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Tropical Storm ELIDA Forecast Discussion Number 2

2014-06-30 22:46:32| National Hurricane Center (East Pacific)

Issued at 200 PM PDT MON JUN 30 2014 000 WTPZ45 KNHC 302046 TCDEP5 TROPICAL STORM ELIDA DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052014 200 PM PDT MON JUN 30 2014 Satellite imagery indicates that the overall cloud pattern associated with Elida has changed little, with the main convection displaced in the southeastern quadrant of the circulation due to moderate to strong northwesterly vertical wind shear. Despite the rather disheveled looking cloud appearance, two ASCAT passes at 1606 UTC and 1700 UTC indicated that Elida still possessed a well-defined circulation center and 45-kt winds in the southeastern quadrant. Therefore, the initial intensity is being maintained at 45 kt for this advisory. The initial motion estimate is an uncertain 295/03 kt. The aforementioned ASCAT wind data indicate that Elida has slowed down considerably during the past 6 hours. Most of the reliable models have been predicting that a sharp decrease in the forward speed would occur in previous model runs, so the official forecast has followed this scenario for the next 48 hours since Elida now appears to be caught in a break in the east-west oriented subtropical ridge located across south-central Mexico. It is possible that Elida could even stall and move erratically, but the cyclone and its strongest winds are expected to remain offshore of the coast of Mexico during the next 2 days. After that, the subtropical ridge is forecast to rebuild to the north of the cyclone, which should induce a westward motion at a faster forward speed away from Mexico. The official track forecast is a little south of the previous advisory track, and is close to the multi-model consensus TVCE. Moderate to strong northwesterly vertical wind shear is expected to affect the cyclone for at least the next 3 days, which should prevent any significant intensification from occurring despite the very warm sea-surface temperatures and moist mid-level environment surrounding the storm. By days 4 and 5, however, the shear is forecast to decrease significantly, which should allow for some strengthening of the cyclone. The NHC intensity forecast is similar to the multi-model consensus IVCN for the next 72 hours, and then follows a blend of the SHIPS and LGEM intensity guidance after that. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 17.4N 104.2W 45 KT 50 MPH 12H 01/0600Z 17.6N 104.7W 45 KT 50 MPH 24H 01/1800Z 17.6N 104.9W 45 KT 50 MPH 36H 02/0600Z 17.5N 105.0W 45 KT 50 MPH 48H 02/1800Z 17.2N 104.9W 40 KT 45 MPH 72H 03/1800Z 17.1N 105.6W 40 KT 45 MPH 96H 04/1800Z 17.0N 107.0W 45 KT 50 MPH 120H 05/1800Z 17.2N 110.0W 45 KT 50 MPH $$ Forecaster Stewart

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Tropical Storm ELIDA Forecast Discussion Number 1

2014-06-30 16:59:04| National Hurricane Center (East Pacific)

