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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NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI OCT 1 2010
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
SHOWERS AND THUNDERSTORMS REMAIN DISORGANIZED IN ASSOCIATION WITH
A LARGE AREA OF DISTURBED WEATHER LOCATED ABOUT 700 MILES EAST OF
THE LESSER ANTILLES. DEVELOPMENT...IF ANY...OF THIS SYSTEM SHOULD
BE SLOW TO OCCUR...AND THERE IS A LOW CHANCE...20 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT
MOVES WESTWARD OR WEST-NORTHWESTWARD AT 15 TO 20 MPH.
A SURFACE TROUGH OVER THE NORTHWESTERN CARIBBEAN SEA CONTINUES TO
PRODUCE DISORGANIZED SHOWER AND THUNDERSTORM ACTIVITY. THERE IS A
LOW CHANCE...10 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY EASTWARD OR
NORTHEASTWARD. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINS ARE
POSSIBLE DURING THE NEXT DAY OR TWO ACROSS NORTHERN CENTRAL
AMERICA...THE CAYMAN ISLANDS...EASTERN CUBA...JAMAICA...AND
HISPANIOLA.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER BEVEN
yes I've noticed that. A front went through last week and cleaned a couple up but now we have new ones.
They have to get past the Atlantic troughs though which are becoming very powerful. Not only the one off the East Coast but the North Atlantic storms off the Azores should really start to wind up.
Perhaps this season will be a record-breaker in terms of names removed from use.
And yet we had so many in August ready to call the season a dud...
123 days in the books
60 to go and it's turkey and Christmas time.
Judging by the TWO, looks like it will get slower too.
Just a brief (haha) mention in this abbreviated discussion.
Not making too much of it in this short long-term forcst..
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
340 PM EDT FRI OCT 1 2010
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
...UNSETTLED WX CONTS INTO (ERY PART OF) XTNDD FCST...AS STM ALOFT CRSS THE MTNS AND REACHES THE CST...AS CSTL LO PRES IS SLO TO DVLP/MVG
NNE. 00Z/01 ECMWF RMNS THE SLOEST OF THE MDLS W/ MVMNT OF SYS OFF
THE CST BY MIDWEEK. XPCTG CLDNS AND CHC RA TO LINGER TUE (ESP
CNTRL/E SXNS)...AND THEN BRING LWRG POPS (W-E) AND DCRSG CLDNS TUE
NGT/WED. RAINFALL NOT LIKELY TO BE AS SGFNT AS WHAT HAS FALLEN THIS
WK OVR THE FA. AFT WED...SFC HI PRES BUILDS INTO THE RGN FM THE W
BRINGING DRIER/MILDER CONDS. TEMPS AVGG SVRL DEGS F BLO NRML (ESP
DYTM) THROUGH WED...THEN RETURNING TO AOA NRML BY THE END OF THE WK...
Link
"...over the northwestern Caribbean...there is a low chance...of this system becoming a tropical cyclone...as it moves eastward..."
When Lows Collide
Why Igor?
Here is a suggestion that might help you, and I know it helps me. If you are using a pc, put the cursor on the image and right click, then choose "view image". The image will open in a new window at it's full size instead of the shrunken image you see here on the blog.
Dan
An anomoly? Maybe that's why it has such a low chance attached to it.
It was bad up there, no doubt. Just not sure if they will see is as retirement worthy.
Scratch that, the new one shows it elongated again. xD
I heard a quote on an article from up there that said Igor "Was a 50 to a 100 year event."
I give up..This morning 97 was defined Vertex on ASCAT and RGB sat loops..now there is so much scattered convection and little vortices you cant find anything for sure!
Here's an excerpt from the Wiki article:
Significant wind and flooding damage was reported across much of the island of Newfoundland as Igor passed just to the east. Many communities had to declare a state of emergency and some parts of the community of Clarenville were evacuated due to flooding. 238 mm (9.37 inches) of rain fell on the Burin Peninsula at St. Lawrence, making Hurricane Igor at least the third wettest tropical cyclone to be recorded in Canada
Being the third wettest storm would definitely put it in the 'rare events' category. I just don't think they'll retire it is all.
And sometimes when there is something to say.... silence is also best. LOL
Pretty much. What made that mess bad was the very narrow moisture feed from the tropics training over the same area. Forced in between the trough to the west and strong ridging in the western Atlantic. Plenty of moisture advecting N from the Caribbean. The northern end of the system formed an extratropical low and the remnants followed behind.
That pattern still exists to a fair extent although the moisture maybe not quite as deep.
A wait and see. For now, maybe just a bit more rain for areas that don't need it. It would be sub-tropical at best.
AOI
TS BUSTED FORECAST ALIBI
Question is, how much of it do you remember? ;-)
Pressures are still high and ship reports don't show a circulation just a NE/SE wind vertex so not to much to worry about but we really need to watch this..Shear will keep it from organizing and is still 20-30knots over the upper half but if it gets a chance it will develop fast.
You've been warned, I'll be right back.
The CMC has the SW tail of 97L's vort winning out.
Although maybe it will dissipate completely. XD
I modified that comment, it went back to being elongated on the 00z update, with the vort to the SW gaining presence, seems 97L is having a vortex fight. XD
For some odd reason, I believe that there was a discussion about priests and me going to catholic school K - 12th grade. I was amazed that I did not get banned and no matter how much I drink tonight, I refuse to get on that topic again. LOL
It's believed that Environment Canada will likely request retirement of Igor, as they did with 2003's Hurricane Juan...
Don't ignore it and give it till D-max, now if by d-max it doesn't manage anything, well then we can chill. XD
But we will get RAIN..a lot of rain..then some more rain..and after that..rain.
I hate rain in the week -.-
I wish 97L would turn into a major so it could turn to the NE. XD
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