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Tropical Depression FIFTEEN-E Forecast Discussion Number 2
2015-09-06 10:56:09| National Hurricane Center (East Pacific)
Issued at 300 AM MDT SUN SEP 06 2015 000 WTPZ45 KNHC 060856 TCDEP5 TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL EP152015 300 AM MDT SUN SEP 06 2015 Deep convection associated with the depression has increased in coverage overnight, but the overall organization of the cyclone has not changed very much. The center appears to be located near the eastern edge of the deep convection due to moderate northeasterly shear. An ASCAT overpass at 0416 UTC was very helpful in locating the center and revealed wind speeds of around 30 kt, which is used as the initial intensity for this advisory. The shear is forecast to decrease during the next 24 hours, which should allow for steady strengthening, and the depression is likely to become a tropical storm very soon. The cyclone is expected to remain in a favorable environment through late Tuesday, and the NHC forecast calls for the system to become a hurricane within the next couple of days. This is supported by the SHIPS and LGEM models. After 72 hours, decreasing sea surface temperatures and increasing shear should cause weakening by days 4 and 5. The depression is moving northwestward at about 10 kt. The cyclone is expected to continue moving northwestward over the next 3 to 4 days while it remains on the southwestern side of a mid-level ridge over Mexico. The models are in relatively good agreement on this scenario, but have trended a little northward after 72 hours and indicate a faster forward motion through much of the forecast period. As a result, the new NHC forecast is faster than the previous advisory, and has also been nudged northward after 48 hours. The new forecast lies along the southern edge of the guidance envelope in best agreement with the GFS. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 13.7N 108.3W 30 KT 35 MPH 12H 06/1800Z 14.9N 109.5W 40 KT 45 MPH 24H 07/0600Z 16.4N 111.1W 50 KT 60 MPH 36H 07/1800Z 18.2N 112.8W 60 KT 70 MPH 48H 08/0600Z 19.7N 114.2W 65 KT 75 MPH 72H 09/0600Z 21.7N 116.4W 65 KT 75 MPH 96H 10/0600Z 23.0N 118.5W 55 KT 65 MPH 120H 11/0600Z 24.0N 122.0W 45 KT 50 MPH $$ Forecaster Brown
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Tropical Storm GRACE Forecast Discussion Number 4
2015-09-06 10:40:07| National Hurricane Center (Atlantic)
Issued at 500 AM AST SUN SEP 06 2015 000 WTNT42 KNHC 060840 TCDAT2 TROPICAL STORM GRACE DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 500 AM AST SUN SEP 06 2015 Deep convection has become better organized during the past several hours, with a more pronounced curved band developing to the west and south of the center. Recent microwave imagery, especially a 0331 UTC GCOM pass, showed a surprisingly well-organized inner core, with the low-level center located a little farther south than previous estimates. Subjective Dvorak estimates are T3.0/45 kt from TAFB and T2.5/35 kt from SAB, and the initial intensity is therefore raised to 40 kt. If Grace is as well organized as suggested by the microwave data, this intensity could be conservative. With the slight southward adjustment of the initial position, the estimated motion is now 270/11 kt. Grace is located due south of a mid-tropospheric anticyclone, and a ridge axis extends westward across the Atlantic to north of the Lesser Antilles. This pattern is expected to change little during the forecast period, which should keep Grace on a general westward path through day 5. The guidance is in generally good agreement, and the updated NHC track is shifted a little bit south of the previous forecast, mainly to account for the adjusted initial position. This solution is a bit south of the TVCN model consensus and leans closest to the GFS, HWRF, and the Florida State Superensemble. Grace will be moving through a low-shear environment for the next 36 to 48 hours, which is likely to support additional strengthening while it moves westward over the tropical eastern Atlantic. Between days 3 through 5, while Grace is moving over the central tropical Atlantic, vertical shear is forecast to increase to over 20 kt and veer from southwesterly to westerly by the end of the forecast period. Such a hostile environment should induce weakening beginning on day 3. The new NHC intensity forecast indicates continued gradual strengthening through 36 hours while the shear is low and shows a slightly higher peak intensity than the previous forecast. Weakening could be fast once the shear sets in, and the day 4 and 5 intensities are unchanged from before. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 12.4N 28.5W 40 KT 45 MPH 12H 06/1800Z 12.6N 30.8W 45 KT 50 MPH 24H 07/0600Z 12.8N 33.6W 50 KT 60 MPH 36H 07/1800Z 13.1N 36.3W 55 KT 65 MPH 48H 08/0600Z 13.4N 39.1W 55 KT 65 MPH 72H 09/0600Z 14.0N 44.7W 50 KT 60 MPH 96H 10/0600Z 14.5N 50.5W 40 KT 45 MPH 120H 11/0600Z 15.5N 55.5W 35 KT 40 MPH $$ Forecaster Berg
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Tropical Depression FRED Forecast Discussion Number 30
2015-09-06 10:37:42| National Hurricane Center (Atlantic)
