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Tropical Storm Cristobal Forecast Discussion Number 19

2020-06-06 10:42:02| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Sat Jun 06 2020 000 WTNT43 KNHC 060841 TCDAT3 Tropical Storm Cristobal Discussion Number 19 NWS National Hurricane Center Miami FL AL032020 400 AM CDT Sat Jun 06 2020 Satellite imagery this morning shows that Cristobal does not have a classic tropical cyclone structure, probably due to interaction with a mid- to upper-level trough and the associated entrainment of dry air. The circulation is elongated north-south near the center, and multiple low-cloud swirls are preset. In addition, the strongest convection is well removed from the center of Cristobal to the north and east. The initial intensity is held at 40 kt based on earlier scatterometer data and continuity from the previous advisory. The initial motion is now 350/12. There is no change in the track forecast philosophy from the previous advisory. A south to north steering flow between a deep-layer ridge over the western Atlantic and the aforementioned trough over the western Gulf of Mexico should cause Cristobal to continue moving generally northward for the next 36 h or so. This motion should take the center of the storm across the Louisiana coast by Sunday night. Around the landfall time, a slight turn to the northwest is expected as a mid-level ridge moves across the central and eastern U.S. to the north of the cyclone. Overall, the models remain in good agreement, although the GFS and ECMWF have shifted a little to the left of their previous forecasts. The new official forecast is similar to the previous forecast and lies near the various consensus models. Cristobal is expected to slowly strengthen until it makes landfall along the northern Gulf coast in a couple of days. However, the broad structure of the cyclone, the dry air entrainment, and moderate wind shear should prevent a significant amount of intensification. One change from the previous forecast is that the global models suggest that Cristobal will undergo extratropical transition over the upper Mississippi River valley in about 4 days, and it should persist a little longer than previously forecast. Cristobal is likely to remain a broad and asymmetric storm when it makes landfall. Therefore, users are urged to not focus on the exact forecast path as the associated winds, storm surge, and rainfall will extend well to the east of the center. Key Messages: 1. Damaging and deadly flooding was already occurring in portions of Mexico and Central America. Additional rainfall from Cristobal will continue to slowly subside, however life threatening flash floods and mudslides will still be possible into Saturday. Refer to products from your local weather office for more information. 2. 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 along the Florida Big Bend and 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. 3. Tropical storm force winds are expected by late Saturday night along the northern Gulf Coast from southeastern Louisiana to the western Florida Panhandle, including metropolitan New Orleans, 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. 4. 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. Significant flooding will be possible on the smaller tributaries, especially where heavier rainfall occurs over portions of the Mid-South and Gulf Coast. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 23.8N 90.2W 40 KT 45 MPH 12H 06/1800Z 25.0N 90.4W 45 KT 50 MPH 24H 07/0600Z 26.8N 90.4W 50 KT 60 MPH 36H 07/1800Z 28.8N 90.5W 50 KT 60 MPH 48H 08/0600Z 30.6N 91.3W 40 KT 45 MPH...INLAND 60H 08/1800Z 33.2N 92.1W 30 KT 35 MPH...INLAND 72H 09/0600Z 36.4N 92.4W 25 KT 30 MPH...INLAND 96H 10/0600Z 45.0N 89.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 120H 11/0600Z 52.5N 83.5W 25 KT 30 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven

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Tropical Storm Cristobal Forecast Discussion Number 18

2020-06-06 04:39:37| National Hurricane Center (Atlantic)

