July Atlantic hurricane outlook

By: Dr. Jeff Masters , 12:55 PM GMT on July 13, 2012

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It's mid-July, and we have yet to see a named storm form in the Atlantic this month. The computer models are not predicting any development through at least July 20, and if we make it all the way to the end of the month without a named storm forming, it will be the first July since 2009 without a named storm. Since the current active hurricane period began in 1995, 13 of 17 years (76%) have had a named storm form during July. The busiest July occurred in 2005, when five named storms and two major hurricanes formed. These included Hurricane Dennis and Hurricane Emily--the strongest hurricanes ever observed so early in the season. Only eight major hurricanes have formed in July since record keeping began in 1851. As seen in Figure 1, most of the last half of July activity occurs in the Gulf of Mexico and waters off the Southeast U.S. coast. These type of storms form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance (as happened for Alberto, Beryl, Chris, and Debby in 2012.) There will be at least two cold fronts moving off the U.S. Mid-Atlantic coast over the next two weeks. The first of these fronts will push offshore around July 20, and we will need to watch the waters offshore of North Carolina for development then. Formation potential will be aided by ocean temperatures that are about 0.7°C (1°F) above average along the U.S. East Coast.


Figure 1. Tracks of all tropical storms and hurricanes 1851 - 2006 that formed July 16-31. The U.S. coast from North to Texas are the preferred strike locations. Only a few storms have formed in the tropical Atlantic and Caribbean in July. Wind shear is typically too high and SSTs too cool in July to allow African waves in the Caribbean and tropical Atlantic to develop into tropical storms. However, a few long-track "Cape Verdes" hurricanes have occurred in July, spawned by tropical waves that came off the coast of Africa. African tropical waves serve as the instigators of about 85% of all major hurricanes.


Figure 2. The seasonal distribution of Atlantic hurricane activity shows that July typically has low activity. Image credit: NHC.

Sea Surface Temperatures: slightly above average
The departure of Sea Surface Temperatures (SST) from average over the tropical Atlantic between Africa and Central America was about 0.3°C above average during June (Figure 3.) This figure has not changed much over the first two weeks of July. These temperatures are not warm enough to appreciably affect the odds of a July named storm or hurricane. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. The latest 2-week run of the GFS model predicts continued average-strength trade winds through late-July, so SSTs should remain about 0.3°C above average during this period, due to average amounts of cold water mixing up from below due to the wind action on the water.


Figure 3. Sea Surface Temperature (SST) departure from average for July 12, 2012. SSTs were 0.3°C above average over the tropical Atlantic's Main Development region for hurricanes, from Africa to Central America between 10° and 20° North Latitude. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, the hallmark of a developing El Niño episode. Image credit: NOAA/NESDIS

El Niño on the way?
For two consecutive weeks, ocean temperatures 0.5 - 0.6°C above average have been present in the tropical Eastern Pacific, which is right at the threshold for a weak El Niño episode. NOAA's Climate Prediction Center has issued an El Niño Watch, and gives a 61% chance that El Niño conditions will be present during the August - September - October peak of the Atlantic hurricane season. The likely development of a full-fledged El Niño episode means that Atlantic hurricane activity will probably be suppressed in 2012, due to the strong upper-level winds and high wind shear these events typically bring to the tropical Atlantic.


Figure 4. Sea Surface Temperature (SST) departure from average for the the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). El Niño conditions exist when the SST in this region rises 0.5°C above average. As of July 9, 2012, SSTs in the Niño 3.4 region had risen to 0.5°C above average. To be considered an "El Niño episode", El Niño conditions must occur for five consecutive months, using 3-month averages. Image credit: NOAA Climate Prediction Center.

