Alberto weakens, brings light rains to Georgia and South Carolina

By: Dr. Jeff Masters , 3:31 PM GMT on May 20, 2012

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Tropical Storm Alberto continues to move slowly to the west-southwest off the coast of South Carolina, and is bringing light rains to the coasts northern Georgia and southern South Carolina. Recent radar and satellite loops show that Alberto has weakened late this morning, and has lost most of its heavy thunderstorms. Upper level winds out of the west-southwest are creating a moderate 15 - 20 knots of wind shear over Alberto, and these winds are driving dry air into the storm, which has caused it to deteriorate. The dry air impinging on Alberto can be seen in water vapor satellite loops. Yesterday, Alberto was over the warm 81°F (27°C) water of the Gulf Stream, but today, the storm has moved west of the Gulf Stream, and is now centered over cooler waters of 79°F (26°C). This gives the storm a lot less energy to power it, and as Alberto drifts farther to the west-southwest today, ocean temperatures will get even cooler. A hurricane hunter aircraft is scheduled to visit Alberto this afternoon.


Figure 1. Late morning visible satellite image of Alberto.

Forecast for Alberto
Sporadic rain showers from Alberto are likely to affect the Georgia and South Carolina coasts today, and the coasts of North Carolina and South Carolina on Monday. The heaviest rains and tropical storm-force winds should remain offshore, but even if Alberto did make landfall, the storm is too small to cause major flooding problems, particularly since the coast is under moderate to severe drought. Alberto's rains will be generally less than an inch over land areas, which will not be plentiful enough to cause significant drought relief. Wind shear is expected to increase to the high range, 30 - 40 knots, tonight through Monday, which should be able to rapidly disrupt a storm as small as Alberto. Steering currents are weak, and Alberto will wander off the coast of South Carolina through Monday morning, before getting caught up by a trough of low pressure on Monday night which should lift the storm out to the northeast. NHC is giving Alberto a less than 5% chance of reaching hurricane strength. Alberto should cause little or no damage to the coast, except perhaps for some coastal erosion due to high waves.


Figure 2. Late morning total rainfall image of Alberto from the Charleston, SC radar. Alberto's rains have been less than one inch along the coast, and most of the rain has fallen offshore.


Figure 3. Late morning radar image of Alberto from the Charleston, SC radar.

Alberto in historical context
Alberto is earliest-forming tropical storm in the Atlantic Basin since Ana in 2003, which formed on April 21. Alberto is one of only three Atlantic tropical storms to form in May in the past 31 years. The others were Tropical Storm Arthur of 2008, and Tropical Storm Arlene of 1981. There was also a subtropical storm, Andrea, that formed in May of 2007. Formation of an early season tropical storm from an old frontal boundary, like occurred with Alberto, is not a harbinger of an active hurricane season--it's more of a random occurrence. Early season storms that form in the Caribbean, though, often signal that a busy hurricane season may occur.

I'll have an update Monday morning.

Jeff Masters

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835. wunderkidcayman
2:16 PM GMT on May 21, 2012
convection and vort should develop closer to where that lwer shear is in GOH
Member Since: June 13, 2009 Posts: 2 Comments: 12509
834. RitaEvac
2:08 PM GMT on May 21, 2012
Quoting jeffs713:

Yep. I've seen bigger masses of clouds in an MCS.


Past few MCSs over TX put it to shame
Member Since: July 14, 2008 Posts: 1 Comments: 9648
833. WunderAlertBot (Admin)
2:07 PM GMT on May 21, 2012
JeffMasters has created a new entry.
832. kmanislander
2:07 PM GMT on May 21, 2012
Back in a while
Member Since: August 19, 2006 Posts: 0 Comments: 15882
831. stormwatcherCI
2:07 PM GMT on May 21, 2012
Quoting kmanislander:


The rain gauge must be broken LOL
I think so. I hear thunder now again. I heard it earlier but it had stopped . Rain is continuous.
Member Since: October 9, 2008 Posts: 0 Comments: 8426
830. stormpetrol
2:06 PM GMT on May 21, 2012




Member Since: April 29, 2007 Posts: 0 Comments: 8023
829. kmanislander
2:06 PM GMT on May 21, 2012
Quoting stormwatcherCI:
I have a feeling that rainfall amount is incorrect. It has been raining heavily since before 6 am.


