Home › discussion
 

Keywords :   


Tag: discussion

Hurricane Lee Forecast Discussion Number 32

2017-09-26 04:39:36| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Mon Sep 25 2017 000 WTNT44 KNHC 260239 TCDAT4 Hurricane Lee Discussion Number 32 NWS National Hurricane Center Miami FL AL142017 1100 PM AST Mon Sep 25 2017 The satellite presentation of Lee has improved over the past 6 hours. Cloud tops have cooled and the eye has become more distinct. Dvorak intensity estimates around 0000 UTC from TAFB and the UW-CIMSS ADT were higher than the last advisory, and the intensity estimate from the ADT has gone up even more since then. The initial intensity has been increased only slightly to 80 kt, but it is possible that Lee is a little stronger than that. Lee appears to have moved out of the moderate shear zone associated with an upper-level trough, and is accelerating away from any cold water it may have previously upwelled. Further intensification in the short term seems likely, and this is supported by all of the intensity guidance. The new NHC intensity forecast is a little higher than the previous forecast, and lies between the higher dynamical models (HWRF, HMON), and the lower statistical models (SHIPS, LGEM). After about 36 hours, a sharp increase in northerly shear associated with the outflow from Maria and an approaching mid-latitude trough should cause Lee to weaken. Given the small size of Lee, it is possible that weakening could occur even faster than indicated in the official forecast. Lee has continued to move toward the west-southwest, and the initial motion estimate is 240/7 kt. There is no change to the forecast reasoning, and Lee is expected to move generally westward for the next 36 hours, along the southern edge of a mid-level ridge. After that time, a combination of Maria and the aforementioned trough should cause Lee to recurve and rapidly accelerate toward the northeast. Since Lee is moving a little faster than previously forecast, the NHC forecast has been adjusted westward for the first 36 hours of the forecast, but is generally close to the previous forecast track after that. Lee should be extratropical by no later than day 5, and some of the models indicate that it will be absorbed within a frontal boundary sooner than that. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 30.2N 51.5W 80 KT 90 MPH 12H 26/1200Z 30.2N 52.8W 85 KT 100 MPH 24H 27/0000Z 30.5N 54.6W 90 KT 105 MPH 36H 27/1200Z 31.0N 55.9W 90 KT 105 MPH 48H 28/0000Z 31.7N 56.7W 85 KT 100 MPH 72H 29/0000Z 35.3N 55.0W 70 KT 80 MPH 96H 30/0000Z 42.0N 46.0W 55 KT 65 MPH 120H 01/0000Z 49.0N 28.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Zelinsky

Tags: number discussion lee forecast

 

Hurricane Maria Forecast Discussion Number 39

2017-09-25 22:39:34| National Hurricane Center (Atlantic)

Issued at 500 PM EDT Mon Sep 25 2017 000 WTNT45 KNHC 252039 TCDAT5 Hurricane Maria Discussion Number 39 NWS National Hurricane Center Miami FL AL152017 500 PM EDT Mon Sep 25 2017 Maria's coldest cloud tops and deepest convection continue to be over the far eastern and northern portions of the circulation, but a small area of convection has re-developed near the center this afternoon. SFMR data from a NOAA aircraft investigating Maria indicate that the maximum winds remain near 70 kt, and that the area of hurricane-force winds extends about 90 nm from the center over the eastern semicircle. Maria continues its slow northward trek. A slow northward motion should continue for another couple of days as Maria moves around the western side of a subtropical ridge over the western Atlantic, but the forward speed is atypically slow due to ridging over the northeastern United States. A deep mid-latitude trough will be moving into the northeastern U.S. late this week, which is expected to cause Maria to accelerate northeastward after 72 hours. The track guidance remains tightly clustered through the first 48 to 72 hours, but there are still some speed differences beyond that time. The NHC forecast track lies near the middle of the guidance envelope through 72 h, and is close to the various consensus aids late in the period. Cooler waters, moderate westerly shear, and dry air are expected to cause a gradual decrease in wind speed over the next few days. However, Maria is likely to remain a strong cyclone throughout the forecast period. Extratropical transition is likely to begin in 96 h with Maria completing this process near the end of the forecast period. KEY MESSAGES: 1. Maria is forecast to continue moving northward, paralleling the U.S. east coast, and it is likely that some direct impacts will occur along portions of the North Carolina coast beginning Tuesday, where a Tropical Storm Warning is in effect. 2. Storm surge flooding, especially along the sound side of the North Carolina Outer Banks, is possible beginning on Tuesday, and a Storm Surge Watch has been issued for portions of eastern North Carolina. 3. Swells generated by Maria are affecting much of the east coast of the United States from Florida through southern New England. These swells are also affecting Bermuda, Puerto Rico, the northern coast of Hispaniola, the Turks and Caicos Islands, and the Bahamas. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office for more information. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 31.7N 73.1W 70 KT 80 MPH 12H 26/0600Z 32.5N 73.2W 65 KT 75 MPH 24H 26/1800Z 33.5N 73.2W 65 KT 75 MPH 36H 27/0600Z 34.4N 73.1W 60 KT 70 MPH 48H 27/1800Z 35.3N 72.8W 60 KT 70 MPH 72H 28/1800Z 36.3N 69.6W 60 KT 70 MPH 96H 29/1800Z 38.8N 60.5W 60 KT 70 MPH 120H 30/1800Z 45.0N 45.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown

Tags: number discussion maria forecast

 
 

Hurricane Lee Forecast Discussion Number 31

2017-09-25 22:39:05| National Hurricane Center (Atlantic)

Issued at 500 PM AST Mon Sep 25 2017 000 WTNT44 KNHC 252038 TCDAT4 Hurricane Lee Discussion Number 31 NWS National Hurricane Center Miami FL AL142017 500 PM AST Mon Sep 25 2017 Little Lee has weakened a little since the previous advisory. Over the past few hours, the previously clear 10-15 nmi diameter eye has become cloud filled, briefly becoming completely obscured. An average of the available intensity estimates from TAFB, SAB, UW-CIMSS ADT, UW-CIMSS SATCON, and NHC AODT is 75 kt, and that is initial intensity used for this advisory. Lee has completed a tight cyclonic loop and is now moving toward the west-southwest or 255/07 kt. A narrow mid-level ridge is expected to continue building to the north of Lee, forcing the small hurricane on a westward track for the next day or so. As an upper-level trough approaches from the west, the hurricane should turn toward the northwest on Wednesday and Thursday as the western portion of the subtropical ridge erodes. By Friday and beyond, Lee is forecast to get caught up in the brisk southwesterly flow ahead of the aforementioned trough and accelerate toward the northeast at forward speeds in excess of 20 kt. The official track forecast has been shifted westward closer to the consensus models through 96 h, and then lies close to the previous advisory track at 120 h. The modest southeasterly vertical wind shear that has been affecting Lee today is forecast by the GFS and ECMWF global models to abate shortly, and remain at less than 10 kt for the next 48 hours or so. As a result, some slight strengthening will be possible when the cyclone moves over warmer 28 deg C SSTs in 36-48 hours. Afterwards, increasing southwesterly vertical shear should induce slow but steady weakening, with Lee making the transition into an extratropical low by 120 h when the cyclone will be located over 18C-20C water temperatures and in a 30-40 kt sheared environment. Lee is forecast to remain a compact hurricane throughout the forecast period, with only a small increase in the 50- and 34-kt wind radii expected. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 30.5N 50.6W 75 KT 85 MPH 12H 26/0600Z 30.4N 51.6W 75 KT 85 MPH 24H 26/1800Z 30.5N 53.4W 75 KT 85 MPH 36H 27/0600Z 31.0N 55.0W 80 KT 90 MPH 48H 27/1800Z 31.8N 55.6W 80 KT 90 MPH 72H 28/1800Z 34.5N 54.3W 75 KT 85 MPH 96H 29/1800Z 40.2N 47.5W 60 KT 70 MPH 120H 30/1800Z 46.9N 35.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart

Tags: number discussion lee forecast

 