Wind shear: above average
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart. The jet stream has two bands of strong high-altitude winds that are currently bringing high wind shear to the Atlantic. The southern branch (subtropical jet stream) is bringing high wind shear to the Caribbean, and the northern branch (polar jet stream) is bringing high wind shear to the waters offshore of New England. This configuration often leaves a "hole" of low shear between the two branches, off the Southeast U.S. coast and over the Gulf of Mexico. The jet stream is forecast to maintain this two-branch pattern over the coming two weeks. Wind shear has been about 10 - 20% higher than average over the first two weeks of July, and is predicted to be mostly above average for the coming two weeks. This will cut down on the odds of a July storm.


Figure 5. Vertical instability over the Caribbean Sea in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.

Dry air: above average
As seen in Figure 5, there has been an unusual amount of dry, stable air in the Caribbean this year creating low levels of vertical instability. This has occurred due to a combination of dry air from Africa, and upper-atmosphere dynamics creating large areas of sinking air that dry as they warm and approach the surface. The Gulf of Mexico and tropical Atlantic between the coast of Africa and the Lesser Antilles have also seen low vertical instability this summer. June and July are the peak months for dry air and dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past two weeks. Expect dry air to be a major deterrent to any storms that try to form in the tropical Atlantic during July.

Steering currents: average
The predicted steering current pattern for the next two weeks is a typical one for July. We have an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. These troughs are frequent enough and strong enough to recurve any tropical storms or hurricanes that might penetrate north of the Caribbean Sea. Steering current patterns are predictable only about 3 - 5 days in the future, although we can make very general forecasts about the pattern as much as two weeks in advance. There is no telling what might happen during the peak months of August, September, and October--we might be in for a repeat of the favorable 2010 and 2011 steering current pattern, which recurved most storms out to sea--or the unfavorable 2008 pattern, which steered Ike and Gustav into the Gulf of Mexico.

Summary: a below average chance of a July tropical storm
Given that none of the computer models are forecasting tropical storm formation in the coming seven days, SSTs are only slightly above average, and wind shear and vertical stability are above average, I'll go with a 30% chance of a named storm forming in the Atlantic during the remainder of July.


Figure 6. Hurricane Emilia over the Eastern Pacific at 20:35 UTC July 10, 2012. At the time, Emilia was a Category 3 hurricane with 125 mph winds. Emilia peaked earlier in the day as a Category 4 storm with 140 mph winds--the strongest hurricane in the East Pacific so far in 2012. Image credit: NASA.

An active Eastern Pacific hurricane season
It's been a very active start to the Eastern Pacific hurricane season, where we've already had six named storms, four hurricanes, and three intense hurricanes. A typical season has 4 named storms, 2 hurricanes, and 0 intense hurricanes by July 14. The formation of Tropical Storm Fabio on July 12 marks the 4th earliest formation of the Eastern Pacific's season's sixth storm. The record is held by the year 1985, when the season's sixth storm formed on July 2. Record keeping began in 1949.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

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1661. pcola57
Hey washingtonian115 you got mail..
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Quoting WxGeekVA:


Mine got cancelled again... because her parents grounded her for something stupid... we are gonna do that on Tuesday though


You got me all wrong...I wasn't talking about actual twinkle twinkle stars. LOL.
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Quoting MississippiWx:


No kidding! I did my share of star-gazing, let me assure you. ;-)


Mine got cancelled again... because her parents grounded her for something stupid... we are gonna do that on Tuesday though
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Quoting washingtonian115:
A lot of teenage boys getting bone... errr am I allowed to post that on the blog?.
Lol XD
Member Since: October 15, 2011 Posts: 0 Comments: 4459
Quoting washingtonian115:
A lot of teenage boys getting bone... errr am I allowed to post that on the blog?.


no....god no
Member Since: February 11, 2012 Posts: 0 Comments: 9737
Quoting yoboi:


who is JFV???


A troll who has been on this blog for some time and comes back after bring banned with new usernames... Some of the other members of the blog can probably fill you in better than I can.
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Time to go..............Good Night Folks.
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Quoting WxGeekVA:


Who knows these days...


