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Tropical Depression Fifteen-E Forecast Discussion Number 3

2017-09-12 10:38:24| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Tue Sep 12 2017 000 WTPZ45 KNHC 120838 TCDEP5 Tropical Depression Fifteen-E Discussion Number 3 NWS National Hurricane Center Miami FL EP152017 200 AM PDT Tue Sep 12 2017 Shortwave and BD-curve infrared imagery earlier showed a deep convective burst with -70C cold tops near the surface center. That convective mass has since been displaced about 90 miles west of the exposed center and has warmed and diminished. Therefore, the initial intensity is held at 25 kt and agrees with the Dvorak intensity estimates from SAB and TAFB. The intensity forecast has become a bit problematic. Earlier SHIPS model runs indicated that the shear would either persist or increase. The latest run, however, reveals the shear decreasing considerably after 48 hours. On the other hand, the GFS, ECMWF, and the LGEM intensity guidance all show the depression gradually weakening and becoming a remnant low in 5 days or less, while the UKMET strengthens the cyclone to a tropical storm around day 3. A third scenario is indicated in the HFIP Corrected Consensus (HCCA) technique, which is similar to the GFS, ECMWF and the LGEM, but shows dissipation in less than 48 hours. The NHC forecast reflects some increase in intensity at the 24 hour period, but after that time, it shows weakening to a remnant low in 3 days, out of respect for the GFS and ECMWF global models, the LGEM, and the HFIP Corrected Consensus (HCCA) technique. The motion is estimated to be westward, or 260/13 kt. A low- to mid-level subtropical ridge extending over the eastern Pacific from the Baja California peninsula is forecast to build slightly southwestward later today influencing the depression to turn west-southwestward. At the 36 hour period, the cyclone should gradually turn back toward the west followed by a northwestward motion around 72 hours in response to an increasing weakness in the ridge along 123W. Around day 4, the depression is forecast to turn back toward the west within the low-level trade wind flow. The official forecast is slightly south of the previous forecast and is in the middle of the ECMWF and HCCA solutions. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 15.8N 115.1W 25 KT 30 MPH 12H 12/1800Z 15.5N 116.9W 25 KT 30 MPH 24H 13/0600Z 15.1N 118.8W 30 KT 35 MPH 36H 13/1800Z 15.1N 120.4W 30 KT 35 MPH 48H 14/0600Z 15.3N 121.6W 25 KT 30 MPH 72H 15/0600Z 15.9N 123.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 16/0600Z 15.9N 125.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 17/0600Z...DISSIPATED $$ Forecaster Roberts

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Hurricane Jose Forecast Discussion Number 28

2017-09-12 10:36:52| National Hurricane Center (Atlantic)

Issued at 500 AM AST Tue Sep 12 2017 000 WTNT42 KNHC 120836 TCDAT2 Hurricane Jose Discussion Number 28 NWS National Hurricane Center Miami FL AL122017 500 AM AST Tue Sep 12 2017 Jose continues to be affected by 20 kt of northerly vertical shear, and recent microwave imagery shows that the low-level center is to the northeast or north of a large burst of convection that shows little evidence of banding. While satellite intensity estimates have changed little since the last advisory, the sheared appearance suggests the cyclone has continued to weaken, and the initial intensity is thus reduced to 65 kt in best agreement with the CIMSS satellite consensus. The hurricane appears to have turned eastward with an initial motion of 090/5. As a mid-level ridge first builds around and then moves northeast of the cyclone, the track guidance forecasts Jose to make an anticyclonic half-loop during the next 72 h. After that time, the confidence in the forecast decreases as the guidance diverges significantly. One the right side, the ECMWF and Canadian models forecast a turn toward the north and northeast, while on the left side the UKMET forecasts a westward motion towards the Bahamas. The GFS, HWRF, and the various consensus models are between these extremes in forecasting a turn toward the northwest and eventually north-northwest. The new forecast track is in best agreement with these models and shifts slightly to the right of the previous advisory by 120 h. A strong upper-level anticyclone near 28N 74W is the source of the current shear. As mentioned in the previous advisory, this feature is supposed to weaken and pass north of the cyclone without allowing much decrease in the shear through 48 h. The large-scale models then suggest the possibility of lighter shear from 48-72 h, followed by increasing shear as Jose encounters an upper-level trough moving eastward from the southeastern United States. Overall, the intensity guidance shows small fluctuations in strength during the forecast period, and there is little agreement in the guidance on the timing of the various ups and downs. The intensity forecast will follow the shear trends in calling for some additional weakening during the next 12-24 h, modest re-intensification during the lighter shear, and no change during the subsequent increase in shear. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 27.5N 69.0W 65 KT 75 MPH 12H 12/1800Z 27.5N 68.0W 60 KT 70 MPH 24H 13/0600Z 26.9N 66.5W 60 KT 70 MPH 36H 13/1800Z 26.0N 66.0W 60 KT 70 MPH 48H 14/0600Z 25.3N 66.3W 65 KT 75 MPH 72H 15/0600Z 25.5N 69.0W 70 KT 80 MPH 96H 16/0600Z 27.5N 72.5W 70 KT 80 MPH 120H 17/0600Z 30.0N 74.0W 70 KT 80 MPH $$ Forecaster Beven