Issued at 1000 PM CDT Fri Jun 05 2020 025 WTNT43 KNHC 060239 TCDAT3 Tropical Storm Cristobal Discussion Number 18 NWS National Hurricane Center Miami FL AL032020 1000 PM CDT Fri Jun 05 2020 The NOAA and Air Force Hurricane Hunters have been investigating Cristobal this evening and they have found that the storm is a little stronger. The pressure has dropped to 998 mb and a combination of flight-level, SFMR, and dropsonde data support a wind speed of about 40 kt. Cristobal continues to have a large and asymmetric appearance with most of the showers and thunderstorms and strong winds to the north and east of the center. The storm is moving northward at a slightly faster pace, about 12 kt. A south to north steering flow between a deep-layer ridge over the western Atlantic and a mid- to upper-level trough over the western Gulf of Mexico should cause Cristobal to continue moving generally northward for the next couple of days. This motion should take the center of the storm across the Louisiana coast by Sunday night. Around the landfall time, a slight turn to the northwest is expected as a mid-level ridge moves across the central and eastern U.S. Overall, the models are in fairly good agreement and only small changes were made to the previous NHC track forecast. This prediction lies near the middle of the guidance envelope. Cristobal will likely continue to slowly strengthen until it makes landfall along the northern Gulf coast in a couple of days. However, the broad structure of the cyclone, dry air on the west side of the system, and moderate wind shear should prevent a significant amount of intensification. The NHC intensity forecast is largely an update of the previous one and is close to the various consensus models. Cristobal is likely to remain a broad and asymmetric storm when it makes landfall. Therefore, users are urged to not focus on the exact forecast path as the associated winds, storm surge, and rainfall will extend well to the east of the center. 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 for another day or so. 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. 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 along the Florida Big Bend and 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. 3. Tropical storm force winds are expected by late Saturday night along the northern Gulf Coast from southeastern Louisiana to the western Florida Panhandle, including metropolitan New Orleans, 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. 4. 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. Significant flooding will be possible on smaller tributaries, especially where heavier rainfall occurs over portions of Louisiana and Mississippi. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 22.7N 90.1W 40 KT 45 MPH 12H 06/1200Z 24.1N 90.3W 45 KT 50 MPH 24H 07/0000Z 25.9N 90.3W 50 KT 60 MPH 36H 07/1200Z 27.7N 90.2W 50 KT 60 MPH 48H 08/0000Z 29.5N 90.8W 45 KT 50 MPH...INLAND 60H 08/1200Z 31.7N 91.9W 35 KT 40 MPH...INLAND 72H 09/0000Z 34.4N 92.8W 25 KT 30 MPH...INLAND 96H 10/0000Z 42.0N 90.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 11/0000Z...DISSIPATED $$ Forecaster Cangialosi

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Tropical Storm Cristobal Forecast Discussion Number 17

2020-06-05 22:52:04| National Hurricane Center (Atlantic)

Issued at 400 PM CDT Fri Jun 05 2020 000 WTNT43 KNHC 052051 TCDAT3 Tropical Storm Cristobal Discussion Number 17 NWS National Hurricane Center Miami FL AL032020 400 PM CDT Fri Jun 05 2020 The center of the tropical cyclone has moved into the Gulf of Mexico to the north of the Yucatan Peninsula. Earlier scatterometer and surface synoptic data indicated that the system had already re-strengthened into a tropical storm. The system has been exhibiting fairly well-defined convective banding over the northern and eastern portions of the circulation. However, the central convection is minimal at this time and upper-level outflow is being restricted over the southwestern quadrant due to a trough over the Bay of Campeche. The current intensity is kept at 35 kt in agreement with the earlier observations. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the storm in a few hours, which should provide a good estimate of Cristobal's strength. Although the cyclone will be traversing fairly warm waters during the next couple of days, dry mid-level air and some southwesterly shear is expected to limit intensification. The official intensity forecast is about the same as the previous ones and close to the model consensus. Cristobal has moved a little faster over the past several hours, and the current motion is estimated to be northward at 11 kt. For the next couple of days, the cyclone should continue to move generally northward through a weakness between subtropical high pressure areas. A bend toward the north-northwest is forecast just after landfall on the northern Gulf Coast due to the slight building of a ridge to the northeast of Cristobal. The size of the wind field and timing of the new track forecast require the issuance of storm surge and tropical storm warnings for a portion of the northern Gulf of Mexico coast at this time. 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. 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 has been issued for those areas. Life-threatening storm surge remains possible along the Florida Big Bend and 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. 3. Tropical storm force winds are expected by late Saturday night along the northern Gulf Coast from southeastern Louisiana to the western Florida Panhandle, including metropolitan New Orleans, and a Tropical Storm Warning has been issued for this area. These winds will arrive well in advance of and extend well east of Cristobals center. 4. 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. Significant flooding will be possible on smaller tributaries, especially where heavier rainfall occurs over portions of Louisiana and Mississippi. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 21.4N 89.7W 35 KT 40 MPH 12H 06/0600Z 22.9N 90.0W 40 KT 45 MPH 24H 06/1800Z 24.9N 90.1W 45 KT 50 MPH 36H 07/0600Z 26.7N 90.1W 50 KT 60 MPH 48H 07/1800Z 28.5N 90.4W 50 KT 60 MPH 60H 08/0600Z 30.4N 91.1W 40 KT 45 MPH...INLAND 72H 08/1800Z 32.8N 92.2W 30 KT 35 MPH...INLAND 96H 09/1800Z 39.5N 91.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 10/1800Z 50.0N 85.0W 20 KT 25 MPH...POST-TROP/INLAND $$ Forecaster Pasch

