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Tropical Depression Fourteen Forecast Discussion Number 4
2020-08-21 10:44:30| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Fri Aug 21 2020 000 WTNT44 KNHC 210844 TCDAT4 Tropical Depression Fourteen Discussion Number 4 NWS National Hurricane Center Miami FL AL142020 500 AM EDT Fri Aug 21 2020 Recent METOP-A/B ASCAT overpasses and earlier aircraft reconnaissance data indicate that the depression's circulation is not well-defined. In fact, the scatterometer data revealed multiple swirls, particularly, one newly developed circulation near a recent strong burst of deep convection near the coast of Honduras. Highest sustained winds from the scatterometer pass were 25-30 kt. For this advisory, the initial position is an uncertain centroid position of the multiple surface centers and the intensity is held at 30 kt. A 53rd Air Force Reserve reconnaissance flight is scheduled for this morning and will hopefully paint a clearer picture on the depression's location. Deep convection has been increasing during the past few hours, especially in the north portion of the depression, so gradual strengthening is still expected before it makes landfall on the east side of the Yucatan Peninsula in about 48 hours. After that time, some weakening is forecast while the cyclone traverses the peninsula. The system is expected to enter the warm waters of the southern Gulf of Mexico around the 60 hr period and restrengthen through the remainder of the forecast. Global models, however, are indicating increasing south-southwesterly shear as the cyclone enters the northwest portion of the gulf which could prevent it from reaching hurricane strength prior to landfall. For now, the forecast will reflect a low-end hurricane making landfall, similar to the HCCA intensity model. The new intensity forecast is basically an update of the previous advisory and is based on a compromise of the various multi-model consensus aids. The initial motion is estimated to be west-northwestward, or 290/10 kt. The depression is forecast to be steered generally northwestward during the next few days by a western extension of the atlantic subtropical ridge that stretches westward across Florida and into the eastern and central Gulf of Mexico. This general motion should result in landfall over the northeastern Yucatan Peninsula on Saturday, with the system entering the northwestern Gulf by the middle of next week. I think it's worth noting that both the UKMET and the DWD, Germany ICON global models are showing some binary interaction between the depression and Tropical Depression Thirteen around the 96-120 hr period while both systems are situated in the Gulf of Mexico. If this scenario actually occurs, the interaction could delay or slow tropical depression Fourteen's landfall over the northwestern Gulf coast. The NHC forecast track is again adjusted a little to the right of the previous forecast and lies close to the TVCA and HCCA consensus solutions. Key Messages: 1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and is likely to produce tropical-storm-force winds and heavy rainfall over portions of the coasts of Nicaragua and Honduras, including the Bay Islands, through today. The system is expected be near or at hurricane strength when it reaches the Yucatan Peninsula of Mexico late Saturday where a Hurricane Watch and a Tropical Storm Warning are in effect. 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Some strengthening is anticipated while it moves northwestward over the western Gulf of Mexico early next week, but it is too soon to know exactly how strong it will get or the location and magnitude of impacts it will produce along the central or northwestern Gulf Coast. Interests in that area should continue monitoring the progress of this system over the next few days. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 15.4N 83.1W 30 KT 35 MPH 12H 21/1800Z 16.3N 84.3W 40 KT 45 MPH 24H 22/0600Z 17.7N 85.4W 50 KT 60 MPH 36H 22/1800Z 19.2N 86.4W 60 KT 70 MPH 48H 23/0600Z 20.7N 87.5W 50 KT 60 MPH...INLAND 60H 23/1800Z 22.5N 88.8W 50 KT 60 MPH...OVER WATER 72H 24/0600Z 24.5N 90.2W 65 KT 75 MPH 96H 25/0600Z 28.1N 93.0W 65 KT 75 MPH 120H 26/0600Z 30.4N 94.6W 45 KT 50 MPH...INLAND $$ Forecaster Roberts
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