Alex, strongest June hurricane in 44 years, is now a tropical storm

By: Dr. Jeff Masters , 2:20 PM GMT on July 01, 2010

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Hurricane Alex, the strongest June hurricane in 44 years, is Tropical Storm Alex, thanks to passage over the rugged terrain of Mexico. Alex made landfall at 9pm CDT last night, 110 miles south of Brownsville, Texas, as a Category 2 hurricane with 105 mph winds. Alex was the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the west coast of Florida. Brownsville long-range radar shows that Alex's heavy rains continue to pound the Texas/Mexico border region, and satellite estimates of rainfall (Figure 1) show that some of Alex's spiral bands dumped rains in excess of five inches today, in addition to the 5+ inches that fell yesterday. The Brownsville airport received 6.46" of rain as of 8am CDT today from Alex. Alex is being blamed for at least thirteen deaths in Central America and Mexico due to flooding, though none of these deaths occurred in the region where the storm made landfall. Alex spawned two tornadoes that hit South Texas, and there were at least four other reports of tornado funnel clouds that did not touch ground. Alex may continue to spawn isolated tornadoes today over South Texas and northern Mexico.


Figure 1. Radar-estimated rainfall so far today for Alex.


Figure 2. Snapshot of the Brownsville long-range radar showing Hurricane Alex at landfall at 8pm CDT Wednesday June 30, 2010.


Figure 3. Alex nearing landfall in northeastern Mexico at 12:10 CDT June 30, 2010, as seen by the MODIS instrument on NASA's Terra satellite. Image credit: NASA.

Storm Surge
Alex's maximum storm surge occurred along a 50-mile stretch of the Mexican coast centered about 75 miles south of Brownsville, Texas. The National Hurricane Center Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model predicted that the maximum water depth at the coast reached about 5 - 6 feet above ground level (Figure 3.) A storm surge of 1 - 2 feet was predicted by SLOSH for the Brownsville, Texas region. A storm surge of about 2 feet was observed in South Texas at the South Padre Island Coast Guard Station and Port Isabel.


Figure 4. Hurricane Alex's Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The maximum surge occurred to the right of where Alex's core made landfall, over a sparsely populated marshy area. This "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. For more information on storm surge, consult our detailed storm surge pages.

Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. There have been only eleven hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.

Alex's bizarre behavior
Alex had several rather remarkable features I've never seen in a hurricane. Firstly, it underwent an eyewall replacement cycle as a Category 1 hurricane with 80 mph winds. Usually, we don't see the inner eyewall collapse and an eyewall replacement cycle occur until a hurricane reaches Category 3 strength. I've seen it happen on occasion to a Category 2 storm, but never a Category 1. Secondly, after Alex's inner 9-mile diameter eyewall collapsed at 10am EDT yesterday morning, an outer spiral band began to become the new eyewall. Winds in this outer spiral band/new eywall increased as the day progressed, as typically happens in an eyewall replacement cycle. However, part way through that process, Alex suddenly reversed course, and was able to build a small inner eyewall with a 12-mile diameter that was completed by landfall. I've never seen a hurricane change its mind in the middle of an eyewall replacement cycle and build an inner eyewall so fast. Finally, Alex had an unusually weak winds, considering how low the pressure was. The pressure was more typical of a hurricane one Saffir-Simpson category stronger than what the surface winds suggested.

Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical depression the Western Caribbean on Tuesday. None of the other models is showing tropical development worthy of concern over the coming seven days.

Wind and ocean current forecast for the BP oil disaster
Alex is continuing to generate very rough conditions over the Deepwater Horizon blowout location, with 5 - 9 foot waves and 3 - 4 foot swells. The wind and seas will gradually subside today, according to the latest marine forecast from NOAA. The resulting currents induced by Alex's strong winds will push oil to many protected bays and estuaries that haven't seen oil yet. 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 5 - 15 knots Friday through Tuesday but remain mostly 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
I'll have an update Friday morning. Dr. Rob Carver plans on summarizing Alex in his blog later today.

Jeff Masters

Hurricane Alex (LRandyB)
Weather inbound to Hurricane Alex.
Hurricane Alex

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Quoting Levi32:


Low pressure is relative Drak, and doesn't have to be a closed circulation. Take a gander at the surface station east of Apalachicola reporting 1018.2mb just south of the low center, and pressures are higher at all the stations surrounding it. Clear evidence of a weak low.



No, I see a bunch of 1018mb readings in the general area. No relative low pressure center exists.
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Quoting BermudaHigh:
I cannot believe this, anotehr GOm storm.


As soon as one tropical cyclone makes landfall and weakens, another develops. I have a bad feeling about this season.
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Quoting StSimonsIslandGAGuy:
Looking at the satellite pics, of which xcool's in #469 is a good example, there seems to be tremendous northerly shear over us and the northeast gulf. I don't think we have to worry about development there at this time.


