je.st

Home › discussion

Tag: discussion

Tropical Storm Henri Forecast Discussion Number 8

2021-08-17 22:40:11| National Hurricane Center (Atlantic)

Issued at 500 PM AST Tue Aug 17 2021 000 WTNT43 KNHC 172040 TCDAT3 Tropical Storm Henri Discussion Number 8 NWS National Hurricane Center Miami FL AL082021 500 PM AST Tue Aug 17 2021 Henri appears to be gaining strength. Satellite images show banding features becoming increasingly curved, especially on the east side of the system, and an eye feature has been occasionally seen in radar images from Bermuda. The upper-level outflow is also well established to the north and east of the center. The center itself is estimated to be located near the western edge of the convection, but it is possible that a new center is forming farther east. The initial intensity is raised to 55 kt following the Dvorak classification from TAFB. The initial wind radii has been expanded outward based on an earlier ASCAT pass. The tropical storm appears to have slowed down, and the latest initial motion estimate is 255/2 kt. A subtropical ridge over the western Atlantic is building eastward to the north of Henri, and this feature should steer the storm westward at a slightly faster pace during the next two to three days. After that time, the ridge is expected to weaken and shift farther east as a cut off low or negatively-tilted trough develops over the northeast U.S. This change in the steering pattern should cause Henri to turn northeastward between Bermuda and the east coast of the U.S in the 72-120 h period. There is a fair amount of spread in exactly when and where Henri makes this turn and the GFS and EC ensembles have some members not far offshore of New England and Atlantic Canada. Overall, the guidance has shifted westward again this cycle, and the NHC track forecast has been adjusted accordingly from days 3 to 5. The northwesterly shear currently affecting Henri is subsiding, which should allow the storm to gain a little more strength tonight. However, a round of moderate northerly shear is expected to setup over Henri on Wednesday and Thursday and that will likely temporarily end the opportunity for strengthening. Although this shear would typically cause some weakening, the combination of warm SSTs and increasing mid-level moisture could offset the negative influences of the shear. By Friday and over the weekend, the shear is expected to lessen again and since the other environmental factors are predicted to remain favorable for the storm, strengthening is shown from days 3-5. This forecast is above the previous one, and lies fairly close to the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 30.4N 64.2W 55 KT 65 MPH 12H 18/0600Z 30.3N 65.5W 60 KT 70 MPH 24H 18/1800Z 30.2N 67.0W 60 KT 70 MPH 36H 19/0600Z 30.2N 68.6W 60 KT 70 MPH 48H 19/1800Z 30.3N 70.0W 60 KT 70 MPH 60H 20/0600Z 31.0N 71.1W 60 KT 70 MPH 72H 20/1800Z 32.0N 71.5W 65 KT 75 MPH 96H 21/1800Z 35.5N 69.6W 70 KT 80 MPH 120H 22/1800Z 39.1N 65.2W 70 KT 80 MPH $$ Forecaster Cangialosi

