Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 02:12 PM GMT del 26 Giugno 2010
The first named storm of the Atlantic hurricane season of 2010 is here. Tropical Storm Alex formed last might from an African tropical wave that plowed through the Caribbean this week. Alex's formation location is a typical one for June tropical storms, and the formation date of June 25 is also a fairly typical date for the first storm of the season to form (we average about one June named storm every two years in the Atlantic.) Heavy rainfall will ramp up through the day in Honduras, Belize, and Mexico's Yucatan Peninsula, as Alex continues to intensify, and flooding from these heavy rains will be the main concern from Alex today and Sunday. Satellite loops show that Alex's heavy thunderstorm are growing in intensity and areal coverage at a respectable pace. There is an upper-level high pressure system a few hundred miles west of Alex, and the clockwise flow air around this high is bringing upper-level winds out of the northwest of about 10 knots over the storm, contributing to the 10 knots of wind shear observed in this morning's wind shear analysis from the University of Wisconsin's CIMSS group. Sea Surface Temperatures are very warm, 29 - 30°C, and dry air is not a problem for Alex. We currently don't have a Hurricane Hunter aircraft in the storm, so we will have to wait until 2pm this afternoon to get an updated estimate of Alex's surface winds. The latest satellite estimates of Alex's winds at 8am EDT put the storm's strongest winds at 40 mph.
Figure 1. Satellite image of the tropics at 9am EDT Saturday 6/26/10. Image credit: GOES Science Project.
Forecast for Alex
As I discussed in last night's post, an examination of the nineteen tropical cyclones that have formed in the Western Caribbean and hit the Yucatan Peninsula over the past twenty years reveals that 8 went on to make a second Gulf Coast landfall in Mexico, 5 hit the U.S. Gulf Coast, and 6 died after hitting the Yucatan. The ones that died all took a more southerly path across the Yucatan, spending more time over land than Alex will. Alex is large enough and moving far enough north across the Yucatan that passage over the peninsula will not kill it. So, will Alex follow the path climatology says is more likely, and make a second landfall along the Mexican Gulf Coast?
Figure 2. Forecast swath of tropical storm force winds (34 - 63 knots, green colors) and hurricane force winds (yellow and orange colors) as predicted by this morning's 2am EDT run of the HWRF model. Image credit: Morris Bender, NOAA GFDL team.
The key question remains how Alex will react to the trough of low pressure expected to swing down over the Eastern U.S. on Monday. Some of yesterday's model runs predicted that this trough would be strong enough to pull Alex northwards through the oil slick region into the northern Gulf of Mexico coast. However, the models that were predicting this (the GFS, GFDL, and HWRF models) are all backing off on that prediction. It now appears likely that Alex will cross the Yucatan, emerge into the Gulf of Mexico, then slow down as the trough to its north weakens the steering currents in the Gulf of Mexico on Monday. By Tuesday, the influence of the trough will wane, high pressure will build in, and Alex will resume a west-northwest, or possibly a due west or west-southwest motion, towards the Texas/Mexico border region. Based on the current trends in the models, Alex's tropical storm force winds are likely to stay well south of the oil slick region (Figure 2.) I put the odds of Alex bringing tropical storm-force winds to the oil slick region at 10%. The most significant impact Alex will likely have on the oil slick region is to bring 2 - 4 foot swells that may wash oil over some of the containment booms. These swells will reach the oil slick region on Tuesday and Wednesday.
Continued intensification of Alex is likely today, up until landfall. It is a good thing the storm waited until last night to get organized; had it formed a day earlier, it could have easily been a hurricane in the Western Caribbean today. Once Alex emerges back into the Gulf of Mexico on Monday, it will likely take the storm at least 24 hours to get re-organized, particularly since the total ocean heat content is low for the 100-mile-wide stretch of water on the west side of the Yucatan Peninsula. Once Alex moves more than 100 miles from the Yucatan, total heat content of the ocean increases substantially, and Alex will have the opportunity to intensify significantly. Steering currents will be weak in the Gulf next week, and it appears that Alex will have time to intensify into a hurricane before making its second landfall along the South Texas/northern Mexico coast. Wind shear is expected to be light, and dry air not a significant impediment. Most of the models are calling for landfall on Wednesday, but I wouldn't be surprised to see this delayed until Thursday. I give Alex a 60% chance of becoming a hurricane in the Gulf of Mexico next week.
Elsewhere in the tropics
A tropical wave (Invest 94L) is a few hundred miles northeast of the northernmost Lesser Antilles Islands. This wave is producing a modest amount of heavy thunderstorm activity, and is passing beneath a trough of low pressure that is generating 30 - 40 knots of wind shear, and is not a threat to develop today. However, by Monday, the storm will be in a region of much lower wind shear, and NHC is giving the storm a 10% chance of developing into a tropical depression by Monday morning. None of the models currently develop 94L, but Bermuda should keep and eye on this system, as it will pass very close to the island on Tuesday.
Extreme heat wave in Africa and Asia continues to set all-time high temperature records
A withering heat wave of unprecedented intensity and areal covered continues to smash all-time high temperatures Asia and Africa. As I reported earlier this week, Kuwait, Saudi Arabia, Iraq, Chad, Niger, Pakistan, and Myanmar have all set new records for their hottest temperatures of all time over the past six weeks. The remarkable heat continued over Africa and Asia late this week. The Asian portion of Russia recorded its highest temperate in history yesterday, when the mercury hit 42.3°C (108.1°F) at Belogorsk, near the Amur River border with China. The previous record was 41.7°C (107.1°F) at nearby Aksha on July 21, 2004. (The record for European Russia is 43.8°C--110.8°F--set on August 6, 1940, at Alexandrov Gaj near the border with Kazakhstan.) Also, on Thursday, Sudan recorded its hottest temperature in its history when the mercury rose to 49.6°C (121.3°F) at Dongola. The previous record was 49.5°C (121.1°F) set in July 1987 in Aba Hamed.
We've now had eight countries in Asia and Africa, plus the Asian portion of Russia, that have beaten their all-time hottest temperature record during the past two months. This includes Asia's hottest temperature of all-time, the astonishing 53.5°C (128.3°F) mark set on May 26 in Pakistan. All of these records are unofficial, and will need to be certified by the World Meteorological Organization (WMO). According to Chris Burt, author of Extreme Weather, the only year which can compare is 2003, when six countries (the UK, France, Portugal, Germany, Switzerland, and Liechtenstein) all broke their all-time heat records during that year's notorious summer heat wave. Fortunately, the residents of the countries affected by this summer's heat wave in Asia and Africa are more adapted to extreme high temperatures, and we are not seeing the kind of death tolls experienced during the 2003 European heat wave (30,000 killed.) This week's heat wave in Africa and the Middle East is partially a consequence of the fact that Earth has now seen three straight months with its warmest temperatures on record, according to NOAA's National Climatic Data Center. It will be interesting to see if the demise of El Niño in May will keep June from becoming the globe's fourth straight warmest month on record.
Wind and ocean current forecast for the BP oil disaster
East to southeast winds of 5 - 15 knots will blow in the northern Gulf of Mexico today through Wednesday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should push the oil to the west and northwest onto portions of the Louisiana and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. I would expect Mississippi to have its most serious threat of oil yet early next week as these winds continue. The long range outlook shows a continuation of east to southeast winds along the northern Gulf of Mexico coast.
Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
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 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
Wunderground's severe weather expert Dr. Rob Carver will likely be posting at least one update on Alex this weekend. My next update will be Sunday morning.
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