Andrea Intensifies to a 60 mph Tropical Storm, Spawns 5 Tornadoes in Florida

By: Dr. Jeff Masters , 1:30 PM GMT on June 06, 2013

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Tropical Storm Andrea has exceeded expectations. An Air Force hurricane hunter plane flying through Andrea near 3 am EDT found that a strong band of heavy thunderstorms with moderate turbulence and intense lightning had wrapped partway around the center, and Andrea had intensified into a respectable tropical storm with 60 mph sustained winds and a central pressure of 997 mb. The intensification occurred despite the presence of a large area of dry air to the storm's west, and high wind shear of 25 knots. Satellite loops show that Andrea has expanded in size this morning, and its heavy thunderstorms have become more intense. The heaviest thunderstorms were in a band well away from the center, extending from Tampa southwestwards over the Gulf of Mexico. There is a large slot of dry air behind this band, and Andrea may be able to close this intrusion of dry air off early this afternoon, and build additional heavy thunderstorms near its center. However, given the continued presence of dry air and increasing wind shear, and little time before landfall, it will be difficult for Andrea to reach hurricane strength before landfall occurs early this evening--though I won't rule out intensification to a 70 mph tropical storm. Heavy rains of 3 - 6" that have the potential to cause flash flooding will be the storm's main threat. Carrabelle, near Apalachicola, reported 4.5" of rain in a 5-hour period ending at 8 am EDT. Tornadoes in some of the heavier thunderstorms in Andrea's spiral bands are also a concern, and the storm had already spawned five tornadoes as of 9 am EDT. Bands of heavy thunderstorms with embedded rotating thunderstorms capable of generating tornadoes where over both the west and east coasts of Florida between 6 am - 8am, triggering tornado warnings in the counties near Fort Lauderdale and Tampa Bay. A tornado hit The Acreage in Palm Beach County at 6:45 am EDT, injuring one person, damaging homes, and downing trees and power lines. Two other tornadoes were reported on Florida's east coast, one in Broward County, and one in Palm Beach County. Andrea also spawned two tornadoes southeast of Tampa Bay between 2:30 am and 4 am EDT Thursday, but damage was minor. Most of South and Central Florida are under a tornado watch today. A storm surge of 2 - 5 feet is predicted for Tampa Bay northward to Apalachicola, and rip currents will be a risk for swimmers who brave the high surf. As of 9 am EDT Thursday, our wundermap with the storm surge layer turned on was showing storm surge levels just over 1 foot near Tampa and Apalachicola on Florida's Gulf Coast.

We won't have any new wind measurements from the Hurricane Hunters until about 3 pm EDT. Buoy 42036, 122 miles west-northwest of Tampa, reported sustained winds of 40 mph, gusting to 51 mph, between 7 am - 8 am EDT, when the center of Andrea was located about 60 miles to the south-southwest. Winds at a personal weather station at Bald Point State Park near Apalachicola hit 39 mph at 9 am EDT. Winds at Cedar Key were sustained at 28 mph, gusting to 34 mph, at 8:33 am EDT.



Figure 1. Composite radar reflectivity image of Tropical Storm Andrea at 9 am EDT Thursday, June 6, 2013.

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

Andrea gave us a lake (LakeWorthFinn)
... in our yard this morning
Andrea gave us a lake

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If Andrea managed to do so well in such an unfavorable conditions, I am little scared to see what rest of 2013 will be like. This is just an impressive start to the season.
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Quoting TylerStanfield:

The key thing to add to that, is that it Wont get out of the shear... Not with it's life.


well if it gets stronger it will move further N quicker and high shear if it stays weak it will move further W and deal with less shear

plus the ensemble models have been showing some kind development in the W Caribbean within that time frame that the tropical wave is expected to reach the W Caribbean so just something to keep an eye on in the long range
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Good morning!! everybody!!, Andrea surprise everybody going up to 60mph overnight.
Here in Miami very windy!! and it's getting very very dark!!!,we are under a Tornado watch,I believe looking at the Satellite presentation that we are going to get a lot of nasty weather in the next few hours due to the tail of Andrea,I'm looking at the GOM Rainbow loop and this tail is growing stronger,bigger and moving in our direction hope that we don't have any damages from this.
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Quoting KEEPEROFTHEGATE:


How much does it cost to buy that thing?

I'm sick of having only the pathetic, inaccurate amount of information NWS gives to the general public.

I shouldn't have to try to measure and calculate the distance to a storm myself, because they don't give the data to people, when the computer does it automatically.
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Quoting GTcooliebai:
Sun is coming out here in Pinellas County which means the potential for some stronger storms to form.


beach weather!
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Quoting Torito:
Best wave i have seen in a long time...



If there is anything left of it when it gets close to the Leewards, wake me up :) Pretty impressive for June, tho.
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Quoting Torito:
In the meanwhile, while everyone is watching andrea, a wave is getting sheared (i think) in the atlantic. xD



It also is just sitting there...