No kidding! I did my share of star-gazing, let me assure you. ;-)
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1651. yoboi
Quoting WxGeekVA:




1. It's not cheating unless you ACT on it, and I'm not going to do that...

2. And I was joking, calm down.

3. And welcome to my ignore list again JFV.


who is JFV???
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Quoting washingtonian115:
A lot of teenage boys getting bone... errr am I allowed to post that on the blog?.

I would say no, lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32531
Quoting MississippiWx:


Haha...Well, we were about a mile from the Flora-Bama, but we never went. We kinda had our own lounge in our beautiful condo. :-)


I hear ya......Next time, rent a motorcycle (preferably a Harley) if you don't own one and roll on over there for some raw oysters and brews..... :)
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Quoting washingtonian115:
A lot of teenage boys getting bone... errr am I allowed to post that on the blog?.




I see what you did there
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Quoting MississippiWx:


Thanks!



Haha thanks. Well, it is probably bad considering those girls are about 12 or 13. :-/


Who knows these days...
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Quoting allancalderini:
They are amazing good job at capture them.


Thanks!

Quoting WxGeekVA:


Is it bad that the first thing that I noticed in the top picture were the girls on the beach?

Good pictures too anyway, better than a lot of those I have taken!


Haha thanks. Well, it is probably bad considering those girls are about 12 or 13. :-/
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Quoting weathermanwannabe:
1632. MississippiWx 11:00 PM EDT on July 14, 2012

Good for you. Did you get a chance to have a few at the Flora-Bama Lounge?...............:)


Haha...Well, we were about a mile from the Flora-Bama, but we never went. We kinda had our own lounge in our beautiful condo. :-)
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Quoting fmhurricane2009:


Very nice pics, thanks for sharing!


Thanks for the positive feedback and you are welcome!
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Quoting Dull2012:


Since you're in a relationship, you bet my !@# it is.

Keep in mind that's called psychological cheating, in case you weren't aware of that.




1. It's not cheating unless you ACT on it, and I'm not going to do that...

2. And I was joking, calm down.

3. And welcome to my ignore list again JFV.
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Quoting WxGeekVA:


Is it bad that the first thing that I noticed in the top picture were the girls on the beach?

Good pictures too anyway, better than a lot of those I have taken!


no, i did the same thing :)
Member Since: February 11, 2012 Posts: 0 Comments: 9737
..here we go...
Member Since: August 14, 2010 Posts: 10 Comments: 17487
Quoting MississippiWx:
I was a bit of a photographer this past week. I just got back from a week long vacation in Perdido Key, FL and had a wonderful time. I made sure to bring my phone to the beach during the day so I could take pictures if I saw anything cool/interesting. I found this developing thunderstorm over the Gulf pretty cool. You can see the rain shaft forming and the flat base of the storm as the tops blossom into the atmosphere. I watched it from its infancy...should have time-lapsed it, I supposed. Hindsight is a 20/20, I guess.



Here's a rainbow I was able to get on camera on the way home. I was in the backseat, so sorry about my bro's nasty foot getting into the picture. Just ignore that and gaze upon this giant rainbow. :-)



Is it bad that the first thing that I noticed in the top picture were the girls on the beach?

Good pictures too anyway, better than a lot of those I have taken!
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Quoting MississippiWx:
I was a bit of a photographer this past week. I just got back from a week long vacation in Perdido Key, FL and had a wonderful time. I made sure to bring my phone to the beach during the day so I could take pictures if I saw anything cool/interesting. I found this developing thunderstorm over the Gulf pretty cool. You can see the rain shaft forming and the flat base of the storm as the tops blossom into the atmosphere. I watched it from its infancy...should have time-lapsed it, I supposed. Hindsight is a 20/20, I guess.