Tags: number discussion storm tropical

Hurricane Linda Forecast Discussion Number 31

2021-08-17 22:35:34| Tropical Depression LIDIA

Issued at 1100 AM HST Tue Aug 17 2021

Tags: number discussion linda forecast

Tropical Storm Grace Forecast Discussion Number 17

2021-08-17 16:53:03| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT Tue Aug 17 2021 000 WTNT42 KNHC 171452 TCDAT2 Tropical Storm Grace Discussion Number 17 NWS National Hurricane Center Miami FL AL072021 1100 AM EDT Tue Aug 17 2021 The cloud pattern of Grace is gradually becoming better organized on satellite images, but the system still lacks distinct banding features over the eastern semicircle. Cirrus-level outflow from the system appears to be well defined. Flight-level and SFMR-observed surface winds, as well as dropsonde measurements, support an intensity of 45 kt for this advisory. Not much change in intensity is likely through this afternoon while the circulation of Grace interacts with the island of Jamaica. Thereafter, since the cyclone will be over the very high heat content waters of the northwestern Caribbean Sea with modestly low vertical shear tonight and Wednesday, strengthening is anticipated. Grace will likely become a hurricane tomorrow and continue to intensify before moving over the Yucatan Peninsula. The interaction with that land mass is expected to temporarily interrupt strengthening, with some reintensification over the Bay of Campeche in 3-4 days. The official intensity forecast is near the model consensus for the first half of the forecast period, but below the consensus for the latter part of the period owing to the inherent uncertainties for that extended time frame. Grace continues to move just a little north of due west, or at about 280/13 kt. A well-defined 500 mb ridge should remain entrenched to the north of the tropical cyclone for the next several days. Therefore, a continued west to west-northwestward track is likely to continue for most, if not all, of the forecast period. The official forecast is close to the previous one through 72 hours and just slightly south of it at 4-5 days. This is very similar to the latest multi-model consensus prediction. Key Messages: 1. Heavy rainfall across Haiti, Cuba, Jamaica, the Cayman Islands, and the northern Yucatan Peninsula may lead to flash, urban, and small stream flooding, with the potential for mudslides highest in Haiti and Jamaica. 2. Tropical storm conditions are expected over portions of Jamaica today, and over the Cayman Islands later today and tonight. Tropical storm conditions are expected over portions of the southern coast of Cuba today in the warning area, spreading westward to possibly other portions of the southern coast of Cuba this evening through Wednesday morning. 3. There is an increasing risk of wind, rainfall, and storm surge impacts on the Yucatan Peninsula of Mexico Wednesday night and Thursday, and a Hurricane Warning will likely be needed for that area later today. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 18.3N 76.8W 45 KT 50 MPH 12H 18/0000Z 18.8N 79.0W 55 KT 65 MPH 24H 18/1200Z 19.2N 82.2W 65 KT 75 MPH 36H 19/0000Z 19.7N 85.3W 70 KT 80 MPH 48H 19/1200Z 20.4N 88.3W 65 KT 75 MPH...INLAND 60H 20/0000Z 20.9N 91.3W 60 KT 70 MPH...OVER WATER 72H 20/1200Z 21.1N 94.0W 65 KT 75 MPH 96H 21/1200Z 21.5N 98.5W 65 KT 75 MPH...INLAND 120H 22/1200Z 21.5N 103.0W 30 KT 35 MPH...POST-TROP/INLAND $$ Forecaster Pasch

Tags: number discussion grace storm

Tropical Storm Henri Forecast Discussion Number 7

2021-08-17 16:35:30| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Tue Aug 17 2021 000 WTNT43 KNHC 171435 TCDAT3 Tropical Storm Henri Discussion Number 7 NWS National Hurricane Center Miami FL AL082021 1100 AM AST Tue Aug 17 2021 Henri remains a sheared tropical storm. Geostationary satellite images and microwave data show a relatively large area of deep convection (~200 miles across), but the center of the storm is located near the western edge of the thunderstorms due to ongoing northwesterly vertical wind shear. The latest Dvorak estimates have been steady at 3.0/45 kt from TAFB and SAB, and based on that data, the initial intensity is held at 45 kt. The center of Henri is located roughly 130 miles south-southeast of Bermuda currently, and this will likely be as close as the storm gets to the island. The tropical storm is gradually turning to the west, as expected, and the initial motion is estimated to be 255/5 kt. A subtropical ridge over the western Atlantic is building eastward to the north of Henri, and this feature should steer the storm westward at a slightly faster pace during the next two or three days. After that time, the ridge is expected to weaken and shift farther east as a cut off low or negatively-tilted trough develops over the northeast U.S. This change in the steering pattern should cause Henri to turn northeastward between Bermuda and the east coast of the U.S in the 72-120 h period. The NHC track forecast is a little faster than the previous one in the short term and farther west than the previous one from days 3-5, trending toward the latest consensus models. The northwesterly shear currently affecting Henri is expected to subside later today, and that should allow the storm to gain strength during the next 12-24 hours. However, a round of moderate northerly shear is expected to setup over Henri during the 24-96 hour period. Although this shear would typically cause some weakening, the combination of warm SSTs and increasing mid-level moisture could offset the negative influences of the shear. Therefore, no change in strength is predicted beyond the 24 h period. Some of the models suggest that the shear could lessen again this weekend, so although not explicitly forecast, some strengthening is possible then. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 30.4N 64.3W 45 KT 50 MPH 12H 18/0000Z 30.4N 65.1W 50 KT 60 MPH 24H 18/1200Z 30.3N 66.5W 55 KT 65 MPH 36H 19/0000Z 30.3N 68.2W 55 KT 65 MPH 48H 19/1200Z 30.4N 69.7W 55 KT 65 MPH 60H 20/0000Z 30.7N 70.6W 55 KT 65 MPH 72H 20/1200Z 31.6N 71.3W 55 KT 65 MPH 96H 21/1200Z 34.1N 69.6W 55 KT 65 MPH 120H 22/1200Z 37.4N 66.0W 55 KT 65 MPH $$ Forecaster Cangialosi

Tags: number discussion storm tropical