Issued at 500 AM AST SUN SEP 06 2015 000 WTNT41 KNHC 060837 TCDAT1 TROPICAL DEPRESSION FRED DISCUSSION NUMBER 30 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062015 500 AM AST SUN SEP 06 2015 Thunderstorm activity has continued to pulse near the center of Fred overnight, however, strong northwesterly shear is causing the cloud tops to be quickly shunted southeastward. The initial intensity is maintained at 30 kt, which is in agreement with a Dvorak T-number of 2.0 from TAFB. Little overall change in strength is expected today. In 24 to 36 hours the shear is expected to diminish, which could allow a brief opportunity for Fred to restrengthen. After that time, the cyclone is expected to enter an area of stronger westerly upper-level winds and cooler SSTs, which should halt further intensification. Late in the period, strong shear and marginal SSTs should cause weakening. An alternate scenario shown by the ECMWF is for the shear to cause Fred to weaken and become a trough of low pressure within the next 12 to 24 hours. Fred has finally made its much anticipated northward turn. A turn toward the northeast should occur later today as the cyclone is steered around the western periphery of a low-level ridge to its northeast. A turn toward the east and then southeast are forecast late in the period as a high pressure ridge builds to the north of the cyclone. The new NHC track is similar to the previous advisory and is in best agreement with the 0000 UTC GFS model. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 24.9N 43.2W 30 KT 35 MPH 12H 06/1800Z 26.0N 43.0W 25 KT 30 MPH 24H 07/0600Z 27.5N 41.9W 25 KT 30 MPH 36H 07/1800Z 29.2N 40.1W 30 KT 35 MPH 48H 08/0600Z 30.5N 38.5W 35 KT 40 MPH 72H 09/0600Z 32.2N 36.0W 35 KT 40 MPH 96H 10/0600Z 32.5N 33.5W 35 KT 40 MPH 120H 11/0600Z 31.5N 32.0W 30 KT 35 MPH $$ Forecaster Brown
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Tropical Depression FRED Forecast Discussion Number 29
2015-09-06 04:45:07| National Hurricane Center (Atlantic)
Issued at 1100 PM AST SAT SEP 05 2015 000 WTNT41 KNHC 060245 TCDAT1 TROPICAL DEPRESSION FRED DISCUSSION NUMBER 29 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062015 1100 PM AST SAT SEP 05 2015 After being devoid of convection for about the past 12 hours, a new burst of thunderstorms has begun near the center of Fred. Cirrus clouds motions suggest that shear remains fairly strong near the center of Fred, although seemingly less than this time yesterday. The initial intensity will remain 30 kt, in line with the TAFB satellite estimate. Shear is expected to diminish in about a day, which could allow the cyclone to reintensify around that time while it moves over warm waters. However, any intensification is expected to be short-lived with marginal water temperatures and increasing shear likely by Wednesday. The NHC forecast is close to the previous one through 48 h, and is reduced a little bit at long range to reflect the less favorable conditions. Fred is moving northwestward at about 9 kt into a break in the subtropical ridge. The depression should turn to the north and then northeast during the day on Sunday while the cyclone moves on the northwestern side of the ridge, with that motion expected to continue for a couple of days. Model guidance is generally faster during this time, and the new offical forecast is faster than the previous one. The cyclone could turn then eastward and southeastward on days 4 and 5 due to ridging building over the northeastern Atlantic. The track forecast is of low confidence at long range due to considerable uncertainty about the strength of the tropical cyclone and the evolution of the ridge. There have not been any big changes to the model consensus, so the official forecast is basically an update of the previous one at 96 and 120 hours. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 24.1N 43.1W 30 KT 35 MPH 12H 06/1200Z 24.8N 43.3W 25 KT 30 MPH 24H 07/0000Z 26.4N 42.5W 25 KT 30 MPH 36H 07/1200Z 28.0N 41.0W 30 KT 35 MPH 48H 08/0000Z 29.5N 39.2W 35 KT 40 MPH 72H 09/0000Z 32.0N 36.0W 35 KT 40 MPH 96H 10/0000Z 32.5N 33.0W 35 KT 40 MPH 120H 11/0000Z 31.5N 31.5W 35 KT 40 MPH $$ Forecaster Blake
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Tropical Storm GRACE Forecast Discussion Number 3
2015-09-06 04:44:10| National Hurricane Center (Atlantic)
Issued at 1100 PM AST SAT SEP 05 2015 000 WTNT42 KNHC 060244 TCDAT2 TROPICAL STORM GRACE DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 1100 PM AST SAT SEP 05 2015 Most of the deep convection associated with Grace is located west and southwest of the estimated center position, consistent with light-to-moderate easterly shear analyzed over the cyclone by UW-CIMSS and the SHIPS model. The initial intensity remains 35 kt based on the latest Dvorak classifications from TAFB and SAB. Grace will be moving over warm waters and in a low shear environment for the next 24 to 36 hours, which should support some strengthening. After that time, the shear becomes westerly and increases with the cyclone moving over slightly cooler waters. As a result, much of the intensity guidance suggests that Grace will weaken later in the period, with dissipation also possible. The new NHC intensity forecast is similar to the previous one and is close to the latest IVCN intensity consensus. The initial motion estimate is 280/12. Grace should continue moving generally westward to west-northwestward to the south of a subtropical ridge for the next several days. The track model guidance is in good agreement on this scenario, although there is some variability in forward speed. The new NHC track forecast is an update of the previous one and lies a little south of the consensus given that Grace is forecast to be weaker by the end of the period. This track is close to the latest predictions from the GFS model and the FSU Superensemble. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 12.8N 27.5W 35 KT 40 MPH 12H 06/1200Z 13.0N 29.5W 40 KT 45 MPH 24H 07/0000Z 13.3N 32.3W 45 KT 50 MPH 36H 07/1200Z 13.6N 35.1W 50 KT 60 MPH 48H 08/0000Z 14.1N 38.0W 45 KT 50 MPH 72H 09/0000Z 14.8N 44.2W 45 KT 50 MPH 96H 10/0000Z 15.3N 49.5W 40 KT 45 MPH 120H 11/0000Z 16.0N 54.5W 35 KT 40 MPH $$ Forecaster Brennan
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