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Hurricane Jose Forecast Discussion Number 27

2017-09-12 04:59:35| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Mon Sep 11 2017 000 WTNT42 KNHC 120259 TCDAT2 Hurricane Jose Discussion Number 27 NWS National Hurricane Center Miami FL AL122017 Issued by the NWS Weather Prediction Center College Park MD 1100 PM AST Mon Sep 11 2017 Jose remains resilient in the face of 25 kts of northeasterly shear, with a new burst of deep convection near the center giving the system a slightly better satellite presentation over the last couple of hours. Even so, the convection is pulsing, and satellite based intensity estimates support lowering the initial intensity estimate to 75 kt for this advisory. Due to some uncertainty as to the center location, the initial motion for this advisory is approximated to be 045/05 kts. Latest round of forecast guidance is consistent with the ongoing forecast philosophy, with Jose expected to complete an anticyclonic or clockwise loop over the next 3 days. A mid-level ridge to the southeast of Jose will shift west then northwest of Jose, leading to a southeastward motion on Tuesday and Wednesday. As the ridge shifts to the north of the cyclone, Jose will briefly stall before resuming a more typical track toward the west and northwest on days 4 and 5. Even with such a complex track expected to evolve, there is good agreement amongst most of the model guidance. The latest official forecast is very close to the previous one, nudged only slightly northward toward the FSSE and other consensus members, but left of the GFS and ECMWF ensemble means. UKMET and its ensemble mean continue to be on the southwest side of the guidance cone, and these outliers therefore have little impact on the official track forecast at this time. The shear that Jose is encountering is associated with an upper-level ridge centered to the northwest, and even as this feature weakens the next day or so, moderate shear is forecast persist as Jose remains over 29C water. These conflicting inputs are expected to lead to little change in intensity through day 3, with some potential for Jose to intensify toward the end of the forecast period as shear relaxes as Jose moves away from its own cold wake. The latest intensity forecast is of low confidence at this time due to the above factors and keeps Jose a hurricane through the forecast period, and closely resembles SHIPS and IVCN intensity guidance. The National Hurricane Center in Miami will resume issuance of advisories for Jose at the next forecast cycle. Thanks to the Weather Prediction Center, NWS Forecast offices, supporting staff and many participating partners for ensuring a successful continuity of operations during the past several days. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 27.1N 69.5W 75 KT 85 MPH 12H 12/1200Z 27.5N 69.0W 70 KT 80 MPH 24H 13/0000Z 27.1N 67.6W 70 KT 80 MPH 36H 13/1200Z 26.0N 66.5W 70 KT 80 MPH 48H 14/0000Z 25.4N 66.3W 65 KT 75 MPH 72H 15/0000Z 25.3N 68.7W 65 KT 75 MPH 96H 16/0000Z 27.0N 72.0W 70 KT 80 MPH 120H 17/0000Z 29.5N 75.0W 75 KT 85 MPH $$ Forecaster Birchard/Roth/Sisko

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Tropical Depression Fifteen-E Forecast Discussion Number 2

2017-09-12 04:31:22| National Hurricane Center (East Pacific)