Just posted that . 3.86 at my home since midnight
Member Since: August 19, 2006 Posts: 0 Comments: 15882
828. kmanislander
2:05 PM GMT on May 21, 2012
Quoting stormpetrol:


The rain gauge must be broken LOL
Member Since: August 19, 2006 Posts: 0 Comments: 15882
827. stormwatcherCI
2:04 PM GMT on May 21, 2012
Quoting stormpetrol:
I have a feeling that rainfall amount is incorrect. It has been raining heavily since before 6 am.
Member Since: October 9, 2008 Posts: 0 Comments: 8426
826. stormpetrol
2:02 PM GMT on May 21, 2012
Member Since: April 29, 2007 Posts: 0 Comments: 8023
825. stormwatcherCI
1:59 PM GMT on May 21, 2012
Quoting kmanislander:


I am inland so calmer here between 7 and 15 mph
Ok. The sea is pretty rough up here too. I know up by your mother's house has to be getting some good breeze.
Member Since: October 9, 2008 Posts: 0 Comments: 8426
824. reedzone
1:58 PM GMT on May 21, 2012
Quoting jeffs713:

Yep. I've seen bigger masses of clouds in an MCS.


Still a very impressive system, and for the first storm.

- Formed before June 1st (May 19, 2012)
- Peaked 60 mph (6:30 p.m. Saturday
- Smallest TS since Marco in 2008

This has been an awesome storm to track, despite it being "weak"
Member Since: July 1, 2008 Posts: 13 Comments: 7423
823. kmanislander
1:57 PM GMT on May 21, 2012
Quoting stormwatcherCI:
The weather station at Sunset House is showing 4.16" of rain today so far and winds up to 22 mph.


I am inland so calmer here between 7 and 15 mph
Member Since: August 19, 2006 Posts: 0 Comments: 15882
822. nigel20
1:54 PM GMT on May 21, 2012
Good morning all...it's a fairly active day in thd tropics...two TDs and one TS
Member Since: November 6, 2010 Posts: 11 Comments: 8323
821. jeffs713
1:54 PM GMT on May 21, 2012
Quoting reedzone:
Alberto has blown some of the deepest convection in it's lifetime just now.. It's all because it's in warmer waters but it is fighting wind shear of 20-30 knots. It's so cool to know a Tropical Storm is sitting off my beach, just about 50 miles northeast of me, and it's beautiful outside, no wind, clear skies.. This is how remarkably small Alberto is, similar to Marco in 2008.


Yep. I've seen bigger masses of clouds in an MCS.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
820. stormwatcherCI
1:53 PM GMT on May 21, 2012
Quoting kmanislander:


LOL. They may have something to watch for real if this continues to sit and stew
The weather station at Sunset House is showing 4.16" of rain today so far and winds up to 22 mph.
Member Since: October 9, 2008 Posts: 0 Comments: 8426
819. kmanislander
1:52 PM GMT on May 21, 2012
Quoting jeffs713:


Oh, you mean the place that doesn't have any convection, and isn't even in the yellow area of 850mb vort?

Shear is best judged by the CENTER of any circulation. By your own posted map, that would mean 20-30kt.


Shear is 20 to 30 knots. That small pocket near the coast has been like that for several days.
Member Since: August 19, 2006 Posts: 0 Comments: 15882
818. reedzone
1:51 PM GMT on May 21, 2012
Alberto has blown some of the deepest convection in it's lifetime just now.. It's all because it's in warmer waters but it is fighting wind shear of 20-30 knots. It's so cool to know a Tropical Storm is sitting off my beach, just about 100 miles northeast of me, and it's beautiful outside, no wind, clear skies.. This is how remarkably small Alberto is, similar to Marco in 2008.

Member Since: July 1, 2008 Posts: 13 Comments: 7423
817. jeffs713
1:50 PM GMT on May 21, 2012
Quoting wunderkidcayman:


first I said is nearly not that it is
second from this you can see that 10kt line just on the honduras belize coast and its moving N and E by the way this is the 12Z map


Oh, you mean the place that doesn't have any convection, and isn't even in the yellow area of 850mb vort?

Shear is best judged by the CENTER of any circulation. By your own posted map, that would mean 20-30kt.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
816. kmanislander
1:50 PM GMT on May 21, 2012
Quoting RitaEvac:


The government is watching it here in the states



LOL. They may have something to watch for real if this continues to sit and stew
Member Since: August 19, 2006 Posts: 0 Comments: 15882
815. kmanislander
1:48 PM GMT on May 21, 2012
Quoting stormwatcherCI:
No golf for you again today LOL. It is dark and very rainy up here with winds between 30-35 mph. IDK if anything will develop but we sure needed this rain.


