Home › discussion
 

Keywords :   


Tag: discussion

Tropical Depression Six Forecast Discussion Number 7

2018-09-01 04:41:05| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Fri Aug 31 2018 503 WTNT41 KNHC 010241 TCDAT1 Tropical Depression Six Discussion Number 7 NWS National Hurricane Center Miami FL AL062018 1100 PM AST Fri Aug 31 2018 Convection associated with the depression is becoming more concentrated, although the center still appears to be near the eastern edge of the convective mass. The latest satellite intensity estimates from TAFB and SAB are 30 and 25 kt repsectively, while the CIMSS satellite consensus method suggests the cyclone has become a tropical storm. Based on the available data, the initial intensity remains a possibly conservative 30 kt. The depression is feeling the effects of moderate easterly vertical wind shear, with little or no cirrus outflow in the eastern semicircle. The initial motion is now 285/12. Deep layer easterly or east- southeasterly flow on the south side of the subtropical ridge should steer the cyclone generally west-northwestward across the open Atlantic ocean for the next 3-4 days. After that time, the cyclone is expected to turn northwestward toward a weakness in the subtropical ridge. The track guidance remains in good agreement with this scenario, although there remains some spread on how sharp the turn will be near the end of the forecast period. The new forecast track, which is an update of the previous forecast, is near the various consensus models. While the current shear is expected to subside during the next day or so, the forecast track takes the cyclone over waters that cool to near 26C in about 48 h. The intensity forecast thus calls for only gradual intensification through this time. After 48-72 h, the system should move over warmer water, but also should encounter increasing westerly shear. The intensity guidance responds to this combination of ingredients by showing little change in strength. The new intensity forecast, which is unchanged from the previous forecast, is in the stronger portion of the inetnsity guidance and above the forecasts of the consensus models. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 14.2N 25.5W 30 KT 35 MPH 12H 01/1200Z 14.7N 27.4W 35 KT 40 MPH 24H 02/0000Z 15.5N 29.9W 40 KT 45 MPH 36H 02/1200Z 16.3N 32.6W 45 KT 50 MPH 48H 03/0000Z 17.0N 35.2W 50 KT 60 MPH 72H 04/0000Z 18.5N 40.0W 55 KT 65 MPH 96H 05/0000Z 20.5N 44.5W 60 KT 70 MPH 120H 06/0000Z 23.0N 47.5W 55 KT 65 MPH $$ Forecaster Beven

Tags: number discussion tropical depression

 

Tropical Depression Seventeen-E Forecast Discussion Number 1

2018-09-01 04:34:06| Tropical Depression LIDIA

Issued at 900 PM MDT Fri Aug 31 2018

Tags: number discussion tropical depression

 
 

Hurricane Norman Forecast Discussion Number 15

2018-08-31 22:34:32| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Fri Aug 31 2018 824 WTPZ41 KNHC 312034 TCDEP1 Hurricane Norman Discussion Number 15 NWS National Hurricane Center Miami FL EP162018 200 PM PDT Fri Aug 31 2018 Satellite derived mid and upper tropospheric winds and the UW-CIMSS shear analysis indicate that the persistent northeasterly vertical shear has increased to 20-25 kt, and has continued to impede outer deep convective banding development in the northern portion of Norman's inner core. The cloud pattern has also become somewhat asymmetric (northeast to southwest). A series of recent microwave images, however, show that the eyewall is now closed, although the eye temperature has warmed a bit during the past 6 hours. The Dvorak satellite intensity classifications from TAFB and SAB also support these observations, and the initial intensity is reduced to 110 kt. Although there may still be some fluctuations in intensity, gradual weakening is forecast through day 5, primarily due to the shear predicted by the GFS and ECMWF Decay-SHIPS intensity models. Intrusion of stable air mass, beyond day 3, northeast of the Hawaiian Islands will also promote this weakening trend. The official intensity forecast has changed little from the previous advisory, and is still based on the HFIP Corrected Consensus Approach and IVCN intensity models. The initial motion is estimated to be west-southwest, or 255/7 kt. An anchored mid- to upper-level ridge that stretches west-southwestward from the Baja California peninsula should steer Norman west-southwestward during the next 12 hours or so. Afterward, the southwestern-most segment of the ridge axis between Miriam and Norman weakens as Miriam continues on a northward track. This change in the synoptic steering pattern should influence Norman to turn back toward the west or west-northwest by early next week. Only slight along-track speed adjustments were made to this advisory, which follows a blend of the HCCA and TVCN consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 16.5N 121.5W 110 KT 125 MPH 12H 01/0600Z 16.2N 122.6W 100 KT 115 MPH 24H 01/1800Z 16.2N 124.4W 95 KT 110 MPH 36H 02/0600Z 16.6N 127.0W 90 KT 105 MPH 48H 02/1800Z 17.3N 129.9W 85 KT 100 MPH 72H 03/1800Z 18.9N 136.0W 80 KT 90 MPH 96H 04/1800Z 20.0N 141.1W 70 KT 80 MPH 120H 05/1800Z 20.9N 144.7W 65 KT 75 MPH $$ Forecaster Roberts

Tags: number discussion forecast norman

 

Tropical Depression Six Forecast Discussion Number 6

2018-08-31 22:33:35| National Hurricane Center (Atlantic)

