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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Just a long range extension of the already unreliable NAM.
Pressure can be deceiving when it comes to wind speed, but that kind of pressure would likely be a Cat 3.
60 m/h this is getting good with the hot tower they probably will up it
I traveled to the mississippi coastline a few years after Katrina hit. Many neighborhoods were wiped out and only concrete slabs stood where homes use to. It was a wake up call.
Yeah on satellite, but the LLC is displaced well to the south of the MLC and the convection, near DMAX as more convection fires off, that may change.
Not that good.
Its an extrapolation of the NAM based on the GFS.
The 60mph reading is not accurate, marked as suspect data. TS is currently still at 50mph.
The zonal jet over southern Canada is a part of it, yes, as it indicates above-normal heights. The entire hemispheric pattern has been leading to this, though. Over the last several days I have been speaking of the strong troughing becoming entrenched in Alaska, which is being held there by the persistent ridging over northeastern Asia (which happens to be a teleconnection to south Canada ridging as well). This has forced elevated heights to develop over western Canada, which is drawing the Texas ridge back to the west over the Rockies.
With the Atlantic ridge holding strong in the western Atlantic, evidenced by troughs constantly being shunted out of that region, there is a break between the two ridges, right over the southeastern United States. The fact that the Texas ridge is now in the Rockies means that the eastern Gulf of Mexico is now opened up as well as the southeast coast. Strong troughs try to enter the eastern U.S., but get redirected quickly out to the northeast, leaving a persistent zonal flow over southern Canada most of the time, with the weakness between the ridges south of it, drawing tropical activity northward towards the coast. This kind of a pattern is nothing short of classic for a U.S. landfall. That may sound a bit hyped, but it is inevitable that we see this type of pattern at some point this year.
Thats pretty much closed.
i spy with my lil eye an EYE
It is basically an extended NAM out to 192 hours, with GFS input for the boundary conditions.
According to shear maps wind shear is moderate (10-20 knots)
Thank you for being a teacher
I can picture the warning signs (warning dont feed the tiger):)
Transmitted: 20th day of the month at 01:02Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)
Storm Number & Year: 08L in 2011
Storm Name: Harvey (flight in the North Atlantic basin)
Mission Number: 4
Observation Number: 11
A. Time of Center Fix: 20th day of the month at 0:40:10Z
B. Center Fix Coordinates: 16°06'N 84°46'W (16.1N 84.7667W)
B. Center Fix Location: 246 miles (396 km) to the ESE (113°) from Belize City, Belize.
C. Minimum Height at Standard Level: 1,413m (4,636ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 43kts (~ 49.5mph)
E. Location of the Estimated Maximum Surface Wind: 6 nautical miles (7 statute miles) to the NW (321°) of center fix
F. Maximum Flight Level Wind Inbound: From 100° at 46kts (From the E at ~ 52.9mph)
G. Location of Maximum Flight Level Wind Inbound: 11 nautical miles (13 statute miles) to the N (3°) of center fix
H. Minimum Sea Level Pressure: 998mb (29.47 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,528m (5,013ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,527m (5,010ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section - Remarks That Were Decoded...
Maximum Wind Outbound: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Surface (likely estimated by SFMR) Wind Outbound: 61kts (~ 70.2mph) in the quadrant at 3:45
Remarks Section - Additional Remarks...
MAX SFC WND OUTBOUND 61 KTS, 345/03 FM FL CNTR, NW QUAD, 00:41:10Z
GOOD BANDING WEST SIDE APPROX 30 NM FM FL CNTR
Thanks for the info i didnt know that
Transmitted: 20th day of the month at 01:02Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)
Storm Number & Year: 08L in 2011
Storm Name: Harvey (flight in the North Atlantic basin)
Mission Number: 4
Observation Number: 11
A. Time of Center Fix: 20th day of the month at 0:40:10Z
B. Center Fix Coordinates: 16°06'N 84°46'W (16.1N 84.7667W)
B. Center Fix Location: 246 miles (396 km) to the ESE (113°) from Belize City, Belize.
C. Minimum Height at Standard Level: 1,413m (4,636ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 43kts (~ 49.5mph)
E. Location of the Estimated Maximum Surface Wind: 6 nautical miles (7 statute miles) to the NW (321°) of center fix
F. Maximum Flight Level Wind Inbound: From 100° at 46kts (From the E at ~ 52.9mph)
G. Location of Maximum Flight Level Wind Inbound: 11 nautical miles (13 statute miles) to the N (3°) of center fix
H. Minimum Sea Level Pressure: 998mb (29.47 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,528m (5,013ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,527m (5,010ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section - Remarks That Were Decoded...