Yup, that's Alex's outflow. Concern doesn't start in earnest for another 3-4 days, if we still have heavy precip action going on in the NE gulf.
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488. IKE
Quoting txag91met:
ECMWF has a tropical storm in the Gulf heading north in about 9-10 days...


I was just fixing to post that....Link
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Quoting tropicfreak:


NHC could put it straight to TD status, skipping invest. However I'm not 100% positive this is going to happen, Recon needs to invesigate it first once the COC moves over water.


It's not even invest-worthy. Pressures need to lower back down for it to do anything, and they will be falling back to at least 1012mb levels in 3-4 days.
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Quoting Drakoen:
Looks like the wave near 35W will be the one to watch when it gets into the Caribbean


Wave? All I see is a big mess.
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Quoting Drakoen:
The most that exist at the surface is an weak inverted surface trough and that may be pushing it... Surface pressures are high= no low pressure center.


Low pressure is relative Drak, and doesn't have to be a closed circulation. Take a gander at the surface station east of Apalachicola reporting 1018.2mb just south of the low center, and pressures are higher at all the stations surrounding it. Clear evidence of a weak low.

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Quoting Levi32:
Here's a zoomed-in visible loop showing the surface low as a well-defined spin over the eastern Florida panhandle, east of Tallahassee.


NHC could put it straight to TD status, skipping invest. However I'm not 100% positive this is going to happen, Recon needs to invesigate it first once the COC moves over water.
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Looks like the wave near 35W will be the one to watch when it gets into the Caribbean
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Quoting Levi32:
12z ECMWF 240 hours develops the wave currently at 40W and brings it into the Gulf of Mexico in 10 days.



Looking at some of the upper air conditions down the road for that wave...I'd be shocked if we see any development in the next 3-4 days but once it reaches the Caribbean I think there could be trouble brewing.
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Quoting Levi32:


Bonnie.


NHC should have been thinking, Bonnie and Colin just doesn't sound right. Probably be lethal though.
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478. xcool
hey JFV
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Drakoen:


This reveals winds out of the east south of the suspected low.


But the winds are always out of the east at some point in the lower lats.. normally the wind clocks 360 around and in front of temperate fronts. But at lower lats (and in the summer up to about 25-30N) when the trades build north the fronts stall and you get a northerly wind then a trough with mixed winds and easterlies below that..the time to watch for this to develop into a TS or STS is farther along the front to the east where it stalls over water..pieces break off.. boats often get surprised by the sudden development of these.. 4 people I knew disappeared off the coast 3 years ago due to one of these occurring in May.
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12z ECMWF 240 hours develops the wave currently at 40W and brings it into the Gulf of Mexico in 10 days.

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Quoting Drakoen:
Ruc 18z analysis supports an 850mb cyclonic circulation near the FL/GA border just north of Tallahassee.



Plenty of mid level energy around that area helping with the rainfall today. Once that front finally pushes south of the border we may see more of a surface low develop since the tail-end of the front will be nicely positioned in the NE GOM.
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ECMWF 12z yet another Caribbean storm
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471. xcool
ECMWF nice :)
Member Since: September 26, 2009 Posts: 2 Comments: 15684
The most that exist at the surface is an weak inverted surface trough and that may be pushing it... Surface pressures are high= no low pressure center.
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469. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
ECMWF has a tropical storm in the Gulf heading north in about 9-10 days...
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Maybe we need a dry period for a week or so round here............
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Quoting StSimonsIslandGAGuy:
What there is is some decent rains. We have had 0.31" yesterday, and 0.20" today so far. Hopefully we will get more along the stalled front.

The main conclusion I draw when "there's a circulation!" "Is not" "Is too!!" is going on in the blog is that there is no significant circulation at this time.


Which is a true statement... it is not significant and pressures are over 1018mb. Nothing to worry about for a few days yet.
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Quoting atmosweather:
NWS Melbourne, FL Discussion from this morning:

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE UPPER LEVEL RIDGE AND SURFACE HIGH REMAINS THE DOMINANT
WEATHER FEATURES THROUGH THE FOURTH OF JULY. GFS CONTINUES TO SHOW
A SURFACE WAVE DEVELOPING OVER THE NORTHERN GULF AND THE UPPER
LEVEL TROUGH SQUEEZING OUT THE RIDGING...BUT TEND TO GRAVITATE
TOWARD THE ECMWF WHICH KEEPS DRY AND STABLE CONDITIONS OVER THE
REGION THROUGH THE EXTENDED PERIODS.


