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Hurricane CARLOS Forecast Discussion Number 26

2015-06-17 05:01:36| National Hurricane Center (East Pacific)

Issued at 1000 PM CDT TUE JUN 16 2015 000 WTPZ43 KNHC 170301 TCDEP3 HURRICANE CARLOS DISCUSSION NUMBER 26 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 1000 PM CDT TUE JUN 16 2015 Tiny hurricane Carlos' surface circulation is appearing to become unglued from its deep convection and its mid-level circulation. While a mid-level center may be co-located within the convection near 17.5N 105.0W, the surface center is located substantially farther northeast. However, it is an open question as to where exactly it is currently located. My best estimate shown below is based upon last-light visible imagery and a very timely 0051Z WindSat microwave pass. The initial position suggests a current motion of 315/4 kt. Decaying Carlos should continue to move toward the northwest at about the same rate of speed, as it gets advected along by the low-level flow. As all of the global models lose the circulation of Carlos within a day, the track forecast is based upon a blend of persistence and the BAM advection models. Due to the more northward initial position, the track prediction is farther north than that from the previous advisory. The areal extent of deep convection is also diminishing and the Dvorak intensity estimates from TAFB and SAB are dropping in response. The initial intensity of 65 kt is based upon a 4.0 CI number from both agencies, which represents a substantial drop from what the aircraft reconnaissance observed only several hours ago. It is quite possible that the tropical cyclone is even weaker than indicated here, given the rather abrupt dislocation of the convection from the center. Embedded within an increasingly dry and stable atmosphere coupled with moderate northerly vertical shear, Carlos should continue to weaken. The official forecast is a blend between the LGEM and SHIPS statistical models (which slowly weaken Carlos) and the HWRF and GFDL dynamical models (which nearly immediately dissipate Carlos). This forecast is substantially below the predictions from the last advisory due to the quick reversal from intensification to weakening. Given the tiny size of the system, the very rapid dissipation indicated by the dynamical models is not out of the question. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 18.2N 104.5W 65 KT 75 MPH 12H 17/1200Z 18.6N 105.0W 55 KT 65 MPH 24H 18/0000Z 19.1N 105.7W 45 KT 50 MPH 36H 18/1200Z 19.5N 106.2W 35 KT 40 MPH 48H 19/0000Z 19.8N 106.8W 25 KT 30 MPH 72H 20/0000Z...DISSIPATED $$ Forecaster Landsea

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Tropical Storm BILL Forecast Discussion Number 5

2015-06-17 04:42:03| National Hurricane Center (Atlantic)

Issued at 1000 PM CDT TUE JUN 16 2015 000 WTNT42 KNHC 170241 TCDAT2 TROPICAL STORM BILL DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL022015 1000 PM CDT TUE JUN 16 2015 Bill has continued to weaken while it moves farther inland over Texas. The initial intensity is estimated at 35 kt, but surface observations indicate that these winds are confined to a few rainbands over water to the southeast of the center. Because most of the circulation is already inland, additional weakening is anticipated, and Bill is expected to become a tropical depression Wednesday morning, and a remnant low on Thursday. The best estimate of the initial motion is toward the north or 350 degrees at 10 kt, and this is based primarily on NWS Doppler Radar data. Bill is forecast to move northward for the next day or so around the western periphery of high pressure centered over the southeastern United States. After that time, the cyclone or its remnants will move toward the northeast while embedded within the mid-latitude westerlies. Most likely the system will become absorbed by a front by day 4. The main hazard from Bill is expected to be primarily heavy rainfall and flooding across portions of eastern Texas and eastern Oklahoma over the next day or two. Please see products from your local National Weather Service office for more information on the flood threat. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 29.5N 97.0W 35 KT 40 MPH...INLAND 12H 17/1200Z 31.0N 97.3W 30 KT 35 MPH...INLAND 24H 18/0000Z 33.2N 97.3W 25 KT 30 MPH...INLAND 36H 18/1200Z 34.8N 96.3W 25 KT 30 MPH...POST-TROP/INLAND 48H 19/0000Z 35.5N 94.5W 20 KT 25 MPH...POST-TROP/INLAND 72H 20/0000Z 37.5N 90.5W 15 KT 15 MPH...POST-TROP/INLAND 96H 21/0000Z...ABSORBED BY FRONTAL SYSTEM $$ Forecaster Avila

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Tropical Storm BILL Forecast Discussion Number 4

2015-06-16 22:53:02| National Hurricane Center (Atlantic)

Issued at 400 PM CDT TUE JUN 16 2015 000 WTNT42 KNHC 162052 TCDAT2 TROPICAL STORM BILL DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL022015 400 PM CDT TUE JUN 16 2015 After an earlier westward wobble, Bill is now moving toward the north-northwest or north based on Doppler radar data. My best estimate for a storm motion is 330/08 kt. Bill is expected to move north-northwestward tonight and turn toward the north over north-central Texas on Monday as the cyclone moves through a break in the subtropical ridge. By 36-48 hours, Bill is forecast to get caught up into the mid-latitude westerlies and accelerate off to the northeast and east-northeast. By 120 hours, the remnant circulation is expected to merge with a frontal system across the Ohio Valley region. The global models are in good agreement on this developing scenario and the NHC forecast track is just an update of the previous one, and lies close to a blend of the slower GFS, ECMWF, and UKMET global models. Although the inner-core banding structure of Bill has improved in radar imagery, the cyclone is expected to slowly weaken as the system continues to move farther inland. Bill should weaken to a tropical depression by Wednesday morning and become a remnant low by Wednesday evening when the system is moving across northern Texas. The GFS, ECMWF, and UKMET models now suggest that baroclinic forcing associated with an upper-level trough will help maintain the post-tropical remnants as a distinct entity for a few days before being absorbed by a frontal system by day 5. Tropical-storm-force winds and heavy rains continue to occur well away from the center. The main hazard from Bill is expected to be heavy rainfall and flooding across portions of eastern Texas and eastern Oklahoma over the next day or two. Please see products from your local National Weather Service office for more information on the flood threat. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 28.4N 96.8W 45 KT 50 MPH...INLAND 12H 17/0600Z 29.9N 97.5W 30 KT 35 MPH...INLAND 24H 17/1800Z 32.0N 97.7W 25 KT 30 MPH...INLAND 36H 18/0600Z 33.6N 97.1W 25 KT 30 MPH...POST-TROP/INLAND 48H 18/1800Z 34.7N 95.7W 20 KT 25 MPH...POST-TROP/INLAND 72H 19/1800Z 36.7N 92.0W 15 KT 15 MPH...POST-TROP/INLAND 96H 20/1800Z 39.0N 86.0W 15 KT 15 MPH...POST-TROP/INLAND 120H 21/1800Z...ABSORBED BY FRONTAL SYSTEM $$ Forecaster Stewart