Hurricane Lee Forecast Discussion Number 30

2017-09-25 16:45:36| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Mon Sep 25 2017 000 WTNT44 KNHC 251445 TCDAT4 Hurricane Lee Discussion Number 30 NWS National Hurricane Center Miami FL AL142017 1100 AM AST Mon Sep 25 2017 While Lee is still displaying a distinct 10-15 nm eye in the GOES-16 visible imagery this morning, the deep convection of the cirrus canopy is lopsided with most of the cold cloud tops west of the center. This may be due to moderate vertical shear induced by an upper-low southwest of the hurricane. The SAB, TAFB, and Advanced Dvorak Technique intensity estimates have not changed, so 80 kt is retained for the maximum sustained winds. Lee is now moving again, with a 12-h motion of south-southwest at 2 kt. As a narrow mid-level ridge builds to the north of Lee, the hurricane should turn toward the west on Tuesday and west-northwest on Wednesday at a slightly faster forward speed. Starting in about three days, Lee should begin recurvature toward the northeast, accelerating to over 20 kt by day 5 as the hurricane enters the mid-latitude westerlies. The official track forecast is shifted some toward the west through day 4, toward the tightly-packed global and hurricane model guidance. The moderate vertical shear affecting Lee and some upwelled cool water under the hurricane may cause slightly weakening shortly. After Lee moves back toward warmer water, the hurricane may restrengthen some, but it is not anticipated that the system will reach major hurricane status. The official intensity forecast is similar to the previous advisory and is based upon the HWRF, LGEM, and COAMPS guidance. Lee remains a tiny hurricane, though no recent information has been available about its wind radii. The official size forecast anticipates a slight increase in tropical storm force and hurricane force wind radii, based upon the RVCN size consensus method. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 30.8N 49.9W 80 KT 90 MPH 12H 26/0000Z 30.6N 50.6W 75 KT 85 MPH 24H 26/1200Z 30.6N 52.1W 80 KT 90 MPH 36H 27/0000Z 31.0N 53.6W 85 KT 100 MPH 48H 27/1200Z 31.5N 54.5W 85 KT 100 MPH 72H 28/1200Z 33.4N 54.8W 80 KT 90 MPH 96H 29/1200Z 37.9N 50.3W 70 KT 80 MPH 120H 30/1200Z 45.0N 39.0W 50 KT 60 MPH $$ Forecaster Landsea

Tags: number discussion lee forecast

 

Tropical Depression Pilar Forecast Discussion Number 8

2017-09-25 16:44:34| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Mon Sep 25 2017 000 WTPZ43 KNHC 251444 TCDEP3 Tropical Depression Pilar Discussion Number 8 NWS National Hurricane Center Miami FL EP182017 900 AM MDT Mon Sep 25 2017 Water vapor satellite imagery indicates that strong southwesterly vertical wind shear, along with an abundance of dry mid-/upper-level air, ahead of sharp shortwave trough moving across southern Baja California is taking its toll on Pilar. Convection has weakened considerably and has been displaced to the north and east of the poorly defined low-level circulation center. A blend of Dvorak satellite T-numbers and current intensity (CI) estimates from TAFB and SAB is a consensus T2.0/30 kt, resulting in Pilar being downgraded to a tropical depression. The shear is forecast to increase to more than 30 kt by 12 h, so continued weakening and degeneration into a remnant low is forecast today, followed by dissipation on Tuesday...if not sooner. The initial motion estimate is 335/06 kt. Pilar and its remnants are expected to continue moving in this general direction, accompanied by a slight decrease in forward speed, for the next day or so until dissipation occurs. The new NHC track forecast is similar to the previous advisory track, and lies close to a blend of the NOAA-HCCA and TCVA consensus track models. The main hazard associated with Pilar will continue to be heavy rainfall, which could trigger life-threatening flash floods and mudslides, over the states of Nayarit, the southern portion of Sinaloa, and the southwestern portion of Durango during the next day or so. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 22.8N 107.0W 30 KT 35 MPH 12H 26/0000Z 23.4N 107.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 26/1200Z...DISSIPATED $$ Forecaster Stewart

Tags: number discussion tropical depression

 

Sites : [646] [647] [648] [649] [650] [651] [652] [653] [654] [655] [656] [657] [658] [659] [660] [661] [662] [663] [664] [665] next »