Large and intensifying Hurricane Alex bears down on northeastern Mexico, South Texas
Hurricane Alex continues to intensify as it slowly bears down on the coast of northeastern Mexico. Brownsville long-range radar shows the spiral bands of Alex, which has dumped heavy rains of up to four inches in northeastern Mexico and near Brownsville, according to satellite estimates of rainfall. The Brownsville airport received 0.78" of rain in the hour ending at 8am CDT, and 0.61" in the hour ending at 9am CDT. Floods from Alex have already killed ten people--six in Nicaragua, and two each in El Salvador and Guatemala.
Figure 1. Snapshot of the Brownsville long-range radar showing Hurricane Alex approaching the coast.
The 7:12am CDT eye penetration of the Hurricane Hunters found a central pressure of 959 mb, a modest 2 mb drop from the reading four hours previous to that. They noted a very tiny eye, ten miles in diameter, with a gap in the northwest side. Tiny eyes like this tend to be unstable, and in the 9:05am CDT eye penetration, the Hurricane Hunters found that the inner eyewall had collapsed, and the pressure had risen 2 mb, to 961 mb. A new, much larger eye will form today as the day progresses. During these "eyewall replacement cycles", a hurricane will typically weaken a few millibars , and the strongest winds will spread out over a larger area as the hurricane conserves angular momentum. Thus, the hurricane still has about the same amount of destructive power, it is just spread out over a larger area. This tends to increase the hurricane's storm surge, but lessens the wind damage, since the extreme winds of the inner eyewall are no longer present. Satellite loops show a large, well-organized storm with increasing amounts of low-level spiral bands forming, and improving upper-level outflow. Data from last night's flight of the NOAA jet showed an unusually moist atmosphere surrounds Alex, so dry air is no longer a problem for it. It's a good thing Alex has less than a day before making landfall, or else is would be a large and very powerful major hurricane.
Figure 2. Visible light image of Tropical Storm Alex taken at 19:35 UTC (2:35 pm CDT) on June 29, 2010, by NASA's Aqua satellite. At the time, Alex was a tropical storm with 70 mph winds. Image credit: NASA.
Storm Surge
Traditionally, a storm's ranking on the Saffir-Simpson Scale--the familiar Category 1, 2, 3, 4, 5 rankings we always talk about--have also been used to quantify storm surge threat. However, large, weaker storms that cover a huge area of the Gulf of Mexico, like Alex, can generate a larger storm surge than a smaller but more intense hurricane with a higher Saffir-Simpson rating. Thus, the National Hurricane Center has formally discontinued use of the Saffir-Simpson scale to characterize storm surge, and is studying the possibility of issuing separate Storm Surge Warnings a few years from now. These would be in addition to their traditional Hurricane Warnings. To give us a better idea of a storm's surge potential, Dr. Mark Powell of NOAA's Hurricane Research Division has developed the Integrated Kinetic Energy scale to rank storms. The scale ranges from 0 to 6, and a parallel wind damage scale that runs from 0 to 6 is also generated. Alex had an Integrated Kinetic Energy of 2.6 on the 0 to 6 scale at 1:30pm CDT yesterday, and its destructive potential rating for winds was just 1.2. Thus, Alex's surge ranked alomst one-and-a-half categories higher in destructive potential than its wind. These numbers have probably increased by a full category since yesterday afternoon. NHC is giving a 40% - 60% chance of a storm surge of at least 3 feet affecting the Brownsville area, and 10% - 30% chance the surge will exceed 5 feet. In theory, a Category 2 hurricane moving WNW at 5 mph can bring a storm surge of up to 8 - 9 feet to the South Texas and northern Mexican coast.
