Home › discussion
 

Keywords :   


Tag: discussion

Hurricane Teddy Forecast Discussion Number 21

2020-09-17 17:03:23| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Thu Sep 17 2020 000 WTNT45 KNHC 171502 CCA TCDAT5 Hurricane Teddy Discussion Number 21...Corrected NWS National Hurricane Center Miami FL AL202020 1100 AM AST Thu Sep 17 2020 Corrected to add Key Messages Since the previous advisory, Teddy's satellite appearance has steadily improved. There is now a ragged warming eye surrounded by a ring of convection with cloud tops colder than -60 degrees C. Very recently the objective satellite intensity estimates from UW-CIMSS have been rapidly increasing. And although a blend of the 1130 and 1200 UTC Dvorak intensity estimates from SAB and TAFB, respectively, averaged out to an intensity of about 95 kt, the improved satellite presentation since that time suggests that the hurricane should have winds of at least 105 kt, which is the initial intensity for this advisory, which could even be a little conservative based on the latest UW-CIMMS ADT and SATCON values of 120 and 111 kt, respectively. There will be NOAA and Air Force Reserve Hurricane Hunter aircraft inside Teddy later today, which should provide much more detail on the structure and intensity of Teddy. The only negative factor for intensification during the next 24 h is about 10 to 15 kt of vertical wind shear. However, Teddy has been able to begin the latest burst of intensification despite that shear. Therefore additional strengthening is anticipated through this evening, and Teddy is forecast to become a category 4 hurricane by tonight. The overall environment does not change significantly for the next couple of days, so other than some fluctuations intensity such as due to potential eyewall replacement cycles, no change in strength is indicated during that time. As Teddy continues moving northwest over the weekend, it is likely to begin to encounter some of the cooler waters upwelled by Hurricane Paulette last week. This could cause the cyclone to slowly weaken. By late this weekend, increasing vertical wind shear should also contribute to weakening. Due to the fast increase in intensity this morning, the latest NHC intensity is a bit higher than all of the guidance for the first 48 h, but the overall intensity trends are closely mirrored by the various multi-model consensus. Beyond 48 h, the NHC forecast closely follows the LGEM guidance. Teddy continues to move northwestward at 10 kt. The track forecast and reasoning both remain straightforward and unchanged for the next 72 h. The latest NHC model guidance is in excellent agreement that a deep-layer ridge situated over the central Atlantic will force Teddy on a northwestward track toward the western Atlantic. There is a little less divergence among the models on days 4 and 5 then on previous cycles, and these differences are due to timing differences in where and how fast the hurricane begins to recurve ahead of an approaching mid-latitude trough and frontal system moving off the coast of the eastern United States in about 3 days. The new NHC track forecast is little changed from the previous one, and is in the middle of the tightly clustered track guidance. On the forecast track, Teddy will make its closest approach to Bermuda on Monday. Key Messages: 1. Teddy is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island late Sunday or Monday. While the exact details of Teddy's track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda is increasing. 2. Swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States late this week and into the weekend. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 19.3N 53.0W 105 KT 120 MPH 12H 18/0000Z 20.4N 54.0W 115 KT 130 MPH 24H 18/1200Z 21.8N 55.5W 115 KT 130 MPH 36H 19/0000Z 23.5N 57.0W 115 KT 130 MPH 48H 19/1200Z 25.5N 58.9W 110 KT 125 MPH 60H 20/0000Z 27.3N 60.9W 105 KT 120 MPH 72H 20/1200Z 28.7N 62.7W 100 KT 115 MPH 96H 21/1200Z 32.4N 63.4W 95 KT 110 MPH 120H 22/1200Z 38.9N 62.3W 85 KT 100 MPH $$ Forecaster Latto

Tags: number discussion forecast hurricane

 