It has hit the wall of west winds
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Quoting TBayEyes:


Yeah not sure. I think conditions did improve too, but that was the opposite of what was being forecast wasn't it?

I get the sense that dry air + wind shear > tropical wave.

Like dry air and wind shear will always win out.

For instance, that the wave that has been noted out in the atlantic. Yesterday people were saying watch that it looks vigorous etc, and other said yeah BUT wind shear is gonna rip it up.

I understand why wind shear doesn't help in development, but if a wave is gaining power, it seems like the wind shear just finds another path around the system.

Or almost like the system consumes the wind shear and adds to the over all disturbance of the growing tropical wave.

I bet it has something to do with angular momentum.


Depends on the situation.... If the system develops upper level ridging, the shear will go around it, if it doesn't and there is high shear, the odds are against it. Dry air harder to predict because there are no "rules" so to speak. If the system ingests dry air, it more than likely wont intensify quickly ex:Isaac. But if it is able to keep the dry air out of the circulation it should be fine...
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Lowest radar angle.

This might be a tornado forming. This is inland and east of St. Petersburg.

Z5 44 dBZ 3,000 ft. 1 kg/m² 0% chance 0% chance 0.00 in. 85 knots S (184)
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Quoting wunderkidcayman:

oh dear god I hope they make it

hey tylerstnfield you know I was pullin you leg the other night right

Yep..... :|
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This is all i can find on the wave, and it is from accuweather, so im pretty weary.... .-.

Elsewhere, there is a fast-moving tropical wave moving westward to the Lesser Antilles around 72 west and another one near 44 west. Some enhanced shower activity is noted with both of these waves, but no development is expected with high wind shear over the basin.

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Quoting TampaSpin:
I am getting pounded by rain in TaMPA....it is POURING
yeah thats the band that came over my area awhile ago..tons of rain with it and gusty winds....easing up by me now
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Quoting SouthernIllinois:

Then this afternoon and evening primarily. At least on a severe level. Although thunderstorms and lightning will persist into the night. But the best chance for isolated tornadoes and damaging wind gusts will persist from now until mid evening. That severe threat will diminish as the low moves across the peninsula to your north.
Excellent. Thank you!
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Quoting TylerStanfield:

They may, but it'll probably be making landfall as they investigate, most likely. It has about 4 hours left over water, and Recon will be flying in about 3 hours...

oh dear god I hope they make it

hey tylerstnfield you know I was pullin you leg the other night right
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Quoting Torito:
Anyone think that that wave can develop if it can get out of the shear present where it is located?


The key thing to add to that, is that it Wont get out of the shear... Not with it's life.
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Quoting weatherh98:


Just google CIMSS

That's what I do.


alright, thanks. :P
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Sun is coming out here in Pinellas County which means the potential for some stronger storms to form.
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C1 49 dBZ 1,000 ft. 1 kg/m² 0% chance 0% chance 0.00 in. 65 knots S (188

G6 46 dBZ 9,000 ft. 3 kg/m² 0% chance 0% chance 0.00 in. 66 knots SSW (193)
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Quoting Waltanater:
I thought conditions improved as time went on!? Shear decreased and wasn't the dry air to the west of the storm? Also SST almost always contributes to a storm's formation especically in the GOM. Maybe a little luck too. I'm sure there are other factors.


Yeah not sure. I think conditions did improve too, but that was the opposite of what was being forecast wasn't it?

I get the sense that dry air wind shear > tropical wave.

Like dry air and wind shear will always win out.

For instance, that the wave that has been noted out in the atlantic. Yesterday people were saying watch that it looks vigorous etc, and other said yeah BUT wind shear is gonna rip it up.

I understand why wind shear doesn't help in development, but if a wave is gaining power, it seems like the wind shear just finds another path around the system.

Or almost like the system consumes the wind shear and adds to the over all disturbance of the growing tropical wave.

I bet it has something to do with angular momentum.

And what is SST? lol i don't have enough knowledge to connect these acronyms with the words, but I am pretty good at understand the words :)
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Quoting Torito:


thanks for putting that there, i lost the link for it (AGAIN.)


Just google CIMSS

That's what I do.
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Anyone think that that wave can develop if it can get out of the shear present where it is located?

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Quoting wunderkidcayman:
ok so main question will the HH fly and will they make it before Andrea makes landfall

They may, but it'll probably be making landfall as they investigate, most likely. It has about 4 hours left over water, and Recon will be flying in about 3 hours...
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Quoting SouthernIllinois:

It's not a guess, Scott. The other Scott made his prediction based upon observing trends of upper level wind analysis along with steering currents, associated moisture available, shear levels, SST's, among MANY other factors. In addition, he made this forecast a couple days ago, when this system was already an invest and had illustrated tropical potential shall it develop. And guess what? It did develop, and lived up to his forecast.


