Two African waves that may develop
Hello everyone, it's Jeff Masters back with you again after a long stretch of vacation. Now that the peak part of hurricane season is upon us, I'll be with you every day for the next few months, in what promises to be an unusually active Atlantic hurricane season. We've got several threats to talk about today, most notably a strong African wave near 12.5°N 30.5°W, about 400 miles west-southwest of the Cape Verde Islands. This system, dubbed Invest 92L by NHC, is moving west to west-northwest at 10 - 15 mph, and has the potential to develop into a tropical depression or tropical storm before arriving near the northern Lesser Antilles Islands early next week. Recent visible satellite loops show that 92L is beginning to develop a surface circulation, and heavy thunderstorms are slowly building along the western edge of the center. However, a separate area of heavy thunderstorms lies 400 miles to the east, just south of the Cape Verde Islands, and this blob is interfering with consolidation of the center near the blob of heavy thunderstorms at 30.5°W. Water vapor satellite loops show that a large area of dry air from Africa lies just to the west of 92L, but the atmosphere in the immediate vicinity of 92L is moist, so dry air is currently not a problem for the storm. The SHIPS model is diagnosing low shear, 5 - 10 knots, over 92L, but the University of Wisconsin CIMSS analysis shows that moderate shear of 10 - 20 knots is affecting 92L. Sea surface temperatures are 26.5° - 27°C, which is very close to the 26.5°C threshold usually needed to support a tropical storm.
Figure 1. Noon satellite photo of Invest 92L.
Forecast for 92L
Low to moderate wind shear of 5 - 15 knots is predicted along 92L's path over the coming three days, which should allow the storm to steadily organize, assuming it can shut out any incursions of dry air that might intrude. The latest 00Z and 06Z model runs of the four best models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET) show little or no development of 92L, and NHC gave 92L just a 20% chance of developing into a tropical depression by Friday morning in their 8am outlook. Given the recent improvement in the satellite appearance of 92L, I would put these odds at 30%. A steady west to west-northwest motion for 92L is predicted by all of the models, which would put the storm in the vicinity of the northern Lesser Antilles Islands by Sunday. On Saturday and Sunday, 92L is expected to enter a region where an upper-level low pressure system will bring high wind shear of 20 knots to the storm, which should slow development. This upper-level low is also expected to turn 92L more to the northwest, so the storm may pass north of the Lesser Antilles. It is too early to know if 92L will recurve out to sea and potentially threaten Bermuda, or continue to the northwest towards the U.S. East Coast.
Figure 2. NASA MODIS image taken at 10:40am EDT 8/10/11 of the tropical wave emerging from the coast of Africa. The GFS model is predicting this system will develop into a tropical storm early next week. Image credit: NASA.
Tropical wave emerging from the coast of Africa
A strong tropical wave currently emerging from the coast of Africa near 8°N has a modest amount of spin and heavy thunderstorm activity associated with it, and has the potential to develop early next week once it moves past the Cape Verde Islands. The GFS model has been developing this system into a tropical storm in several of its recent runs. A westerly track towards the Lesser Antilles is expected by the GFS model.
Jeff Masters
Reader Comments
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I am a resident of Galveston and I beg to disagree. The middle of July happens to be the slowest time - we get such crowds for the 4th and there is a slump right afterwards. If you look at hotel occupancy and beach counts, we are back where we were before Ike, and higher on the holidays.
That said, if you drive off the main drag, you will still see many blue roofs (most now shredded) and derelict buildings. Whereas tourism has recovered, the population has not and the economy is keeping things down. It is a great time to buy property on the island.
I wished he'd give it a break, the system hasn't even formed yet and he's calling fish. It's only an INVEST.
I would say no. There is a long-advertised shortwave along 50-51W breaking a somewhat weak A/B ridge in half. The models respond by bringing 92L towards this weakness. Some runs have even hinted at a weak trough split here and a subsequent area of vorticity ahead of 92L drifting to the SW into the Caribbean. That part seems pretty iffy.
700mb @ 18Z
click to enlarge
Still looks to me like Emily is trying to come back around again.
You sound a lot like pottery lol.
Unusual, but not unheard of, I guess. Since the monster earthquake in Japan, there have been 70 6.0 or larger quakes on the planet: 21 in March, 14 in April, 5 in May, 10 in June, 19 in July, and--so far--just one in August. It's definitely a bit of a drought. But there were two on May 15, then none until June 1, so we've another week to go before equaling that seismic lull...
It does appear that her energy got split, looking at the imagery posted above.
That's at least half of her moisture circling around the big High, and some of her vorticity.