"TEND TO GRAVITATE" ... that's pretty slick too. Not yet gravitating, certainly not there yet, but tending toward gravitating. My question: what is the forward speed of the center of the tendency, and how close is it to gravitating?
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Quoting StormSurgeon:
C'mon guys, Alex was a great warm up to the season (maybe too good), but let's not be overwhelmed this early, ok? Lots to come, but be patient. The rust is off, if you know what I mean. What's the "B" storms name anyway?


Bonnie.
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Quoting StSimonsIslandGAGuy:
What there is is some decent rains. We have had 0.31" yesterday, and 0.20" today so far. Hopefully we will get more along the stalled front.

The main conclusion I get when "there's a circulation!" "Is not" "Is too!!" going on is that there is no significant circulation at this time.


Is that avatar pic really necessary? Looks like a pic out of the GQ "cut box". lol Quite disturbing...
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C'mon guys, Alex was a great warm up to the season (maybe too good), but let's not be overwhelmed this early, ok? Lots to come, but be patient. The rust is off, if you know what I mean. What's the "B" storms name anyway?
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459. xcool
my july Forecast 3 storms & start from july 01 to july 17.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Drakoen:
Looks like you have learned more from JB than just weather... LOL


Uhuh....ok Drak.

Watch JB videos and call him a hypist. If he was who people make him out to be, he would have been Texas-casting Hurricane Alex, which he heavily did not do.
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457. xcool
Drakoen lmao
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Ruc 18z analysis supports an 850mb cyclonic circulation near the FL/GA border just north of Tallahassee.

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Looks like you have learned more from JB than just weather... LOL
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Quoting Levi32:


See post 445.

If you read my blog or even my earlier comment you will see I expect no significant deepening of a surface low for a few days yet, if there is any at all. When have you known me to be an over-eager hypist?



We don't. At least some of the WE doesn't
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Quoting Drakoen:


You just said the low is east of Tallahasse and now you are saying it is south of? No, there is no surface low there. What I do see without any visible loops or surface observations is your over-eagerness.
At best there is a mid level circulation there according to cimss 850mb vorticity.


Wow, and we arent even in the heat of and invest....
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Quoting Drakoen:


You just said the low is east of Tallahasse and now you are saying it is south of? No, there is no surface low there. What I do see without any visible loops or surface observations is your over-eagerness.
At best there is a mid level circulation there according to cimss 850mb vorticity.


See post 445.

If you read my blog or even my earlier comment you will see I expect no significant deepening of a surface low for a few days yet, if there is any at all. When have you known me to be an over-eager hypist?
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That's a stretch.
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Quoting atmosweather:
And from NWS Tallahassee this morning:

SFC ANALYSIS REVEALS AN E-W
STATIONARY FRONT ACROSS CENTRAL GEORGIA AND ALABAMA SEPARATING MID
70S DEWPOINTS TO THE SOUTH FROM MID 60S DEWPOINTS TO THE NORTH. IN
ADDITION...SFC OBS INDICATES A WEAK INVERTED TROUGH ORIGINATING IN
APALACHEE BAY STRETCHING NORTH INTO SOUTH GEORGIA NEAR VALDOSTA.
REGIONAL RADAR ALSO INDICATES SOME LOW TO MID-LEVEL CYCLONIC

TURNING WITH THIS FEATURE.


That looks right to me based on what I see.
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Quoting Levi32:


Looks like a weak surface low to me based on surface obs. A NNW and WSW reading are found near the Florida coast.

Typical of a stalled front.. it leaves a trough with cold air on one side and warm on the other. Then it begins to oscillate along the trough.. many times a low form from these oscillations. An during the season storm, usually subtropical form from these. But it will need some time to cook.
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Quoting Levi32:
12z ECMWF shows the weak surface trough drifting over the Gulf of Mexico but doesn't do anything with it. It seems more interested in the Caribbean. The last few runs have tried to develop that tropical wave that it shows in the central Caribbean here at 144 hours.


I've been noticing that as well over the past few days. Seems pretty consistent. That's an area that I would watch as that time approaches.

Oh by the way, hi everyone!
Member Since: August 2, 2006 Posts: 47 Comments: 11707
Quoting Drakoen:


This reveals winds out of the east south of the suspected low.



Here...i see the easterly barbs you are talking about...thought you were referring to just north of Florida/Georgia border.

This is where the low is...perhaps not a closed low due to those 2 obs but a surface low nonetheless...surface obs support it.

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Quoting Levi32:


You just showed exactly where the low is. Look at this visible loop again and tell me where the center of spin is and you'll see those surface obs are easterlies on the north side of the low like one would expect.


You just said the low is east of Tallahasse and now you are saying it is south of? No, there is no surface low there. What I do see without any visible loops or surface observations is your over-eagerness.
At best there is a mid level circulation there according to cimss 850mb vorticity.
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Quoting Baybuddy:
Didnt Spurious coach @ north carolina?


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

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