Home › discussion
 

Keywords :   


Tag: discussion

Tropical Storm Narda Forecast Discussion Number 9

2019-09-30 16:59:26| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Mon Sep 30 2019 000 WTPZ41 KNHC 301459 TCDEP1 Tropical Storm Narda Discussion Number 9 NWS National Hurricane Center Miami FL EP162019 900 AM MDT Mon Sep 30 2019 Recent microwave data and surface observations from Mexico indicate that the center of Narda is located just offshore of the west coast of mainland Mexico, north of Islas Marias. The cyclone continues to produce a large area of deep convection near and to the west of its center. The latest Dvorak intensity estimates from both TAFB and SAB support tropical storm strength, so the initial intensity has been raised to 35 kt, making Narda a tropical storm once again. An automated observing site near San Blas, Mexico recently reported a wind gust to 38 kt, and a pressure of 1002.8 mb was observed at Islas Marias earlier this morning. Some additional strengthening is possible today while Narda moves over the warm waters of the Gulf of California, however, interaction with land is likely to occur by Tuesday, and gradual weakening should begin by that time. If the center moves to the right of the NHC track forecast, landfall and weakening would occur much sooner. Narda is moving northwestward at 13 kt. The tropical storm should continue to move northwestward around the southwestern periphery of a large mid-level anticyclone centered over the southeastern United States. Although the various global model ensemble means take Narda farther westward over the Gulf of California during the next couple of days, the operational ECMWF and UKMET models show the cyclone moving inland over mainland Mexico within the next day or so. This is the solution that the NHC track forecast leans toward, and it is possible that Narda will move onshore farther south than implied by the exact forecast track. The main threat posed by Narda continues to be very heavy rainfall, due to large amounts of moisture being advected northward and northeastward over Mexico on the eastern side of the cyclone's circulation. These rains, which could total as much as 15 inches in a few locations, will result in life-threatening flash floods and mudslides. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 22.5N 106.4W 35 KT 40 MPH 12H 01/0000Z 24.0N 107.5W 40 KT 45 MPH 24H 01/1200Z 25.7N 109.0W 35 KT 40 MPH...INLAND 36H 02/0000Z 27.2N 110.1W 35 KT 40 MPH...INLAND 48H 02/1200Z 28.4N 111.1W 30 KT 35 MPH...INLAND 72H 03/1200Z...DISSIPATED $$ Forecaster Brown

Tags: number discussion storm tropical

 

Hurricane Lorenzo Forecast Discussion Number 32

2019-09-30 10:38:48| National Hurricane Center (Atlantic)

Issued at 500 AM AST Mon Sep 30 2019 000 WTNT43 KNHC 300838 TCDAT3 Hurricane Lorenzo Discussion Number 32 NWS National Hurricane Center Miami FL AL132019 500 AM AST Mon Sep 30 2019 The satellite presentation of Lorenzo has generally changed little during the last several hours. The hurricane continues to maintain a well-defined inner core with a ragged cloud-filled eye. The outer bands are well established to the north and east of the center, but are restricted on the south side of the circulation due to some southwesterly shear and drier air being wrapped into that portion of the cyclone. The initial intensity estimate is set at 90 kt based on T5.0/90 kt Dvorak classifications from TAFB and SAB. Lorenzo is moving north-northeastward at 11 kt through a break in the Atlantic subtropical ridge. The models generally agree that Lorenzo should pick up forward speed and move northeastward during the next day or two as a trough amplifies over the central Atlantic. This flow should take the core of Lorenzo near or to the west of the western Azores late Tuesday and early Wednesday. After that time, the spread in the guidance increases with several of the models including the GFS, HWRF, and HMON showing Lorenzo turning north-northeastward or northward as it moves around the east side of a large extratropical low. The new ECMWF run has shifted closer to the GFS/HWRF/HMON solutions, but it still is considerably to the east of those models as it shows less interaction with the extratropical low. The NHC track forecast has been adjusted a little to the left to come into better agreement with the latest consensus aids. Although the spread in the models is not as large as it was yesterday, the forecast beyond 48 hours is still of low confidence given the uncertainty in the longer-term steering flow. The intensity forecast appears to be more straightforward than the track forecast. The bulk of the guidance shows the hurricane maintaining its intensity or weakening slightly during the next day or two while it remains over relatively warm waters and in moderate wind shear conditions. It seems likely that Lorenzo will be a significant hurricane when it passes near the Azores in about 2 days. After that time, more notable weakening should occur due to a significant drop off in SSTs, drier air, and much stronger shear. In fact, these conditions should ultimately lead to extratropical transition, which is expected to be complete by 72 hours. Dissipation is now predicted to occur by day 5 following the global model guidance. Key Messages: 1. Lorenzo is a large and powerful hurricane, and its hurricane- and tropical-storm-force wind fields are expected to expand further during the next few days. Hurricane and Tropical Storm Watches are in effect for the Azores, and Hurricane and Tropical Storm Warnings could be required later today for those islands. 2. Large swells generated by Lorenzo will continue to spread across much of the north Atlantic basin during the next few days. These swells will produce life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 28.7N 43.1W 90 KT 105 MPH 12H 30/1800Z 30.3N 42.3W 85 KT 100 MPH 24H 01/0600Z 32.7N 40.3W 85 KT 100 MPH 36H 01/1800Z 36.0N 36.6W 85 KT 100 MPH 48H 02/0600Z 40.5N 31.0W 80 KT 90 MPH 72H 03/0600Z 52.0N 20.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 04/0600Z 57.0N 13.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 05/0600Z...DISSIPATED $$ Forecaster Cangialosi

