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Tropical Depression RICK Forecast Discussion Number 17

2015-11-22 15:45:10| National Hurricane Center (East Pacific)

Issued at 700 AM PST SUN NOV 22 2015 000 WTPZ41 KNHC 221445 TCDEP1 TROPICAL DEPRESSION RICK DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 700 AM PST SUN NOV 22 2015 Dry air and southwesterly shear has taken its toll on the tropical cyclone since yesterday. Deep convection associated with Rick has become well separated from the low-level center and diminished overnight, with the tropical cyclone becoming a swirl of mostly low- to mid-level clouds. The initial wind speed remains 30 kt, which is a blend of the Dvorak T- and CI-numbers from TAFB. Increasing shear, dry air, and decreasing sea surface temperatures are expected to cause the cyclone to spin down during the next couple of days, and Rick is forecast to become a remnant low later today. The remnant circulation should dissipate in 3 to 4 days. Rick is moving northwestward or 305/8 kt. The cyclone is predicted to turn north-northwestward and northward during the next 24 to 36 hours as it is steered between a shortwave trough to its west and a low- to mid-level ridge over western Mexico. After that time, the low-level steering currents are expected to weaken, and the remnant low should become nearly stationary. The updated NHC forecast track is similar to the previous advisory and is near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 22/1500Z 17.8N 118.5W 30 KT 35 MPH 12H 23/0000Z 18.6N 119.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 23/1200Z 19.7N 120.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 24/0000Z 20.5N 120.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 24/1200Z 21.0N 120.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 25/1200Z 20.7N 119.6W 15 KT 15 MPH...POST-TROP/REMNT LOW 96H 26/1200Z...DISSIPATED $$ Forecaster Brown

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Tropical Depression RICK Forecast Discussion Number 16

2015-11-22 09:34:36| National Hurricane Center (East Pacific)

Issued at 100 AM PST SUN NOV 22 2015 000 WTPZ41 KNHC 220834 TCDEP1 TROPICAL DEPRESSION RICK DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 100 AM PST SUN NOV 22 2015 Rick is barely hanging on as a tropical cyclone. Convective cloud tops have warmed considerably since the previous advisory, and the overall convective pattern has become disheveled looking with the low-level circulation center now fully exposed more than 60 nmi to the northwest of the closest convective cells. The initial intensity has been decreased to 30 kt based on 25-kt to 30-kt satellite intensity estimates, making Rick a tropical depression. Rick has made the expected turn toward the west-northwest and is now moving 290/10 kt. There is essentially no significant change to the previous forecast track reasoning. The latest NHC model guidance continues to show Rick turning northwestward and slowing down later today, followed by a northward drift on Monday and Tuesday as the cyclone continues to weaken, becoming more vertically shallow and trapped in weak steering currents within a break in a low- to mid-level ridge. The official track forecast is similar to the previous advisory track and lies close to the consensus of the GFS and ECMWF model tracks. Microwave satellite images indicate that dry and stable air has now wrapped all the way around the cyclone and has penetrated into the inner-core region, effectively cutting off convective development there. The combination of even drier air and cooler sea-surface temperatures, along with southwesterly vertical wind shear increasing to more than 30 kt by late tonight or Monday morning, is expected to produce further weakening for the rest of the forecast period. Rick should become a remnant low by tonight or early Monday, and dissipate by 96 h, if not sooner. The NHC intensity forecast closely follows the the IVCN consensus intensity model. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 17.3N 117.9W 30 KT 35 MPH 12H 22/1800Z 18.0N 119.0W 30 KT 35 MPH 24H 23/0600Z 19.2N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 23/1800Z 20.3N 120.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 24/0600Z 20.9N 120.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 25/0600Z 21.3N 120.0W 15 KT 15 MPH...POST-TROP/REMNT LOW 96H 26/0600Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm RICK Forecast Discussion Number 15

2015-11-22 03:39:05| National Hurricane Center (East Pacific)

