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Tropical Storm Fred Forecast Discussion Number 27

2021-08-16 10:50:38| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Mon Aug 16 2021 000 WTNT41 KNHC 160850 TCDAT1 Tropical Storm Fred Discussion Number 27 NWS National Hurricane Center Miami FL AL062021 400 AM CDT Mon Aug 16 2021 Earlier reconnaissance aircraft data and satellite imagery indicated that Fred's low-level circulation center briefly emerged out from underneath the southwestern edge of the convective cloud shield between 0200-0400 UTC. The circulation center, however, has recently moved back underneath the edge of the main region of convection, with a new bust of thunderstorms having developed over or near the low-level center. Having said that, Fred still remains a sheared tropical cyclone, with Tallahassee NOAA Doppler radar data indicating that the upper-level circulation at around 30,000 ft is tilted about 40 nmi northeast of the low-level center. The last reports from the Air Force Reserve reconnaissance aircraft indicated that the central pressure had risen from 999 mb to 1004 mb during the time the low-level center was fully exposed southwest of the deep convection. However, the pressure has likely fallen again now the center is back underneath the convection. An intensity of 45 kt is being maintained for this advisory based on the last reliable reconnaissance SFMR data of about 45 kt, which corresponds well with a T3.0/45 kt Dvorak satellite shear-pattern intensity estimate. Fred is moving northward now, or 355/08 kt. The latest NHC model guidance remains in excellent agreement that Fred will continue moving in a general northward motion today as the cyclone moves through a break in the subtropical ridge that is oriented east-to-west across northern Florida. Landfall is expected in the western Florida Panhandle region by late afternoon or evening today. The track guidance has shifted slightly to the east of the previous advisory track, and the new official forecast track has been nudged in that direction, but not as far east as the tightly packed consensus models owing to the strength of the ridge noted in 16/0000 UTC upper-air data. Fred is forecast to remain in moderate vertical wind shear conditions throughout the 48-h forecast period. However, the shear vector is expected to gradually back around from the current southwesterly direction to more of a south-southwesterly component right up until landfall occurs, which will align more with Fred's track direction. This reduction in the effective shear across the cyclone should allow for some additional strengthening until landfall occurs, with the distinct possibility that Fred could reach a peak intensity of 55 kt in 18 hours. After landfall, the combination of land interaction and the vertical shear increasing to more than 20 kt should result in rapid weakening, with Fred forecast to dissipate by 60 hours over the southern Appalachian Mountains. The official intensity forecast closely follows a blend of the HCCA and IVCN intensity consensus models. Users are reminded not to focus on the exact forecast track of Fred, since rainfall, storm surge, and wind hazards will extend over an area well east of the center. KEY MESSAGES: 1. Through Tuesday, heavy rainfall may lead to flash, urban, small stream, and isolated river flooding impacts across the Southeast. By the middle of the week as Fred lifts northward and inland, heavy rainfall and flooding will impact the southern and central Appalachians, the Piedmont of the Southeast, and the Mid-Atlantic. 2. Dangerous storm surge inundation is possible along portions of the coast of the Florida Panhandle and the Florida Big Bend region, and a Storm Surge Warning is in effect for this area. Interests in these areas should follow any advice given by local officials. 3. Tropical storm conditions are expected in the tropical storm warning area beginning later this morning. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 27.9N 86.0W 45 KT 50 MPH 12H 16/1800Z 29.1N 86.1W 50 KT 60 MPH 24H 17/0600Z 31.0N 85.7W 40 KT 45 MPH...INLAND 36H 17/1800Z 33.1N 85.2W 25 KT 30 MPH...INLAND 48H 18/0600Z 35.6N 84.2W 20 KT 25 MPH...POST-TROP/INLAND 60H 18/1800Z...DISSIPATED $$ Forecaster Stewart

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Tropical Depression Eight Forecast Discussion Number 2

2021-08-16 10:50:11| National Hurricane Center (Atlantic)

