TD 8 forms; 97L a potential threat to the Caribbean and U.S.
Tropical Depression Eight formed last night near the coast of Honduras, and is headed westwards towards a landfall in Belize on Saturday. TD 8 is a small storm, so will impact a relatively small area of northern Honduras, northern Guatemala, all of Belize, and southern portions of Mexico's Yucatan Peninsula. TD 8 has just enough room between its center and the coast of Honduras to intensify into a moderate strength tropical storm with 50 - 60 mph winds before landfall. It is very unlikely TD8 has the time or room to intensify into a hurricane; NHC gave the storm just a 7% chance of making it to hurricane strength in their 11am EDT wind probability forecast. Should TD8 make it to tropical storm strength, it would be called Harvey.
Figure 1. Morning satellite image of TD 8.
Invest 97L likely to become a tropical storm next week, could threaten the U.S.
A tropical wave near 14°N 48°W, about 800 miles east of the Lesser Antilles Islands, is moving westward near 20 mph. This wave, designated Invest 97L by NHC yesterday, has seen a marked increase in its heavy thunderstorm activity this morning, but dry air to the north and west is slowing development. An impressive amount of large-scale spin is obvious in visible satellite loops, but the storm is at least a day away from forming a well-defined surface circulation. Ocean temperatures are about 28.5°C, about 2°C above the threshold needed to support a tropical storm, and wind shear is low, 5 - 10 knots.
Figure 2. Morning satellite image of the tropical wave 97L.
The computer models have shown an unusual amount of agreement in developing 97L over the past few days, and all the ingredients seem to be in place for a tropical storm to form by Monday or Tuesday as 97L crosses the Northeast Caribbean. The atmosphere is expected to be moister over the Caribbean, wind shear will remain a low 5 - 10 knots, and sea surface temperatures will increase to near 29°C. The main impediment for development will likely be two-fold: too much dry, stable air, and proximity to land.
As seen in Figure 3, there has been an unusual amount of dry, stable air in the Atlantic this year, 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. This stable air has been largely responsible for the fact that none of our seven tropical storms so far this year has made it to hurricane strength, despite the presence of sea surface temperatures that are the 3rd warmest on record across the tropical Atlantic. Tropical Storm Emily in early August encountered problems with dry air when it crossed the Northeast Caribbean, and 97L may have similar difficulties.
Figure 3. Vertical instability of the atmosphere during 2011 in the Caribbean (left) and tropical Atlantic between the Lesser Antilles Islands and coast of Africa (right.) 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. Observed vertical instability (blue line) has been much lower than the climatological average from previous years (black line), due to an unusual amount of dry air in the atmosphere, inhibiting tropical storm development this year. Image credit: NOAA/CIRA.
Encounters with land will be another potential major problem for 97L. Most of the computer models take 97L near or over Puerto Rico Sunday night, then very close to or over mountainous Hispaniola Monday night through Tuesday. It is unlikely that 97L will be stronger than a 55 mph tropical storm when it encounters these islands, and passage over the islands could severely disrupt the storm. However, if 97L takes a path just south or north of Hispaniola, the potential exists for the storm to intensify into a hurricane.
There will be moderate wind shear of 10 - 20 knots to the north of the islands early next week, so a path just to the south of the Dominican Republic and Haiti would be more likely to let 97L intensify into a hurricane. A west-northwest motion is likely for 97L through Wednesday, which would bring the storm to the vicinity of Jamaica-Central Cuba-the Central Bahamas on Wednesday. On Wednesday and Thursday, the models agree that a trough of low pressure will dip down over the Eastern U.S., which is likely to turn 97L to the north. The exact timing and strength of this trough varies considerably from model to model, and will be critical in determining where and when 97L will turn to the north. The best model for predicting the timing and strength of such troughs over the past two years has been the ECMWF (European Center model), and this model currently brings 97L into the Florida Keys on Thursday night next week. You can view ECMWF forecasts on our wundermap with the model layer turned on. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on our computer model forecast page that plots positions from the other major models.
Remember that a 7-day forecast by even our best model will be off by an average of over 700 miles, so it is too early to tell what part of the U.S. might be most at risk from a strike by 97L. This weekend would be a good time to go over your hurricane preparedness.
Figure 4. Morning satellite image of Invest 98L off the coast of Africa.
Invest 98L near the coast of Africa
A tropical wave near the coast of Africa, a few hundred miles southeast of the Cape Verde Islands, is moving west to west-northwestward at 10 - 15 mph. This wave, designated Invest 98L by NHC yesterday, is large and well-organized, with a modest amount of spin and heavy thunderstorm activity. 98L will bring strong, gusty winds and heavy rains to the Cape Verde Islands today and Saturday as the storm skirts to the south. So far this morning, top sustained winds measured in the islands were 24 mph at Mindelo. Water temperatures are warm, near 27 - 28°C, and wind shear is low, 5 - 10 knots, so 98L should continue to organize today. NHC gave the storm a 50% chance of developing into a tropical depression in their 8am advisory. Once 98L passes to the west of the Cape Verde Islands, it has a long stretch of ocean to cross before it could affect any other land areas. Approximately 70 - 80% of all tropical cyclones that pass this close to the Cape Verde Islands end up curving out to sea and not affecting any other land areas, according to Dr. Bob Hart's excellent historical probability of landfall charts. The latest set of long-range model runs go along with this idea, but it is too early to be confident of this.