Issued at 500 PM AST Fri Aug 31 2018 848 WTNT41 KNHC 312033 TCDAT1 Tropical Depression Six Discussion Number 6 NWS National Hurricane Center Miami FL AL062018 500 PM AST Fri Aug 31 2018 High resolution satellite images reveal that the disturbance has developed a well-defined circulation with a cyclonically curved convective band near the center, and plenty of showers in the southern semicircle. The surface pressure in the Cabo Verde Island of Santiago dropped to 1005 mb at 1800 UTC as the cyclone passed to its south. In addition, Dvorak numbers are gradually increasing, and now support classifying the system as a tropical depression. The depression is becoming better organized, and it will most likely reach tropical storm status in the next several hours. The environmental conditions are favorable for some strengthening during the next 2 to 3 days while the shear is low. Later in the forecast period, the shear is expected to increase, and the SSTs will become marginal halting the strengthing process. The models, primarily the HWRF, are a little less aggressive with the intensity, so the NHC forecast is adjusted slightly downward. Now that the center has formed, we have a better estimate of the initial motion, which is toward the west or 270 degrees at 13 kt. The depression is gradually becoming steered by the flow around the subtropical ridge, and consequently it has increased its forward speed. This prevailing flow pattern should keep the cyclone on a general west to west-northwest track for the next 2 to 3 days. After that time, a weakness in the ridge will induce a more northwestward to north-northwestward track over the open Atlantic Ocean. The track guidance is very consistent with this solution mainly for the next 3 days. Thereafter, the confidence in the track forecast decreases as the guidance envelope widens and becomes bounded by the westernmost ECMWF and the easternmost HWFI. The NHC forecast continues to be in the middle of the envelope and is very close to the corrected consensus HCCA, which has had great skill so far this year. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 13.8N 24.7W 30 KT 35 MPH 12H 01/0600Z 14.3N 26.7W 35 KT 40 MPH 24H 01/1800Z 14.9N 29.2W 40 KT 45 MPH 36H 02/0600Z 15.8N 31.8W 45 KT 50 MPH 48H 02/1800Z 16.5N 34.5W 50 KT 60 MPH 72H 03/1800Z 18.0N 39.5W 55 KT 65 MPH 96H 04/1800Z 20.0N 44.0W 60 KT 70 MPH 120H 05/1800Z 23.0N 48.0W 55 KT 65 MPH $$ Forecaster Avila

Tags: number discussion tropical depression

 

Hurricane Norman Forecast Discussion Number 14

2018-08-31 16:38:59| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Fri Aug 31 2018 619 WTPZ41 KNHC 311438 TCDEP1 Hurricane Norman Discussion Number 14 NWS National Hurricane Center Miami FL EP162018 800 AM PDT Fri Aug 31 2018 Norman appears to be undergoing an eyewall replacement cycle. Although a lack of earlier microwave imagery hasn't helped to support this speculation, enhanced infrared BD-Curve images, however, revealed a collapse of the inner core in the northeast quadrant several hours ago. Currently, that portion of the eyewall has begun to fill in with a solid ring completely surrounding the eye, albeit, rather thin. Consequently, subjective and objective T-numbers, as well as an earlier SATCON analysis, support a slight decrease of the initial intensity to 115 kt. Further slow weakening is forecast through the entire period, although there could be fluctuations in the short-term due to the aforementioned inner core structure evolution. There also appears to be some modest northeasterly shear impinging the northeast portion of the cyclone, which could hamper strengthening. The Decay SHIPS intensity model indicates that the shear will persist during the next couple of days. Through the remaining part of the forecast, decreasing SSTs and the intrusion of a more stable/drier environment from the north should lead to further weakening. The NHC forecast is similar to the previous one, and follows the NOAA-HCCA and IVCN intensity consensus models. The initial motion is estimated to be west-southwest, or 245/7 kt. The cyclone's motion is currently influenced by a northeast-southwest oriented mid-to-upper tropospheric ridge residing between Hurricane Miriam to the west, and Norman to the east. This current motion is expected to continue for the next 36 hours, or so. Afterward, the ridge between the two tropical cyclones is expected to weaken as Miriam continues on a generally northward track. This change in the synoptic steering pattern should cause Norman to turn to the west and then west-northwest with an increase in forward speed. The official forecast has changed little over the past 6 hours and is based on a blend of the HCCA and TVCN consensus models. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 16.7N 120.8W 115 KT 130 MPH 12H 01/0000Z 16.4N 122.0W 105 KT 120 MPH 24H 01/1200Z 16.2N 123.8W 100 KT 115 MPH 36H 02/0000Z 16.3N 125.9W 95 KT 110 MPH 48H 02/1200Z 16.8N 128.6W 90 KT 105 MPH 72H 03/1200Z 18.3N 134.4W 80 KT 90 MPH 96H 04/1200Z 19.5N 140.0W 70 KT 80 MPH 120H 05/1200Z 20.5N 144.0W 60 KT 70 MPH $$ Forecaster Roberts

Tags: number discussion forecast norman

 

Sites : [540] [541] [542] [543] [544] [545] [546] [547] [548] [549] [550] [551] [552] [553] [554] [555] [556] [557] [558] [559] next »