Tropical Storm Andrea Forms in Gulf of Mexico

By: Dr. Jeff Masters , 11:15 PM GMT on June 05, 2013

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The Atlantic has its first named storm of the 2013 hurricane season: Tropical Storm Andrea. An Air Force hurricane hunter plane was able to locate a closed center of circulation, and found surface winds of 40 mph in the large area of thunderstorms on the east side of the center. Satellite loops show that Andrea is a lopsided storm. It's center of circulation is exposed to view, due to a large region of dry air that covers the entire Central and Western Gulf of Mexico. This dry air is from a trough of low pressure whose upper level winds are also creating moderate wind shear of 15 - 20 knots over Andrea. Wind shear is forecast to rise to the high range, 20 - 40 knots, by Thursday. Andrea is forecast to make landfall along the northern Gulf Coast of Florida by Thursday evening, so the system has a short window of time to intensify. Given the large amount of dry air to Andrea's west, and the forecast for increasing shear up until landfall, I expect that the strongest sustained winds Andrea could have before landfall are 50 mph. Heavy rains will be the storm's main threat, though a few isolated EF-0 tornadoes will also be possible in some of the heavier thunderstorms in Andrea's spiral bands. A storm surge of 2 - 4 feet is predicted for Tampa Bay northward to Apalachicola, and rip currents will be a risk for swimmers who brave the high surf. Fort Pickens, located in Gulf Islands National Seashore on a barrier island offshore from Pensacola, Florida, has been closed to visitors due to the approaching storm. A single 2-lane road vulnerable to storm surges runs to Fort Pickens. Officials want to prevent a repeat of the situation that occurred in September 2011, when Tropical Storm Lee pushed a storm surge over the road that blocked it with sand and debris, trapping numerous campers and visitors in Fort Pickens. As of 7 pm EDT, our wundermap with the storm surge layer turned on was showing storm surge levels were less than 1 foot along the Florida coast.


Figure 1. MODIS image of Tropical Storm Andrea in its formative stages, taken at 12:20 pm EDT Wednesday, June 5, 2013, five hours before it was named. Image credit: NASA.

Andrea's place in history
Andrea formed in a typical location for early-season storms. The Gulf of Mexico, Western Caribbean, and Bahamas are the usual areas for the genesis of June tropical storms. Andrea's formation date of June 5 is over a month earlier than the average July 9 date for formation of the season's first named storm. On average, the Atlantic sees one June named storm every two years. In 2012, we'd already had two named storms by this point in the season--Alberto and Beryl. This year is the second time a storm named Andrea has appeared in the Atlantic. The previous incarnation, Subtropical Storm Andrea of 2007, wandered off the U.S. East Coast in May, and never made landfall. The 2013 version of Andrea is highly unlikely to get its name retired, and we'll be seeing a third coming of the storm in 2019.

Jeff Masters

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Most of us ate some crow on this one. Chalk it up to shaking off the dust and getting back into it.i like mine grilled.
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Quoting belizeit:
Good Morning . I see HH found 70 MPH surface winds on there last pass . Andrea is looking Sub Tropical on the radar and satelite


Can anyone confirm this?

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Quoting LargoFl:
folks up in the panhandle of florida need to prepare for a stronger storm than was anticipated last night..tons of rain and wind with this growing stronger storm, its going to catch alot of people off guard gee.


I think you mean Northern Florida. Most of the Panhandle is going to be on the West side of this storm and feel little from this storm. It's Central to Northern Florida that will be the main focus for this storm. We sure could use the rain further West though.
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I'd really like to see a graph of vertical instability in the GOM, right now. The last two seasons have seen lots of storms that failed to intensify in the western half, and below average vertical instability was probably the cause.

If vertical instability in the GOM is currently above average, that could explain why Andrea has strengthened, despite dry air and shear.
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Good morning y'all, Andrea is kinda surprising this morning. Beat my expectations.

Kinda wonder how much rain Jackonville(near downtown) is going to get. Kinda hard finding good estimates.
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Good Morning
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Quoting RyanSperrey:
Huge eye on Andrea if it's able to wrap itself all the way around. Shear is it's enemy right now though, cutting off it's western outflow channels and limiting the growth of thunderstorms.

But she is definitely fighting.
doin't have much time and with sun rising higher and getting closer to landfall very breezy rainy day with some flooding and watch for isolated tornadoes that's where we could get some hurricane wind gusts from should be clearing out after noon and done by 3 for fla
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Quoting KEEPEROFTHEGATE:
good points with that just poking at ya a little morning wash
No harm taken Keeper.
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Going to be a loooooonnnnnggggggg year...... models wrong, NHC wrong, bloggers wrong... crow for everybody

jeessh
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Quoting washingtonian115:
Actually I had a a very valid point as to why it may not form..Heavy shear and dry air.I was using common sense...


common sense didnt win..LOL
Member Since: August 19, 2006 Posts: 13 Comments: 16083
Quoting washingtonian115:
Actually I had a a very valid point as to why it may not form..Heavy shear and dry air.I was using common sense...
good points with that just poking at ya a little morning wash
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Quoting robintampabay:
Where are all the people who said Andrea would not form, then Andrea would not get stronger than 45 MPH. RTS, Seminole something or another, come get your crow.



By the way kudos to StormTrackerScott. He called Andrea a few days ago.
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Quoting SouthernIllinois:

Why are you singling her out? If I recall correctly, half the blog was saying it wouldn't form into Andrea.
just joking with wash no harm she is my friend I mean no harm just ranging her up a little
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Huge eye on Andrea if it's able to wrap itself all the way around. Shear is it's enemy right now though, cutting off it's western outflow channels and limiting the growth of thunderstorms.