Tags: number discussion forecast hurricane

 
 

Hurricane Lorenzo Forecast Discussion Number 31

2019-09-30 04:42:46| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Sun Sep 29 2019 000 WTNT43 KNHC 300242 TCDAT3 Hurricane Lorenzo Discussion Number 31 NWS National Hurricane Center Miami FL AL132019 1100 PM AST Sun Sep 29 2019 There haven't been a lot of changes with Lorenzo this evening, with a small cloud-filled eye remaining visible and an enormous cloud shield expanding in the northern semicircle. Satellite intensity estimates support a somewhat lower intensity than the previous advisory, so the initial wind speed is set to 95 kt. It should be emphasized that even though the peak winds are down since yesterday, the area of the hurricane-force winds has more than doubled during that time. Earlier aircraft data indicated that the large hurricane is upwelling a significant amount of cooler waters under the storm, and this is anticipated to cause Lorenzo to slowly weaken during the next couple of days. While the SSTs drop off considerably after late tomorrow, which would normally cause faster weakening, most of the guidance is showing a favorable trough interaction at that time with strong upper-level divergence. These effects are expected to offset, and Lorenzo is likely to be a category 1 or 2 hurricane near the Azores. Little change was made to the previous forecast, except to raise the intensity a little higher near the Azores after more heavily weighting the global models, which have been good performers for this cyclone. The guidance is in very good agreement on Lorenzo becoming an extratropical cyclone in about 72 hours, and that is reflected in the latest forecast. Lorenzo continues north-northeastward at 9 kt through a break in the subtropical ridge. The forecast track confidence remains very high through 48 hours as the hurricane is accelerated toward the northeast ahead of a mid-latitude trough, and the new forecast is essentially an update of the previous one. After that time, however, there is a very large spread in the guidance caused by whether Lorenzo is captured by the mid-latitude trough or if it remains separate. There isn't much change in the newest guidance, although it should be noted that the 12Z ECMWF solution is pretty far east of its ensemble mean. The forecast track confidence is extremely low beyond 72 hours, and the new NHC track was nudged just a little to the left from the previous advisory, slightly east of the various consensus aids. Key Messages: 1. Lorenzo is a large and powerful hurricane, and its hurricane- and tropical-storm-force wind fields are expected to expand further during the next several days. Hurricane and Tropical Storm Watches have been issued for the Azores, and these winds could start late Tuesday or early Wednesday. 2. Large swells generated by Lorenzo will continue to spread across much of the north Atlantic basin during the next few days. These swells will produce life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 27.6N 43.5W 95 KT 110 MPH 12H 30/1200Z 28.9N 42.9W 90 KT 105 MPH 24H 01/0000Z 31.0N 41.5W 90 KT 105 MPH 36H 01/1200Z 33.9N 38.6W 85 KT 100 MPH 48H 02/0000Z 37.5N 34.2W 85 KT 100 MPH 72H 03/0000Z 48.0N 22.5W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 04/0000Z 53.0N 17.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 05/0000Z 54.0N 17.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake

Tags: number discussion forecast hurricane

 

Tropical Depression Narda Forecast Discussion Number 7

2019-09-30 04:31:53| National Hurricane Center (East Pacific)

