97L a major rainfall threat; October hurricane outlook; NC rains finally end
A large and complex region of disturbed weather (Invest 97L), centered about 800 miles east of the Lesser Antilles Islands, is headed west-northwest at 15 - 20 mph and will bring heavy rain showers and gusty winds to the northern Lesser Antilles Islands on Saturday and Sunday. Wind shear is a moderate 5 - 15 knots over 97L, and the waters beneath are very warm, 29°C. However, recent satellite imagery shows that the intensity and areal coverage of 97L's heavy thunderstorms have decreased this morning, thanks to some dry air being ingested into the storm. The SHIPS model predicts that wind shear over 97L will rise to the high range, 20 - 30 knots, Saturday through Tuesday, but some of the global computer models depict only moderate amounts of shear for 97L during this period. The NOGAPS model is the only model currently showing significant development 97L, and that model predicts 97L will be near Puerto Rico on Monday, the Dominican Republic on Tuesday, Haiti on Wednesday, and Eastern Cuba and the southeast Bahamas on Thursday. NHC is giving 97L a 40% chance of developing into a tropical depression by Sunday, but as of this morning, had not tasked the Hurricane Hunters to fly into the storm over the next two days. 97L will slow down to 5 - 10 mph on Sunday, bringing the potential for an extended 3 - 4 day period of heavy rains for the islands in its path. Even if 97L does not develop into a tropical depression, its slow motion may result in life-threatening flash flooding and mudslides in Puerto Rico, the Dominican Republic, Haiti, and eastern Cuba next week.
Figure 1. Morning satellite image of Invest 97L.
October hurricane outlook
October is here, and it is time to take stock of where we stand and how far we have to go before hurricane season is over. The beginning of October traditionally marks the two-thirds point of hurricane season; approximately one-third of all hurricanes and 28% of named storms occur after October 1. Tropical Storm Nicole brought us up to fourteen named storms for the year, and I expect about 4 - 5 more named storms this year with 2 - 3 of these being hurricanes. That would add up to 18 - 19 named storms for the season, putting 2010 in 3rd - 5th place all-time for most named storms. Since record keeping began in 1851, only four seasons have finished with more than eighteen named storms. These seasons were 2005 (28 named storms, with the 17th named storm, Rita, occurring by October 1); 1933 (21 named storms, with the 18th named storm occurring by October 1;) 1995 (19 named storms, with the 15th named storm, Opal, occurring by October 1;) and 1887 (19 named storms, with the 10th named storm occurring by October 1.) The most likely time to get activity is during the first two weeks of October. There are still two weeks of peak hurricane season left before the activity traditionally begins to decline steeply (Figure 2.) Given the record warm sea surface temperatures in the Atlantic this fall, the presence of La Niña in the Eastern Pacific keeping wind shear lower than average, and the observed increase in late-season activity in recent decades, I expect this year's peak portion of hurricane season will last until the end of October. I predict three named storms, two hurricanes, and one intense hurricane will form in the Atlantic this month, with two named storms and one hurricane occurring in November - December, making 2010 as the third busiest Atlantic hurricane season of all-time.
Figure 2. Climatological frequency of Atlantic named storms and hurricanes.
Jamaica cleans up after Nicole
Tropical Storm Nicole lasted only six hours as a tropical storm, but the storm's torrential rains hit Jamaica hard. Nicole's rains killed at least six people on the island, and at least thirteens others are missing and feared dead. The storm cut power to 170,000 island residents, and caused millions of dollars in damages. Wunderground member JamaicaZed wrote me to say his rain gauge in the Kingston suburb of Norbrook caught 17.39" of rain Monday through Thursday, with 11.10" coming on Wednesday.
Historic rainfall event for eastern North Carolina ends
The rains have finally ended In North Carolina, where tropical moisture streaming northward in advance of Nicole generated a historic rainfall event this week. Wilmington, NC set records this week for the heaviest 3-day, 4-day, and 5-day rainfall events in city history, and the month of September ended up as the second rainiest month ever recorded in the city. A remarkable 22.54" of rain fell on Wilmington during the 5-day period Sunday through Thursday. The previous record was 19.06", set in September 1999 during Hurricane Floyd. Fortunately, eastern North Carolina was under moderate drought conditions prior to this week's rainfall onslaught, with just 0.18" of rain falling during the first 25 days of September. Only minor to moderate flooding is occurring on North Carolina rivers, with just one river, the Northeast Cape Fear River near Chinquapin, expected to experience major flooding. Portlight.org is beginning to identify needs in Eastern North Carolina in the wake of the flooding, and expects to perform the first deployment of their new relief trailer within the next few days and send a truck loaded with water, food and personal hygiene supplies.
The most remarkable thing about Wilmington's second-wettest month in history is that it came without a hurricane affecting North Carolina. All four of the other top-five wettest Septembers in history were due, in large part, to hurricanes:
#1 23.41 inches 1999 (Hurricanes Dennis and Floyd)
#2 22.72 inches 2010 (plume of tropical moisture in advance of TS Nicole)
#3 20.10 inches 1877 (Hurricane Four)
#4 18.94 inches 1984 (Hurricane Diana)
#5 16.93 inches 1924 (Hurricane Five and Tropical Storm Eight)
Figure 3. Radar-estimated precipitation for North Carolina since Sunday shows that the precursor moisture from Nicole has brought widespread rain amounts of fifteen inches (white colors.)