Jeff Masters
Reader Comments
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lol
TOWARD THE END OF THE WEEK AND INTO THE WEEKEND...ALL EYES ARE
LIKELY TO BE ON THE AREA OF DISTURBED WEATHER CURRENTLY IN THE
ATLANTIC EAST OF THE LESSER ANTILLES. RECENT SUITE OF GLOBAL
MODELS INDICATES THAT A W-WNW TRACK IS LIKELY THROUGH THE
CARIBBEAN NEAR THE GREATER ANTILLES AND CUBA. THEREAFTER...ALTHOUGH
BEGINNING TO FILL...ENOUGH OF A WEAKNESS IS PROGGED TO REMAIN
ACROSS THE EASTERN GULF COAST REGION/SOUTHEAST CONUS TO INDUCE
WHATEVER BECOMES OF THIS FEATURE ON A MORE POLEWARD TRACK. WHETHER
THIS SCENARIO HOLDS REMAINS TO BE SEEN...AND WILL BEAR WATCHING
OVER THE NEXT SEVERAL DAYS.
Does or did anyone else see this fill?
we reach peak in 21 days
then the slow steady drop in activity till the end
from the 20th of august till 20th of sept is the most activity
at least this year
then a couple of more maybe a screamer or two for oct
and 1 to 3 for november
Just a few days ago many was bashing the MODELS.......lol
Again if all of this comes to pass with the track and even close to the intensity, these models are worth all the money they spend on them by far.Before you know it they will be predicting storms before they even exit Africa. Well maybe not but the possibility is there
Katrina survived crossing FL when 90% said she was doom. Some blame the everglades.
Sounds good, lets go together :-)
I repeat. That's the average of statistical data. Nature doesn't answer to that. A hurricane season's peak is not one date. Early September is absolutely part of the peak of the season.
08L/TS/H/CX
NEARING LANDFALL
It was Charley(2004) not Charlie(1951)
The everglades make sense, plus we do not have any high terrain, but Katrina passed east to west this would be going south to north and that is a lot of time over land. Those are the things that are really making me wonder about the intensity they forcast.
Yea, but I'm pretty sure they didn't have computer models back then.
My point is that for 12 consecutive days, the models have been almost carbon copies of one another. (bar a few) but you get my point. Not really flip flopping that much. I think Wilma may have fit the bill too, but She was stalled for quite a while, and the cold front picked her up. But other than her. Come on 12 days out and it's still hitting FL.
INV/XX/97L
MARK
14.66N/53.12W
Well, sure, they after all, are twins.
You're stormtop's kid, aren't you?
Of course calling on the charts. I'm well aware the peak of the season is mid September. Statistically yes you are correct. However September is the PEAK MONTH, that's what I was referring to. Need you attack me with your stats? They only mean so much. I know what I'm talking about. You don't need make a correction and give yourself some false sense of superiority by defeating the sarcastic guy.
June~ 1-0-0
Arlene: 65 Mph, 993 MB, 25 Deaths
July~ 3-0-0
Bret: 65 Mph, 996 MB, 0 Deaths
Cindy: 60 Mph, 1000 MB, 0 Deaths
Don: 50 Mph, 998 MB, 0 Deaths
August~ So Far: 4-0-0
Emily: 50 Mph, 1003 MB, 5 Deaths
Franklin: 45 Mph, 1004 MB, 0 Deaths
Gert: 60 Mph, 1000 MB, 0 Deaths
Harvey(So far): 60 Mph, 994 MB, 0 Deaths
August~ Forecast for the rest of the month
Irene
September~
Jose
Katia
Lee
Maria
Nate
October~
Ophelia
Phillipe
Rina
November~
Sean
00z Invest97y Cycle NHC model tracks
Invest97 Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)
Dynamic Models (More sophisticated models)
Deep layer steering, There is no where else for it to go. Where ever the weakness is yabang...
Date : 20 AUG 2011 Time : 034500 UTC
Lat : 16:13:12 N Lon : 85:19:16 W
CI# /Pressure/ Vmax
3.5 / 993.2mb/ 55.0kt
Final T# Adj T# Raw T#
3.5 3.8 4.2
Center Temp : -67.1C Cloud Region Temp : -68.4C
Scene Type : EMBEDDED CENTER CLOUD REGION
Positioning Method : FORECAST INTERPOLATION
Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC
Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 35km
- Environmental MSLP : 1010mb
Satellite Viewing Angle : 22.4 degrees
65 Mph, 993 MB estimated by Satellite from Harvey, nearing Hurricane Status according to Raw T#, though should be a 60 Mph or slightly higher 65 Mph storm at Intermediate advisory...
2km Storm Relative IR Imagery with BD Enhancement Curve
Allot of warm water in the glades, Lake Okeechobee, and may skirt the west side. I just hope the levy's in Okeechobee are intact if a direct hit (use to live in Clewiston).
I like your breakdown save for one thing....
I have a hard time believing that we will only have 1 more named storm the rest of August
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TS Harvey Floater - Rainbow Color Infrared Loop
Now, it just disturbing how the 2 weeks of models flip flopping back and fourth east and west with Florida somewhere in the middle and have slowly come together over time into what is becoming a remarkably tight consensus in days 5-7 all things considered. Dislike...
Viewing: 3201 - 3251
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