Issued at 1000 PM CDT Sun Sep 29 2019 000 WTPZ41 KNHC 300231 TCDEP1 Tropical Depression Narda Discussion Number 7 NWS National Hurricane Center Miami FL EP162019 1000 PM CDT Sun Sep 29 2019 My best estimate of Narda's position based on conventional and microwave satellite imagery, along with surface observations, is inland near Puerto Vallarta, Mexico. There may be other small swirls embedded within a surface trough that lies from the Islas Marias archipelago southeastward to Puerto Vallarta, Narda, and Manzanillo. However, the mid-level circulation center that we have been tracking, which is near ground level in this mountainous region, is the feature that has had the most continuity. A curved band of intense deep convection consisting of cloud tops of -85C to -90C, with isolated overshooting tops to -95C, wraps about half around the center and generally corresponds to 35-kt winds. Due to land interaction, however, the initial intensity is being held just below tropical storm strength or 30 kt. The initial motion is 315/18 kt. A large ridge anchored to the east of Narda is expected to steer the the cyclone northwestward for the next 3 days. This will result in Narda emerging back over the Pacific Ocean in about 6 hours, then passing near or over the Islas Marias islands Monday morning, followed by a track near or just offshore the northwestern coast of Mexico Monday night and Tuesday. A second landfall is expected along the coast of Mexico on Wednesday, followed by dissipation Wednesday night or early Thursday. The new NHC forecast track is similar to the previous advisory, and lies just a tad to the left of the consensus models TVCN and HCCA, which move the center inland in about 24 hours. The intensity forecast remains highly uncertain, and leans toward a consensus of the wind fields in the global models, which show Narda regaining tropical storm status in 6-12 hours as a band of 35-kt winds forms between the center and the mountainous coastline, likely due to funneling/orographic effects. The upper-level environment is forecast to be conducive for additional strengthening when Narda moves over the very warm waters of the Gulf of California after 12-18 hours, but land interaction is expected to temper any significant strengthening. Thus, the intensity forecast is flat-lined at 35-kt, although some fluctuations in the intensity is likely. Due to Narda being forecast to regain tropical storm status, tropical storm warnings and watches have been issued for portions of northwestern Mexico. The primary threat from Narda will continue to be very heavy rainfall, which should result in life-threatening flash flooding and mudslides over portions of the southern coast of Mexico. Rainfall totals of up to 15 inches are possible. This rainfall threat is expected to continue even if the system dissipates as a tropical cyclone. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 20.6N 105.2W 30 KT 35 MPH...INLAND 12H 30/1200Z 22.0N 106.4W 35 KT 40 MPH...OVER WATER 24H 01/0000Z 24.0N 108.0W 35 KT 40 MPH 36H 01/1200Z 25.4N 109.4W 35 KT 40 MPH 48H 02/0000Z 26.7N 110.3W 35 KT 40 MPH 72H 03/0000Z 29.2N 111.4W 30 KT 35 MPH...INLAND 96H 04/0000Z...DISSIPATED INLAND $$ Forecaster Stewart

Tags: number discussion tropical depression

 

Tropical Depression Narda Forecast Discussion Number 6

2019-09-29 22:58:39| National Hurricane Center (East Pacific)

Issued at 400 PM CDT Sun Sep 29 2019 000 WTPZ41 KNHC 292058 TCDEP1 Tropical Depression Narda Discussion Number 6 NWS National Hurricane Center Miami FL EP162019 400 PM CDT Sun Sep 29 2019 Narda has become less organized during the past several hours. The primary center has been over the mountains of southwestern Mexico between Lazaro Cardenas and Manzanillo, and the associated convection has been decreasing. A 17Z ASCAT-C overpass suggests two other vorticity centers are located offshore, one near a cluster of convection to the southwest of Manzanillo and the other to the southwest of Lazaro Cardenas. The scatterometer data showed 35 kt winds southeast of the primary center, and given the decrease in organization since that time it is estimated that Narda has dropped below tropical storm strength. The initial motion is a rather uncertain 315/17 kt, which is faster than in the previous advisory. Over the next couple of days, Narda will be steered generally northwestward close to the coast of mainland Mexico along the southwestern periphery of a large high pressure area. After that time, a mid- to upper-level trough approaching the northern Baja California peninsula from the west should cause the system to turn north-northwestward and move over northwestern mainland Mexico. The track guidance has shifted to the right since the last advisory. However, due to the uncertainty in what will happen to the center, including the possibility it could re-form offshore, the new forecast track will be to the left of the model consensus. The new track will be faster than the previous track based on a combination of the initial motion and faster guidance. The intensity forecast is highly uncertain. The official forecast will follow the previous forecast in calling for Narda to weaken while over Mexico, and then re-intensify a little when the system emerges over water. However, there remain two alternative scenarios. The first of these is that the circulation dissipates completely as it passes over the mountains of western Mexico. The second is that the center re-forms offshore, either from the vorticity center currently southwest of Manzanillo or, as suggested by some of the global models, from a new center north of Cabo Corrientes. If such a re-formation occurs, this could lead to significant changes in both the intensity and the track forecasts. The primary threat from Narda is very heavy rainfall, which should result in life-threatening flash flooding and mudslides over portions of the southern coast of Mexico. Rainfall totals of up to 15 inches are possible. This rainfall threat is expected to continue even if the system dissipates as a tropical cyclone. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 19.1N 103.5W 30 KT 35 MPH...INLAND 12H 30/0600Z 20.8N 105.2W 25 KT 30 MPH...INLAND 24H 30/1800Z 23.0N 106.9W 25 KT 30 MPH...OVER WATER 36H 01/0600Z 24.7N 108.4W 30 KT 35 MPH 48H 01/1800Z 25.7N 109.5W 35 KT 40 MPH 72H 02/1800Z 28.5N 110.5W 30 KT 35 MPH...INLAND 96H 03/1800Z...DISSIPATED $$ Forecaster Beven

Tags: number discussion tropical depression

 

Sites : [322] [323] [324] [325] [326] [327] [328] [329] [330] [331] [332] [333] [334] [335] [336] [337] [338] [339] [340] [341] next »