth look like the low is..this storm look like is moving move north to me.


thats exactly where the spin is, looks mid level though. new convection is popping though. (new convection is red)

Member Since: Posts: Comments:
The anticyclone keeps shifting west, ahead of convection.
Member Since: Posts: Comments:
986. Chigz
Look at the Wave around 40W - 7N - impressive convection with some spin!!
Member Since: Posts: Comments:
Quoting VAbeachhurricanes:


a little little spin


That's quite a wave over the central Atlantic.
Member Since: Posts: Comments:
How can you determine wind speed in the euro model?
Member Since: Posts: Comments:
Circulation is moving W to WNW. Convection is moving north around the center, making it appear to have a northward movement. If you speed up the visible loops, it's easy to discern movement.
Member Since: Posts: Comments:
I have a ton of work to get done this afternoon! I'll check back in late tonight maybe!
Member Since: Posts: Comments:
981. 900MB
I think we will have Alex sometime tomorrow. The spin looks like it is picking up and centered at 71.7W 17N. A little dmax and I think we are on our way....
Member Since: Posts: Comments:
Holy cow, that system gets HUGE in the gulf. I hope that isn't accurate. It would create a big storm surge, and push oil all over. Yuck.
Member Since: Posts: Comments:
Quoting Hurricanes101:


1 or 2 runs had it developed by Thursday, in fact I dont think any of the models ever developed it before then

Recon scheduled for Wednesday made many expect development by then, now they are seeing the reality that it will take longer

Well good call, I kept my mouth shut yesterday as I was about to call for development this morning.
Member Since: Posts: Comments:
Looks like the rain from 93L is coming ashore here.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting WaterWitch11:
the images coming out of brazil due to the flooding are unbelievable.


Indeed: http://www.liveleak.com/view?i=4bd_1277218759
Member Since: Posts: Comments:
974. IKE
A key to where it goes is the trough in the east next week, assuming 93L develops and then where would it get turned toward the coast.

If it stays a wave it probably continues west to WNW into Mexico or extreme southern Texas.
Member Since: Posts: Comments:
Nary a mention of the poor people in Haiti, where it must just be miserable with the rain and no shelter.

Member Since: Posts: Comments:
Still 20% at 2
Member Since: Posts: Comments:
971. xcool
WOW CRAZY GFDL & ECMWF
Member Since: September 26, 2009 Posts: 2 Comments: 15603
The fact that we have no 18Z coordinates for 93L yet tells you that this is still disorganized
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Look how much larger the system gets in the GOM
Member Since: October 28, 2006 Posts: 57 Comments: 29714


a little little spin
Member Since: Posts: Comments:
Forget the Yucatan, 93L may just bypass the whole westward thing altogether and head straight for the Florida Straits.
Member Since: Posts: Comments:
Quoting IKE:


I don't think it ever developed it before the end of the week.


Yep. It was always forecast to develop at the end of the week. The appearance yesterday just wasn't really expected, but it was still deceiving. Right now is the best circulation 93L has had in its lifetime.
Member Since: Posts: Comments:
964. IKE
Quoting Hurricanes101:
Tuesday - 168 hours



I'd say anywhere from east Texas...eastward COULD get something significant from 93L.
Member Since: Posts: Comments:
ECMWF 12z looks like the GFDL 12z
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Member Since: Posts: Comments:
Seems to me that it would be a relatively good thing for a weak hurricane to strike the Cape San Blas to Cedar Key area, this would disperse the Oil away from the coast? Or am I wrong?
Member Since: Posts: Comments:
Quoting helove2trac:
They are probably watchin twc and saying only 20%


LMAO!
Member Since: Posts: Comments:
I don't want to wish cast but us in the Northern Gulf definately don't want this one in our vecinity. Hopefully the early tracks hold true taking this in the direction of the Western Gulf. I don't think any of us from Louisiana to Florida want this so early in the season.
Member Since: Posts: Comments:
958. IKE
Quoting Ivanhater:
12z euro hurricane in central gulf


Figures. Models have trended stronger today.

Anybody RIP's 93L is foolish.
Member Since: Posts: Comments:
957. xcool
Ivanhater YEP
Member Since: September 26, 2009 Posts: 2 Comments: 15603
anyone know what the conditions are like in Haiti? it looks like heavy rains and I'm wondering how it's affecting the displaced from the earthquake. With recents floods and deaths in China and Brazil, I fear for those in Haiti.
Member Since: Posts: Comments:
Quoting smarterthanyou:
Florida, once thought
to be almost Paradise
now, just poison


your doomsday haikus
once mildly entertaining
now just on my nerves

and btw, your last one only had four in the last line not five
Member Since: Posts: Comments:
Tuesday - 168 hours

Member Since: March 10, 2010 Posts: 1 Comments: 7233
sorry couldn't get link or pic to post.

http://moe.met.fsu.edu/cgi-bin/gfdltc2.cgi?time=2010062212-invest93l&field=Sea Level Pressure&hour=Animation
Member Since: Posts: Comments:
12z euro hurricane in central gulf
Member Since: Posts: Comments:
Quoting IKE:


I don't think it ever developed it before the end of the week.


1 or 2 runs had it developed by Thursday, in fact I dont think any of the models ever developed it before then

Recon scheduled for Wednesday made many expect development by then, now they are seeing the reality that it will take longer
Member Since: March 10, 2010 Posts: 1 Comments: 7233
949. IKE
Quoting Hurricanes101:


yup ECMWF does not develop 93L until Friday -Saturday now

people here will have no hair by then lol


I don't think it ever developed it before the end of the week.
Member Since: Posts: Comments:
Quoting IKE:
And that's 6 days away on the ECMWF...just north of the Yucatan. That's next Monday. Anything after 144 hours is a coin-flip.


I'd day anything after 24 with this system with no low is a coin flip.
Member Since: Posts: Comments:
the images coming out of brazil due to the flooding are unbelievable.
Member Since: Posts: Comments:
It's going to wait until my son is at scout camp. How's that for forecasting? LOL. It always works. Nothing makes a better week than storm prep and slogging around soggy scouts.
Member Since: Posts: Comments:

Viewing: 996 - 946

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.