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Hurricane CARLOS Forecast Discussion Number 25

2015-06-16 22:40:33| National Hurricane Center (East Pacific)

Issued at 400 PM CDT TUE JUN 16 2015 000 WTPZ43 KNHC 162040 TCDEP3 HURRICANE CARLOS DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 400 PM CDT TUE JUN 16 2015 Carlos is a feisty little hurricane. Despite the hurricane's satellite presentation, the Air Force reconnaissance aircraft measured maximum 700-mb flight-level winds of 90 kt and SFMR winds between 80-85 kt. The maximum surface winds are therefore estimated to be 80 kt. The flight meteorologist also indicated that Carlos's eye was about 7-8 n mi wide. There continues to be low confidence in the intensity forecast, since none of the models seem to be able to handle Carlos's size particularly well. The statistical- dynamical models keep Carlos as a hurricane for another three days or so, while the global and regional dynamical models indicate fast weakening (the ECMWF shows dissipation within 24 hours!). The NHC official intensity forecast indicates gradual weakening through day 3, with dissipation by day 4. However, Carlos's small size makes it susceptible to large swings in intensity, and even a slight increase in shear or dry air could lead to faster weakening than indicated. Based on the aircraft fixes, Carlos appears to have turned northwestward, or 305/4 kt, toward a break in the subtropical ridge located over northern Mexico and Texas. Since the most reliable track models dissipate the cyclone so soon, the official forecast relies on the remaining available guidance (GFDL, NAVGEM, and GFNI) more than usual. The updated NHC track forecast is essentially a blend of the available guidance and the previous official forecast. Due to the high uncertainty in the track and intensity forecasts, the tropical storm warning and hurricane watch for the coast of Mexico will be unchanged. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 17.8N 104.4W 80 KT 90 MPH 12H 17/0600Z 18.2N 104.9W 75 KT 85 MPH 24H 17/1800Z 18.9N 105.6W 65 KT 75 MPH 36H 18/0600Z 19.6N 106.1W 55 KT 65 MPH 48H 18/1800Z 20.2N 106.5W 45 KT 50 MPH 72H 19/1800Z 21.6N 107.4W 35 KT 40 MPH 96H 20/1800Z...DISSIPATED $$ Forecaster Berg

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Tropical Storm BILL Forecast Discussion Number 3

2015-06-16 16:56:35| National Hurricane Center (Atlantic)

Issued at 1000 AM CDT TUE JUN 16 2015 000 WTNT42 KNHC 161456 TCDAT2 TROPICAL STORM BILL DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL022015 1000 AM CDT TUE JUN 16 2015 Tropical Storm Bill is nearing the central Texas coast just south of Port O'Connor, and the cyclone should move inland shortly. Although the satellite presentation isn't terribly impressive, NOAA Doppler radar data and SFMR, flight-level, and dropsonde wind reports from an Air Force Reserve reconnaissance aircraft support an intensity of 50 kt. After Bill makes landfall, steady weakening will begin as the cyclone moves farther inland over Texas, although the GFS suggests that baroclinic forcing will help maintain the post-tropical remnants as a distinct entity for a few days. The initial motion estimate is 305/09 kt. Bill is expected to move around the southwestern and western periphery of a mid-level high located over the southeastern U.S. during the next day or two. By 48 hours, the cyclone is forecast to get caught up in the mid-latitude westerlies, resulting in a turn and acceleration to the northeastward to east-northeast. The global and regional models are in good agreement on this scenario, and the official forecast is very similar to the previous advisory track and a consensus of the GFS and ECMWF models. Although the storm's strongest winds are located very close to the center, tropical-storm-force winds and heavy rains are occurring well away from the center. The main hazard from Bill is expected to be heavy rainfall and flooding across portions of eastern Texas and eastern Oklahoma over the next day or two. Please see products from your local National Weather Service office for more information on the flood threat. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 28.2N 96.4W 50 KT 60 MPH 12H 17/0000Z 29.7N 97.1W 35 KT 40 MPH 24H 17/1200Z 31.6N 97.7W 30 KT 35 MPH...INLAND 36H 18/0000Z 33.4N 97.4W 25 KT 30 MPH...POST-TROP/INLAND 48H 18/1200Z 34.9N 96.2W 20 KT 25 MPH...POST-TROP/INLAND 72H 19/1200Z 36.8N 92.6W 15 KT 15 MPH...POST-TROP/INLAND 96H 20/1200Z 39.3N 87.2W 15 KT 15 MPH...POST-TROP/INLAND 120H 21/1200Z...DISSIPATED $$ Forecaster Stewart

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