Maximum Wind Outbound: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Surface (likely estimated by SFMR) Wind Outbound: 61kts (~ 70.2mph) in the quadrant at 3:45
Remarks Section - Additional Remarks...
MAX SFC WND OUTBOUND 61 KTS, 345/03 FM FL CNTR, NW QUAD, 00:41:10Z
GOOD BANDING WEST SIDE APPROX 30 NM FM FL CNTR
Maximum Surface (likely estimated by SFMR) Wind Outbound: 61kts (~ 70.2mph) in the quadrant at 3:45
Might have something to do with it. 70mph seems fairly unlikely to me, I have to say.
970mb is probably around a category 2 hurricane. Of course, pressure readings don't always correspond to winds....look at Alex from last year.
DGEX....not a model I would use or trust. There's better modeling out there than that.
When is your next blog gonna come out???
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)
Storm Number & Year: 08L in 2011
Storm Name: Harvey (flight in the North Atlantic basin)
Mission Number: 4
Observation Number: 11
A. Time of Center Fix: 20th day of the month at 0:40:10Z
B. Center Fix Coordinates: 16°06'N 84°46'W (16.1N 84.7667W)
B. Center Fix Location: 246 miles (396 km) to the ESE (113°) from Belize City, Belize.
C. Minimum Height at Standard Level: 1,413m (4,636ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 43kts (~ 49.5mph)
E. Location of the Estimated Maximum Surface Wind: 6 nautical miles (7 statute miles) to the NW (321°) of center fix
F. Maximum Flight Level Wind Inbound: From 100° at 46kts (From the E at ~ 52.9mph)
G. Location of Maximum Flight Level Wind Inbound: 11 nautical miles (13 statute miles) to the N (3°) of center fix
H. Minimum Sea Level Pressure: 998mb (29.47 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,528m (5,013ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,527m (5,010ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section - Remarks That Were Decoded...
Maximum Wind Outbound: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northwest quadrant at 0:41:40Z
Maximum Surface (likely estimated by SFMR) Wind Outbound: 61kts (~ 70.2mph) in the quadrant at 3:45
Remarks Section - Additional Remarks...
MAX SFC WND OUTBOUND 61 KTS, 345/03 FM FL CNTR, NW QUAD, 00:41:10Z
GOOD BANDING WEST SIDE APPROX 30 NM FM FL CNTR
Yes. However, right now the eastern Gulf is the most likely area at play. Of course, anyone in the Gulf from southeast Louisiana eastward should monitor it just in case any unexpected deviations in the track occur. But again, the eastern Gulf is the most likely area at play if this system does get into the Gulf, and I would not bet my money on a hit west of the central Florida panhandle, barring significant changes in the pattern, which seems unlikely.
LOL, no it was more like the helicoptor landing and soldiers jumping out with m16's yelling at us to get back inside and then no recess for a month followed by recess with armed soldiers spread out around the perimeter of the playground guarding us.
MAX SFC WND OUTBOUND 61 KTS, 345/03 FM FL CNTR, NW QUAD, 00:41:10Z
GOOD BANDING WEST SIDE APPROX 30 NM FM FL CNTR
In the morning. I don't do more than one a day, though chances are I would do multiple updates if a major storm was threatening land.
Pretty sure you drop 1mb for every 10 knots.
could also be some turbulence concerns as well with hot tower development so close to the coast.
The HDOD messages can be marked as suspect, but that was in the 'REMARKS' section of the Vortex message, which they themselves write, which makes me wonder.
Good evening Gro..
That's what it looked like. As soon as they hit that they climbed. Also noticed the turbulence looks to be overall rough for a TS.
Okay Ill be lookin for it, you help understanding so muucch thanks for it
As for the 61kt SFC winds...I find that hard to believe. But hey, I'm not the one on the plane.
This pretty lady ships them to Houston. I discovered my first pair last Spring while in your beautiful city.
Lol, this is kind of my feeling too. 70mph doesn't seem likely to me, but if that's what they are measuring and reporting, then I guess they know better than me.
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