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Hurricane CARLOS Forecast Discussion Number 21

2015-06-15 22:56:57| National Hurricane Center (East Pacific)

Issued at 400 PM CDT MON JUN 15 2015 000 WTPZ43 KNHC 152056 TCDEP3 HURRICANE CARLOS DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 400 PM CDT MON JUN 15 2015 Earlier this afternoon, an Air Force Reserve reconnaissance aircraft investigating Carlos found 700 mb flight-level winds of 69 kt along with SFMR surface winds of 64-67 kt in light rain areas. Two dropsondes released in the eyewall also reported surface winds of 62 and 64 kt. Based on these wind data, the initial intensity of Carlos has been increased to 65 kt, making the cyclone a category 1 hurricane once again. The initial motion estimate is 285/05 kt. The latest NHC model guidance has maintained a bifurcation in the track forecasts after 36-48 hours. The UKMET, NAVGEM, HWRF, and the BAM models continue to take a significantly weaker cyclone off to the west, whereas the ECMWF and GFDL models, and now the GFS model as well, keep Carlos a little stronger and closer to the southwestern coast of Mexico. Given the relative weakness of the mid-level ridge to the north and northeast of Carlos, which is expected to further weaken as the large low pressure system currently located over the west-central Gulf of Mexico moves across Texas in 24-48 hours, a forecast track to the west-northwest and closer to the coast of Mexico is the preferred scenario at this time. The NHC official track forecast lies close to a blend of the ECMWF, FSSE, GFDL, and GFS forecast tracks. However, only a slight deviation to the right of the forecast track would bring Carlos inland along the southwestern coast of Mexico. The general trend in the models is for the vertical wind shear to continue to weaken to around 5 kt by 24 hours. The combination of light shear and warm SSTs of around 29C could result in some slight strengthening during the next day or so. However, given the compact nature of Carlos, any fluctuations in intensity should be short-lived, so the official forecast calls for a steady intensity during that time. By 72 hours, Carlos will be moving into unfavorable thermodynamic conditions and could also be interacting with the higher terrain of Mexico, resulting in the cyclone weakening to a tropical depression by 72 hours, and degenerating into a remnant low by 96 hours. Dissipation of the small storm is expected by 120 hrs, if not sooner. The intensity forecast is similar to the previous advisory and the LGEM model. FORECAST POSITIONS AND MAX WINDS INIT 15/2100Z 17.0N 103.0W 65 KT 75 MPH 12H 16/0600Z 17.3N 103.7W 65 KT 75 MPH 24H 16/1800Z 17.9N 104.5W 65 KT 75 MPH 36H 17/0600Z 18.6N 105.2W 60 KT 70 MPH 48H 17/1800Z 19.5N 105.8W 50 KT 60 MPH 72H 18/1800Z 21.0N 106.2W 30 KT 35 MPH 96H 19/1800Z 22.0N 106.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 20/1800Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm CARLOS Forecast Discussion Number 20

2015-06-15 16:40:25| National Hurricane Center (East Pacific)

