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Tropical Storm ERIKA Forecast Discussion Number 2
2015-08-25 10:38:23| National Hurricane Center (Atlantic)
Issued at 500 AM AST TUE AUG 25 2015 000 WTNT45 KNHC 250838 TCDAT5 TROPICAL STORM ERIKA DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052015 500 AM AST TUE AUG 25 2015 The cloud pattern of Erika has not changed much overnight, with the convection located near the center and in the southern semicircle. The latest Dvorak estimates are T2.5/35 kt from TAFB and SAB, and the initial intensity remains 40 kt based on the earlier buoy data. Erika will be moving over warming SSTs with light to moderate shear for the next 36 to 48 hours, and the NHC forecast shows steady intensification during this time. After that, Erika could encounter increasing westerly shear due to interaction with an upper-level low near Hispaniola and there is the potential for land interaction with the Greater Antilles. The HWRF and LGEM models show more strengthening during this time, while the GFDL and SHIPS models are less aggressive. There is also disagreement among the global models. The GFS weakens Erika to a trough by 5 days while the ECMWF has trended stronger and the UKMET continues to show a more robust cyclone. The NHC intensity forecast has been adjusted upward a bit at days 4 and 5 and is close to or a bit below the IVCN intensity consensus. Due to the large spread in the guidance, the intensity forecast at days 3-5 is of even lower confidence than usual. The initial motion estimate of 275/17 is based largely on continuity, given the difficulty locating the center with infrared imagery. The track guidance is in good agreement through 36 hours, as Erika should be steered westward to west-northwestward south of the subtropical ridge. At 48 hours and beyond, there are two distinct camps of track guidance. The UKMET, HWRF, and GFDL show a deeper system that moves northwestward, while the GFS, ECMWF, and GEFS ensemble mean show a weaker cyclone and a more west- northwestward motion. The NHC forecast has been nudged a bit to the right this cycle and remains close to the ECMWF and GEFS ensemble mean. This track is to the right of the GFS but well left of the TVCA multi-model consensus. Given the divergence in the guidance, confidence in the track forecast late in the period is low. Based on the new forecast, Tropical Storm Watches have been issued for portions of the Lesser Antilles. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 14.6N 49.4W 40 KT 45 MPH 12H 25/1800Z 15.2N 51.9W 45 KT 50 MPH 24H 26/0600Z 16.0N 54.8W 50 KT 60 MPH 36H 26/1800Z 16.9N 57.9W 55 KT 65 MPH 48H 27/0600Z 17.6N 61.0W 60 KT 70 MPH 72H 28/0600Z 19.3N 66.2W 60 KT 70 MPH 96H 29/0600Z 21.5N 71.0W 65 KT 75 MPH 120H 30/0600Z 24.0N 75.0W 70 KT 80 MPH $$ Forecaster Brennan
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Tropical Depression TWELVE-E Forecast Discussion Number 2
2015-08-25 10:34:21| Tropical Depression LIDIA
Issued at 200 AM PDT TUE AUG 25 2015
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depression
Tropical Storm ERIKA Forecast Discussion Number 1
2015-08-25 04:47:05| National Hurricane Center (Atlantic)
Issued at 1100 PM AST MON AUG 24 2015 000 WTNT45 KNHC 250246 TCDAT5 TROPICAL STORM ERIKA DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052015 1100 PM AST MON AUG 24 2015 Satellite imagery, buoy observations, and a very recent ASCAT pass suggest that the circulation associated with the area of low pressure over the tropical Atlantic has become better defined. Deep convection also became better organized during the afternoon and has persisted in a band over the southeastern portion of the circulation this evening. The NOAA buoy reported peak south- southwesterly winds of 39 kt, and a minimum pressure of 1004 mb. Based on these data, advisories are being initiated on a 40-kt tropical storm. Erika becomes the 5th tropical storm of the 2015 Atlantic hurricane season. During the next couple of days, Erika will be moving through an environment characterized by warm water, a moist air mass, and generally low vertical wind shear. These factors should allow strengthening. After 48 hours, Erika will be approaching an upper-level low/trough that is forecast to be near Hispaniola, which is expected to cause an increase in westerly wind shear. The NHC intensity forecast calls for steady intensification during the next 48 hours, and is close to the SHIPS model and intensity consensus. After that time, the intensity guidance diverges with the statistical guidance and the HWRF bringing Erika to hurricane strength. Meanwhile, the ECMWF and GFS weaken the system in about 3 days, due to the increasing shear. The NHC intensity forecast is between these scenarios and shows no change in strength after 48 hours. Due to the large spread in the intensity guidance, the intensity forecast at days 3-5 is of low confidence. Erika is moving quickly westward across the tropical Atlantic or 275/17 kt. The tropical cyclone is forecast to move westward to west-northwestward to the south of a deep-layer ridge over the central Atlantic during the next few days. The forward speed of Erika should gradually decrease as the cyclone nears the western portion of the ridge. The track guidance is tightly clustered through 72 hours, with more spread after that time. The bifurcation appears to be the result of the future strength of Erika. The models that have a deeper depiction of the cyclone show more of a northwestward turn late in the period, while the models that weaken Erika indicate a more westward motion. The NHC forecast is close to the ECMWF and GFS ensemble mean, which is south of the consensus but not as far south as the GFS. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 14.4N 47.7W 40 KT 45 MPH 12H 25/1200Z 14.9N 50.1W 45 KT 50 MPH 24H 26/0000Z 15.8N 53.3W 50 KT 60 MPH 36H 26/1200Z 16.5N 56.4W 55 KT 65 MPH 48H 27/0000Z 17.1N 59.6W 60 KT 70 MPH 72H 28/0000Z 18.5N 64.5W 60 KT 70 MPH 96H 29/0000Z 20.5N 69.5W 60 KT 70 MPH 120H 30/0000Z 22.0N 73.0W 60 KT 70 MPH $$ Forecaster Brown
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Tropical Depression TWELVE-E Forecast Discussion Number 1
2015-08-25 04:43:59| Tropical Depression LIDIA
Issued at 800 PM PDT MON AUG 24 2015
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Remnants of DANNY Forecast Discussion Number 25
2015-08-24 16:39:44| National Hurricane Center (Atlantic)
Issued at 1100 AM AST MON AUG 24 2015 000 WTNT44 KNHC 241439 TCDAT4 REMNANTS OF DANNY DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 AM AST MON AUG 24 2015 Although an Air Force Hurricane Hunter aircraft found a few light westerly winds, they were neither strong nor extensive enough to support the existence of a well-defined circulation. In addition, surface synoptic data from the Lesser Antilles suggest that the system has degenerated into a trough. The system also lacks sufficient organized deep convection to qualify as a tropical cyclone. Therefore, this is the last advisory on Danny. The remnants of Danny should continue to move westward over the northeastern Caribbean, and global model guidance show the system losing its identity within 48 hours or less. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web at http://www.opc.ncep.noaa.gov/shtml/NFDHSFAT1.shtml. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 16.0N 62.0W 25 KT 30 MPH...REMNANTS 12H 25/0000Z...DISSIPATED $$ Forecaster Pasch
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