000 WTNT45 KNHC 230853 TCDAT5 Hurricane Maria Discussion Number 29 NWS National Hurricane Center Miami FL AL152017 500 AM EDT Sat Sep 23 2017 Maria is sending mixed signals regarding its intensity this morning. One one side, the 35 n mi wide eye has become better defined in satellite imagery, and the last report from an Air Force Reserve Hurricane Hunter aircraft indicated that the central pressure had fallen to 952 mb. On the other side, the aircraft-reported winds decreased a little since the previous advisory, with maximum 700-mb flight-level winds of 110 kt and maximum surface wind estimates from the Stepped Frequency Microwave Radiometer near 100 kt. Based on the aircraft winds, the initial intensity is lowered to 105 kt. Various analyses show that Maria is experiencing about 15 kt of southwesterly shear, which is likely the reason for an asymmetric distribution of convection in the eyewall at this time. The hurricane is likely to stay over warm water in an environment of light to moderate shear for the next 36-48 h. The intensity forecast during this time will show some fluctuations in strength, with the forecast lying near the upper edge of the intensity guidance. After 48 h, the forecast track takes Maria over the cold sea surface temperatures left behind by former hurricane Jose, which are below 26C in some areas. This should cause a pronounced weakening, and the new forecast is similar to the old forecast in showing such a trend during this time. The initial motion remains 345/8. Maria is currently being steered by a subtropical ridge to the east of the hurricane and a mid- to upper-level trough over the southeastern United States. This combination should cause a north-northwestward to northward motion for the next couple of days. After that, the ridge is forecast to amplify toward the northwest due to the influence of a mid- to upper-level ridge in the westerlies moving through the northeastern United States. The track guidance has responded to this evolution by shifting westward since the last advisory, with several of the global models now calling for Maria to come close enough to the U. S. east coast to cause direct impacts before the system recurves into the westerlies around 120 h. The latter part of the forecast track is also shifted to the west, but it lies to the east of the consensus models and the center of the guidance envelope. If the current model trends continue, additional westward adjustments to the track forecast will be necessary later today. KEY MESSAGES: 1. Swells from Maria are expected to increase along the coast of the southeastern United States and will likely cause dangerous surf and life-threatening rip currents for the next several days. 3. Maria will likely move between the east coast of the United States and Bermuda by the middle of next week. While the forecast track has moved closer to the U. S. east coast, it is still too soon to determine what, if any, direct impacts there might be in these areas. 4. For more information on the flooding and rip current hazards in the United States, please monitor information from your local National Weather Service forecast office at www.weather.gov. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 24.8N 72.0W 105 KT 120 MPH 12H 23/1800Z 26.0N 72.4W 110 KT 125 MPH 24H 24/0600Z 27.7N 72.7W 110 KT 125 MPH 36H 24/1800Z 29.2N 72.9W 105 KT 120 MPH 48H 25/0600Z 30.3N 73.0W 100 KT 115 MPH 72H 26/0600Z 32.0N 73.0W 85 KT 100 MPH 96H 27/0600Z 34.0N 73.0W 70 KT 80 MPH 120H 28/0600Z 36.0N 71.5W 65 KT 75 MPH $$ Forecaster Beven