Issued at 1000 AM CDT MON JUN 15 2015 000 WTPZ43 KNHC 151440 TCDEP3 TROPICAL STORM CARLOS DISCUSSION NUMBER 20 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 1000 AM CDT MON JUN 15 2015 First-light visible satellite imagery indicates Carlos remains a very small tropical cyclone. An earlier GCOM-AMSR microwave pass also indicated the compact nature of the system, including a closed 5-10 nmi diameter eye. The consensus of satellite intensity estimates is 55 kt, but we'll hold the initial intensity at 60 kt pending the arrival of a United States Air Force Reserve hurricane hunter aircraft. The initial motion estimate is 290/05 kt. Carlos is expected to maintain a slow west-northwestward motion and move essentially parallel to the south-central coast of Mexico for the next 24-36 hours. After that time, there is a distinct bifurcation in the model guidance with how strong the mid-level ridge across northern Mexico and Texas is forecast to be. The GFS, UKMET, NAVGEM, HWRF, and the BAM models keep the ridge stronger and also weaken Carlos, resulting in the cyclone moving westward at 48 hours and beyond. In contrast, the ECMWF and GFDL models weaken the ridge and keep Carlos stronger, and gradually move the cyclone northwestward and then northward near the southwestern coast of Mexico during that time. Given that the large low pressure system currently located over the central Gulf of Mexico is forecast to move inland over Texas by 48 hours, which should act to weaken the mid-level ridge to the north and northeast of Carlos, the ECMWF-GFDL solution is preferred at this time. The NHC official track forecast is essentially just an update of the previous advisory, and lies close to a blend of the ECMWF, FSSE, and GFDL forecast tracks. However, only a slight deviation to the right of the forecast track would bring Carlos inland along the southwestern coast of Mexico. The very small size of Carlos makes the cyclone susceptible to small fluctuations in the vertical wind shear. However, the general trend in the GFS-based SHIPS intensity model is calling for the shear to decrease to less than 5 kt by 48 hours and beyond, which should allow for some strengthening to occur over 29C SSTs . Carlos is expected to weaken into a depression by 72 hours due to land interaction and an unfavorable thermodynamic environment, becoming a remnant low by 96 hrs, and dissipating by 120 hrs. The intensity forecast is similar to the previous advisory and closely follows the LGEM model. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 17.0N 102.5W 60 KT 70 MPH 12H 16/0000Z 17.3N 103.3W 60 KT 70 MPH 24H 16/1200Z 17.8N 104.2W 65 KT 75 MPH 36H 17/0000Z 18.4N 105.0W 60 KT 70 MPH 48H 17/1200Z 19.4N 105.6W 50 KT 60 MPH 72H 18/1200Z 21.2N 106.1W 30 KT 35 MPH 96H 19/1200Z 22.8N 106.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 20/1200Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm CARLOS Forecast Discussion Number 19

2015-06-15 10:39:53| National Hurricane Center (East Pacific)

Issued at 400 AM CDT MON JUN 15 2015 000 WTPZ43 KNHC 150839 TCDEP3 TROPICAL STORM CARLOS DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 400 AM CDT MON JUN 15 2015 Enhanced BD-curve infrared imagery shows that the cloud pattern of Carlos has diminished in size during the past 12 hours. A subsequent 0348 UTC ASCAT-B overpass also indicated a decrease in the overall extent of the tropical-storm-force winds. The subjective or objective T-numbers for this advisory remain unchanged as well as the initial intensity of 60 kt, although this could be generous. The intensity forecast remains quite uncertain, especially since the GFS continues to show Carlos dissipating over water and offshore of Cabo Corrientes, Mexico in less than 72 hours. On the other hand, the statistical-dynamical guidance continue to indicate gradual strengthening through 3 days before leveling off as a category 1 hurricane. The NHC intensity forecast is a compromise of both solutions, showing slight restrengthening to a hurricane in 24 hours. Afterwards, gradual weakening into a depression is expected in 72 hours due to land interaction and an unfavorable thermodynamic environment. Beyond the 72 hour period, the forecast calls for further weakening into a remnant low in 96 hours and dissipation at day 5. It appears as though Carlos is finally feeling the affects of the building mid-tropospheric ridge over central Mexico, and is now moving west-northwestward or 295/5 kt. The cyclone should continue on this track through the 36 hour period. Afterwards, the dynamical models show a weakness developing in the ridge to the north of Carlos which should turn the system more northwestward and toward the coast of Mexico. The official forecast reflects this expected change in the steering pattern. The NHC forecast is again shifted to the left of the previous advisory and is weighed heavily on a blend of the GFS, ECMWF, and the Florida State Superensemble. An Air Force Hurricane Hunter aircraft is scheduled to investigate Carlos later today and should provide a good estimate of the intensity. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 16.7N 101.8W 60 KT 70 MPH 12H 15/1800Z 17.0N 102.6W 60 KT 70 MPH 24H 16/0600Z 17.4N 103.6W 65 KT 75 MPH 36H 16/1800Z 17.9N 104.5W 60 KT 70 MPH 48H 17/0600Z 18.7N 105.1W 50 KT 60 MPH 72H 18/0600Z 20.7N 105.8W 30 KT 35 MPH 96H 19/0600Z 22.3N 106.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 20/0600Z...DISSIPATED $$ Forecaster Roberts

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Tropical Storm CARLOS Forecast Discussion Number 18

2015-06-15 04:31:51| National Hurricane Center (East Pacific)