It's interesting, anytime one tries to do this, even if it's just part of the energy. The left over moisture is significant, at the least.
Locally the strong heat ridge remains in place with yesterday being the tenth straight day at or above 100…we will do it again today and likely again Friday. The streak to break the 1980 record is 14 and to tie it would be on Sunday. It would appear that the ridge may weaken just enough over the weekend to drop 1-3 degrees off the high temperature which would support 98-101 across the region, so it is in question if the current 100 degree streak will be broken or tied.
Heat:
Below is some comparison data to the summer of 1980 (hottest summer ever for TX) and 2011 for the number of days at or above 100:
College Station: 43 (1980), 38 (2011)
Huntsville: 43 (1980), 45 (2011)
Conroe: 22 (1980), 27 (2011)
BUSH IAH: 32 (1980), 21 (2011)
Hobby: 8 (1980), 6 (2011)
Dallas: 69 (1980), 47 (2011)
Waco: 63 (1980), 59 (2011)
Austin Mabry: 32 (1980), 57 (2011), record year is 69 in 1925
Del Rio: 56 (1980), 63 (2011), record year is 78 in 1953
San Antonio: 31 (1980), 33 (2011), record year is 59 in 2009
Number of consecutive days at or above 100 degrees:
Dallas: 42 (1980), 40 (2011)
Waco: 42 (1980), 42 (2011) *Today will break this record*
BUSH IAH: 14 (1980), 10 (2011)
So far for August of 2011, most of the climate sites in SE TX are on their way to breaking their hottest monthly temperature FOR ANY MONTH by 2-3 degrees!
Drought:
Things are bad and getting worse by the day with respect to water supply, vegetation, and agricultural impacts. The impacts to agriculture and livestock are approaching severe levels with cattle running out of drinking water from drying creeks and ponds. Vegetation has stopped growing and died in many ranch areas with feed being trucked into from the central plains for cattle. We are really getting into a bad situation quickly and we desperately need widespread rainfall. The majority of irrigation currently is just to keep vegetation alive at this point and with increasing water conservation measures likely vegetation already stressed is going to suffer even more.
Houston has now gone 198 days between 1.0 inch rainfall events breaking the previous record of 192 days from 1917-1918
Only 6.36 inches of rain has fallen in the last 191 days for the City of Houston (IAH) making this by far the driest Feb-Aug 10 period ever. This breaks the previous record by an astounding 6.25 inches of rainfall…that is an amazing record!!! At Hobby Airport for the same time period the record is being broken by 5.17 inches!
The period from August 2010 to August 2011 is now the driest 1-year period ever for the City of Houston.
Water Supply:
For the first time since the drought of 1988 the City of Houston is going to be requesting emergency releases from Lake Conroe to help stabilize the rapid fall that is occurring on Lake Houston (the primary water supply for the City of Houston). This is only the third time ever this action has been required. Water intake pipes on Lake Houston are getting dangerously low to becoming exposed and causing damage to the water supply system. With this action likely next week, the City of Houston will move to Stage 2 water conservation (mandatory water restrictions). This is going to have a significant impact on the lake levels at Conroe as releases begin, and the lake will begin to fall due to the releases that are going to be required to help stop the rapid decline on Lake Houston.
Lake Somerville and Lake Texana are now close to 50% of their capacity and falling. Lake Somerville has lost an astounding 11% of its capacity in the last 3 weeks!
Outlook:
I have really no good news, as any rains over the next 48 hours will likely be focused west of SE TX. 14 day outlook continues to feature below normal rainfall unless something can develop and threaten from the tropics.
NOAA issued a La Nina Watch this week suggesting that the return of cooling in the central Pacific may once again result in La Nina conditions this fall-winter-spring….if this happens rainfall will average below normal through much of this winter and this drought will only worsen if we do not get some kind of tropical system in the next 2 months.
True. AK had a 6-7 mag 2 months ago and that is where I would place money for one again. Higher? Yeah we are due but so are a lot of other places. I would place higher bets on something in Europe...Iceland or the Med before us. Not a lot of money though. Gotta be a volcano ready to go in the Med somewhere which is usually proceeded by a quake of some sort.
Yeah, we are probably DOOM.
I saw that gap there also. Two weeks, from what I gathered, is the usual gap. All the while, pressure builds...........oooohhhhhhh..........
Good Morning Saint :-)
Most of those 6.0+ quakes were off the coast of Japan.
LOL, he only got half your post this time. ;^)
Yes, they continue to get moderately large aftershocks.
Good mornin'!
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