Issued at 800 AM PDT MON JUN 30 2014 000 WTPZ45 KNHC 301458 TCDEP5 TROPICAL STORM ELIDA DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052014 800 AM PDT MON JUN 30 2014 Conventional and microwave satellite imagery indicate that the low pressure area offshore of the southwestern coast of Mexico has become better organized overnight. First-light visible imagery shows a partially exposed low-level center of circulation on the northwestern edge of a deep convective cloud mass due to strong northwesterly vertical wind shear. In addition, ship A8ER9, the Zim Savannah, reported 50-knot winds somewhat above 10 meters at 0900 UTC in the northwestern quadrant, and then reported 42 kt at 1200 UTC in the southeastern quadrant after it passed through the center. Based primarily on the aforementioned ship data, the initial intensity estimate is set at 45 kt. The initial motion estimate is 310/10. Elida should move northwestward today, parallel to the southwestern coast of Mexico, in response to a weakness in the subtropical ridge extending southwestward from the Gulf of Mexico. However, the forward motion of the storm should markedly decrease after that once the cyclone reaches a col area, with a west-southwestward or southwestward drift shown by global models in a day or two. The subtropical ridge is forecast to rebuild to the north of Elida later in the forecast period, which should allow for Elida to move westward away from the coast at a faster forward speed. The NHC track forecast is close to the multi-model consensus TVCE but not as fast as the ECMWF by day 5. Although the sea surface temperatures are very high along the track of Elida, strong upper-level northwesterly winds associated with an upper-level trough over the Gulf of Mexico should inhibit significant intensification during the next few days. After about 72 hours, the shear is forecast to decrease, but by then the cyclone should be embedded in a somewhat drier and more stable environment. The NHC intensity forecast is near the multi-model consensus IVCN. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 17.3N 103.9W 45 KT 50 MPH 12H 01/0000Z 17.9N 104.2W 45 KT 50 MPH 24H 01/1200Z 18.2N 104.7W 45 KT 50 MPH 36H 02/0000Z 18.1N 104.9W 45 KT 50 MPH 48H 02/1200Z 17.9N 105.0W 45 KT 50 MPH 72H 03/1200Z 17.8N 105.3W 40 KT 45 MPH 96H 04/1200Z 17.6N 106.7W 40 KT 45 MPH 120H 05/1200Z 17.6N 109.3W 40 KT 45 MPH $$ Forecaster Kimberlain

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Tropical Storm DOUGLAS Forecast Discussion Number 8

2014-06-30 16:35:48| National Hurricane Center (East Pacific)

Issued at 800 AM PDT MON JUN 30 2014 000 WTPZ44 KNHC 301434 TCDEP4 TROPICAL STORM DOUGLAS DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042014 800 AM PDT MON JUN 30 2014 Douglas has changed little in organization during the past 6 hours. The cyclone has maintained a broad inner core with most of the convective banding features being well removed from the center. The current intensity has been held at 35 kt, which is in agreement with satellite intensity estimates from TAFB, SAB, and UW-CIMSS ADT. The initial motion estimate is 305/08 kt. There is no significant change to the previous track forecast or reasoning. Douglas is expected to move west-northwestward for the next 48 hours or so toward a weakness in the subtropical ridge to the north of the cyclone, which will result in a gradual decrease in Douglas' forward speed. By late in the forecast period, the ridge is expected to strengthen, which should turn the cyclone more westward as it comes under the influence of moderate low-level trade wind flow. This motion will bring Douglas over cooler waters, causing the cyclone to gradually weaken. The official forecast track is a little to the right of the previous advisory track, but only to account for the more northward initial position. Otherwise, the new forecast track closely follows the multi-model consensus TCVE. Although the vertical wind shear is expected to remain weak at less than 10 kt for the next 3 days or so, the broad inner-core wind field and sea-surface temperatures decreasing to less than 27C argues for only slight intensification over the next couple of days. After that, Douglas will be moving over sub-26C SSTs and into a drier and more stable thermodynamic environment, which should result in steady weakening. The NHC intensity forecast is similar to the previous advisory and follows the consensus model IVCN. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 17.4N 114.0W 35 KT 40 MPH 12H 01/0000Z 18.1N 115.1W 40 KT 45 MPH 24H 01/1200Z 18.7N 115.9W 40 KT 45 MPH 36H 02/0000Z 19.1N 116.6W 40 KT 45 MPH 48H 02/1200Z 19.3N 117.1W 35 KT 40 MPH 72H 03/1200Z 19.5N 117.9W 30 KT 35 MPH 96H 04/1200Z 19.5N 119.1W 25 KT 30 MPH 120H 05/1200Z 19.5N 121.1W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart

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Tropical Storm DOUGLAS Forecast Discussion Number 7

2014-06-30 10:32:30| National Hurricane Center (East Pacific)