Issued at 900 PM MDT Mon Sep 11 2017 000 WTPZ45 KNHC 120231 TCDEP5 Tropical Depression Fifteen-E Discussion Number 2 NWS National Hurricane Center Miami FL EP152017 900 PM MDT Mon Sep 11 2017 The tropical depression remains sheared, and convection has decreased since this afternoon. The initial intensity has been held at 25 kt based on a blend of the most recent TAFB and SAB Dvorak classifications. Little change in intensity is forecast for the next few days. The GFS and ECMWF both indicate that the strong easterly wind shear will not decrease for the next 36 to 48 hours, which should prevent significant strengthening and could cause the cyclone to quickly become a remnant low. After that time, the forecast becomes more complicated since the depression, or its remnants, may interact with another surface low pressure system forecast to develop over the open East Pacific. As a result of this proximity, some of the model trackers depict strengthening near the end of the forecast period. Because most of the models depict the other developing low as the dominant system in any potential interaction, I am electing to discount that possibility for now. The official forecast instead shows the depression becoming a remnant low within 72 hours, and dissipating entirely sometime after 96 h, similar to the previous advisory. The depression is moving just south of due west at 13 kt. The low- to mid-level components of a ridge located to the north should keep the cyclone moving generally westward through the forecast period, until it dissipates. The ECMWF solution seems to be the most reasonable of the dynamical models because it keeps the depression separate from any other developing low pressure systems. The new official forecast track is therefore most similar to the ECMWF, and is not significantly different from the previous forecast. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 16.2N 113.6W 25 KT 30 MPH 12H 12/1200Z 15.9N 115.2W 30 KT 35 MPH 24H 13/0000Z 15.4N 117.2W 30 KT 35 MPH 36H 13/1200Z 15.2N 119.0W 25 KT 30 MPH 48H 14/0000Z 15.3N 120.4W 25 KT 30 MPH 72H 15/0000Z 16.0N 122.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 16/0000Z 16.5N 124.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 17/0000Z...DISSIPATED $$ Forecaster Zelinsky

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Hurricane Jose Forecast Discussion Number 26

2017-09-11 23:07:04| National Hurricane Center (Atlantic)

Issued at 500 PM AST Mon Sep 11 2017 000 WTNT42 KNHC 112106 TCDAT2 Hurricane Jose Discussion Number 26 NWS National Hurricane Center Miami FL AL122017 Issued by the NWS Weather Prediction Center College Park MD 500 PM AST Mon Sep 11 2017 Jose is a very messy looking hurricane late this afternoon. Persistent northeast shear of 20 to 25 knots has eradicated the central features of the system, leaving a fairly amorphous blob of intermittent, bursting convection. The satellite intensity estimates came in at 4.3 from ADT, 4.5 from SAB, and 5.0 from TAFB. The initial intensity was lowered to 85 kt, which is probably generous given the recent rapid degradation in the satellite presentation. The best guess at an initial motion is 350/10. Jose is expected to slowly complete an anticyclonic or clockwise loop over the next few days, as a mid-level high to the southeast of Jose builds southwest of the tropical cyclone in about 24 hours, then to the west of it in 36 to 48 hours, and northeast of it in about 3 days. By days 4 to 5 the high becomes more well established, and Jose will increase speed a bit as it emerges from the loop and treks toward the west-northwest. The guidance is tightly clustered through the next few days, but diverges a bit in days 4 and 5, with more recent runs showing Jose gaining a bit more latitude in the longer time ranges. Have nudged the forecast track a little farther north toward the GFEX, but the official track remains close to the consensus guidance. There seems to be better agreement in the models regarding the magnitude of the northerly shear, which is expected to continue to weaken the cyclone for the next few days despite warm SSTs. Jose is also expected to cross it's own wake in a few days which also will be unfavorable for strengthening. In the 4 to 5 day period, the models suggest the shear may relax enough to allow for some re-intensification of Jose, but confidence at this point is rather low. Our intensity forecast closely follows the statistical models, and is near the lower end of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 26.4N 69.2W 85 KT 100 MPH 12H 12/0600Z 27.2N 69.0W 80 KT 90 MPH 24H 12/1800Z 27.0N 67.7W 75 KT 85 MPH 36H 13/0600Z 26.3N 66.7W 70 KT 80 MPH 48H 13/1800Z 25.3N 66.1W 70 KT 80 MPH 72H 14/1800Z 24.4N 68.6W 65 KT 75 MPH 96H 15/1800Z 26.0N 71.6W 70 KT 80 MPH 120H 16/1800Z 28.1N 74.5W 75 KT 85 MPH $$ Forecaster R Ballard

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