Tropical Storm Lee Forms Between Africa And The Leeward Islands, Could Pose A Grave Long-range Threat To Our Region And USA Eastern Seaboard

000

WTNT33 KNHC 060237

TCPAT3

BULLETIN

Tropical Storm Lee Advisory Number   3

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Tue Sep 05 2023

...LEE EXPECTED TO RAPIDLY INTENSIFY INTO AN EXTREMELY DANGEROUS

HURRICANE BY THE WEEKEND...

SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION

-----------------------------------------------

LOCATION...13.5N 43.0W

ABOUT 1230 MI...1980 KM E OF THE LESSER ANTILLES

MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H

PRESENT MOVEMENT...WNW OR 290 DEGREES AT 16 MPH...26 KM/H

MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES

WATCHES AND WARNINGS

--------------------

There are no coastal watches or warnings in effect.

Interests in the Leeward Islands should monitor the progress of

this system.

DISCUSSION AND OUTLOOK

----------------------

At 1100 PM AST (0300 UTC), the center of Tropical Storm Lee was 

located near latitude 13.5 North, longitude 43.0 West. Lee is moving 

toward the west-northwest near 16 mph (26 km/h), and this motion is 

expected to continue for the next few days with a slight reduction 

in forward speed.

Maximum sustained winds have increased to near 50 mph (85 km/h) with 

higher gusts. Strengthening is expected, and Lee is forecast to 

become a hurricane by tomorrow night and a major hurricane by 

Friday.

Tropical-storm-force winds extend outward up to 70 miles (110 km)

from the center.

The estimated minimum central pressure is 1003 mb (29.62 inches).

HAZARDS AFFECTING LAND

----------------------

None.

Key messages for Lee can be found in the Tropical Cyclone Discussion

under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC and on the

web at hurricanes.gov/text/MIATCDAT3.shtml

NEXT ADVISORY

-------------

Next complete advisory at 500 AM AST.

$$

Forecaster Reinhart

000

WTNT33 KNHC 051456

TCPAT3

BULLETIN

Tropical Depression Thirteen Advisory Number   1

NWS National Hurricane Center Miami FL       AL132023

1100 AM AST Tue Sep 05 2023

...NEW TROPICAL DEPRESSION FORMS IN THE CENTRAL TROPICAL ATLANTIC...

...FORECAST TO BECOME A POWERFUL HURRICANE BY THE END OF THE WEEK...

SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION

-----------------------------------------------

LOCATION...12.5N 40.2W

ABOUT 1425 MI...2295 KM E OF THE LESSER ANTILLES

MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H

PRESENT MOVEMENT...WNW OR 285 DEGREES AT 15 MPH...24 KM/H

MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES

WATCHES AND WARNINGS

--------------------

None.

Interests in the Leeward Islands should monitor the progress of

this system.

DISCUSSION AND OUTLOOK

----------------------

At 1100 AM AST (1500 UTC), the center of Tropical Depression

Thirteen was located near latitude 12.5 North, longitude 40.2 West.

The depression is moving toward the west-northwest near 15 mph (24

km/h), and this motion is expected to continue for the next few 

days.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.

The depression is forecast to be a hurricane in a couple of days 

and could become a major hurricane in a few days. 

The estimated minimum central pressure is 1008 mb (29.77 inches).

HAZARDS AFFECTING LAND

----------------------

None.

Key messages for the depression can be found in the Tropical Cyclone

Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC. 

NEXT ADVISORY

-------------

Next complete advisory at 500 PM AST.

$$

Forecaster Blake

832 

WTNT43 KNHC 060238

TCDAT3

Tropical Storm Lee Discussion Number   3

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Tue Sep 05 2023

The satellite structure of Lee has continued to improve tonight. A 

prominent curved band of deep convection wraps around the western 

and southern portions of the circulation. Recent SSMIS and GMI 

microwave images reveal deep convection is occurring near the 

center, though it is slightly displaced by some northeasterly shear. 

There are also hints of a formative inner core trying to take shape, 

all of which suggest that Lee is strengthening. The initial 

intensity is raised to 45 kt for this advisory, in best agreement 

with a T3.0 Dvorak classification from TAFB.

Lee continues to move west-northwestward at about 15 kt. A mid-level 

ridge over the central subtropical Atlantic is expected to be the 

primary steering mechanism for the next several days, with Lee 

forecast to continue on a west-northwestward heading across the 

central tropical Atlantic through the forecast period. Once again, 

the track guidance is in fairly good agreement on this scenario. 

Overall, the latest NHC track forecast is very similar to the 

previous prediction, with only minor adjustments that keep our 

forecast between the simple and corrected consensus aids. Users are 

reminded that the average NHC forecast track errors are around 125 

and 175 n mi on days 4 and 5, respectively. Thus, it is too soon to 

determine exactly how close this system will be to the Leeward 

Islands by the weekend.

