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Tropical Depression Cristobal Forecast Discussion Number 15
2020-06-05 10:36:25| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Fri Jun 05 2020 000 WTNT43 KNHC 050836 TCDAT3 Tropical Depression Cristobal Discussion Number 15 NWS National Hurricane Center Miami FL AL032020 400 AM CDT Fri Jun 05 2020 Cristobal's structure has continued to degrade since the last advisory. Radar imagery from Sabancuy, Mexico shows little banding near the center of the cyclone, though substantial convection is still present in the northeast quadrant, over the Yucatan peninsula. Earlier ASCAT data showed winds of 25-30 kt over the southern Gulf of Mexico, and slightly stronger east-southeasterly winds over the western Caribbean Sea. The initial intensity remains 30 kt, but it should be noted that the highest wind speeds over land associated with the circulation of Cristobal are likely lower. Cristobal is forecast to remain over land for another 12 to 18 hours, and little change in strength is anticipated during that time. Once the system moves over the Gulf of Mexico, gradual strengthening still seems likely until Cristobal reaches the northern U.S. Gulf Coast, and the NHC intensity forecast is largely unchanged from the previous advisory. The depression has completed a slow counter-clockwise loop and now appears to be heading north-northeastward near 6 kt. The initial position and motion are somewhat uncertain since the declining structure of the cyclone makes it difficult to pinpoint a center position at night. An upper-level trough to the west and a mid-level ridge to the east of Cristobal are contributing to the deep southerly flow that should steer the cyclone generally northward for the next few days. All of the global models forecast this to occur, though the exact forward speed at which Cristobal will move is more uncertain. Overall, the 6Z guidance shows the cyclone moving northward at a slightly faster pace and the NHC track forecast has been adjusted accordingly. It now slightly lags the consensus but is still faster than the ECMWF and the ECMWF ensemble mean. Regardless of its exact track and forward speed, Cristobal is expected to have a broad and asymmetric wind field as it approaches the northern Gulf coast. The strongest winds, highest storm surge, and heaviest rains could be well removed from the center of circulation. Therefore, it is important that users do not focus on the exact forecast path of the center of the cyclone. Key Messages: 1. Damaging and deadly flooding was already occurring in portions of Mexico and Central America. Cristobal is expected to produce additional extreme rainfall amounts through the end of the week. The heaviest additional rainfall is expected over far southern Mexico and portions of the Yucatan Peninsula, while also extending along the Pacific coast from Chiapas to Guatemala and El Salvador. This rainfall could cause widespread life-threatening flash floods and mudslides. Refer to products from your local weather office for more information. 2. Cristobal is forecast to re-emerge over the southern Gulf of Mexico later today and move northward over the central and northern Gulf of Mexico over the weekend. There is a risk of tropical storm force winds this weekend from Louisiana to the western Florida Panhandle and a risk of dangerous storm surge from Louisiana to the Florida Big Bend. These hazards will arrive well in advance of and extend well east of Cristobal's center. Storm surge and tropical storm watches will likely be issued for a portion of the U.S. Gulf Coast later today. 3. Heavy rainfall will spread into portions of the Gulf Coast from east Texas to Florida this weekend into early next week, with areas of flash flooding possible. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 18.8N 90.1W 30 KT 35 MPH 12H 05/1800Z 20.1N 90.1W 30 KT 35 MPH...INLAND 24H 06/0600Z 22.0N 90.3W 35 KT 40 MPH...OVER WATER 36H 06/1800Z 23.8N 90.4W 40 KT 45 MPH...OVER WATER 48H 07/0600Z 25.7N 90.3W 45 KT 50 MPH...OVER WATER 60H 07/1800Z 27.6N 90.4W 50 KT 60 MPH...OVER WATER 72H 08/0600Z 29.6N 91.2W 45 KT 50 MPH...INLAND 96H 09/0600Z 34.0N 92.5W 30 KT 35 MPH...INLAND 120H 10/0600Z 40.0N 90.0W 25 KT 30 MPH...INLAND $$ Forecaster Zelinsky
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