It's called a "Guess" or he should go work immediatley at the NHC and be top official cause we don't have the tech skill to predict it! understand that part.. we Don't Have The "TECH" To Predict Intensity! He got his props..lets drop it
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I am getting pounded by rain in TaMPA....it is POURING
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Quoting scottsvb:
highest wind gust so far is 63mph over tampa bay in the past 15 minutes just above the surface...aka nws ruskin


That's right.

That would be under the same cell/feeder band, I was talking about on Radar. So my calculation of the elevation the radar was looking at was very good. Since 370ft is well about the tree line and most buildings, you'd expect the wind to be 10 to 15mph faster or so.
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Quoting Torito:
Best wave i have seen in a long time...

For June anyway... I've seen better waves.
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Quoting Torito:
Best wave i have seen in a long time...


so very true
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Quoting weatherh98:


Good guess


thanks for putting that there, i lost the link for it (AGAIN.)
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Quoting SouthernIllinois:

I'm thinking from early afternoon through the evening. It really depends what you define "the worst" as. If you are referring to storm surge, then this afternoon around high tide when the center of the storm will be nearest you. If you are referring to wind and flash flooding associated with heavy rain, then this afternoon through all evening.

Hope that helps.

Natalie
I was thinking about tornado warnings and severe thunderstorms.
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490. 7544
Quoting hydrus:


thanks that tail to her south looks to be getting stronger moving east ?
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Quoting scottsvb:


It's called "guess" and I give him credit for that. Anyone can say it can be 40 or 60 or 80 on a system before it develops. So unless he has a degree in Meteorology and since the experts can't predict intensity..it's a good guess. :)
ditto...I agree with this scott's reasoning, but also give the other scott credit.
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Quoting Waltanater:
I thought conditions improved as time went on!? Shear decreased and wasn't the dry air to the west of the storm? Also SST almost always contributes to a storm's formation especically in the GOM. Maybe a little luck too. I'm sure there are other factors.


Like vertical instability. Maybe someone could post a graph for the GOM. I can't find it on the NOAA site.
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Quoting 900MB:
THERE ARE NO CHANGES TO THE TROPICAL STORM WARNINGS ON THIS
ADVISORY. BASED ON THE ASSUMPTION THAT ANDREA WILL BECOME
POST-TROPICAL IN 36 TO 48 HOURS...WE DO NOT EXPECT TO EXTEND THE
TROPICAL WARNINGS ANY FURTHER NORTH ALONG THE COAST. OUR CURRENT
INTENTION IS THAT ANY HAZARDOUS WIND CONDITIONS FROM THE DELMARVA
PENINSULA NORTHWARD TO NEW ENGLAND WOULD BE HANDLED BY LOCAL
NATIONAL WEATHER SERVICE WARNING PRODUCTS.


I still dont understand why NHC hands off to locals when transition occurs. Long Island is still due for 45mph sustained winds and surge. It was this lack of continuity that caused issues with Sandy and lead Mayor Bloomberg to declare that Sandy "will not be a tropical storm or anything like it" 48 hours before the superstorm hit!


I don't disagree with you, but that is also why the NHC is working on being explicit about saying what the plan is. Last year, there was no real emphasis on articulating that plan, hence the confusion.


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Quoting TropicalAnalystwx13:
On its current trajectory, Tropical Storm Andrea is 82 miles away from landfall just north of Cedar Key. If we assume at will remain at a constant speed of 15 mph up to this point...which it likely won't...that puts Andrea's center over water for another 5.4 hours.
Thanks for the calculations. That's where I live.
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Quoting TropicalAnalystwx13:
On its current trajectory, Tropical Storm Andrea is 82 miles away from landfall just north of Cedar Key. If we assume at will remain at a constant speed of 15 mph up to this point...which it likely won't...that puts Andrea's center over water for another 5.4 hours.

She's accelerating, so she probably only has 3 or 4 hours left.
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Quoting weatherh98:


Tornado vortex signature

It's the upside down triangle:)


thank you. I had seen that a few times but couldn't figure it out.

There was another acronym used that I had to ask about in another blog.

SPC = Storm Prediction Center
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Quoting Torito:
In the meanwhile, while everyone is watching andrea, a wave is getting sheared (i think) in the atlantic. xD



Good guess
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479. 900MB
Quoting weatherh98:




He's a news reporter assigned to the weather...


C'mon. Al can stand outdoors and pretend to be blown away by the wind with the best of em'.
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ok so main question will the HH fly and will they make it before Andrea makes landfall
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Quoting TBayEyes:


i have to believe that there are other factors at play with a system like this other than wind shear and dry air.

I have yet to hear anyone explain why this system developed in spite of that.

THAT will be a discussion I'd like to hear about.
I thought conditions improved as time went on!? Shear decreased and wasn't the dry air to the west of the storm? Also SST almost always contributes to a storm's formation especically in the GOM. Maybe a little luck too. I'm sure there are other factors.
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Best wave i have seen in a long time...

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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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