The atmospheric and oceanic conditions appear extremely favorable 

for rapid intensification (RI) during the next several days, 

particularly once the northeasterly shear over Lee subsides in a day 

or so. The forecast track of Lee brings the cyclone over anomalously 

warm SSTs during the next several days, with generally low shear and 

favorable upper diffluence to support significant strengthening. The 

updated NHC intensity forecast has been adjusted slightly higher 

than the previous one, toward the latest IVCN and HCCA aids. This 

forecast calls for Lee to become a hurricane in 24 h and a major 

hurricane by 60 h, with continued intensification thereafter. It is 

noted that the regional hurricane models depict even stronger 

solutions, so future adjustments could be necessary. Regardless, 

Lee bears close monitoring as there is high confidence it will 

become a very powerful hurricane by this weekend.

KEY MESSAGES:

1. Lee is forecast to become a major hurricane by late this week and 

could bring impacts to the Leeward Islands this weekend. While it is 

too soon to determine the location and magnitude of these possible 

impacts, interests in this area should monitor the progress of Lee 

and further updates to the forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 13.5N  43.0W   45 KT  50 MPH

 12H  06/1200Z 14.1N  44.9W   55 KT  65 MPH

 24H  07/0000Z 14.9N  47.2W   65 KT  75 MPH

 36H  07/1200Z 15.7N  49.7W   75 KT  85 MPH

 48H  08/0000Z 16.6N  52.2W   90 KT 105 MPH

 60H  08/1200Z 17.8N  54.8W  105 KT 120 MPH

 72H  09/0000Z 18.9N  57.1W  115 KT 130 MPH

 96H  10/0000Z 20.8N  61.5W  125 KT 145 MPH

120H  11/0000Z 22.5N  65.0W  130 KT 150 MPH

$$

Forecaster Reinhart

382 

WTNT43 KNHC 051459

TCDAT3

Tropical Depression Thirteen Discussion Number   1

NWS National Hurricane Center Miami FL       AL132023

1100 AM AST Tue Sep 05 2023

Satellite images indicate that the tropical wave (Invest AL95) that 

we have been following for several days has become better organized 

this morning, with many curved low-level banding features.  A 

partial scatterometer pass near 1201 UTC indicated a well-defined 

center had formed, with winds speeds of about 30 kt.  Thus, 

advisories have been initiated on Tropical Depression Thirteen, and 

the current intensity is set to 30 kt.

The depression is moving west-northwestward at about 13 kt.  A 

mid-level ridge over the central Atlantic is expected to persist to 

the north of the tropical cyclone, keeping the system moving with 

this general motion through Saturday.  The spread in the model 

guidance is remarkably low for a first advisory, and the official 

forecast is near or west of the model consensus.  However, it 

should be noted that the NOAA corrected-consensus aids and some 

ensemble members are still to the left of the official forecast, so 

it is too early to determine exactly how close this system will get 

to the Leeward Islands given the average track forecast error at 

those time ranges.

The environment around the depression appears to be conducive for 

strengthening.  The only obvious hindering factor is 

light-to-moderate northeasterly shear, which should keep the 

intensification rate in check in the short term.  However, in two to 

three days, this shear is forecast to relax with an upper-level 

ridge building near the cyclone, and the system should be moving 

over record-warm waters of near 30 deg C east of the Lesser Antilles 

(that would look more in place in the Gulf of Mexico).  These 

factors could support rapid intensification by the end of the week, 

although it too early to determine exactly when this might occur 

until a better-defined inner core forms.  The NHC intensity forecast 

is extremely bullish for a first forecast, but remarkably lies 

below the intensity consensus.  All indications are that the 

depression will become a strong hurricane by the end of the forecast 

period.

KEY MESSAGES:

1. The depression is forecast to become a major hurricane by 

this weekend and could bring impacts to the Leeward Islands by that 

time. While it is too soon to determine the location and magnitude 

of these possible impacts, interests in this area should monitor 

the progress of the depression and updates to the forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 12.5N  40.2W   30 KT  35 MPH

 12H  06/0000Z 12.8N  42.1W   40 KT  45 MPH

 24H  06/1200Z 13.6N  44.7W   50 KT  60 MPH

 36H  07/0000Z 14.4N  47.2W   60 KT  70 MPH

 48H  07/1200Z 15.3N  49.7W   70 KT  80 MPH

 60H  08/0000Z 16.2N  52.2W   80 KT  90 MPH

 72H  08/1200Z 17.3N  54.7W   95 KT 110 MPH

 96H  09/1200Z 19.4N  59.1W  115 KT 130 MPH

120H  10/1200Z 21.5N  63.5W  120 KT 140 MPH

$$

Forecaster Blake