Here's a rainbow I was able to get on camera on the way home. I was in the backseat, so sorry about my bro's nasty foot getting into the picture. Just ignore that and gaze upon this giant rainbow. :-)

They are amazing good job at capture them.
Member Since: October 15, 2011 Posts: 0 Comments: 4459
1632. MississippiWx 11:00 PM EDT on July 14, 2012

Good for you. Did you get a chance to have a few at the Flora-Bama Lounge?...............:)
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Quoting MississippiWx:
I was a bit of a photographer this past week. I just got back from a week long vacation in Perdido Key, FL and had a wonderful time. I made sure to bring my phone to the beach during the day so I could take pictures if I saw anything cool/interesting. I found this developing thunderstorm over the Gulf pretty cool. You can see the rain shaft forming and the flat base of the storm as the tops blossom into the atmosphere. I watched it from its infancy...should have time-lapsed it, I supposed. Hindsight is a 20/20, I guess.



Here's a rainbow I was able to get on camera on the way home. I was in the backseat, so sorry about my bro's nasty foot getting into the picture. Just ignore that and gaze upon this giant rainbow. :-)



Very nice pics, thanks for sharing!
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I was a bit of a photographer this past week. I just got back from a week long vacation in Perdido Key, FL and had a wonderful time. I made sure to bring my phone to the beach during the day so I could take pictures if I saw anything cool/interesting. I found this developing thunderstorm over the Gulf pretty cool. You can see the rain shaft forming and the flat base of the storm as the tops blossom into the atmosphere. I watched it from its infancy...should have time-lapsed it, I supposed. Hindsight is a 20/20, I guess.



Here's a rainbow I was able to get on camera on the way home. I was in the backseat, so sorry about my bro's nasty foot getting into the picture. Just ignore that and gaze upon this giant rainbow. :-)

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1630. yoboi
Quoting goosegirl1:


No- floods happen everywhere. Some may make fun of "mountain people", but how many complaints did you hear coming from us a couple weeks ago after the big storm knocked out power for days? We know how to deal with all kinds of adversity.


i don't knock mountain people, i am cajun so we probably sort of the same breed we know how to survive...
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Quoting yoboi:


did ya move from there?


No- floods happen everywhere. Some may make fun of "mountain people", but how many complaints did you hear coming from us a couple weeks ago after the big storm knocked out power for days? We know how to deal with all kinds of adversity.
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Quoting weathermanwannabe:
If we get a typical "cluster" of CV storms at some point (as documented by Klotzbach in a few papers), we have observed that the CV waves can spit out an average of around one storm every 7-10 days in a 3-4 storm cluster. If El Nino does kick into gear by September-October, total numbers will depend on when the first cluster develops. If it is a mid-August start, we could have 4 storms in the mid-Aug to mid-Sept period and a few more in late-Sept early-Oct before activity dies down in October. If we have a late-August start, it could boil down to only about 4-5 storms. If El Nino is not as strong going into late-Sept early-Oct, we could pick up a few more in October.

The total numbers are going to boil down to the strength of the El Nino effects right after the peak period.

The trajectory and potential landfall location of these storms (regardless of the numbers) is the main issue...................


Well said.
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If we get a typical "cluster" of CV storms at some point (as documented by Klotzbach in a few papers), we have observed that the CV waves can spit out an average of around one storm every 7-10 days in a 3-4 storm cluster (not every wave during the peak develops). If El Nino does kick into gear by September-October, total numbers will depend on when the first cluster develops. If it is a mid-August start, we could have 4 storms in the mid-Aug to mid-Sept period and a few more in late-Sept early-Oct before activity dies down in October. If we have a late-August start, it could boil down to only about 4-5 storms. If El Nino is not as strong going into late-Sept early-Oct, we could pick up a few more in October.

The total numbers are going to boil down to the strength of the El Nino effects right after the peak period.

The trajectory and potential landfall location of these storms (regardless of the numbers) is the main issue...................
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Thanks guys :).Georgiastorms yes really.
Member Since: August 14, 2010 Posts: 10 Comments: 17487
I just noticed my new avatar is sideways :) Anyone know how to fix it? Maybe edit the picture for size?

