Ana, Bill,--and Claudette?
After one of the slowest starts to hurricane season in the past twenty years, the hurricane season of 2009 has exploded with activity over the past 48 hours. This morning, Tropical Depression Four joined Ana and Bill in the Atlantic, and appears poised to become Tropical Storm Claudette later today. Indeed, this may already be Claudette, as morning's QuickSCAT pass showed top winds of 45 mph. NEXRAD radar animations out of Tallahassee, FL, show a small but well-organized tropical cyclone with plenty of heavy thunderstorm activity, and improving low-level spiral banding. Satellite loops show an area of intense thunderstorms with cold cloud tops expanding near the storm's center.
Figure 1. Current long-range radar out of Tallahassee, FL.
It's pretty amazing (and a little unnerving) how quickly this storm sprang up. TD 4 developed literally overnight, and has the potential to be a strong tropical storm by the time it makes landfall tonight along the Florida Peninsula. TD 4 reminds me of 2007's Hurricane Humberto, which became a hurricane just 24 hours after first appearing as a tropical depression. I don't think TD 4 has time to reach hurricane strength, since wind shear as diagnosed by the SHIPS model was moderate, 10 - 15 knots, but it does have time to strengthen into a 50 - 60 mph tropical storm before landfall. Given that the storm is so small, storm surge flooding should not exceed 3 -5 feet, and will not be the major hazard from TD 4; inland flooding from heavy rain of 3 - 6 inches is likely to be the main threat from the storm.
Tropical Storm Ana continues to struggle
Tropical Storm Ana continues to struggle. Dry air continues to plague the storm, thanks to the large area of Saharan air the storm is embedded in. Ana's heavy thunderstorms are limited to just one small spot near the center. Wind shear appears to have lessened some, though, since yesterday. Thunderstorms were not able to form at all near the center yesterday, since strong wind shear tends to blow a storm's heavy thunderstorms to one side of the storm, exposing the low-level center to view. With heavy thunderstorms building near the center this morning, shear appears to be less of a problem for the storm. Top winds seen by this morning's QuikSCAT pass were about 35 mph. The outer rain showers from Ana should appear on radar out of Martinique today.
Shear is low (5 - 10 knots), and is forecast to remain low for the next two days. SSTs are warm, 28°C, and will warm further over the next two days. However, there is so much dry air around Ana that significant strengthening appears unlikely. Nearly all of the models predict Ana will dissipate sometime in the next three days, though the HWRF and GFDL predict that this will happen because Ana will move over the rugged terrain of Hispaniola. Ana is likely not strong enough to survive an encounter with the big island that the Dominican Republic and Haiti share. At this time, it does not appear that Ana will be moist enough to cause a major flooding disaster on Hispaniola.
Figure 2. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the northwest of Tropical Storm Bill. Image credit: NOAA/SSD
Tropical Storm Bill gathers strength
Tropical Storm Bill is gathering strength in the middle Atlantic Ocean, and appears poised to become a powerful Cape Verdes-type hurricane later this week. QuikSCAT data from this morning shows a large circulation with top winds of 35 - 40 mph. Water vapor imagery (Figure 2) shows that there is some dry air to the northwest of Bill, and this dry air is being drawn into Bill's center, slowing intensification. It will likely take another day before Bill can moisten the atmosphere enough to ward off the dry air, and allow more significant intensification.
Wind shear is low, 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 15 knots, for the next five days. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next four days, then warm substantially as the storm nears the Lesser Antilles Islands. The combination of low wind shear and sufficiently warm SSTs should allow Bill to intensify steadily to hurricane strength by Wednesday.
The big news is that our most reliable computer model from last year--the ECMWF model--appears to have made the right call yesterday, forecasting that a major trough of low pressure would develop along the U.S. East Coast, turning Bill more to the north. All of the other models--with the notable exception of the UKMET model--have now jumped on the ECMWF bandwagon, forecasting that Bill will pass well north of the Lesser Antilles Islands. The UKMET has Bill hitting the islands, but is being discounted since it is an outlier. It currently appears that the trough approaching the U.S. East Coast will be strong enough to recurve Bill before it reaches the U.S., though it is too early to be confident of this. Several of the longer range models show Bill passing near Bermuda or Nova Scotia, Canada.