Just started gusting to 19 mph and steady out of the East around 12
Member Since: August 19, 2006 Posts: 0 Comments: 15882
814. RitaEvac
1:47 PM GMT on May 21, 2012
Quoting kmanislander:


Cannot say. We have to wait and see if anything forms first as the conditions prevailing at that time will determine intensity and track


The government is watching it here in the states

Member Since: July 14, 2008 Posts: 1 Comments: 9648
813. kmanislander
1:46 PM GMT on May 21, 2012
Quoting stormwatcherCI:
No golf for you again today LOL. It is dark and very rainy up here with winds between 30-35 mph. IDK if anything will develop but we sure needed this rain.


Yeah, a real bummer :-(

Dead calm here and rain measurement now close to 4 inches since midnight
Member Since: August 19, 2006 Posts: 0 Comments: 15882
812. stormpetrol
1:45 PM GMT on May 21, 2012
Just took a drive downtown, Grand Cayman . IMO they need to get that cruiseship out of port, it is also unsafe to load and unload passengers in this type of weather. There is also small ocean swells on that side, typically not seen with just rainy weather!
Member Since: April 29, 2007 Posts: 0 Comments: 8023
811. kmanislander
1:44 PM GMT on May 21, 2012
Quoting BrickellBreeze:


Whatever Develops, when it eventually moves north into Cuba, Bahamas, South Florida (?) will have to fight high shear, dry air, and land.

So I'm assuming the intensity it may reach in the general safety of the Carribean, will be it's peak.

What's your thought on track?


Cannot say. We have to wait and see if anything forms first as the conditions prevailing at that time will determine intensity and track
Member Since: August 19, 2006 Posts: 0 Comments: 15882
810. wunderkidcayman
1:43 PM GMT on May 21, 2012
Quoting jeffs713:


Where do you see that? I see 20-40kt in the GoH. The map you posted is m/s.


first I said is nearly not that it is
second from this you can see that 10kt line just on the honduras belize coast and its moving N and E by the way this is the 12Z map
Member Since: June 13, 2009 Posts: 2 Comments: 12509
809. stormwatcherCI
1:42 PM GMT on May 21, 2012
Quoting kmanislander:


Good morning

Very heavy rain in South Sound. 2.5 inches since midnight and climbing quickly now
No golf for you again today LOL. It is dark and very rainy up here with winds between 30-35 mph. IDK if anything will develop but we sure needed this rain.
Member Since: October 9, 2008 Posts: 0 Comments: 8426
808. AussieStorm
1:42 PM GMT on May 21, 2012
Quoting jeffs713:

How can you estimate track on something that hasn't formed?

you beat me to that question. Maybe showing on models.
Member Since: September 30, 2007 Posts: 9 Comments: 15962
807. AussieStorm
1:40 PM GMT on May 21, 2012
Quoting wunderkidcayman:

that id for belize not mexico

Click the link that says, Mexico Radars
Click the Belize Radar to go to the page, Link is inbed.
Member Since: September 30, 2007 Posts: 9 Comments: 15962
806. jeffs713
1:40 PM GMT on May 21, 2012
Quoting wunderkidcayman:
trock wise for PRE 94L I'll say is tracking NE toward Cayman Cuba NW Bahamas/SE Florida

How can you estimate track on something that hasn't formed?
Member Since: August 3, 2008 Posts: 16 Comments: 5890
805. AussieStorm
1:37 PM GMT on May 21, 2012
Quoting Tropicsweatherpr:


Hi Aussie. Is on the Pacific Mexican coast,but Grothar posted a good graphic.

Yeah I know. I was just giving the Radars for Mexico.
Member Since: September 30, 2007 Posts: 9 Comments: 15962
804. wunderkidcayman
1:36 PM GMT on May 21, 2012
Quoting AussieStorm:


Mexico Radars.


that id for belize not mexico
Member Since: June 13, 2009 Posts: 2 Comments: 12509
803. jeffs713
1:36 PM GMT on May 21, 2012
Quoting wunderkidcayman:
wind shear is nearly 10kt in the GOH


Where do you see that? I see 20-40kt in the GoH. The map you posted is m/s.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
802. Tropicsweatherpr
1:36 PM GMT on May 21, 2012
Quoting AussieStorm:


Mexico Radars.