We got lucky- we took a drive to Dolly Sods this afternoon, and watched a thunderstorm pop up to the east and move down the valley below. I took it with a Samsung Galaxy tablet, so the quality is not the best but the storm still looks pretty cool.

Also, for some reason, WU thinks I took this in Antarctica. Rest assured I didn't drive that far today!
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Quoting presslord:
A Higgs-Boson walks into a church...the priest says "We don't allow Higgs-Boson here"...the Higgs-Boson says " But....without me....How can you have mass?!?!"


Behind the times....
Member Since: February 11, 2012 Posts: 0 Comments: 9737
Quoting Dull2012:


That's why I love you so much, D.C chick, ^_^.
I love her two she is one of my favorite bloggers in here.
Member Since: October 15, 2011 Posts: 0 Comments: 4459
Emilia and Fabio

Member Since: July 21, 2011 Posts: 83 Comments: 7167

A very impressive looking waterspout from Bradenton Bch. in Manatee County. a couple of miles off the coast about 3:30 in a Special Marine Warning (Credit: Meridith Garofalo.)

Right now, there are very few storms this evening. Near Captiva and Arcadia in SWFL. Near Palm Harbor/Dundein in Pinellas County, other than a small cluster of showers off the east coast of FL, you really have to look towards an area from Charlotte NC to the Piedmont Triad (Greensboro/High Point)

Over the next few day, the chances for a more severe storm over florida exists with higher PWAT columns and day time heating (higher temps 93-95F), any tornado (or tornado like) pictures I get I will pass them on to you.

Have a great nite
FM
(Edited: Image was not formatted correctly post 1614) Sorry :(
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Quoting washingtonian115:
I don't know how to post images.You'll have to ask ncstorm.


what?!!!!
really?
Member Since: February 11, 2012 Posts: 0 Comments: 9737
Quoting hydrus:
I was goin easy..:) It looks a lil messy dont it..?..:)


F U is not that easy
Member Since: February 11, 2012 Posts: 0 Comments: 9737
1618. yoboi
Quoting goosegirl1:



I was 17 during the WV floods. A lot of people, including me, experienced a defining moment that week, and will remember it for the rest of their lives. It was the first time (but not the last) that I realized a hurricane could affect an area that far inland.


did ya move from there?
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I'm not to sure.
Member Since: August 14, 2010 Posts: 10 Comments: 17487
TROPICAL STORM EMILIA DISCUSSION NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052012
800 PM PDT SAT JUL 14 2012

THE LOW-LEVEL CENTER OF EMILIA HAS CONTINUED TO MOVE AWAY FROM THE
REMAINING DEEP CONVECTION OVER THE PAST FEW HOURS. AN ASCAT PASS
AROUND 1800Z SUGGESTED THAT PEAK WINDS AT THAT TIME WERE AROUND 40
KT. GIVEN THE DECAY OF THE CLOUD PATTERN SINCE THE ASCAT PASS THE
INITIAL INTENSITY IS LOWERED TO 35 KT...IN AGREEMENT WITH A BLEND
OF THE LATEST TAFB AND SAB DVORAK ESTIMATES. THE OFFICIAL FORECAST
SHOWS EMILIA WEAKENING TO A TROPICAL DEPRESSION IN 12 HOURS AND
BECOMING A REMNANT LOW BY SUNDAY NIGHT...AS THE CYCLONE MOVES OVER
SSTS AROUND 24C AND THROUGH A VERY DRY ATMOSPHERIC ENVIRONMENT.

THE INITIAL MOTION IS WESTWARD AT 14 KT...AND THIS SHOULD CONTINUE
FOR THE NEXT NEXT FEW DAYS AS EMILIA IS STEERED BY THE LOW-LEVEL
TRADE WIND FLOW. THE NEW NHC FORECAST IS SIMILAR TO THE PREVIOUS
ONE AND IS CLOSE TO THE MIDDLE OF THE GUIDANCE ENVELOPE.

