Home › discussion
 

Keywords :   


Tag: discussion

Tropical Storm KARL Forecast Discussion Number 38

2016-09-23 22:49:57| National Hurricane Center (Atlantic)

Issued at 500 PM AST FRI SEP 23 2016 000 WTNT42 KNHC 232049 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 38 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 500 PM AST FRI SEP 23 2016 Satellite imagery contintues to show a well-developed outflow pattern around Karl with the center noted on the southeastern edge of the colder cloud tops. Aircraft reconnaissance data has indicated a gradual drop in pressure to 988 mb, based on a dropsonde report of 989 mb with 12 kt of wind at the surface. A peak 850-mb flight-level wind of 62 kt was measured, which equates to an surface intensity of 50 kt. Reliable SFMR data also showed maximum surface winds around 50 kt, and that will remain the initial intensity. Latest aircraft fixes had also indicated that Karl was beginning to turn more northward as it moves around the western edge of the mid-Atlantic subtropical ridge. Karl is expected to remain over sea surface temperatures of between 29-30C for the next 24 hours or so while at the same time, some brief relaxation in the vertical shear is forecast. These conditions should favor some continued slow strenghthening, which is generally supported by a majority of models. The models also suggest that Karl could reach hurricane strength by 24 hours as the system moves to the east of Bermuda. Continued strengthening of Karl is likely through 36 hours, then it is expected to gradually transition to extratropical status by 48 hours as it becomes absorbed by a rapidly approaching cold front. The latest official forecast has shifted Karl slightly west of the previous track during the next 12 hours, but otherwise, there are no significant changes from the previous advisory. Karl should make a sharp turn and acceleration to the northeast beyond 12 hours as it encounters increasing westerly flow in advance of an amplifying upper trough and associated cold front across the northwest Atlantic. Karl should then become absorbed by another extratropical low over the north Atlantic in 72 hours. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 29.9N 65.1W 50 KT 60 MPH 12H 24/0600Z 31.3N 64.3W 55 KT 65 MPH 24H 24/1800Z 33.7N 60.8W 65 KT 75 MPH 36H 25/0600Z 37.1N 54.0W 70 KT 80 MPH 48H 25/1800Z 42.0N 44.6W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 26/1800Z...DISSIPATED $$ Forecaster Sullivan/Berg

Tags: number discussion storm karl

 

Tropical Storm KARL Forecast Discussion Number 37

2016-09-23 16:45:24| National Hurricane Center (Atlantic)

Issued at 1100 AM AST FRI SEP 23 2016 000 WTNT42 KNHC 231445 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 37 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1100 AM AST FRI SEP 23 2016 A NOAA P3 flight continued to fly through Karl for a few hours after the release of the last advisory, and while it didn't find winds higher than 50 kt, dropsonde data did indicate that the minimum pressure had fallen to 992 mb. Microwave data indicate that Karl is still under the influence of 15-20 kt of south- southeasterly shear. The convective pattern has continued to improve, however, with an elongated curved band extending to the northeast and east of the central convection. With sea surface temperatures running between 29-30C for the next 24 hours and vertical shear expected to decrease slightly, it seems likely that Karl will continue to strengthen during the next couple of days. The intensity guidance is in fairly good agreement on the intensification trend, and in fact most of the models are showing Karl reaching a strength between 60 and 65 kt in about 24 hours. Therefore, the updated official forecast now shows Karl reaching hurricane intensity at that time. Continued strengthening is likely after that time, and the peak intensity shown in the official forecast is slightly higher than the previous forecast at 48 hours, which is in line with the latest guidance. Karl will be in the process of extratropical transition at that time, but the global models fields only agree that the transition will be complete by 72 hours. Karl should then be absorbed by a larger extratropical low by day 4. The last fix from the NOAA P3 was a little east of the previous Air Force fixes, so it's possible that Karl's center has begun to move east of due north. Until we know for sure, the initial motion is set to be northward, or 360/10 kt. Karl is located near the western edge of the subtropical ridge axis, and it should become increasingly embedded in the mid-latitude westerlies during the next couple of days. Therefore, the cyclone is forecast to turn northeastward and begin accelerating within the next 24 hours, with the motion becoming even faster by 72 hours. The spread among the track models is extremely tight on this forecast cycle, and very little change was required from the previous advisory. The new official forecast lies very close to the TVCN multi-model consensus. Since Karl is now forecast to become a hurricane by 24 hours while the center is passing just to the east of Bermuda, the Bermuda Weather Service has elected to issue a Hurricane Watch for the island. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 28.6N 64.8W 50 KT 60 MPH 12H 24/0000Z 30.2N 64.8W 55 KT 65 MPH 24H 24/1200Z 32.3N 62.7W 65 KT 75 MPH 36H 25/0000Z 34.9N 57.8W 70 KT 80 MPH 48H 25/1200Z 38.9N 49.8W 75 KT 85 MPH 72H 26/1200Z 50.7N 29.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 27/1200Z...ABSORBED BY A LARGER EXTRATROPICAL LOW $$ Forecaster Berg/Sullivan/Gerhardt/Schichtel

Tags: number discussion storm karl

 
 

Tropical Storm LISA Forecast Discussion Number 16

2016-09-23 16:34:29| National Hurricane Center (Atlantic)