Hi Aussie. Is on the Pacific Mexican coast,but Grothar posted a good graphic.
Member Since: April 29, 2009 Posts: 75 Comments: 14570
801. wunderkidcayman
1:35 PM GMT on May 21, 2012
trock wise for PRE 94L I'll say is tracking NE toward Cayman Cuba NW Bahamas/SE Florida
Member Since: June 13, 2009 Posts: 2 Comments: 12509
800. AussieStorm
1:27 PM GMT on May 21, 2012
Quoting Tropicsweatherpr:
Does anyone has a graphic of the Mexican coast that has the cities? I am very interested because a cruise ship (Millenniun) will make a stop in Puerto Vallarta on Thursday.

Link


Mexico Radars.

Member Since: September 30, 2007 Posts: 9 Comments: 15962
799. BrickellBreeze
1:21 PM GMT on May 21, 2012
Quoting kmanislander:
Vorticity in the GOH is way up now as well. If shear eases off it would not take long for this feature to spin up


Whatever Develops, when it eventually moves north into Cuba, Bahamas, South Florida (?) will have to fight high shear, dry air, and land.

So I'm assuming the intensity it may reach in the general safety of the Carribean, will be it's peak.

What's your thought on track?
Member Since: March 22, 2012 Posts: 0 Comments: 723
798. AussieStorm
1:18 PM GMT on May 21, 2012
Quoting wunderkidcayman:
wow if shear is expected to be this low in the GOH and W caribin 48 hours we very well may get TS Beryl at maybe 50-70mph maybe higher I am not saying that it will happen but it may happen

This is 240hr ECMWF. Long way out but the ECMWF did predict Alberto.

Member Since: September 30, 2007 Posts: 9 Comments: 15962
797. RitaEvac
1:15 PM GMT on May 21, 2012
Near Galveston TX last evening



Member Since: July 14, 2008 Posts: 1 Comments: 9648
796. stormpetrol
1:13 PM GMT on May 21, 2012
Member Since: April 29, 2007 Posts: 0 Comments: 8023
795. LargoFl
1:13 PM GMT on May 21, 2012
Quoting WxGeekVA:
GEE SOMETHING IS STARTING TO LOOK LIKE IT WANTS TO DEVELOP
Member Since: August 6, 2011 Posts: 4 Comments: 40995
794. wunderkidcayman
1:09 PM GMT on May 21, 2012
just realised right now we have a whole lot of Caymanian blogger on now
so hello fello Caymanian blogger how are you doin so enjoying the public holiday
Member Since: June 13, 2009 Posts: 2 Comments: 12509
793. kmanislander
1:08 PM GMT on May 21, 2012
Vorticity in the GOH is way up now as well. If shear eases off it would not take long for this feature to spin up
Member Since: August 19, 2006 Posts: 0 Comments: 15882
792. stormpetrol
1:07 PM GMT on May 21, 2012
Link

Nasty day downtown, Grand Cayman. You can hardly see the cruiseship for the rain.
Member Since: April 29, 2007 Posts: 0 Comments: 8023
791. ncstorm
1:07 PM GMT on May 21, 2012
UK Met has the caribbean/bahamas storm as well..




Member Since: August 19, 2006 Posts: 13 Comments: 16041
790. wunderkidcayman
1:06 PM GMT on May 21, 2012
wind shear is nearly 10kt in the GOH
Member Since: June 13, 2009 Posts: 2 Comments: 12509
789. kmanislander
1:02 PM GMT on May 21, 2012
Quoting stormwatcherCI:
In East End too and winds are now 30-35 mph.


Good morning

Very heavy rain in South Sound. 2.5 inches since midnight and climbing quickly now
Member Since: August 19, 2006 Posts: 0 Comments: 15882
788. wunderkidcayman
1:00 PM GMT on May 21, 2012
Quoting Grothar:


LOL. It's OK kid, when they tease you, they like you. It's when they ignore you that you have to worry.

I know


Quoting BrickellBreeze:


If a System does form, it will be a large one....

or maybe a meduem one
Member Since: June 13, 2009 Posts: 2 Comments: 12509
787. stormpetrol
12:58 PM GMT on May 21, 2012
Raining here non stop in South Sound since around 4am.
Member Since: April 29, 2007 Posts: 0 Comments: 8023
786. wunderkidcayman
12:57 PM GMT on May 21, 2012
wow if shear is expected to be this low in the GOH and W caribin 48 hours we very well may get TS Beryl at maybe 50-70mph maybe higher I am not saying that it will happen but it may happen
Member Since: June 13, 2009 Posts: 2 Comments: 12509
785. stormwatcherCI
12:57 PM GMT on May 21, 2012
Member Since: October 9, 2008 Posts: 0 Comments: 8426

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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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