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| #904312 (Received by flhurricane at: 4:58 PM 23.Sep.2017) TCDAT5 Hurricane Maria Discussion Number 31 NWS National Hurricane Center Miami FL AL152017 500 PM EDT Sat Sep 23 2017 Maria`s eye became cloud filled again today, although convective cloud tops have been cooling within the eyewall during the past couple of hours. A NOAA Hurricane Hunter plane conducting a research mission has not yet sampled the entire circulation, but they did report that the central pressure had fallen by a couple of millibars. In addition, a Coyote unmanned aerial vehicle launched by the plane has been measuring winds of 120-125 kt at altitudes of 1200-1300 ft, which supports maximum surface winds of 100 kt. The initial motion remains north-northwestward, or 345/8 kt, but Maria is expected to turn northward by this evening or overnight while moving between a mid-level high near Bermuda and a cut-off low over the northeastern Gulf coast. A blocking ridge sliding eastward over the northeastern U.S. should cause Maria to slow down to a forward motion of 5 kt or less beginning in about 36 hours, lasting through the end of the forecast period. The track models appear to have stabilized for the moment, with this being the first cycle in about a day where they have not shown a significant westward shift. Therefore, the updated NHC track forecast is relatively unchanged from the previous forecast during the first 3 days. The day 4 point was shifted a little closer to the North Carolina coast to be closer to the consensus aids and the Florida State Superensemble, and all the models indicate that a northeastward motion away from the coast should begin by day 5. Vertical shear will remain relatively low over Maria for the next several days, and the hurricane will be moving over warm waters at least for the next 3 days. However, the depth of the thermocline does become more shallow, with oceanic heat content values steadily decreasing over the next 36 hours. With Maria expected to slow down, upwelling of colder water becomes a greater factor, and that could modulate the hurricane`s intensity during the next several days. Maria also could still move over Jose`s cold wake in 4-5 days, which would likely cause additional weakening. The NHC intensity forecast remains just above the intensity consensus, however it should be noted that the normally skillful HCCA model is toward the lower end of the guidance suite. It therefore wouldn`t be surprising if Maria weakened more than shown in the official forecast. KEY MESSAGES: 1. Maria`s forecast track has shifted closer to the U.S. east coast, and it is becoming increasingly likely that some direct impacts will occur along portions of the coast next week. Interests along the coast of the Carolinas and the Mid-Atlantic should monitor the progress of Maria, as tropical storm or hurricane watches may be needed for part of this area on Sunday. 2. Swells from Maria are increasing along the coast of the southeastern United States and are expected to reach the Mid-Atlantic coast tonight and on Sunday. These swells will likely cause dangerous surf and rip currents at the beach through much of next week. For more information, please monitor information from your local National Weather Service office at www.weather.gov. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 26.3N 72.5W 100 KT 115 MPH 12H 24/0600Z 27.6N 72.8W 100 KT 115 MPH 24H 24/1800Z 29.1N 73.1W 100 KT 115 MPH 36H 25/0600Z 30.1N 73.3W 95 KT 110 MPH 48H 25/1800Z 31.1N 73.3W 90 KT 105 MPH 72H 26/1800Z 32.9N 73.3W 80 KT 90 MPH 96H 27/1800Z 34.5N 73.5W 70 KT 80 MPH 120H 28/1800Z 35.0N 72.0W 65 KT 75 MPH $$ Forecaster Berg |
