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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(sry)
Time: 21:14:30Z
Coordinates: 24.35N 96.9333W
Acft. Static Air Press: 843.4 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,108 meters (~ 3,635 feet)
Extrap. Sfc. Press: 956.0 mb (~ 28.23 inHg)
D-value: -
That's 1 kt from a cat. 2. Looks like we could have a cat. 2 at landfall. Which would make this storm an Ike-sized Dolly cane.
Wow, how did you manage that?
URNT15 KNHC 302118
AF304 1201A ALEX HDOB 40 20100630
210830 2440N 09658W 8428 01300 9790 +162 +162 080086 087 066 013 03
210900 2438N 09658W 8430 01282 9767 +181 +176 081085 086 069 006 00
210930 2437N 09658W 8433 01261 9742 +191 +176 081089 090 073 004 00
211000 2435N 09658W 8432 01243 9721 +188 +177 080092 094 077 013 00
211030 2433N 09658W 8430 01216 9697 +174 +174 081092 093 079 024 03
211100 2432N 09658W 8428 01190 9662 +179 +179 080082 089 082 027 03
211130 2430N 09658W 8436 01161 9630 +200 +182 083057 065 077 014 03
211200 2429N 09658W 8428 01158 9620 +194 +185 089043 045 053 008 00
211230 2427N 09658W 8428 01148 9604 +205 +187 085039 040 043 003 00
211300 2425N 09658W 8433 01135 9590 +214 +190 078033 036 042 003 03
211330 2424N 09657W 8426 01129 9579 +215 +195 068024 026 036 004 03
211400 2422N 09657W 8432 01117 9570 +217 +200 058014 018 033 004 03
211430 2421N 09656W 8434 01108 9560 +226 +206 286007 013 028 003 00
211500 2419N 09654W 8436 01109 9563 +231 +212 249026 032 035 004 00
211530 2418N 09653W 8435 01141 9593 +214 +214 237043 048 044 004 03
211600 2417N 09653W 8427 01159 9615 +210 +210 236051 055 053 003 03
211630 2416N 09653W 8429 01180 9643 +196 +196 247065 067 065 004 01
211700 2414N 09653W 8430 01202 9665 +207 +207 244066 067 066 004 00
211730 2413N 09653W 8430 01224 9687 +202 +202 246061 065 066 006 00
211800 2412N 09653W 8442 01228 9713 +189 +189 252060 062 066 006 01
$$
;
Pat LMAO ... classic SNL stuff right there!!! Thanks for sharing!
That reading was suspect, the official highest found was 77 knots.
Really, though, they have got to renew that program for longer. What is it, quarterly? (I think) We all are paying for congress to have meetings and a vote on NFIP over and over again. Does that strike anyone else as stupid?
It's already the second strongest in terms of pressure, I think.
It would've probably given Aubrey a good run for her money.
Multiple mesocyclones within the inner inner eyewall. Brownsville is getting hit by the outer "eyewall" band. The eye looks like it wobbled to the SW, took a tiny retrograde loop and is heading back WNW, which could mean it'll be another four to seven hours till landfall.
Wheres Taz?
LOL...yeah, really!
It's legit.
Water levels cannot have peaked yet...or maybe they have.
pine hole eye
It is beautiful, amazing and thankfully moving into a sparsely populated area in Mexico
And a boat and oars, if you can fit it in.
I know click2houston.com has reporters down there. Try that for coverage
Omar(2008) and Fred(2009) both had min pressures of 958mb. Omar peaked at 135mph, Fred at 120mph.
you think he can make it?
SATCON (2mem): MSLP = 960 hPa MSW = 87 kt
ADT: 977 hPa 80 kt Scene: EYE
CIMSS AMSU: 955 hPa 94 kt Bias Corr: 0 (TPC)
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
429 PM CDT WED JUN 30 2010
...UPDATED RAINFALL TOTALS AND WIND GUSTS...
THE FOLLOWING ARE THE MOST CURRENT STORM TOTALS AND WIND GUSTS
FROM A COMBINATION OF AUTOMATED OBSERVING SITES...MESO
NETWORKS...AND COOPERATIVE AND PUBLIC OBSERVERS. WE THANK ALL
THOSE PROVIDING RAPID UPDATES THROUGH THE STORM.
RAINFALL
LOCATION COUNTY RAINFALL (IN)
WESLACO EOC HIDALGO 7.00
BROWNSVILLE EOC CAMERON 6.00
BROWNSVILLE/AIRPORT CAMERON 5.20
HARLINGEN/VALLEY CAMERON 1.87
MCALLEN/MILLER HIDALGO 3.73
BAYVIEW/CAMERON CO CAMERON 3.61
SOUTH PADRE ISLAND CAMERON 4.17
WESLACO/MID VALLEY HIDALGO 4.86
EDINBURG HIDALGO 3.95
FALFURRIAS/BROOKS CO BROOKS 1.82
HEBBRONVILLE/JIM HOGG CO JIM HOGG 0.88
ZAPATA ZAPATA 0.39
SANTA ANA/LOWER RGV NWR HIDALGO 3.29
ATASCOSA/LOWER RGV NWR CAMERON 3.39
SAN MANUEL/LOWER RGV NWR HIDALGO 2.86
FALCON LAKE/UPPER RGV NWR ZAPATA 0.99
MATAMOROS TAMPAULIPAS, MX 9.00
PEAK WINDS
LOCATION
SOUTH PADRE ISLAND CAMERON 54 MPH AT 1255 PM
BAYVIEW/CAMERON COUNTY CAMERON 52 MPH AT 911 AM
BROWNSVILLE/AIRPORT CAMERON 48 MPH AT 352 PM
HARLINGEN/VALLEY CAMERON 47 MPH AT 414 PM
MCALLEN/MILLER HIDALGO 48 MPH AT 142 PM
WESLACO HIDALGO 41 MPH AT 345 PM
EDINBURG HIDALGO 41 MPH AT 345 PM
ZAPATA ZAPATA 32 MPH AT 345 PM
FALFURRIAS/BROOKS CO BROOKS 31 MPH AT 1146 AM
HEBBRONVILLE/JIM HOGG CO JIM HOGG 31 MPH AT 341 PM
NOTE: PEAK WINDS WERE LIKELY MUCH HIGHER IN EMBEDDED TORNADOES
REPORTED EARLIER TODAY IN PORT ISABEL...WEST OF BROWNSVILLE...AND
NORTH OF RAYMONDVILLE. AN UNOFFICIAL RAINFALL REPORT NEAR THE
BROWNSVILLE AIRPORT WAS MORE THAN 6 INCHES AS OF 130 PM. SOUTH
PADRE ISLAND RAINFALL INCLUDES ONLY TODAYS REPORTED AMOUNT.
MCALLEN/MILLER PEAK WIND REPORT OCCURRED ON THE 29TH.
ADDITIONAL PEAK WINDS AND RAINFALL REPORTS WILL BE AVAILABLE EVERY
COUPLE OF HOURS OR SO.
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