Issued at 200 AM PDT MON JUN 30 2014 000 WTPZ44 KNHC 300832 TCDEP4 TROPICAL STORM DOUGLAS DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042014 200 AM PDT MON JUN 30 2014 Douglas has changed little in organization since the last advisory package. The tropical cyclone has some banding features, but continues to have limited deep convection near its center. The current intensity is held at 35 kt in agreement with Dvorak estimates from TAFB, SAB, and data from an ASCAT overpass. This is only slightly below the latest objective Dvorak estimate from UW/CIMSS. Latest center fixes show a considerable deceleration, and the initial motion estimate is 300/8, much slower than previous estimates. Apparently there has been a substantial weakening of the mid-level ridge to the north of Douglas. The global models show a slight weakness in the mid-level ridge to the north of the tropical cyclone for the next 72 hours or so. This should result in an even slower forward motion toward the west-northwest or northwest. Late in the forecast period, the ridge strengthens somewhat to the north of Douglas, and this, along with steering by the low-level flow, should cause the weakening cyclone to turn toward the west with some increase in forward speed. The latest official forecast is slower than the previous one, and quite close to the newest dynamical model consensus. The storm is already moving over slightly cooler waters, but there is well-defined upper-tropospheric outflow over the system. Vertical shear should remain weak for the next few days, and given the favorable dynamics, some strengthening is still forecast. The official wind speed forecast is a little above the latest intensity model consensus, IVCN. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 16.6N 113.1W 35 KT 40 MPH 12H 30/1800Z 17.2N 114.3W 40 KT 45 MPH 24H 01/0600Z 18.0N 115.4W 45 KT 50 MPH 36H 01/1800Z 18.5N 116.2W 45 KT 50 MPH 48H 02/0600Z 18.8N 116.8W 45 KT 50 MPH 72H 03/0600Z 19.0N 117.5W 35 KT 40 MPH 96H 04/0600Z 19.0N 118.5W 30 KT 35 MPH 120H 05/0600Z 19.0N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Pasch

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Tropical Storm DOUGLAS Forecast Discussion Number 6

2014-06-30 04:48:00| National Hurricane Center (East Pacific)

Issued at 800 PM PDT SUN JUN 29 2014 000 WTPZ44 KNHC 300247 TCDEP4 TROPICAL STORM DOUGLAS DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042014 800 PM PDT SUN JUN 29 2014 The satellite appearance of the tropical cyclone has improved during the past several hours. Deep convection has increased near the center and the primary band wraps farther around the southern and southwestern portions of the circulation. Dvorak T-numbers are a consensus 2.5 from TAFB and SAB, and the initial intensity is increased to 35 kt. Douglas becomes the fourth tropical storm of the 2014 eastern North Pacific hurricane season. Although Douglas has recently been moving more westward, the longer-term initial motion estimate is 295 degrees at 14 kt. Douglas is expected to move west-northwestward during the next few days while it remains to the south of a mid- to upper-level ridge that extends from the southwestern United States westward across the eastern Pacific. The ridge is forecast to weaken during the next couple of days which should cause a reduction in forward speed of the tropical cyclone. Later in the period, Douglas should turn westward as it weakens and becomes a more shallow system. Although the track guidance generally agrees with this scenario, there is quite a bit of spread later in the period as to how far north Douglas gets before making the westward turn. For now, the NHC track forecast remains along the southern edge of the model envelope. This is close to the previous advisory and is in good agreement with the latest ECMWF. Environmental conditions are expected to remain conducive for strengthening during the next 24 to 36 hours. The main inhibiting factor is still likely to be the large and sprawling structure of the cyclone. After that time, Douglas will be moving over gradually decreasing sea surface temperatures and into a more stable environment. This should cause gradual weakening and the system is forecast to become a remnant low by the end of the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 16.4N 113.0W 35 KT 40 MPH 12H 30/1200Z 17.0N 114.4W 40 KT 45 MPH 24H 01/0000Z 17.9N 115.7W 45 KT 50 MPH 36H 01/1200Z 18.4N 116.6W 50 KT 60 MPH 48H 02/0000Z 18.6N 117.2W 50 KT 60 MPH 72H 03/0000Z 18.8N 118.2W 40 KT 45 MPH 96H 04/0000Z 18.8N 119.2W 30 KT 35 MPH 120H 05/0000Z 18.8N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown

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