Issued at 500 AM AST Mon Aug 16 2021 000 WTNT43 KNHC 160850 TCDAT3 Tropical Depression Eight Discussion Number 2 NWS National Hurricane Center Miami FL AL082021 500 AM AST Mon Aug 16 2021 Satellite imagery and radar data from Bermuda indicate that the tropical depression located about 100 nmi east of Bermuda has been moving southward and also remains a sheared tropical cyclone -- the ongoing saga of the Atlantic basin thus far this hurricane season. Convection has increased and developed closer to the center and a late-arriving ASCAT-C overpass indicated surface winds of 26-27 kt to the south of the well-defined circulation center. Based on those data, the slightly improved convective structure noted in both satellite and radar data, and satellite classifications of T2.0/30 kt, the initial intensity has been increased to 30 kt. The initial motion estimate is 195/04 kt. The small cyclone is starting to make the clockwise turn toward the south-southwest and eventually southwest that the global and regional models have been advertising the past couple of days. The latest NHC model guidance now shows less of a turn to the northwest after 72 hours, with the exception of the GFS, GFS-ensemble, and HMON models, which continue to take the cyclone northward and northeastward around Bermuda on day 4 and 5. The latest NHC track forecast is similar to the previous advisory track through 60 hours, and then widens the track slightly thereafter, but still shows a complete clockwise turn. This track scenario is to the right of the consensus models at all forecast periods, and is of low confidence on days 4 and 5. The vertical wind shear is forecast to remain at or below 10 kt for the next 36 hours or so, and that is most likely the time when the cyclone will strengthen. Thereafter, an increase in the shear to 20 kt or more is expected to cap the intensification process. The HWRF model turn the cyclone into a major hurricane by 72 hours, but this scenario is considered to be an extreme outlier given the amount of shear forecast to affect the system on days 3-5. So far this season, the HWRF model has been very shear resistant and has had a high intensity bias. The official intensity forecast closely follows a blend of the IVCN and HCCA consensus models through 60 hours, and then is below those models due to the high-bias contribution of the HWRF model. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 32.4N 62.9W 30 KT 35 MPH 12H 16/1800Z 31.6N 63.1W 35 KT 40 MPH 24H 17/0600Z 31.0N 63.7W 40 KT 45 MPH 36H 17/1800Z 30.7N 64.5W 45 KT 50 MPH 48H 18/0600Z 30.7N 65.5W 50 KT 60 MPH 60H 18/1800Z 30.8N 66.7W 55 KT 65 MPH 72H 19/0600Z 31.1N 68.0W 55 KT 65 MPH 96H 20/0600Z 32.0N 69.0W 55 KT 65 MPH 120H 21/0600Z 34.0N 68.5W 55 KT 65 MPH $$ Forecaster Stewart

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Tropical Depression Eight Wind Speed Probabilities Number 2

2021-08-16 10:49:40| National Hurricane Center (Atlantic)

Issued at 0900 UTC MON AUG 16 2021 000 FONT13 KNHC 160849 PWSAT3 TROPICAL DEPRESSION EIGHT WIND SPEED PROBABILITIES NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082021 0900 UTC MON AUG 16 2021 AT 0900Z THE CENTER OF TROPICAL DEPRESSION EIGHT WAS LOCATED NEAR LATITUDE 32.4 NORTH...LONGITUDE 62.9 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 06Z MON AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 06Z MON 18Z MON 06Z TUE 18Z TUE 06Z WED 06Z THU 06Z FRI PERIODS TO TO TO TO TO TO TO 18Z MON 06Z TUE 18Z TUE 06Z WED 06Z THU 06Z FRI 06Z SAT FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT CAPE HATTERAS 34 X X( X) X( X) X( X) 1( 1) 1( 2) 1( 3) BERMUDA 34 6 11(17) 12(29) 8(37) 6(43) 2(45) 2(47) BERMUDA 50 X 1( 1) 1( 2) 2( 4) 1( 5) 1( 6) 1( 7) BERMUDA 64 X X( X) X( X) 1( 1) X( 1) X( 1) X( 1) $$ FORECASTER STEWART

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Summary for Tropical Depression Eight (AT3/AL082021)

2021-08-16 10:49:07| National Hurricane Center (Atlantic)

...TROPICAL DEPRESSION PASSING TO THE EAST-SOUTHEAST OF BERMUDA... As of 5:00 AM AST Mon Aug 16 the center of Eight was located near 32.4, -62.9 with movement SSW at 5 mph. The minimum central pressure was 1012 mb with maximum sustained winds of about 35 mph.

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Tropical Depression Eight Public Advisory Number 2

2021-08-16 10:49:07| National Hurricane Center (Atlantic)

Issued at 500 AM AST Mon Aug 16 2021 000 WTNT33 KNHC 160849 TCPAT3 BULLETIN Tropical Depression Eight Advisory Number 2 NWS National Hurricane Center Miami FL AL082021 500 AM AST Mon Aug 16 2021 ...TROPICAL DEPRESSION PASSING TO THE EAST-SOUTHEAST OF BERMUDA... SUMMARY OF 500 AM AST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...32.4N 62.9W ABOUT 110 MI...180 KM E OF BERMUDA MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...SSW OR 195 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...1012 MB...29.89 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Watch is in effect for... * Bermuda A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 AM AST (0900 UTC), the center of Tropical Depression Eight was located near latitude 32.4 North, longitude 62.9 West. The depression is moving toward the south-southwest near 5 mph (7 km/h) and this motion is expected to continue this morning. A slow clockwise turn toward the southwest and west is anticipated during the next couple of days, followed by a continued westward motion on Wednesday. On the forecast track, the center of the depression will pass to the southeast and south of Bermuda during the next few days. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Slow strengthening is forecast and the system is forecast to become a tropical storm later today. The estimated minimum central pressure is 1012 mb (29.89 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are possible across Bermuda and the nearby waters on Tuesday, particularly to the south of the island. NEXT ADVISORY ------------- Next intermediate advisory at 800 AM AST. Next complete advisory at 1100 AM AST. $$ Forecaster Stewart

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