Tropical Depression Vicky Forecast Discussion Number 14

2020-09-17 16:40:00| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Thu Sep 17 2020 000 WTNT41 KNHC 171439 TCDAT1 Tropical Depression Vicky Discussion Number 14 NWS National Hurricane Center Miami FL AL212020 1100 AM AST Thu Sep 17 2020 Vicky is feeling the affects of very strong upper-level winds associated with the outflow of Hurricane Teddy. These winds have caused the remaining convection to be stripped well away from the center, and recent ASCAT data indicates that Vicky has weakened to a tropical depression. The ASCAT data support a peak wind speed of 30 kt. Vertical wind shear of 40-50 kt is forecast to continue plaguing Vicky, and the cyclone should continue to weaken and become a remnant low later today. The global models indicate that the circulation will open up into a trough within 36 to 48 hours, and the official forecast calls for dissipation within that time period. Now that Vicky has become a vertically shallow cyclone, it has turned south of due west and is moving 260/12 kt. Vicky or its remnants should turn west-southwestward later today as it is steered by the low-level northeasterly flow. The latest NHC track forecast is in best agreement with the HFIP corrected consensus model. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 21.4N 38.2W 30 KT 35 MPH 12H 18/0000Z 21.0N 39.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 18/1200Z 20.4N 41.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 19/0000Z 19.6N 43.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 19/1200Z...DISSIPATED $$ Forecaster Brown

Tags: number discussion tropical depression

 
 

Hurricane Teddy Forecast Discussion Number 20

2020-09-17 10:54:10| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 17 2020 000 WTNT45 KNHC 170854 TCDAT5 Hurricane Teddy Discussion Number 20 NWS National Hurricane Center Miami FL AL202020 500 AM AST Thu Sep 17 2020 Several passive microwave overpasses have revealed that Teddy has developed a 25-nmi-wide closed eye, while GOES-16 infrared satellite data shows significant cooling of the cloud tops surrounding a ragged eye feature. As a result, satellite intensity estimates have increased, thus Teddy's intensity has been increased to 90 kt based on a Dvorak classification of T5.0/90 kt from SAB and a recent UW-CIMSS adjusted-ADT value of T5.7/105 kt. The initial motion estimate based on the microwave satellite fixes is 305/10 kt. As described in previous discussions, the track forecast and reasoning both remain straightforward and unchanged for the next 72 h. The latest NHC model guidance is in excellent agreement that a deep-layer ridge situated over the central Atlantic will force Teddy on a northwestward track toward the western Atlantic. There is a little less divergence among the models on days 4 and 5 then on previous runs, and this difference remains related timing differences on where and how fast the hurricane begins to recurve ahead of an approaching mid-latitude trough and frontal system moving off the coast of the eastern United States in about 3 days. The new NHC track forecast is close to the previous advisory track now that it appears that the models have settled down, and lies close to the consensus models TVCA, HCCA, and FSSE. The overall environmental conditions appear to be conducive for Teddy to continue to at least gradually strengthen for the next 36-48 hours. However, with sea-surface temperatures expected to be near 30 deg C in 48-72 hours when the vertical shear is going to be near zero, the intensity forecast at that time could be too low. For now, the official intensity forecast lies near the upper end of the guidance envelope, and shows Teddy's intensity leveling off after 36 hours due to the very dry environment that the hurricane will be moving through, which could disrupt the inner-core convective pattern and eye feature. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 18.3N 52.3W 90 KT 105 MPH 12H 17/1800Z 19.5N 53.5W 90 KT 105 MPH 24H 18/0600Z 20.9N 54.9W 100 KT 115 MPH 36H 18/1800Z 22.5N 56.5W 105 KT 120 MPH 48H 19/0600Z 24.3N 58.2W 105 KT 120 MPH 60H 19/1800Z 26.1N 60.2W 100 KT 115 MPH 72H 20/0600Z 27.6N 62.0W 100 KT 115 MPH 96H 21/0600Z 30.7N 64.0W 95 KT 110 MPH 120H 22/0600Z 36.0N 62.9W 90 KT 105 MPH $$ Forecaster Stewart

