je.st
news
Tropical Storm Emilia Forecast Discussion Number 3
2018-06-28 10:55:21| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Thu Jun 28 2018 000 WTPZ41 KNHC 280855 TCDEP1 Tropical Storm Emilia Discussion Number 3 NWS National Hurricane Center Miami FL EP062018 300 AM MDT Thu Jun 28 2018 Convection has steadily increased and become better organized since the previous advisory, especially in the inner-core region. Satellite intensity estimates at 0600 UTC were T2.0/30 kt from both TAFB and SAB, and T2.3/33 kt from UW-CIMSS ADT. Since that time, however, convection near the low-level center has increased, resulting in a steady increase in the raw ADT estimates to T2.5/35 kt. Based on the latter data, the initial intensity is increased to 35 kt at the advisory time, making Emilia the fifth tropical storm so far this season as well as the fifth tropical storm so far during the month of June. The motion estimate is an uncertain 285/13 kt due to uncertainty in the exact location of the low-level center. Passive microwave satellite data, plus extrapolation of the previous motion, were used to locate the center. However, recent GOES-16 nighttime cloud physics satellite data suggest that the center may be developing closer to the ball of strong convection in the southern portion of the north-to-southwest elongated circulation. Having said that, the latest model guidance remains in fair agreement on Emilia moving in a general west-northwestward direction during the next 96 hours, accompanied by a gradual decrease in forward speed. Afterwards, what should be a weakened and more shallow cyclone is expected to be turned westward by a strong subtropical ridge and brisk easterly tradewind flow. The GFS and UKMET models take Emilia more northwestward into the strong subtropical ridge after 72 hours, which seems unlikely. As a result, the new track forecast is similar to the previous advisory, which lies near the southern edge of the guidance envelope and close to a blend of the ECMWF and HWRF models. Emilia's outflow is good to the west but restricted to the east due to near 20 kt of easterly vertical wind shear. The shear is forecast to decrease to around 15 kt by 48 hours and to less than 10 kt by 72 h and beyond. This should allow for some modest strengthening during the next 48 h while the cyclone remains over SSTs greater than 26 deg C. After that time, however, SSTs drop off sharply to less than 25C, and the cooler water temperatures are expected to combine with much drier mid-level to induce a steady weakening trend despite the favorable shear environment. The new NHC intensity forecast is essentially just the same as the previous advisory, and is slightly higher the consensus intensity model IVCN. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 13.8N 111.3W 35 KT 40 MPH 12H 28/1800Z 14.4N 113.1W 35 KT 40 MPH 24H 29/0600Z 15.2N 115.2W 40 KT 45 MPH 36H 29/1800Z 15.9N 117.0W 45 KT 50 MPH 48H 30/0600Z 16.5N 118.8W 50 KT 60 MPH 72H 01/0600Z 17.6N 121.8W 45 KT 50 MPH 96H 02/0600Z 19.1N 125.3W 35 KT 40 MPH 120H 03/0600Z 20.3N 129.8W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics