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Hurricane NORBERT Forecast Discussion Number 7
2014-09-04 04:59:23| National Hurricane Center (East Pacific)
Issued at 800 PM PDT WED SEP 03 2014 000 WTPZ44 KNHC 040259 TCDEP4 HURRICANE NORBERT DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP142014 800 PM PDT WED SEP 03 2014 Norbert continues to intensify this evening. Evening visible satellite images showed a symmetric central dense overcast feature with curved convective bands wrapping around the center. The latest Dvorak intensity estimates from TAFB, SAB, and UW/CIMMS ADT were between 65 and 77 kt, and the initial wind speed has been increased to 70 kt for this advisory. Norbert is the ninth hurricane to form in the eastern Pacific basin this season. The outflow has become well established, except over the northeastern portion of the cyclone where there is a hint of light to moderate northeasterly shear. However, the shear is not expected to be strong enough to inhibit strengthening during the next day or so while Norbert remains over warm water. The NHC forecast is close to the SHIPS model through 36 h and is similar to the previous advisory. After that time, Norbert will be approaching cooler waters and a drier and more stable airmass, which should cause weakening to commence. A faster rate of weakening is forecast in 48 to 72 hours when the cyclone moves over SSTs below 26C. The hurricane appears to have turned northwestward with an initial motion of 305/7 kt. Norbert should continue on a general northwestward motion during the next several days around the southwestern periphery of a mid-level ridge that extends westward across northern Mexico. The model guidance is in good agreement on the general heading of the cyclone, although there are some differences in the forward speed of Norbert later in the period. Much of the guidance now indicates a faster forward speed late in the period, with the GFS showing a deeper cyclone moving even faster and farther north than the ECMWF, UKMET, and HWRF. The updated NHC track forecast is a little faster than the previous advisory to be in better agreement with the multi-model consensus, but is not nearly as fast as the GFS. Moisture indirectly related to Norbert being pulled northward around the eastern side of cyclone's large circulation is expected to spread across northern Mexico and into the southwestern United States during the next few days. This could result in heavy rains and life-threatening flash flooding in these areas. Please see information from your local weather office for more details. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 19.9N 109.8W 70 KT 80 MPH 12H 04/1200Z 20.7N 110.5W 80 KT 90 MPH 24H 05/0000Z 21.7N 111.4W 85 KT 100 MPH 36H 05/1200Z 22.8N 112.5W 85 KT 100 MPH 48H 06/0000Z 23.7N 113.4W 75 KT 85 MPH 72H 07/0000Z 25.3N 115.5W 55 KT 65 MPH 96H 08/0000Z 27.0N 117.5W 35 KT 40 MPH 120H 09/0000Z 29.0N 118.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown
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