Heavy rains and flooding for New England
The plume of tropical moisture that affected North Carolina is now triggering heavy rains in New England, and flood warnings are posted throughout most of New Jersey, eastern Pennsylvania, eastern New York, Delaware, and Vermont this morning. In New York City, heavy rains this morning have overwhelmed one section of the city's subway system, and flooding closed several key road arteries in the city, snarling the morning commute. About two inches of rain have fallen so far this morning in the city. Severe weather is not expected, and no tornadoes were reported yesterday in association with this weather system.
Elsewhere in the tropics
Disturbed weather continues in the Central Caribbean, where the remnants of Tropical Storm Nicole will bring isolated heavy rain showers today to Hispaniola, Jamaica, Cuba, the Cayman Islands, and northern Honduras. The GFS model predicts this activity will concentrate near Hispaniola over the weekend, then push northwards into the Bahamas, with a subtropical or extratropical storm forming over the Bahamas on Sunday or Monday. This storm could bring 2 - 4 inches of rain to the Bahamas Sunday and Monday. The storm will then move north-northeastwards, parallel to the U.S. East Coast, and not affect any other land areas. Several of the models are predicting the formation of a tropical depression in the Mid-Atlantic 5 - 7 days from now, in a location that would not be of any danger to land areas.
Next update
I'll have an update Saturday morning.
Jeff Masters
Shannon Hills, Ridgeway, VA
Reader Comments
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I hate rain in the week -.-
I wish 97L would turn into a major so it could turn to the NE. XD
i'll be back later
yes, we should see rain that can cause some flooding, that's correct.
Is that not a trough to shear them and pick them up and take them NE?
But yes we are seeing some late waves. But the reason CV season is considered over as I mentioned earlier is troughs and fronts start picking the waves off very quickly before they can make it across the Atlantic. Shear increases, SST drop rapidly from the Canaries current and fronts start making it down into africa as well.
Yes there could be a late season waves that defies odds/fronts and everything and comes all the way across and creams us as a CAT 5. I don't think it's ever happened but I'd be interested if you find something.
I agree, at least one maybe two more named storms from the disturbances rolling off the African coast
Click for larger image:
It was just a guess...I got it wrong :(
hmm...
So anyone got any theories as to why it is so linear?
Thanks nc. I am headed up that way early in the morning to begin identifying communities that are a good fit for the Portlight mission. Specific information and contacts have been hard to come by today, but being in the area tomorrow should make things much easier. So far it seems that Swansboro, Bertie, and Hubert may be some of the areas we begin in. We are also prepared to assist in anyway we can while we are also carrying out an assessment. The Portlight Live Webcam will be running for much of this trip and you can view it here beginning tomorrow morning.
Have to finish getting ready to leave so I can get a little sleep before I head out at about 5am. Y'all have a good night.
"The first storm of 1931 made landfall in the Galveston area as a tropical storm.
A tropical storm formed August 11th in the southern Gulf of Mexico near the Yucatán Peninsula and slammed into the upper Texas coast near Freeport, Texas as a very compact Category 4 hurricane two days later. As the storm moved over the Gulf of Mexico, it intensified from a Category 1 to a Category 4 with winds estimated at 140 mph and an estimated central pressure of 942 millibars in less than one day. The eye crossed the coast about 10 p.m. on August 13, slashing a 30- to 40-mile wide path of destruction across Brazoria County, Texas. Official warning for the storm came just 4 hours prior to landfall, and many people trying to evacuate inland had to abandon their cars in high winds and heavy rains. The 1932 hurricane retained its strength miles from the coast and killed 40 people. The greatest single toll for any town was 7 in West Columbia, Texas, where sustained winds over 100 mph flattened homes. Two neighborhoods that had been constructed for oil industry workers there were wiped clean. Freeport, Angleton and Galveston suffered extensive wind damage, and the inland towns of Brazoria, West Columbia, Damon and Needville, all in the path of the eye, were also devastated. Damage estimates topped $7 million in 1932 U.S. dollars.
The Texas area was alive with activity in 1933, with the second storm making landfall in Mexico after threatening Texas; the fourth storm making landfall near Matagorda Bay in Texas as a 45 mph (70 km/h) tropical storm on July 23. The fifth storm made landfall near Brownsville, Texas on August 5 as a strong tropical storm. The storm produced strong winds and high tides along the coast of Texas, while heavy rains in south Texas and northern Mexico caused heavy damage. High tides from the storm covered parts of South Padre Island. The tenth storm threatened Texas, causing the issuance of tropical storm warnings for portions of the southern Texas coastline. The eleventh storm made landfall just north of Brownsville early on September 5. 179 people were killed and doing 28 million dollars in damage.
