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Tropical Storm NORBERT Forecast Discussion Number 6
2014-09-03 22:56:53| National Hurricane Center (East Pacific)
Issued at 200 PM PDT WED SEP 03 2014 000 WTPZ44 KNHC 032056 TCDEP4 TROPICAL STORM NORBERT DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP142014 200 PM PDT WED SEP 03 2014 Satellite images indicate that Norbert is still on an intensification trend. While no eye is apparent in visible imagery, recent microwave imagery indicates that an eye is trying to form. The cyclone has a long curved band around the southern and western semicircle wrapping into the small central dense overcast. A blend of the subjective and objective Dvorak estimates gives 60 kt as the initial wind speed. It is hard to find a reason why Norbert will not significantly intensify during the next day or so since it will remain over very warm waters, the shear does not appear to be that detrimental, and it already has many features of an inner core. Yet the best model guidance is lower than 6 hours ago, with no forecast above 80 kt for a peak intensity. With so many favorable environmental factors and the low model bias observed this season (and this cyclone), the new NHC forecast will stay close to the previous one. Weakening should begin in a few days when Norbert moves over cooler waters and into the more stable atmosphere of the subtropical eastern Pacific Ocean. After a brief westward track, Norbert appears to be moving more to the west-northwest, or 300/6. Global models are in good agreement on a weakening ridge over northwestern Mexico forcing the storm to move northwestward over the next few days. Model guidance is well clustered on a track offshore of Baja Califoria Sur, except for the GFDL which has a known northward bias in this region. Norbert is still expected to pass close enough to bring tropical- storm-force winds to portions of the state. The new forecast is a little farther south of the previous one during the first 24 hours, mostly because of the earlier westward motion. Little change has been made to the rest of the forecast, which is just to the west of the dynamical track consensus. Moisture from the combination of Norbert and the remnants of Atlantic Tropical Storm Dolly is expected to spread northwestward across northern Mexico during the next couple of days, and into the southwestern United States over the weekend. Heavy rain causing life-threatening flash flooding are possible in those regions. Please see information from your local weather office for more details. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 19.6N 109.2W 60 KT 70 MPH 12H 04/0600Z 20.1N 110.0W 70 KT 80 MPH 24H 04/1800Z 20.9N 110.8W 85 KT 100 MPH 36H 05/0600Z 21.9N 111.6W 90 KT 105 MPH 48H 05/1800Z 23.0N 112.6W 85 KT 100 MPH 72H 06/1800Z 24.5N 114.5W 65 KT 75 MPH 96H 07/1800Z 26.0N 116.7W 45 KT 50 MPH 120H 08/1800Z 28.0N 118.0W 35 KT 40 MPH $$ Forecaster Blake
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