1. Hurricane Isaac Briefing August 28, 2012 100 PM CDT National Weather Service Weather Forecast Office Slidell, LA August 28, 2012 100 PM CDT National Weather Service Weather Forecast Office Slidell, LA

2. Current Satellite

3. Hurricane Isaac

4. Watches/Warnings

5. Hurricane Isaac Track Guidance

6. Hurricane Isaac Intensity Forecast

7. Hurricane Isaac TS Wind Probability Forecast

8. Hurricane Isaac Hurricane Wind Probability Forecast

9. Hurricane Isaac Wind Forecast Strongest winds will be mainly limited to squalls

10. Wind Speed Durations (maximum durations) LocationTropical Storm Force Duration (Sustained) Hurricane Force Duration (Along track and in squalls) Lower Plaquemines Lower St. Bernard Lower Jefferson 24-36 hrs6-10 hrs South Shore24-36 hrs2-6 hrs North Shore LA Florida Parishes LA River Parishes Hancock County 24-36 hrsgusts possible Harrison County Jackson County 18-24 hrsgusts possible SW MS E Central LA 18-30 hrsgusts possible

11. Tide Levels Currently in Spring Tide MS Coast: Tide levels increasing to 8 to 12 feet during high tide cycles Tuesday and Wednesday. SE LA Coast: Tide levels increasing to 5 to 8 feet within Lake Pontchartrain, 6 to 10 feet west of the MS River and 7 to 11 feet east of the MS River through Wednesday high tide cycle. Possibly up to 5 feet in canals and bayous. Currently in Spring Tide MS Coast: Tide levels increasing to 8 to 12 feet during high tide cycles Tuesday and Wednesday. SE LA Coast: Tide levels increasing to 5 to 8 feet within Lake Pontchartrain, 6 to 10 feet west of the MS River and 7 to 11 feet east of the MS River through Wednesday high tide cycle. Possibly up to 5 feet in canals and bayous.

12. Tide Levels

13. Worst case storm surge potential for all locations

14. Current Tide Levels

15. Tide Trends Water levels coming up quickly now, but will likely not peak until some time tomorrow, then staying elevated through Thursday Total surge of 9-12 ft possible Total surge of 9-12 ft possible.

16. Rainfall through Wed.

17. Tornado Threat Today Wednesday

18. Tornado Threat Tornado Watch in effect until 7pm CDT

19. Summary HURRICANE WARNING is in effect from Tangipahoa Parish, southward to Morgan City, eastward through coastal MS. This includes the New Orleans metro area. TROPICAL STORM WARNING is in effect for SW MS and E-central LA including the Baton Rouge metro area. Hurricane Isaac still gradually strengthening. Expected to strengthen only slightly more before landfall. All of southeast LA and southern/coastal MS will be affected by this storm. Offshore rigs and buoys are now reporting sustained tropical storm force winds with some gusts to hurricane force (rigs at elevation 300- 400 feet above water surface). Starting to see frequent gusts to tropical storm force across the south shore. HURRICANE WARNING is in effect from Tangipahoa Parish, southward to Morgan City, eastward through coastal MS. This includes the New Orleans metro area. TROPICAL STORM WARNING is in effect for SW MS and E-central LA including the Baton Rouge metro area. Hurricane Isaac still gradually strengthening. Expected to strengthen only slightly more before landfall. All of southeast LA and southern/coastal MS will be affected by this storm. Offshore rigs and buoys are now reporting sustained tropical storm force winds with some gusts to hurricane force (rigs at elevation 300- 400 feet above water surface). Starting to see frequent gusts to tropical storm force across the south shore.

20. Summary Onset of TS winds: Ongoing some areas. Continuing to spread across the area today Tropical Storm wind duration: 20 to 24 hours for most locations with a few locations up to 36 hours Hurricane force wind duration: 6 to 10 hours in areas within direct path and near the coast. Elsewhere, hurricane force wind gusts will mainly be experienced in squalls. Rainfall: Storm total of 10 to 15 inches expected, some higher amounts possible. Heavy rainfall is a threat across the whole area as reflected in the updated graphic from HPC. Slow movement means a greater threat of heavy rain Flash Flood Watch now in effect for entire area. Tornadoes: SPC Slight Risk today and Wednesday. Onset of TS winds: Ongoing some areas. Continuing to spread across the area today Tropical Storm wind duration: 20 to 24 hours for most locations with a few locations up to 36 hours Hurricane force wind duration: 6 to 10 hours in areas within direct path and near the coast. Elsewhere, hurricane force wind gusts will mainly be experienced in squalls. Rainfall: Storm total of 10 to 15 inches expected, some higher amounts possible. Heavy rainfall is a threat across the whole area as reflected in the updated graphic from HPC. Slow movement means a greater threat of heavy rain Flash Flood Watch now in effect for entire area. Tornadoes: SPC Slight Risk today and Wednesday.

21. Next Update Emails with updated slides will be sent following each advisory. Next webinar will be Wednesday 2 PM CDT. Emails with updated slides will be sent following each advisory. Next webinar will be Wednesday 2 PM CDT.

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