Other Impacts
Alex is bringing bands of heavy rain to the coasts of Texas and Mexico, as seen on the Brownsville, Texas radar. Hurricane local statements with projections for how Alex will affect the coast are now being issued by the National Weather Service in Brownsville and Corpus Christi. Flooding damage from the expected 6 - 12 inches of rain from Alex will be the main concern. Wind damage is a lesser concern, since the core of Alex is making landfall in a swampy, sparsely populated region of Mexico. The combined wind, surge, and flooding damage from Alex may be similar to 2008's Hurricane Dolly, which hit near Brownsville. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall, and did about $1 billion in damage. Dolly also generated two weak EF-0 tornadoes, and Alex is capable of generating a few tornadoes as well, according to the latest discussion from NOAA's Storm Prediction Center. The atmosphere is moderately unstable, there is plenty of moisture, and wind shear at low levels has been increasing this morning. The greatest threat for tornadoes will occur late this afternoon, on the right side of where the storm makes landfall.
Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. Allison briefly became a minimal 75 mph hurricane before weakening and hitting the Florida Panhandle as a tropical storm. Alex is the strongest June hurricane since Hurricane Bonnie of 1986, which had 85 mph winds. Bonnie was the first hurricane I flew into as a member of the Hurricane Hunters. Bonnie made landfall along the upper Texas coast, and caused less than $20 million in damage. If Alex strengthens to 90 mph winds, it will be the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the Florida Keys. There have been only ten hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.
Track forecast for Alex
All of the models take Alex to the west or west-northwest into northern Mexico by early Thursday morning. However, the steering currents are fairly weak, and Alex could stall and move erratically at times today. I don't anticipate that this weakness in the steering currents will allow Alex to move northward and make landfall in Texas. After landfall, the ridge of high pressure forcing Alex westward should remain in place and strengthen, keeping Alex's remnants over northern Mexico for several days.
Intensity forecast for Alex
Alex is over a region of ocean with moderately high total ocean heat content . Wind shear has fallen to a low 5 knots, and is projected by the SHIPS model to remain in the low range, below 10 knots, through landfall. The combination of low wind shear, moderately high ocean heat content, and plenty of moisture should allow Alex to continue to intensify today. Alex's pressure is already characteristic of a Category 3 hurricane, but the storm is so large that it is taking time for the winds to catch up to the pressure falls. It is unlikely that Alex's winds will be at Category 3 strength at landfall, since the storm is undergoing an eyewall replacement cycle, and does not have time to build a tight inner eyewall with strong winds before landfall. A Category 2 storm at landfall looks more likely.
Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical disturbance in the Western Caribbean on Monday. None of the other models is showing anything brewing over the coming seven days.
Wind and ocean current forecast for the BP oil disaster
Alex is generating very rough conditions over the Deepwater Horizon blowout location, with 6 - 8 foot waves and 3 - 4 foot swells. Strong southeast to south winds of 15 - 25 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents will push oil to many protected bays and estuaries that haven't seen oil yet. In addition, the 1 - 2 foot storm surge Alex is generating along the Louisiana coast will act to push oil deep into some low-lying marshlands. While this oil will be diluted some by the wave action, the impact of the oil and accompanying toxic dispersants on the marshlands is of concern. The latest trajectory forecasts from NOAA and the State of Louisiana show oil will also move westward along the central Louisiana coast towards the Texas border. Winds will decrease to 10 - 15 knots Friday through Monday but remain out of the southeast, keeping the pressure on the regions of coast in Louisiana, Alabama, and Mississippi that are seeing oil hit their shores this week.
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
Next post
Either Rob Carver or myself will do an update late this afternoon or this evening.
Jeff Masters
Weather inbound to Hurricane Alex.
Weather inbound to Hurricane Alex.
Flight deck view from a WC-130J Hurricane Hunter aircraft
Reader Comments
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(150h)
I appreciate the link - we have field locations in the area and this helps to know what is going on in the county.
GJT
Pressure is rising due to an EWRC, but winds are also increasing at the surface.
Latest dropsonde information
Significant Wind Levels...
Level Wind Direction Wind Speed
972mb (Surface) 140° (from the SE) 81 knots (93 mph)
963mb 150° (from the SSE) 90 knots (104 mph)
947mb 155° (from the SSE) 90 knots (104 mph)
877mb 170° (from the S) 77 knots (89 mph)
844mb 170° (from the S) 80 knots (92 mph)
I remember a more recent one (Gilbert?) killing hundreds of people who were living in an arroyo because nobody thought to tell them that a storm was coming.
