10:00 am National Hurricane Center update: The low pressure area over the northern Gulf of Mexico has become better organized during the past several hours, with a large convective band in the southern semicircle. The circulation center has also become better defined, although it is still elongated and multiple cloud swirls are seen rotating around the mean center. In addition, Air Force Reserve and NOAA Hurricane Hunter aircraft report flight-level and SFMR winds high enough for an initial intensity of 35 kt. Based on these developments, the system is upgraded to Tropical Storm Barry.
The initial motion is a rather uncertain 270/4. Barry is being steered by a weak low- to mid-level ridge to the north, and a weakness in the ridge is forecast to develop during the next 24-48 hours. This should allow the cyclone to turn northwestward and eventually northward. However, there is a large spread in the track guidance. The HWRF and HMON forecast Barry to move almost due north from its current position with a landfall in Mississippi, while the UKMET takes the cyclone to the upper Texas coast. The GFS, ECMWF, and Canadian models lie between these extremes. Overall, there has been a slight eastward shift of the guidance envelope, so the new forecast track is also adjusted slightly to the east. It should be noted, though, that the new track is west of the consensus models.
Barry is being affected by northerly shear, and water vapor imagery indicates mid- to upper-level dry air moving into the cyclone from the northeast. Some moderate shear is now expected to persist until the cyclone makes landfall. Despite this less than ideal environment, the guidance forecasts slow but steady intensification, so the NHC forecast follows this trend. The new intensity forecast is similar to the previous one in calling for Barry to become a hurricane just before landfall in Louisiana, and it lies between the HCCA and ICON consensus models.
Key Messages:
1. Barry is expected to bring storm surge, rainfall, and wind hazards to the central Gulf Coast during the next several days.
2. There is a danger of life-threatening storm surge inundation along the coast of southern and southeastern Louisiana where a Storm Surge Warning has been issued. The highest storm surge inundation is expected between the Mouth of the Atchafalaya River and Shell Beach. Residents in these areas should listen to any advice given by local officials.
3. A Tropical Storm Warning and Hurricane Watch are in effect for much of the Louisiana coast and additional watches and warnings could be required later today. Residents in these areas should ensure they have their hurricane plan in place.
4. The slow movement of this system will result in a long duration heavy rainfall threat along the central Gulf Coast and inland through the lower Mississippi Valley through the weekend and potentially into early next week. Flash flooding and river flooding will become increasingly likely, some of which may be significant, especially along and east of the track of the system.
FORECAST POSITIONS AND MAX WINDS
INIT 11/1500Z 27.8N 88.7W 35 KT 40 MPH
12H 12/0000Z 27.8N 89.3W 35 KT 40 MPH
24H 12/1200Z 28.1N 90.0W 45 KT 50 MPH
36H 13/0000Z 28.6N 90.8W 55 KT 65 MPH
48H 13/1200Z 29.4N 91.4W 65 KT 75 MPH
72H 14/1200Z 32.0N 91.8W 30 KT 35 MPH…INLAND
96H 15/1200Z 34.5N 91.5W 25 KT 30 MPH…INLAND
120H 16/1200Z 37.0N 89.5W 20 KT 25 MPH…POST-TROP/REMNT LOW
