Frank Revitte National Weather Service. Weather Forecast Office New Orleans/Baton Rouge

Transcription

1 Frank Revitte National Weather Service Weather Forecast Office New Orleans/Baton Rouge

2 Above normal activity 17 Total Named Storms 7 Tropical Storms 4 Hurricanes 6 Major Hurricanes Not the most active, but still set records: Irma Longest lasting category 5 hurricane in the Atlantic (37 hours) Harvey Most rain in the U.S. with 60 inches First time two category 4 landfalls in the US

3 Developed in SW Caribbean Sea and moved northward forward speed was in excess of 25 mph at one point. Passed just east of the Mouth of MS River and landfall near Ocean Springs Maximum wind gust of 71 kts /82 mph measured at Ingalls Shipyard at elevated wind instrument Area between Biloxi and Pascagoula most likely area to have received hurricane force wind gust.

4 Biloxi and Ocean Springs likely received maximum surge of 6 to 9 ft above ground level along immediate coast. Maximum high water mark of 9.7 ft above ground Elsewhere on MS immediate coast storm surge 4 to 6 feet. Louisiana 3 to 5 feet above ground level at immediate coast east of MS River. Due to fast forward speed surge rapidly peaked then quickly subsided

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8 Named Storms Average Colo. State Fcst NOAA Fcst ( May 24) 12 14?? Hurricanes 6 7?? Major Hurricanes 2 3?? Caution: it only takes one

9 It takes MUCH more than warm oceans for hurricane formation and sustainability El Nino = (typically) fewer Atlantic storms La Nina = (typically) more Atlantic storms Reality = it only takes one, so we MUST prepare like we will get hit every year (at work and at home)

10 Five-day plans are great, but you won t always have five days of lead time on the Gulf Coast

11 Five-day plans are great, but you won t always have five days of lead time on the Gulf Coast Hurricane Camille 1969 Wasn t classified as a tropical storm until about 80 hrs before landfall as a category 5 hurricane Intensified from 75 mph winds (category 1) to 120 mph winds (category 3) in 24 hours

12 Five-day plans are great, but you won t always have five days of lead time on the Gulf Coast Hurricane Cindy 2005 Wasn t classified as a tropical storm until about 48 hrs before landfall

13 Verified Position 1PM Mon Along-track errors can reduce lead time. Forecast Position 1PM Mon TS winds started about 12 hours earlier than forecast 72 hrs prior

14 Bottom Line: You won t always have a 5 day lead time on Gulf of Mexico storms, so timetables need to be adaptable! For thought Would you be prepared if you only had 3 days to enact your plan? How about 2?

15 Flooding from storm surge and fresh water (rain) account for over three quarters of deaths directly attributable to Atlantic Basin Tropical Cyclones

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18 1. Where the circulation center crosses the coast 2. Direction of storm motion relative to the coast 3. Wind strength (storm intensity) 4. Radius of maximum winds 5. Overall size of storm (outer wind radii) 6. Slope of the continental shelf 7. Shape of the coastline and other coastal features (barrier islands, bays, rivers, levees, etc) It s Complicated!

19 Landfall to the west Subtle changes can make a large change in storm surge impact Landfall in the middle Landfall to the east

20 Hurricane Nate

21 Hurricane Isaac

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23 1. Forward Speed (slower more rain) 2. Size (bigger more rain) 3. Rain Rate (atmospheric moisture content) 4. Vertical Wind Shear (more rain on one side) 5. Topography (more rain on windward side) 6. Fronts/Upper-Level Troughs It s Complicated!

24 Highest 6-day storm totals: Nederland, TX: new US record! Groves, TX: 60.54

25 Widespread 6 to 10 inches of rain along/west of the Pearl River

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28 New! Locally issued TCV (Tropical Cyclone Watch/Warning product) will include PLAN, PREPARE, and ACT statements in tweetable lengths for wind, surge, flooding rain, and tornado hazards

29 Reasonable worst case scenario. Approximately 80 min after advisory Subtle changes possible with each update No values shows inside risk reduction system Only federal levees in model.

30 Storm Surge Watch there is a possibility of life-threatening storm surge inundation within 48 hours Storm Surge Warning there is a danger of lifethreatening storm surge inundation within 36 hours

31 WILL be tone alerted via NOAA Weather Radio Likely WILL NOT be alerted via Wireless Emergency Alerts in 2018 CAN be issued for areas inside the risk reduction system

32 New! New for 2018: We WILL be able to issue coastal flood advisories or warnings throughout a tropical event Will be issued in situations of non-life threatening flooding caused by a tropical cyclone Note: These are issued on a parish/county scale while storm surge watch/warning is issued on a 2.5km grid

33 Wireless Emergency Alerts (WEA) Wireless Emergency Alert (WEA) is an alerting network in the United States designed to disseminate emergency alerts to mobile devices such as cell phones. WEA messages are triggered by the NWS for the following tropical warnings: - Hurricane Warning: Hurricane Warning this area. Check local media and authorities - Storm Surge Warning*: Life-threatening storm surge danger. Check for possible evacuation orders - Extreme Wind Warning*: Extreme Wind Warning in this area til 7:15 AM CST. Take shelter * While NWS is sending these warnings to FEMA IPAWS for alerting via WEA, the wireless carriers had not enabled WEAs for them through 2017

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35 Potential Tropical Cyclone Watches and warnings for disturbances that are likely to bring tropical storm or hurricane conditions to land within 48 hours but aren t yet tropical cyclones Will have full suite of NHC products

36 Cyclone cy clone ˈsīˌklōn/ nounmeteorology 1. A system of winds rotating inward to an area of low atmospheric pressure, with a counterclockwise (northern hemisphere) or clockwise (southern hemisphere) circulation; a depression. 2. Another term for tropical storm.

37 Available in two versions: Most likely onset (50-50 chance TS Wind earlier/later) Reasonable earliest onset (90 percent chance TS Wind later) Most conservative/safest Can toggle on or off the wind speed probability Will help with H-hour

38 New WFO Tropical Webpage weather.gov/srh/tropical NHC Outlook, Satellite, Radar, Social Media, Preparedness Info, and Links tabs are always available on the site Active Storms, Threats and Impacts, and Local Products tabs become active when there are active U.S. tropical Watches or Warnings Social Media and Local Products tabs allow users to select a WFO to see products from a particular WFO, including the Hurricane Local Statement (HLS)

39 Seasonal Outlooks can give us a general sense of the upcoming tropical activity, but not which areas may be most affected Each season we need to be prepared for a direct impact especially true for coastal LA/MS with its unique vulnerability Flooding from storm surge and fresh water is far and away the most dangerous hazard Depending on storm - evacuate areas of surge and flood risk.

40 Facebook: NWSNewOrleans x x4 Frank Revitte Warning Coordination Meteorologist