Warning people like them now would be a thoughtful gesture. I hope someone is doing that, because I doubt many of them have TV's and smartphones.
WTH? He crazy?
Before the season is best. Best thing to get just before the season begins is batteries and a few gallons of water placed in a nice clean area of the house. Stash away some toiletries not to be used in case of emergency i.e. toilet paper, soap, etc.
If it's a Cat 1 I will know it's got water in it. If it's a Cat 3, I know I'll come home to a concrete slab. :)
now tf, you know that canes do not go in a straight line...and to think its going to go 12 hours in the exact same heading with outside forces acting upon it, is crazy...i expect a shift from nw back to wnw in the next 3-6 hours and a landfall 50-75 miles south of the border...
Staying is always a Personal Option.
Though NOT recommended if possible.
It also shows development of a system up through the Yucatan. Could be a wild two weeks '09
landfall within hours. It's moving on in.
I don't know which is worse the water in the house or the concrete slab.... I guess the water in the house because at least some things might make it through... :(
URNT12 KNHC 301736
VORTEX DATA MESSAGE AL012010
A. 30/17:13:40Z
B. 24 deg 16 min N
096 deg 02 min W
C. 850 mb 1112 m
D. 73 kt
E. 088 deg 13 nm
F. 136 deg 96 kt
G. 068 deg 65 nm
H. 962 mb
I. 14 C / 1518 m
J. 21 C / 1522 m
K. 18 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 1 nm
P. AF304 1201A ALEX OB 04
MAX FL WIND 96 KT E QUAD 16:51:20Z
MAX FL TEMP 22 C 236 / 8 NM FROM FL CNTR
PARTIAL EYEWALL NE QUAD
I am aware I've seen a car floating around 20 feet across a street before reaching an area of less water.
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 17:36Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Storm Number & Year: 01L in 2010
Storm Name: Alex (flight in the North Atlantic basin)
Mission Number: 12
Observation Number: 04
A. Time of Center Fix: 30th day of the month at 17:13:40Z
B. Center Fix Coordinates: 24°16'N 96°02'W (24.2667N 96.0333W)
B. Center Fix Location: 147 miles (236 km) to the SE (142°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,112m (3,648ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 73kts (~ 84.0mph)
E. Location of the Estimated Maximum Surface Wind: 13 nautical miles (15 statute miles) to the E (88°) of center fix
F. Maximum Flight Level Wind Inbound: From 136° at 96kts (From the SE at ~ 110.5mph)
G. Location of Maximum Flight Level Wind Inbound: 65 nautical miles (75 statute miles) to the ENE (68°) of center fix
H. Minimum Sea Level Pressure: 962mb (28.41 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 1,518m (4,980ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,522m (4,993ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 18°C (64°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 96kts (~ 110.5mph) in the east quadrant at 16:51:20Z
Maximum Flight Level Temp: 22°C (72°F) which was observed 8 nautical miles to the SW/WSW (236°) from the flight level center
Remarks Section - Additional Remarks...
PARTIAL EYEWALL NE QUAD
I don't think Texas got that memo. But inland warnings are essential. I'm glad about the change and that everyone is talking about inland dangers. One of the only videos during Rita shows a young couple rescued from their mobile home at the last second by fire fighters and news crew. You can see the trailer park being shredded as they're making their get away. That was in Lake Charles, La. Not on the coast. Like that fireman said, If they tell you to leave LEAVE!! He almost didn't see the couple.
can you post a link or tell me where I can find this?
Was thinking the same thing. The vortex message showed SFMR wind around 73 knots though
I'll take anything that is important.
My apologies...hello, darlin'!
Come Landfall..half the Storm is Inland.
The Impacts have under way for a few Hours now.
Track the Impacts
What are we talking about?
I posted his site on my Facebook. I have over 1,000 friends so hopefully many of them will log on.
I live on the west side of Houston, so we did get that message. :) For Rita in the inland hurricane wind warnings went several counties back from the coast. Can't remember how far for Ike but Dallas was in a TS wind watch, which is amazing at ~300 miles from the coast!
Viewing: 901 - 951
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