Issued at 700 PM PST SAT NOV 21 2015 000 WTPZ41 KNHC 220238 TCDEP1 TROPICAL STORM RICK DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 700 PM PST SAT NOV 21 2015 Rick has not changed much since yesterday. Visible satellite images from earlier this evening and microwave data indicate that the low-level center of the storm is located to the northwest of a pulsing area of deep convection. The initial intensity estimate is again held at 35 kt, in agreement with a blend of the Dvorak classifications from TAFB, SAB, and ADT values from CIMSS at the University of Wisconsin. Dry and stable air has been entraining into the northwestern side of the circulation for some time. The continued effects of dry air, increasing shear, and cooler waters should result in Rick weakening during the next day or so. The cyclone is expected to become a remnant low by Sunday night or early Monday when it moves over sea surface temperatures lower than 26 degrees C and is embedded in hostile atmospheric conditions. The remnant low is expected to gradually weaken and dissipate in 3 to 4 days. Rick continues to move westward at about 10 kt, and the system is a little left of the previous track prediction. The guidance continues to show Rick turning northwestward and slowing down during the next couple of days as the mid-level ridge to the north of the storm breaks down. Little motion is expected beyond a couple of days when the shallow cyclone becomes embedded in weak steering currents. The NHC official track forecast is shifted to the west of the previous one, and is in best agreement with a consensus of the GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 17.0N 117.0W 35 KT 40 MPH 12H 22/1200Z 17.8N 118.4W 35 KT 40 MPH 24H 23/0000Z 19.0N 119.7W 30 KT 35 MPH 36H 23/1200Z 20.0N 120.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 24/0000Z 20.7N 121.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 25/0000Z 21.3N 121.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 26/0000Z...DISSIPATED $$ Forecaster Cangialosi

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Tropical Storm RICK Forecast Discussion Number 14

2015-11-21 22:09:37| National Hurricane Center (East Pacific)

Issued at 100 PM PST SAT NOV 21 2015 000 WTPZ41 KNHC 212109 TCDEP1 TROPICAL STORM RICK DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 100 PM PST SAT NOV 21 2015 Microwave data and visible imagery indicate that the center of Rick is located farther south than estimated on the previous advisory. This places the center a little closer to the deep convection, but there remains little in the way of convective banding. The initial intensity remains 35 kt based on a blend of the latest Dvorak classifications from TAFB and SAB. Satellite imagery shows dry, stable air working its way into the northwestern quadrant of the cyclone. This dry air plus shear increasing above 20 kt tonight should result in weakening, and Rick is expected to become a remnant low by 36 hours. The remnant low should gradually spin down and dissipate in about 4 days. Satellite fixes indicate that Rick has taken a westward jog during the past 6 to 12 hours, and the initial motion estimate is 275/10. Despite this, the overall synoptic reasoning has not changed, and Rick will gradually recurve in the next 2-3 days as it moves around the western edge of the subtropical ridge. As Rick becomes a shallow remnant low, it should move slowly northward until dissipation in the weak low-level flow. The new NHC track forecast is to the left of the previous one due to the initial position and motion, and is close to a blend of the latest GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 16.8N 115.9W 35 KT 40 MPH 12H 22/0600Z 17.3N 117.2W 35 KT 40 MPH 24H 22/1800Z 18.5N 118.8W 30 KT 35 MPH 36H 23/0600Z 19.7N 119.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 23/1800Z 20.7N 120.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 24/1800Z 21.5N 120.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 25/1800Z...DISSIPATED $$ Forecaster Brennan

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Tropical Storm RICK Forecast Discussion Number 13

2015-11-21 15:33:05| National Hurricane Center (East Pacific)

Issued at 700 AM PST SAT NOV 21 2015 000 WTPZ41 KNHC 211432 TCDEP1 TROPICAL STORM RICK DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 700 AM PST SAT NOV 21 2015 The center of Rick continues to be exposed to the northwest of bursting area of deep convection. The initial intensity remains 35 kt, perhaps generously, based on the latest Dvorak estimate from TAFB. The SHIPS model based off GFS model fields shows that the mid-level relative humidity is now below 50 percent and shear will be increasing above 20 kt in the next 24 to 48 hours. These factors, along with cooling SSTs along the track, should result in Rick weakening to a depression later today, and becoming a remnant low in about 36 hours. The initial motion estimate is 290/11, and Rick should gradually slow down and turn poleward during the next 2 to 3 days as the ridge to the north weakens due to an eastward moving mid/upper-level trough. Late in the period, the shallow remnant of Rick should move slowly northward to northeastward in weak low-level flow prior to dissipation. The new NHC track forecast is largely an update of the previous one and is close to the latest GFS/ECMWF consensus. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 17.3N 115.1W 35 KT 40 MPH 12H 22/0000Z 17.7N 116.0W 30 KT 35 MPH 24H 22/1200Z 18.6N 117.4W 30 KT 35 MPH 36H 23/0000Z 19.8N 118.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 23/1200Z 20.8N 119.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 24/1200Z 22.0N 119.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 25/1200Z 22.5N 119.0W 15 KT 15 MPH...POST-TROP/REMNT LOW 120H 26/1200Z...DISSIPATED $$ Forecaster Brennan

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