Tags: number discussion forecast hurricane

 

Tropical Storm Vicky Forecast Discussion Number 13

2020-09-17 10:33:41| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 17 2020 000 WTNT41 KNHC 170833 TCDAT1 Tropical Storm Vicky Discussion Number 13 NWS National Hurricane Center Miami FL AL212020 500 AM AST Thu Sep 17 2020 Strong upper-level westerly winds associated with the outflow of Hurricane Teddy continues to rip across the circulation of Vicky. These very hostile winds aloft are causing Vicky to struggle with maintaining deep convection, which is quite sheared and limited to the northeastern quadrant. The latest satellite intensity estimates range from 25 to 38 kt, and the initial intensity is held at a possibly generous 35 kt. Since the shear is expected to remain strong, Vicky is forecast to weaken to a tropical depression later today, a remnant low by tonight, and dissipate entirely by the weekend. The weak storm is moving west-northwestward at 6 kt. A turn to the west is expected later today, followed by a west-southwest motion after that until the cyclone dissipates in a couple of days. The track forecast lies near the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 21.9N 36.7W 35 KT 40 MPH 12H 17/1800Z 21.6N 38.0W 30 KT 35 MPH 24H 18/0600Z 21.0N 39.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 18/1800Z 20.2N 41.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 19/0600Z 19.4N 43.2W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 19/1800Z...DISSIPATED $$ Forecaster Cangialosi

Tags: number discussion storm tropical

 

Tropical Depression Sally Forecast Discussion Number 25

2020-09-17 10:31:43| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Thu Sep 17 2020 000 WTNT44 KNHC 170831 TCDAT4 Tropical Depression Sally Discussion Number 25 NWS National Hurricane Center Miami FL AL192020 400 AM CDT Thu Sep 17 2020 Although the overall convective cloud and rain shield in satellite and radar imagery continues to erode, Tropical Depression Sally is still producing significant rainfall across east-central Alabama and west-central and central Georgia. Surface observations and Doppler radar data indicate that Sally has weakened to a 25-kt depression over southeastern Alabama. Sally will continue to weaken, and fairly rapidly at that, due to increasing friction and loss of convection owing to very hostile westerly to southwesterly vertical wind shear in excess of 40 kt. Sally will likely degenerate into a remnant low pressure system by tonight or early Friday, and merge with a frontal system over North Carolina by Friday evening. Sally is moving northeastward or 055/10 kt. A northeastward to east-northeastward motion will continue for the next 36 hours or so as the cyclone moves ahead of a broad deep-layer trough over the northeastern United States. The official track forecast is down the middle of the tightly packed NHC model guidance suite, and lies close to the previous advisory track and the consensus model HCCA. This is the last NHC advisory on Sally. Future information on this system, including the rainfall threat, can be found in Public Advisories issued by the Weather Prediction Center beginning at 10 AM CDT, under AWIPS header TCPAT3, WMO header WTNT34 KWNH, and on the web at http://www.wpc.ncep.noaa.gov KEY MESSAGES: 1. Widespread flooding is expected from central Georgia through southeastern Virginia. Along the central Gulf Coast, most widespread moderate to major river flooding from the historic rainfall event will crest by the weekend, but rivers will remain elevated well into next week. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 31.8N 85.7W 25 KT 30 MPH...INLAND 12H 17/1800Z 32.8N 84.2W 25 KT 30 MPH...INLAND 24H 18/0600Z 34.0N 81.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 36H 18/1800Z 35.1N 78.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 19/0600Z...MERGED WITH FRONTAL SYSTEM $$ Forecaster Stewart

Tags: number discussion tropical depression

 

Sites : [184] [185] [186] [187] [188] [189] [190] [191] [192] [193] [194] [195] [196] [197] [198] [199] [200] [201] [202] [203] next »