In 1934, the third storm was a Category 1 hurricane passed over north Florida as a tropical storm and made landfall in central Texas, causing 11 casualties and $1-$2 million in damage. The fifth storm was another Category 1 hurricane that grazed Galveston.
The third storm of the 1936 season caused severe crop damage was reported in San Patricio and Nueces Counties. In all, the hurricane caused $550,000 (1936 USD) in damage, primarily to oil refinery property, though no deaths or injuries were reported. The fourteenth storm of the season made landfall near Brownsville.
The third and fifth storms of 1938 made landfall in the state."
The 1940's had some storms...all of them made landfall North of Galveston however.
Hope this helps :)
Well, candidate-wise, hurricanes made landfall just north of Brownsville in 1909 (Cat 2 Hurricane Two) and 1933 (Cat 3 Hurricane Eleven). There was also the Cat 2 San Zacarias Hurricane of 1910 which came in north of Port Mansfield, and the Cat 4 1916 Texas Hurricane that made landfall just north of that.
Yeah, I was thinking it was Hurricane 11.
Did Jason make that for you? How nice of him.
ah! I see.
I don't even know where the true center ever was or where it is now. I have seen mostly confusion on the part of both the computers and the humans. Everytime I thought it was somewhere, I changed my mind.
Yeah the NHC says 52W but then there is that line of convection east of the islands. :|
This is confusing...
I know this may upset quite a few on this site, but I think it should be noted.
HWRF did really well on intensity with 4 kt error in the last 24hrs.
Yep, Earl was this year's whoops but besides that they have been great.
.
We don't even have the shots of land-canes in Africa to offer some hope:(
We surely can't take any more...a big tree fell in my back yard and I am now wondering if my big mango tree near to the house will be next. Maybe I should go buy a chain saw tomorrow...could be useful considering how the land is so wet, my neighbour has a whole lot of trees too.
Wow. That's an excellent, intelligent, and well-thought out retort. So witty! I've seldom been put in my place the way you just did...
;-)
On a serious note. It is rather telling for those that think the season is over. Really puts the crayons to use in painting a visual of the latter part of hurricane season.
Yes, the synoptic pattern is forcing it to just be a trade wind feature forcing a linear pattern. Its common. 97L was never a threat and really with the front dropping so far south you can just about say the season is over. nothing will survive the change in airmass in southern CONUS
There is a second peak of activity in October if I'm not mistaken.
Nice example of bursting while under shear.
Maybe it is just cirrus extending out from one or two centers of convection that happen to line up.
No it is a convergence zone from the trade winds. Do a streamline analysis and it is obvious.
IT DOES
LOOK AS THOUGH THIS AREA OF LOW PRESSURE WILL BRUSH CLOSE ENOUGH TO
THE CAROLINAS TO BRING A RISK OF MORE RAINFALL. THE BEST CHANCE FOR
THIS WILL BE LATER SAT NIGHT AND SUN AND PRIMARILY ALONG THE
COAST...ESPECIALLY THE CAPE FEAR REGION. THE BOUT OF RAIN THIS TIME
AROUND WILL BE LIGHT AND MEASURABLE RAINFALL SHOULD BE OF SHORT
DURATION AS THE AIRMASS WILL BE MUCH DRIER. PRECIPITABLE WATERS WILL
PEAK AROUND 1.5 INCHES SUN MORNING ACROSS THE CAPE FEAR REGION WITH
AMOUNTS CLOSER TO 1 INCH ELSEWHERE. SATURATION OR NEAR SATURATION
WILL BE LIMITED TO THE FIRST 15 KFT OF THE COLUMN WITH MUCH DRIER
AIR ABOVE THAT. AT THIS TIME...PRECIPITATION AMOUNTS SHOULD BE NEAR
OR BELOW A TENTH OF AN INCH WITH HIGHER AMOUNTS EXPECTED ACROSS THE
OCEAN. TEMPS WILL BE COOLER THAN NORMAL THIS PERIOD. CLOUD COVER
WILL BE MOST PREVALENT ON SUN AND WITH THAT...SOME AREAS WILL NOT
QUITE GET TO 70 DEGREES ALONG THE COAST. WELL INLAND...CLOUDS SHOULD
BE THINNER...AND LOWER 70S WILL BE MORE COMMON. MAXIMUM TEMPS EVEN
ON SAT WITH MORE SUNSHINE WILL BE LIMITED BY THE MUCH COOLER AIRMASS
WHICH WILL BE ADVECTING INTO THE AREA ON NE WINDS. THE COOLEST NIGHT
WILL BE SAT NIGHT. AREAS WELL INLAND SHOULD REACH WELL DOWN INTO THE
50S WITH A FEW UPPER 40S POSSIBLE. ALONG THE COAST WHERE CLOUDS WILL
BE ENCROACHING FIRST...MID AND UPPER 50S WILL BE MORE LIKELY. LOW
CLOUDS SUN NIGHT SHOULD KEEP TEMPS FAIRLY UNIFORM ACROSS THE AREA
AND MAINLY IN THE 50S.
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