But she is definitely fighting.
Member Since: October 25, 2012 Posts: 0 Comments: 284
Where are all the people who said Andrea would not form, then Andrea would not get stronger than 45 MPH. RTS, Seminole something or another, come get your crow.
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Quoting KEEPEROFTHEGATE:
hey wash what was that you were saying about nothing forming

guess what it formed no matter what you may say
Actually I had a a very valid point as to why it may not form..Heavy shear and dry air.I was using common sense...
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there is some thunderstorms starting to develop south of the center trying to close it off from the dry air
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Quoting washingtonian115:
Andrea making a run for hurricane status?




But it looked pathetic yesterday..
hey wash what was that you were saying about nothing forming

guess what it formed no matter what you may say
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Not sure if I am attaching this picture correctly or not. It's been raining off an don for the past couple of days here in Charleston, SC. Then last nioght I got a picture of this salamander swimming across our sidewalk.
Link
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About to get first visible shot of the day.

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Quoting GTcooliebai:
Considering all the obstacles she has had to overcome i.e. shear and dry air I think she has done good for herself. I do think the CMC deserves a trophy what do you all say?


well you know what I would say..I have been posting the model runs for it and hear the usual negative acronymns for it..The CMC was upgraded earlier this year but a lot of people keep forgetting that..
Member Since: August 19, 2006 Posts: 13 Comments: 16083
A look in my rain gauge at 07EDT showed 0.35" overnight in Satellite Beach on the space coast of Florida, with light rain continuing.
Far below my expectations so far ... not that we really need the rain anyways.
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Well...it tried. Still has a very nice circulation for this time of the year.
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Quoting Torito:


NHC has forecast wind speeds at almost 10% chance of hurricane strength by the end of the day today, something to watch...
there could or may be brief hurricane gusts in the bands of precip but not sustain hurricane winds

and watch for naders this kinda thing likes to spin naders up more so during the day than nioght
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Quoting RascalNag:
Andrea's looking healthier by the hour... if she managed to strengthen even through that dry air, who knows what could happen when her circulation closes?


NHC has forecast wind speeds at almost 10% chance of hurricane strength by the end of the day today, something to watch...
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Andrea making a run for hurricane status?




But it looked pathetic yesterday..
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Quoting RascalNag:
Andrea's looking healthier by the hour... if she managed to strengthen even through that dry air, who knows what could happen when her circulation closes?


Lots of shear, so probably won't.
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Considering all the obstacles she has had to overcome i.e. shear and dry air I think she has done good for herself. I do think the CMC deserves a trophy what do you all say?
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Quoting CybrTeddy:


Not true -- Andrea strengthened due to DMAX, which occurs at night. Tropical cyclones, at least the weaker ones, tend to strengthen at night.


True. I just forgot to add that.
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Quoting belizeit:
Good Morning . I see HH found 70 MPH surface winds on there last pass . Andrea is looking Sub Tropical on the radar and satelite


There is nothing subtropical about Andrea.
Member Since: July 8, 2005 Posts: 259 Comments: 24508
Andrea's looking healthier by the hour... if she managed to strengthen even through that dry air, who knows what could happen when her circulation closes?
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Quoting LargoFl:
oh boy, thats a real nasty looking line of storms headed for me and the gulf coast out there..going to get rough here when it hits...looks like this storm is indeed getting stronger.


Stay safe, largo. :P
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Quoting Civicane49:


Different times of day doesn't matter for tropical cyclones to strengthen or weaken. It all depends on the environmental conditions such as sea surface temperatures, shear, etc.


Not true -- Andrea strengthened due to DMAX, which occurs at night. Tropical cyclones, at least the weaker ones, tend to strengthen at night.
Member Since: July 8, 2005 Posts: 259 Comments: 24508
Quoting Civicane49:


Different times of day doesn't matter for tropical cyclones to strengthen or weaken. It all depends on the environmental conditions such as sea surface temperatures, shear, etc.


Ok, well that makes sense. Thanks for the clarification.
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Quoting Jwd41190:
Not to ask a dumb question...but Andrea appeared to strengthen over night. So my question is do most tropical cyclones strengthen over night more or in the day?


That really depends on the situation. During the day, there is more energy in the atmosphere, so the storm is able to fire up a lot more convection to strength itself.

However during the night, it might be easier to tighten it's already formed convection around it's center, why...I'm honestly not sure, but I've seen that several times - maybe someone could give some insight? I like learning!
Member Since: October 25, 2012 Posts: 0 Comments: 284
glad I don't have to drive today
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Good Morning . I see HH found 70 MPH surface winds on there last pass . Andrea is looking Sub Tropical on the radar and satelite
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Recon takes off at 1645Z
Member Since: July 8, 2005 Posts: 259 Comments: 24508
Quoting Jwd41190:
Not to ask a dumb question...but Andrea appeared to strengthen over night. So my question is do most tropical cyclones strengthen over night more or in the day?
more at night and at dmax which is now as the sunrises normally they weaken after the sun is fully up in the sky tropical cyclones feed off the warm waters more if the air temp is lower than the water but as the sun rises the air temps warm higher than the water temps therefore cutting off the feeding off the water sort a speak
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883. MahFL
Quoting RyanSperrey:
Any one have the most recent sea surface pressure reading? I'm looking at Andrea and it was able to fight off the dry air and is rapidly tightening it's rotation, i'm almost ready to say we have a Hurricane on our hands.

Not entirely sure whats causing Andrea to strengthen so quickly this morning, but there ya have it.


997 mb.
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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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