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Tropical Storm Cristobal Forecast Discussion Number 23
2020-06-07 10:45:31| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Sun Jun 07 2020 000 WTNT43 KNHC 070845 TCDAT3 Tropical Storm Cristobal Discussion Number 23 NWS National Hurricane Center Miami FL AL032020 400 AM CDT Sun Jun 07 2020 Cristobal continues to resemble a subtropical cyclone more than a tropical cyclone. The convection near the center remains limited, although it has become a little better organized during the past several hours. In addition, aircraft and scatterometer data show that the radius of maximum winds remains at or above 90 n mi. These data also suggest that a 45 kt intensity may be a bit generous, but since the central pressure remains near 993 mb the intensity has not changed for this advisory. The initial motion is 360/10 between a deep-layer ridge to Cristobal's east and a mid- to upper-level trough over the western Gulf of Mexico. This general motion should continue for 12-18 h, followed by a turn toward the north-northwest due to a mid-latitude ridge passing north of the cyclone. After 36 h, a turn toward the north and north-northeast is expected as Cristobal or its remnants encounter the mid-latitude westerlies. There are no important changes to either the track guidance or the forecast track since the last advisory. The broad nature of the cyclone and significant dry air entrainment is likely to prevent intensification before landfall, and the new intensity forecast holds the intensity constant at 45 kt until that time. Weakening is expected after landfall, with Cristobal weakening below tropical-storm strength just after the 24 h point. The new intensity forecast shows slight re-intensification as the system become extratropical at 72-96 h in agreement with the global model guidance. Cristobal remains a broad and asymmetric storm. Therefore, one should not focus on the exact forecast track, as the associated winds, storm surge, and rainfall will extend well away the center. Key Messages: 1. There is a danger of life-threatening storm surge outside of the Hurricane and Storm Damage Risk Reduction System from the Mouth of the Mississippi River to Ocean Springs, Mississippi, and a Storm Surge Warning is in effect for those areas. Life-threatening storm surge remains possible in other portions of southern and southeastern Louisiana where a Storm Surge Watch is in effect. Residents in these locations should follow advice given by local emergency officials. 2. Tropical storm force winds should spread along the northern Gulf coast from central Louisiana to the western Florida Panhandle, including metropolitan New Orleans today, and a Tropical Storm Warning is in effect for this area. These winds will arrive well in advance of and extend well east of Cristobals center. 3. Heavy rainfall will continue across north Florida this morning, spreading from east to west across the eastern and central Gulf Coast from the Florida Panhandle into Louisiana today. The Central Gulf Coast region will be most prone to issues after the passage of the center of Cristobal from Sunday night into Monday. This heavy rain will move up the Lower and Mid Mississippi Valley Monday into Tuesday, then across the Upper Mississippi Valley and Northern Plains Tuesday and Tuesday night. Flash flooding, and new and renewed significant river flooding is possible, especially where heavier rainfall occurs over portions of the Gulf Coast through the Mississippi Valley. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 27.3N 90.1W 45 KT 50 MPH 12H 07/1800Z 28.7N 90.3W 45 KT 50 MPH 24H 08/0600Z 30.8N 91.2W 35 KT 40 MPH...INLAND 36H 08/1800Z 33.3N 92.3W 30 KT 35 MPH...INLAND 48H 09/0600Z 36.6N 92.6W 25 KT 30 MPH...INLAND 60H 09/1800Z 40.9N 91.4W 25 KT 30 MPH...INLAND 72H 10/0600Z 46.0N 89.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 11/0600Z 52.0N 84.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 12/0600Z...MERGED WITH EXTRATROPICAL LOW $$ Forecaster Beven
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