FORECAST POSITIONS AND MAX WINDS

INIT 15/0300Z 15.7N 134.5W 35 KT 40 MPH
12H 15/1200Z 15.7N 136.6W 30 KT 35 MPH
24H 16/0000Z 15.6N 139.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 16/1200Z 15.5N 142.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/0000Z 15.3N 145.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 18/0000Z 15.0N 150.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/0000Z 15.0N 156.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 20/0000Z...DISSIPATED

$$
FORECASTER BRENNAN
Member Since: July 21, 2011 Posts: 83 Comments: 7167
Emilia down to 40 mph.

BULLETIN
TROPICAL STORM EMILIA ADVISORY NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052012
800 PM PDT SAT JUL 14 2012

...EMILIA WEAKENING...EXPECTED TO BECOME A TROPICAL DEPRESSION
SUNDAY...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...15.7N 134.5W
ABOUT 1675 MI...2700 KM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
Member Since: July 21, 2011 Posts: 83 Comments: 7167

A very impressive looking waterspout from Bradenton Bch. in Manatee County. a couple of miles off the coast about 3:30 in a Special Marine Warning (Credit: Meridith Garofalo.)

Right now, there are very few storms this evening. Near Captiva and Arcadia in SWFL. Near Palm Harbor/Dundein in Pinellas County, other than a small cluster of showers off the east coast of FL, you really have to look towards an area from Charlotte NC to the Piedmont Triad (Greensboro/High Point)

Over the next few day, the chances for a more severe storm over florida exists with higher PWAT columns and day time heating (higher temps 93-95F), any tornado (or tornado like) pictures I get I will pass them on to you.

Have a great nite
FM
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Quoting etxwx:
This is one I remember. Hurricane Juan 1985 The local weatherman kept calling it Wandering Juan. Would have made for an interesting time on the blog...

An upper level low pressure system combined with a tropical wave developed a broad trough of low pressure over the central Gulf of Mexico on October 24. A rapid increase in cloudiness and convection led to the formation of a tropical depression on October 26. A high pressure system to its northeast forced it westward, where it became Tropical Storm Juan later on October 26.

At the time and throughout its lifetime, Juan was very disorganized, and resembled a subtropical cyclone with its winds well away from the center. A developing trough brought the storm northward, where it became better organized. Early on October 28, Juan reached hurricane strength, and hours later it reached a peak of 85 mph (140 km/h) winds.

Under the influence of a large scale upper-level low pressure area, Juan executed a cyclonic loop off the Louisiana coast later on October 28. It turned northward, and hit near Morgan City, Louisiana on the morning of October 29. Still under the influence of the low, Juan again looped to the southeast, and weakened to a tropical storm over land on October 29, and emerged into the Gulf of Mexico on October 30 over Vermilion Bay.

Juan paralleled the southern Louisiana coastline and crossed the extreme southeast portion of the state on October 31. Over the open waters of the Gulf, Juan restrengthened to a 70 mph (110 km/h) storm, just before hitting near the Alabama/Florida border that night. Once over land, Juan rapidly weakened, and became extratropical over Tennessee on November 1. Its remnants accelerated northward into Canada by the morning of November 3. Of interest, an upper level low closed off in the wake of Juan, forming a new occluded cyclone, which added to the rainfall totals across Virginia and West Virginia. The combined impact of Juan and the occluded cyclone that formed in its wake led to a flood of record size across West Virginia.



I was 17 during the WV floods. A lot of people, including me, experienced a defining moment that week, and will remember it for the rest of their lives. It was the first time (but not the last) that I realized a hurricane could affect an area that far inland.
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1611. Patrap
3 Man ISS/Soyuz Launch LIVE from Russia.
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About

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