I'll have an update later today.
Jeff Masters
Reader Comments
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URNT12 KNHC 161655
VORTEX DATA MESSAGE AL042009
A. 16/16:43:20Z
B. 29 deg 04 min N
084 deg 56 min W
C. 925 mb 754 m
D. 35 kt
E. 285 deg 11 nm
F. 072 deg 28 kt
G. 302 deg 25 nm
H. EXTRAP 1008 mb
I. 20 C / 767 m
J. 23 C / 766 m
K. 9 C / NA
L. NA
M. NA
N. 1345 / 9
O. 0.02 / 1.5 nm
P. AF304 0104A CYCLONE OB 02
MAX FL WIND 28 KT NW QUAD 16:34:30Z
MAX OUTBOUND FL WIND 54 KT NE QUAD 16:44:40Z
SLP EXTRAP FROM 925 MB
;
40.3 mph SURFACE
1008 PRESSURE
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 16th day of the month at 16:55Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 02
A. Time of Center Fix: 16th day of the month at 16:43:20Z
B. Center Fix Coordinates: 29°04'N 84°56'W (29.0667N 84.9333W)
B. Center Fix Location: 88 miles (142 km) to the SSE (150°) from Panama City, FL, USA.
C. Minimum Height at Standard Level: 754m (2,474ft) at 925mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 35kts (~ 40.3mph)
E. Location of the Estimated Maximum Surface Wind: 11 nautical miles (13 statute miles) to the WNW (285°) of center fix
F. Maximum Flight Level Wind Inbound: From 72° at 28kts (From the ENE at ~ 32.2mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the WNW (302°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 767m (2,516ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 766m (2,513ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F)
K. 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, Wind, Pressure and Temperature
N. Fix Level: 925mb (If this vortex is from mid 1990's or earlier 925mb might be incorrect. See note.)
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1.5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 28kts (~ 32.2mph) in the northwest quadrant at 16:34:30Z
Maximum Flight Level Wind Outbound: 54kts (~ 62.1mph) in the northeast quadrant at 16:44:40Z
Sea Level Pressure Extrapolation From: 925mb
What does that say? Too small...
Its on the vortex message...
Nevermind, I guess there weren't any 68 mph winds... *looks around* oops.
Transmitted: 16th day of the month at 16:55Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 02
A. Time of Center Fix: 16th day of the month at 16:43:20Z
B. Center Fix Coordinates: 29°04'N 84°56'W (29.0667N 84.9333W)
B. Center Fix Location: 88 miles (142 km) to the SSE (150°) from Panama City, FL, USA.
C. Minimum Height at Standard Level: 754m (2,474ft) at 925mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 35kts (~ 40.3mph)
E. Location of the Estimated Maximum Surface Wind: 11 nautical miles (13 statute miles) to the WNW (285°) of center fix
F. Maximum Flight Level Wind Inbound: From 72° at 28kts (From the ENE at ~ 32.2mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the WNW (302°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 767m (2,516ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 766m (2,513ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F)
K. 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, Wind, Pressure and Temperature
N. Fix Level: 925mb (If this vortex is from mid 1990's or earlier 925mb might be incorrect. See note.)
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1.5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 28kts (~ 32.2mph) in the northwest quadrant at 16:34:30Z
Maximum Flight Level Wind Outbound: 54kts (~ 62.1mph) in the northeast quadrant at 16:44:40Z
Sea Level Pressure Extrapolation From: 925mb
Transmitted: 16th day of the month at 16:55Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 02