Issued at 1100 AM AST FRI SEP 23 2016 000 WTNT43 KNHC 231434 TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 AM AST FRI SEP 23 2016 Lisa's center remains exposed to the southwest of the deep convection due to around 40 kt of southwesterly shear as analyzed by UW-CIMSS and the SHIPS model fields. The initial intensity remains 35 kt based on the latest Dvorak estimate from TAFB, but this could be a little generous. Strong shear is expected to continue for the next 24 to 36 hours. This shear, in combination with a drying mid-level atmosphere and marginal SSTs, should result in weakening. Lisa is forecast to weaken to a tropical depression tonight, and become a remnant low in 24 to 36 hours, as organized deep convection is expected to decay in the harsh environment. The remnant low of Lisa is forecast to open up into a trough in 3 to 4 days, in agreement with the latest GFS and ECMWF solutions. The initial motion estimate is 315/06. Lisa should continue moving generally northwestward around the subtropical ridge for the next 36 hours. After that time, the decaying system should recurve ahead of a deep-layer trough moving across the northern Atlantic. The new NHC track forecast is close to the previous one through 24 hours and has been nudged westward at 36 and 48 hours following the latest trend in the guidance. This forecast is close to the multi-model consensus aid TVCN and the GEFS ensemble mean. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 22.2N 36.3W 35 KT 40 MPH 12H 24/0000Z 23.1N 37.5W 30 KT 35 MPH 24H 24/1200Z 24.2N 39.5W 30 KT 35 MPH 36H 25/0000Z 25.4N 41.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 25/1200Z 27.4N 42.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 26/1200Z 31.5N 40.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 27/1200Z...DISSIPATED $$ Forecaster Brennan

Tags: number discussion storm lisa

 

Tropical Storm LISA Forecast Discussion Number 15

2016-09-23 10:55:56| National Hurricane Center (Atlantic)

Issued at 500 AM AST FRI SEP 23 2016 000 WTNT43 KNHC 230855 TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 500 AM AST FRI SEP 23 2016 The center of Lisa has become fully exposed due to strong shear, like so many Atlantic tropical cyclones in 2016. Some convection remains, although well away from the center, in the northern semicircle. The initial wind speed is reduced to 35 kt, which is on the high side of the latest Dvorak estimates. Very strong shear should cause further weakening, along with marginal SSTS and increasingly dry air aloft. Deep convection will likely be struggling in that environment within 24 hours, and the new forecast has Lisa becoming a remnant low in 36 hours. Most of the global models now show Lisa decaying to a trough in 3 to 4 days before it gets absorbed by a cold front, but either way it should be a weak system by then. Lisa continues moving northwestward at about 8 kt. A track toward the west-northwest or northwest is expected for the next couple of days while the system moves around the subtropical ridge. Afterward the post-tropical cyclone should turn northward as it gets caught up in southerly flow ahead of Karl. The guidance has shifted westward on this cycle, possibly due to a weaker Lisa being steered more by the low-level subtropical ridge. Thus, the official forecast is moved westward as well, near or just west of the model consensus. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 21.8N 35.7W 35 KT 40 MPH 12H 23/1800Z 22.7N 36.8W 30 KT 35 MPH 24H 24/0600Z 23.6N 38.3W 30 KT 35 MPH 36H 24/1800Z 24.6N 40.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 25/0600Z 26.1N 41.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 26/0600Z 30.5N 42.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 27/0600Z...DISSIPATED $$ Forecaster Blake

Tags: number discussion storm lisa

 

Tropical Storm KARL Forecast Discussion Number 36

2016-09-23 10:52:30| National Hurricane Center (Atlantic)

Issued at 500 AM AST FRI SEP 23 2016 000 WTNT42 KNHC 230852 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 36 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 500 AM AST FRI SEP 23 2016 The cloud pattern on satellite is better organized than 24 hours ago and much better than 2 days ago. Although the center is still located on the southern edge of the convection, the cloud pattern is more symmetric, and the outflow is better defined. Tonight's upward trend in organization was confirmed by data from an Air Force Hurricane Hunter plane that just left the cyclone. The estimated minimum central pressure was 999 mb, and there were numerous reports of 45- to 55-kt winds with a peak of 60 kt at 850 mb. A NOAA plane just arrived to the storm and measured a flight-level wind of 61 kt. These winds support an initial intensity of 50 kt. Karl has the opportunity to strengthen during the next couple of days while is moving over warmer water and relatively low shear. After that time, Karl should interact with the baroclinic mid-latitude flow, and in 3 days, Karl is expected to be a powerful extratropical cyclone. It will likely become absorbed by a much larger cyclone by day 5. The intensity forecast is very similar to the previous one, but this one reflects a little stronger cyclone in the short term based on the initial intensity and the current organization trend. Fixes from a reconnaissance plane and satellite give a motion of 325 degrees at 13 kt. Karl is already located on the western edge of the subtropical ridge, and this pattern should force the cyclone to turn northward within the next 12 to 24 hours. Soon thereafter, Karl is forecast to become embedded within a fast-moving westerly flow ahead of an amplifying mid-latitude trough. This should result in a sharp turn to the northeast with an increase in forward speed. The new track forecast brings the core of Karl a little bit closer to Bermuda in about 24 hours. The NHC forecast is in the middle of the tightly packed model guidance. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 27.9N 64.8W 50 KT 60 MPH 12H 23/1800Z 29.5N 65.0W 55 KT 65 MPH 24H 24/0600Z 31.5N 64.3W 60 KT 70 MPH 36H 24/1800Z 33.5N 61.0W 70 KT 80 MPH 48H 25/0600Z 37.0N 54.0W 70 KT 80 MPH 72H 26/0600Z 48.0N 35.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 27/0600Z...ABSORBED BY A LARGER EXTRATROPICAL CYCLONE $$ Forecaster Avila

Tags: number discussion storm karl

 

Sites : [801] [802] [803] [804] [805] [806] [807] [808] [809] [810] [811] [812] [813] [814] [815] [816] [817] [818] [819] [820] next »