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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Awww, I will be in NO this weekend, Sunday night, to pick up my daughter-in-law's truck which just got in from Germany where they were stationed on Monday. I would have enjoyed going and learning more.
I'm pretty sure our anniversary is in May...better check, though...not anywhere near 40 years...just seems like it...
Hi, just wanted say , hope you're doing fine, if I'm not mistaken you said you had to have surgery!
Link
LOL, must have been someone else then. I wished them a happy anniversary then as I knew I'd forget it by this weekend.
Do you think this is for a sampling of 97L's possible future track? Also, since I caught you on here, do you know which model is handling 97L best in regard to error margin? Seen you post those in the past, and was curious.
In the future if you'd like to add commentary don't do it in the same FONT. Make it clear that your comment is just that, not something that the NWS said. Avoid any possibility that what you post can be construed in that way. The NWS statements need to be kept clear, and any digression is treated harshly on this site. If in doubt about FONT, or something else, the responsible thing to do is to simply cut and paste the NWS statement and add any comment in another post.
Where do you live?
08L/TS/H/CX
NEARING LANDFALL
+++!!!
HOUSTON, TEXAS INTERCONTINENTAL AIRPORT HAS REACHED 103 DEGREES THIS AFTERNOON. A
THIS IS THE 19TH CONSECUTIVE DAY THAT THE TEMPERATURE HAS REACHED OR
EXCEEDED 100 DEGREES...AND IS THE LONGEST STRETCH OF CONSECUTIVE 100
DEGREES DAYS SINCE RECORDS FOR HOUSTON BEGAN IN 1889. BEFORE THIS
SUMMER...THE PREVIOUS CONSECUTIVE RECORD WAS 14 DAYS ENDING JULY 19
IN 1980.
INV/XX/97L
MARK
14.71N/52.15W
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 (that 98L will be among the approx. 70-80% , but it is too early to be confident of this.
-- Jeff Masters
Bottom line is the graphic associated with it is red.
You can obviously see the difference between the NHC's TWO and my comment. For one, the NHC's TWO is capitalized, and my comment is not.
Not a big deal.
AGain?!?! And he had been behaving himself so well.....
LOL, ROTF.....
Ayup.... that would be.... pretty interesting.... seems like you can tell the time of day by the pple who come in here to pick on Taz's spelling... I think half the problem is these pple DO realize Taz has some good stuff to say, but they "don't speak the language" so they get frustrated..... maybe even feel a bit... left out???
I like an earlier poster's comment; if you r that irritated by it, there's always the ignore button for you.... If you have a genuine question, ask it.
I also want to remind Wunderbloggers of our excellent tropical page, which has all the common tools you need and more. Hey, u need to let me know when u will be in town... maybe I can take u out to dinner.... Cable Beach is much the same, but also very different... got a new project going out there that would be severely hampered if we get hurricanes through here this season....
that 99L
I have a feeling it will have it.
Really nice structure. Yet I thought it was further south, seems to be almost at 15N.
003500 1617N 08446W 8430 01533 //// +191 //// 101046 047 039 000 05
FM FWC-N
BT
UNCLAS
MSGID/FWC-N/OVLY2/0087/AUG
OVLY/ATL STORM 08L/191800Z9/AUG/1OF1/TROP STORM HARVEY(08L)/METOC
TEXT/12//G/162400N3/0841800W1/S
TEXT/12//G/170600N4/0875400W4/S
TEXT/12//G/180000N9/0915400W9/D
TEXT/12//G/183000N2/0960000W5/D
LINE/4//G/162400N3/0841800W1/170600N4/0875400W4/1 80000N9/0915400W9
/183000N2/0960000W5
ARC/0/G///162400N3/0841800W1/040NM/040NM
ARC/0/G///170600N4/0875400W4/075NM/075NM
TEXT/12//G/142400N1/0814800W1/TROP STORM HARVEY
TEXT/12//G/132400N0/0814800W1/19 AUG 1800Z
TEXT/12//G/122400N9/0814800W1/MAX 40 KT
TEXT/12//G/112400N8/0814800W1/280 AT 10 KT
TEXT/12//G/102400N7/0814800W1/34 KT RADII SHOWN
TEXT/12//G/092400N5/0864800W6/2118Z COMMENT:
TEXT/12//G/082400N4/0864800W6/ DISSIPATING AS A SIGNIFICANT
TEXT/12//G/072400N3/0864800W6/TROPICAL CYCLONE OVER LAND
TEXT/12//G/172400N4/0835400W0/2018Z MAX 55
TEXT/12//G/182400N5/0875400W4/2118Z MAX 30
TEXT/12//G/192400N6/0920000W1/2218Z MAX 25
ENDAT
BT
#0001
NNNN
AL, 97, 2011082000, , BEST, 0, 139N, 518W, 25, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1009, 240, 75, 0, 0, L, 0, , 0, 0, INVEST, M,
Why don't you, he is absolutely correct!!!
SEVERE WEATHER EMERGENCY PLAN
FOR SCHOOLS
While it is designed specifically for schools, the principles used can be applied to any facility that is used by people including businesses, shopping malls, depots, hotels and hospitals.
Link
mag.ncep.noaa.gov/NCOMAGWEB/appcontroller
AS WE MOVE INTO THE LATTER HALF OF AUGUST THE TROPICS ARE
BEGINNING TO BECOME MORE ACTIVE AS WE APPROACH THE STATISTICAL
PEAK OF SEASON IN EARLY SEPTEMBER. TROPICAL STORM HARVEY HAS
FORMED EAST OF THE YUCATAN PENINSULA AND WILL MOVE INTO BELIZE AND
MEXICO OVER THE WEEKEND. THE LONG RANGE MODELS CONTINUE TO DEVELOP
A LARGE TROPICAL CYCLONE NEAR HISPANIOLA AND CUBA LATE NEXT WEEK
BEFORE BRINGING IT NORTHWARD. ALTHOUGH CONSIDERABLE UNCERTAINTY
REMAINS IN THE FORECAST IT APPEARS THAT THE MODELS ARE
CONVERGING ON A SOLUTION THAT WOULD TAKE THIS SYSTEM INTO FLORIDA
OR THE EASTERN GULF OF MEXICO AS A LARGE TROUGH DEVELOPS ACROSS
THE EASTERN UNITED STATES
Levi, assuming 97L does develop, if it did so quickly is there a possibility of it recurving before reaching the East Coast?
Viewing: 2201 - 2251
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