A. Time of Center Fix: 16th day of the month at 16:43:20Z
B. Center Fix Coordinates: 29°04'N 84°56'W (29.0667N 84.9333W) (View map)
B. Center Fix Location: 88 miles (142 km) to the SSE (150°) from Panama City, FL, USA.
C. Minimum Height at Standard Level: 754m (2,474ft) at 925mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 35kts (~ 40.3mph)
E. Location of the Estimated Maximum Surface Wind: 11 nautical miles (13 statute miles) to the WNW (285°) of center fix
F. Maximum Flight Level Wind Inbound: From 72° at 28kts (From the ENE at ~ 32.2mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the WNW (302°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 767m (2,516ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 766m (2,513ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F)
K. 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, Wind, Pressure and Temperature
N. Fix Level: 925mb (If this vortex is from mid 1990's or earlier 925mb might be incorrect. See note.)
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1.5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 28kts (~ 32.2mph) in the northwest quadrant at 16:34:30Z
Maximum Flight Level Wind Outbound: 54kts (~ 62.1mph) in the northeast quadrant at 16:44:40Z
Sea Level Pressure Extrapolation From: 925mb
54 is flight level
Time: 16:52:00Z
Coordinates: 16.6N 59.0833W
Acft. Static Air Press: 705.2 mb (~ 20.82 inHg)
Acft. Geopotential Hgt: 3,104 meters (~ 10,184 feet)
Extrap. Sfc. Press: 1013.0 mb (~ 29.91 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 117° at 25 knots (From the ESE at ~ 28.7 mph)
Air Temp: 9.3°C (~ 48.7°F)
Dew Pt: -13.9°C (~ 7.0°F)
Peak (10s) Flt. Lvl. Wind: 27 knots (~ 31.0 mph)
SFMR Peak (10s) Sfc. Wind: 22 knots* (~ 25.3 mph*)
SFMR Rain Rate: 0 mm/hr* (~ 0 in/hr*)
(*) Denotes suspect data
Right. Temperatures are indeed high there. The map I remember seeing was a temperature anomaly map, which showed the northeast area as lower than normal.
So about 50 mph?
the key called PRTSC (Print Screen) then paste it into an image editing software.
I know. But if you reduce those down its at least around 45 knots.
ty, why is it outbound though? why is it different from max flight level wind of 28knot...
i guess we should be concerned with sealevel winds more, but anyway its a valid question
Coordinates: 29.5667N 84.35W
Acft. Static Air Press: 926.0 mb (~ 27.34 inHg)
Acft. Geopotential Hgt: 812 meters (~ 2,664 feet)
Extrap. Sfc. Press: 1017.6 mb (~ 30.05 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 142° at 38 knots (From the SE at ~ 43.7 mph)
Air Temp: 17.4°C (~ 63.3°F)
Dew Pt: 7.7°C (~ 45.9°F)
Peak (10s) Flt. Lvl. Wind: 40 knots (~ 46.0 mph)
SFMR Peak (10s) Sfc. Wind: 36 knots (~ 41.4 mph)
SFMR Rain Rate: 8 mm/hr (~ 0.31 in/hr
That's what I've been thinking.
--Bubba
Outbound means they got those winds when they were leaving the vortex on that pass. Flight level winds are almost always higher on the NE side than the NW side which explains the difference.
cyclone, I need a crow recipe. I thought for sure Claudette would not develop. I guess I learned a weather lesson. NEVER underestimate the ability of the gulf's waters to spin up systems
Ridiculous.
Besides, why are you wearing a sweater under your Tommy Bahama shirt?
At flight level not the surface
URNT12 KNHC 161655
VORTEX DATA MESSAGE AL042009
A. 16/16:43:20Z
B. 29 deg 04 min N
084 deg 56 min W
C. 925 mb 754 m
D. 35 kt
E. 285 deg 11 nm
F. 072 deg 28 kt
G. 302 deg 25 nm
H. EXTRAP 1008 mb
I. 20 C / 767 m
J. 23 C / 766 m
K. 9 C / NA
L. NA
M. NA
N. 1345 / 9
O. 0.02 / 1.5 nm
P. AF304 0104A CYCLONE OB 02
MAX FL WIND 28 KT NW QUAD 16:34:30Z
MAX OUTBOUND FL WIND 54 KT NE QUAD 16:44:40Z
SLP EXTRAP FROM 925 MB
Viewing: 851 - 901
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