Issued at 1000 PM CDT SUN JUN 14 2015 000 WTPZ43 KNHC 150231 TCDEP3 TROPICAL STORM CARLOS DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 1000 PM CDT SUN JUN 14 2015 The satellite presentation has not changed significantly during the past few hours. The convection surrounding the intermittent eye feature has been fluctuating in intensity and is located mostly to the east of the center. Dvorak T-numbers from TAFB and SAB are lower that earlier, but still suggest an initial intensity of 60 kt. The intensity forecast is uncertain. Most of the global guidance, especially the GFS, basically dissipate the cyclone in the short term, and none of the other models suggest any significant strengthening. Given that Carlos will be moving into a low shear environment and over warm waters for the next day or so, the NHC forecast calls for a very slight strengthening, if at all. Beyond 3 days, the interaction of the circulation with the high terrain of Mexico should result in weakening. The weakening could occur much faster, if an earlier turn to the north-northwest toward land materializes, as indicated by the GFS. The steering currents remain weak and Carlos is moving toward the northwest or 315 degrees at 5 kt. A weakness north of the cyclone should encourage a gradual north-northwesterly turn, and this is the solution of the ECMWF and the GFS. The NHC forecast is a little bit to the left of these two models and the previous official forecast, and is very close to the multi-model consensus. It is difficult to forecast if the cyclone will even exist beyond 3 days. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 16.7N 101.3W 60 KT 70 MPH 12H 15/1200Z 17.1N 102.1W 60 KT 70 MPH 24H 16/0000Z 17.4N 103.0W 65 KT 75 MPH 36H 16/1200Z 18.0N 104.0W 65 KT 75 MPH 48H 17/0000Z 18.7N 104.7W 60 KT 70 MPH 72H 18/0000Z 20.5N 105.5W 30 KT 35 MPH...INLAND 96H 19/0000Z 22.0N 106.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 20/0000Z 24.0N 107.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Avila

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Tropical Storm CARLOS Forecast Discussion Number 16

2015-06-14 16:50:47| National Hurricane Center (East Pacific)

Issued at 1000 AM CDT SUN JUN 14 2015 000 WTPZ43 KNHC 141450 TCDEP3 TROPICAL STORM CARLOS DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 1000 AM CDT SUN JUN 14 2015 The convective pattern of Carlos has eroded slightly since the previous advisory and AMSU microwave satellite imagery indicates that the western half of the eyewall has deteriorated as well. Based on a blend of available satellite intensity estimates, the initial intensity has been lowered to 60 kt. The initial motion estimate is an uncertain 320/02 kt. Steering currents are expected to gradually strengthen as a mid-level ridge over northern Mexico slowly builds to the north of Carlos. The ridge should force the cyclone on a slow west-northwestward track just offshore of the southern coast of Mexico for the next 48 hours or so. As Carlos nears the western periphery of the ridge by 72 hours, the cyclone should turn northwestward to north-northwestward and could move inland. Assuming landfall occurs, the high terrain of the Sierra Madre del Sur mountains would keep the main circulation of Carlos from moving very far inland on days 4 and 5. The global and regional models are in decent agreement on this scenario, and the official forecast track lies close to but is a little slower than the previous advisory track, following a blend of the consensus model TVCN and the FSSE model. Sea-surface temperature data from Remote Sensing Systems this morning indicate that a pool of cooler water has indeed upwelled beneath Carlos, as alluded to in the previous discussion. The colder water, in combination with some dry mid-level downslope flow and modest northeasterly vertical wind shear, has likely caused the short term weakening of the cyclone. However, with Carlos expected to begin moving away from the region of upwelling and into an environment of light shear later today, restrengthening back to hurricane status is forecast to occur by late tonight or Monday morning. Further slow strengthening is expected until landfall occurs. The intensity forecast in the latter part of the forecast period remains highly uncertain since it depends on the extent to which Carlos will interact with the Mexican landmass by day 3 and beyond. The NHC intensity forecast is a blend of the SHIPS intensity model and the previous intensity forecast. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 15.9N 100.4W 60 KT 70 MPH 12H 15/0000Z 16.3N 101.1W 65 KT 75 MPH 24H 15/1200Z 16.8N 102.0W 65 KT 75 MPH 36H 16/0000Z 17.3N 102.8W 70 KT 80 MPH 48H 16/1200Z 17.9N 103.6W 75 KT 85 MPH 72H 17/1200Z 20.2N 104.9W 50 KT 60 MPH...INLAND 96H 18/1200Z 21.9N 105.3W 30 KT 35 MPH...INLAND 120H 19/1200Z 23.8N 105.8W 20 KT 25 MPH...INLAND $$ Forecaster Stewart

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