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Tropical Depression Cristobal Forecast Discussion Number 16

2020-06-05 16:49:29| National Hurricane Center (Atlantic)

Issued at 1000 AM CDT Fri Jun 05 2020 000 WTNT43 KNHC 051449 TCDAT3 Tropical Depression Cristobal Discussion Number 16 NWS National Hurricane Center Miami FL AL032020 1000 AM CDT Fri Jun 05 2020 Although the center of circulation is still over land, the system is gradually becoming better organized on satellite images. A large convective band has become better defined over the northern and eastern portions of the circulation. However, central convective features are still lacking. The current intensity estimate is 30 kt based on surface synoptic observations. Re-intensification should begin later today, and an Air Force Hurricane Hunter aircraft is scheduled to investigate Cristobal this evening as the center moves back over water. Additional intensification is anticipated through early Sunday, however this should be limited due to dry mid-level air and some shear. The official intensity forecast is about the same as in previous advisories and is near or above the latest intensity model consensus. The cyclone is moving a little faster toward the north, or about 360/10 kt. For the next couple of days Cristobal should move mainly northward through a weakness between subtropical anticyclones. A gradual bend toward the north-northwest is likely after the center reaches the northern Gulf coast due to some building of a ridge to the northeast. The official track forecast is a little faster than the previous one and is a blend of the simple and corrected dynamical model consensus tracks. 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 to the east of 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 has already been 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. Life-threatening storm surge is possible along the Florida Big Bend, in portions of southeastern Louisiana, and along the Mississippi coast within the next 48 hours, and a Storm Surge Watch has been issued for these areas. Residents in these locations should follow advice given by local emergency officials. 3. There is an increasing risk of tropical storm force winds beginning Sunday morning from Intracoastal City, Louisiana, to the Alabama/Florida border, including metropolitan New Orleans, and a Tropical Storm Watch has been issued for this area. These winds will arrive well in advance of and extend well east of Cristobals center. 4. Heavy rainfall will spread onto portions of the Gulf Coast, from east Texas to Florida, this weekend into early next week, with areas of flash flooding and rapid rises on smaller streams and rivers possible. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 20.0N 89.9W 30 KT 35 MPH...INLAND 12H 06/0000Z 21.7N 90.0W 40 KT 45 MPH...OVER WATER 24H 06/1200Z 23.8N 90.3W 45 KT 50 MPH 36H 07/0000Z 25.6N 90.3W 45 KT 50 MPH 48H 07/1200Z 27.3N 90.4W 50 KT 60 MPH 60H 08/0000Z 29.1N 90.9W 50 KT 60 MPH...ON COAST 72H 08/1200Z 31.2N 91.9W 40 KT 45 MPH...INLAND 96H 09/1200Z 36.7N 92.1W 30 KT 35 MPH...INLAND 120H 10/1200Z 43.0N 89.5W 25 KT 30 MPH...POST-TROP/INLAND $$ Forecaster Pasch

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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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