Tropical Storm Alberto forms off the South Carolina coast
The first named storm of the 2012 Atlantic hurricane season is here. Tropical Storm Alberto formed this afternoon off the coast of South Carolina--a little going-away present for outgoing NHC director Bill Read, who retires on June 1! Alberto has the potential to hit North Carolina as early as Monday, but since the storm is so small, it would only affect a small area of the coast with high winds and heavy rain. Upper level winds out of the southwest are creating a moderate 15 - 20 knots of wind shear over Alberto, and the storm is over the warm waters of Gulf Stream, which are 81°F (27°C), just above the 26°C threshold usually needed to sustain a tropical storm. The system is tangled up with an upper level trough of low pressure, which is pumping cold, dry air into the storm, slowing development. The dry air impinging on Alberto from the southwest can be seen in water vapor satellite loops. Heavy rain showers from Alberto are located about 50 miles offshore of the coast of South Carolina, as seen on Wilmington radar. At times today, 93L has had a cloud-free center resembling an eye on radar, but this was not a true eye.
Figure 1. True color satellite photo of Alberto taken at 1:50 pm EDT Saturday May 19, 2012. Image credit: NASA.
Forecast for Alberto
Rain showers from Alberto are likely to move onshore between Charleston and Wilmington Saturday night and Sunday, bringing 1 - 3 inches of rain to portions of the coast. The storm is too small to cause major flooding problems, particularly since the coast is under moderate to severe drought. Alberto's rains will not be plentiful enough to cause significant drought relief, except perhaps over a small region near the coast, where (and if) the storm makes landfall. Wind shear is expected to remain in the moderate range, 15 - 20 knots, through Monday, which is low enough to allow some slow development. Since the storm is very small, it is highly vulnerable to even a modest increase in wind shear or dry air, which could rapidly disrupt it. Steering currents are weak, and Alberto will wander off the coast of South Carolina through Sunday, before getting caught up by a trough of low pressure on Monday which should lift it out to the northeast. The moderate wind shear and dry air are likely to keep Alberto below hurricane strength. NHC is giving Alberto a 5 - 10% chance of reaching hurricane strength before dissipating on Thursday as it scoots northeast out to sea.
Figure 2. Late afternoon radar image of Alberto from the Wilmington 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 Sunday morning.
Jeff Masters
Reader Comments
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Alberto appears to be firing off some new convection over the last few frames there.
NEXRAD Radar
Storm Relative Mean Radial Velocity 2.40° Elevation
Range 124 NMI
It is stronger than previously estimated, but not stronger than it was 6 or 12 hours ago.
I agree, we've seen stranger things happen though but the area is not conductive for "Hurricane" formation.. Great analysis btw!
'Towers in the Tempest' is a narrated animation that explains recent scientific insights into how hurricanes intensify. This intensification can be caused by a phenomenon called a 'hot tower'. For the first time, research meteorologists have run complex simulations using a very fine temporal resolution of 3 minutes. Combining this simulation data with satellite observations enables detailed study of 'hot towers'. The science of 'hot towers' is described using: observed hurricane data from a satellite, descriptive illustrations, and volumetric visualizations of simulation data. The first section of the animation shows actual data from Hurricane Bonnie observed by NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft.
Three dimensional precipitation radar data reveal a strong 'hot tower' in Hurricane Bonnie's internal structure. The second section uses illustrations to show the dynamics of a hurricane and the formation of 'hot towers'. 'Hot towers' are formed as air spirals inward towards the eye and is forced rapidly upwards, accelerating the movement of energy into high altitude clouds. The third section shows these processes using volumetric cloud, wind, and vorticity data from a supercomputer simulation of Hurricane Bonnie.
Vertical wind speed data highlights a 'hot tower'. Arrows representing the wind field move rapidly up into the 'hot tower, boosting the energy and intensifying the hurricane. Combining satellite observations with super-computer simulations provides a powerful tool for studying Earth's complex systems.
01L/TS/A/CX
MARK
32.51N78.55W
they believe that ship i guess
*AHEM*
...SHIP INDICATES ALBERTO IS STRONGER...
6:50 PM EDT Sat May 19
Location: 32.2°N 77.9°W
Max sustained: 60 mph
Moving: SW at 3 mph
Min pressure: 995 mb
Lol.
I don't have the HRRR, what's it saying Alberto will do?
I vote 65 mph!
Who said it's peaked yet? DMAX can do wonders to a storm like Alberto.
Hurricane into NC
Ranges from run-to-run, but mostly strengthening it in the short-term.
Link?
Only goes out to 15 hours.
Thanks! I actually just found it on google for anyone who's interested. Very interesting model, too bad it only goes out 15 hours.
Strengthens this system pretty good overnight.
Link
Okay then. It's your opinion. But I still think it could strengthen a little bit more. 65mph, maybe 70mph.
Oh, I guess the model that forecast that wasn't the HRRR then. Sorry about that.
NOW
In a while
Only thing I can think of would be the 00z SPC WRF.
12z run has it around 55 knots (71 knot wind is coming from a low to the east)
Too bad visible is gone:
Thanks for re-posting my image. lol
Interesting...what dobyou think it is? A center relocation with a developing eye maybe?
No this is like snow season and tornado season, the big early one and then some minor stuff after.
Wait a minute, the big early one?!?!??!
Raise the DoomCon.
Category 5 hurricane going to sweeep the mid-atlantic.
SARCASM FLAG_ON
I think this may be peak, or as it reorganizes, it may hit 70.
HRRR has pressures steadily falling for the next 15 hours.
Correct.
Doubt anything significant.
Internals look to have become linear and oriented from W to E.
Might take 3-6 hours to see if anything develops from it.
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