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
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Reed said the same thing earlier. I think he was referring to this:
Animated link:
Link
Position of Irene when the trough digs down is really key. Anywhere from Mobile the the Outer Banks should pay attention.
here is some imagery of the eastern atlantic from NexSat, which shows everything that is going on with 98L and 99L.
NexSat Imagery of the East Atlantic and Africa
Wonder if Doc is going to give us a new blog tonight, or if he'll wait til tomorrow...
Far too conservative.
It's reloading. Just wait a few hours, it will look pretty nice then.
that is for 97L not for are TS
I don't know where the NHC is getting evidence for 50mph winds, though it is probably a good call because chances are the plane will find something close to that strong in a 999mb system. Given its vertical tilt and proximity to the coastline, as well as the convective disorganization in recent hours, I don't think it will get an awful lot stronger than 60mph.
There is no official forecast track. Models are consitently steering towards the East Gulf to the Outer Banks.
BRET: 2.9450
ARLENE: 1.9875
EMILY: 1.9875
CINDY: 1.8800
DON: 1.7000
GERT: 1.6025
FRANKLIN: 0.4050
HARVEY: 0.1600
Read the rest here.
Emergency Water Storage
Containers That Can be Used for Water Storage
Food-grade plastic or glass containers are suitable for storing water. One-, three- and five-gallon water containers can be purchased from most outdoor or hardware stores. Any plastic or glass container that previously held food or beverages such as 2-liter soda bottles or water, juice, punch or milk jugs, also may be used. Stainless steel can be used to store water which has not been or will not be treated with chlorine; chlorine is corrosive to most metals.
55 gal drums, designed specifiacally for water storage can be difficult to transport, if the need arises, but are of a tremendous value in an emergency .When looking for additional food grade containers, the bottom will be stamped with HDPE (High Density PolyEthylene) and coded with the recycle symbol and a “2″ inside. HDPE containers are FDA-approved for food. Containers without these designations aren’t OK because of possible chemical interactions between the water and the plastic.
Clean used containers and lids with hot soapy water. Once the containers have been thoroughly cleaned, rinse them with water and sanitize the containers and lids by rinsing them with a solution of 1 tablespoon chlorine bleach per gallon of water. Leave the containers wet for two minutes, then rinse them again with water. Remember to remove the paper or plastic lid liners before washing the lids. It is very difficult to effectively remove all residue from many containers, so carefully clean hard-to-reach places like the handles of milk jugs. To sanitize stainless steel containers, place the container in boiling water for 10 minutes. Never use containers that previously held chemicals.
Link
Couple fifties from the hh and a 58 on a vort message
No thats 97L
Its nowhere near land.
Aww, I think he's cute.
In terms of its circulation, yes, because it is a negatively-tilted tropical wave (SE to NW). This is actually good for setting up development, but of course eventually we want to see a compact surface circulation close off by itself instead of remaining broad and elongated.
Woohoo! That might buy someone a share in Goldman-Sachs. Nice! Thanks
Incorrect. Flight-level winds have not made it to 35kts yet during the flight, and the vortex message reported 31kt surface winds with 34kt flight-level maximum.
I haven't been monitoring SFMR, but any values more than 5kts above the flight-level wind at the same location shouldn't be trusted, and the NHC generally doesn't either.
000
URNT12 KNHC 192354 CCA
VORTEX DATA MESSAGE AL082011
A. 19/23:27:10Z
B. 16 deg 05 min N
084 deg 36 min W
C. 850 mb 1424 m
D. 31 kt
E. 304 deg 34 nm
F. 054 deg 30 kt
G. 328 deg 71 nm
H. 999 mb
I. 17 C / 1529 m
J. 20 C / 1526 m
K. NA / NA
L. NA
M. NA
N. 1345 / 08
O. 0.02 / 1 nm
P. AF308 0408A HARVEY OB 07 CCA
MAX OUTBOUND AND MAX FL WIND 34 KT E QUAD 23:28:00Z
MAX SFC WND OUTBOUND 44 KTS, 085/03 NM FM FL CNTR, E QUAD, 23:28:00Z
;
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI AUG 19 2011
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM HARVEY...LOCATED ABOUT 130 MILES EAST OF ROATAN HONDURAS.
SHOWERS AND THUNDERSTORMS HAVE BECOME BETTER ORGANIZED IN
ASSOCIATION WITH A LARGE TROPICAL WAVE LOCATED ABOUT 625 MILES EAST
OF THE LESSER ANTILLES. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM OVER THE NEXT COUPLE OF
DAYS. THIS SYSTEM HAS A HIGH CHANCE...60 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES GENERALLY
WESTWARD AT 20 MPH. INTERESTS IN THE LEEWARD ISLANDS SHOULD
MONITOR THE PROGRESS OF THIS DISTURBANCE. LOCALLY HEAVY RAIN AND
GUSTY WINDS ARE LIKELY OVER THE LEEWARD ISLANDS LATE SATURDAY INTO
SUNDAY.
A LARGE BUT DISORGANIZED LOW PRESSURE SYSTEM IS CENTERED ABOUT 100
MILES SOUTHEAST OF THE CAPE VERDE ISLANDS. ALTHOUGH UPPER-LEVEL
WINDS ARE CURRENTLY FAVORABLE FOR SOME DEVELOPMENT...THIS SYSTEM IS
EXPECTED TO ENCOUNTER A MORE STABLE ENVIRONMENT WITH DRIER AIR BY
SUNDAY. THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES TO
THE WEST-NORTHWEST AT 10 TO 15 MPH. REGARDLESS OF DEVELOPMENT...
LOCALLY HEAVY RAIN AND STRONG GUSTY WINDS ARE POSSIBLE IN THE CAPE
VERDE ISLANDS TONIGHT THROUGH SATURDAY.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
this look back at the commets or go too the nhc and you find it
now you guys are spaming the blog with twos
yes
You can use hydrogen peroxide instead of bleach.
nuts too late
OK, thanks
The blog will survive.
I told you that 97L would go "Code Red" by 11 PM as it is now at 60%. I think we will have Tropical Storm Irene sometimes tomorrow.
8 and 2
AL, 08, 2011082000, , BEST, 0, 161N, 847W, 45, 998, TS, 34, NEQ, 35, 0, 0, 35, 1008, 120, 15, 0, 0, L, 0, , 0, 0, HARVEY, M,
Viewing: 2101 - 2151
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