EMO Hurricane Season Briefing 2019
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EMO Hurricane Season Briefing 2019 Presented by Michelle Pitcher, Deputy Director, BWS: 1.BWS oversight & coordination 2.Tropical Cyclone Development & Characteristics 3.NHC Verification Trends 4.BWS Role, Actions and Liaisons Presented by James Dodgson, Director, BWS: 1. Review of 2018 Hurricane Season 2. 2019 Hurricane Season forecast 3. Tropical Cyclone Climatology specific to Bermuda 4. BWS communications Coordination Bermuda Airport Authority (Bermuda Airport Authority Act 2017) Disaster Risk Reduction Skyport & Mitigation Team • Aviation Forecasts, Watches (BDA Government) & Warnings Tropical Updates, Watches, & Warnings • NOTAMs & Flight Plans • www.weather.bm/aviation • Severe Weather Watches & Warnings • Public & Marine Forecasts, Watches & Warnings • Yacht Charts & Briefings • www.weather.bm • Media (TV Channels, Radio & Newspaper) • Climatology Tropical Cyclone Formation Basins Source http://www.srh.noaa.gov/jetstream/tropics/tc_basins.htm These are between 5-15 degrees latitude north & south from the equator and generally tend to move east to west as the hurricanes develop and grow Tropical Cyclone Terminology • *Tropical Depression - A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 33 knots or less. • *Tropical Storm - A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) ranges from 34 to 63 knots. • Hurricane - A tropical cyclone in which the maximum sustained surface wind (using the U.S. 1-minute average) is 64 knots or higher. • Major Hurricane - A hurricane that is classified as Category 3 or higher, 96 knots and higher *Also includes Sub-Tropical Storms + 65-80 Years 2-7 Years - El Nino & La Nina – impact on Tropical Cyclone formation El Nino suppresses Atlantic hurricane development La Nina enhances Atlantic hurricane development Images courtesy of NOAA Tropical Cyclone Formation Main Development Region (MDR) • Warm sea surface temperature (at least 26C/80F) • Moist & Unstable atmosphere •Low wind shear environment • Pre-existing Disturbance • e.g. Tropical Wave, old cold front, upper-level low/trough Tropical Cyclone Formation Tropical Wave in the Easterlies Hurricane Development This feedback mechanism continues as long as the favorable conditions for hurricane growth continue to exist. Major Hurricane Nicole SUOM 1 NPP VIRS Day Night Band 13 Oct 2016 06:15Z Hurricane Winds & Storm Surge Weaker winds on the left side of the storm Storm Surge is a dome of water driven by the persistent strong winds Strongest winds on the right side of the storm National Hurricane Center – Atlantic Basin NHC Performance Measures and Goals: Track & Intensity • As of 9 May 2019 NHC Performance Measures and Goals: Track & Intensity • As of 9 May 2019 Per NHC: • Intensity is usually estimated and not directly measured • Winds damages land stations • NOAA dropsondes sample portions of entire cyclone • Data is readily available over land, but not over the ocean • Greater influence from environmental interactions • Tends to be conservative • “New” GOES16 will provide new data for intensity models; increasing skill BWS, in conjunction with NHC, Responsible for Local Threats, Watches, and Warnings Distance of Centre • Potential Threat: The centre of a tropical cyclone is forecast to come within 400 nautical miles of Bermuda within 72 hours. • Threat: The centre of a tropical cyclone forecast to come within 100 nautical miles of Bermuda OR the effects of the tropical cyclone are possible in 72 hours. Wind Speeds • (*TS) Hurricane Watch: Possible onset of (TS 34-63 knots) Hurricane force (64+ knots) winds within 48 hours or less. • (*TS) Hurricane Warning: Possible onset of (TS 34-63 knots) Hurricane force (64+ knots) winds within 36 hours. * Also includes: Sub-Tropical Storms No Threat: Hurricane Lee 40N 400nm 100nm T+72 hrs 30N T+0 hrs 20N 70W 60W 50W Potential Threat: Tropical Depression Six 40N 400nm 100nm 30N The centre of a tropical system is forecast20N to come within 400 nautical miles of Bermuda within 72 70W hours.60W 50W Threat: Hurricane Nicole 40N 400nm 100nm 30N The centre of a tropical system is forecast to come within20N 100 nautical miles of Bermuda within 72 hours. 70W 60W 50W Implementation T + 72 hours BWS monitoring NHC & other agencies for information Liaison with DRRMT, BAA, Skyport on tropical cyclones moving towards BDA as necessary T = 72 hours Cyclone deemed (Pot.)Threat, Email to: DRRMT, BAA, Skyport, MAROPS, Briefings in person and via video begin T = 48 hours TS/HURCN Watch issued, email updates and briefings continue, EMO Meeting T = 36 hours TS/HURCN Warning issued, email updates and briefings continue T - 36 → 0 hours Continued updates, forecast wind onset and cessation time tables created exclusively for the marine area, the Island, and the Airport Implementation CPA Potential for the strongest winds, highest swells/surge, passage of the eye Winds < 64 knots HURCN Warning downgraded to TS Winds < 34 knots TS Warning downgraded to Small Craft Warning All Clear Final communications to EMO, BAA, Skyport, & MAROPS NB: BWS staff stay at the office for the duration of the event; maintaining continuity of our 24 hour operations EMO Hurricane Season Briefing 1. Review of 2018 hurricane season 2. 2019 hurricane season • Predictions (including season so far) • Atlantic & Bermuda tropical climatology • BWS communications James Dodgson [email protected] Director, Bermuda Weather Service (BWS), a Section of the Aviation Services Delivery Unit, Bermuda Airport Authority Review of 2018 Hurricane Season Very active in the central Atlantic and along parts of the US Gulf coast (e.g. Major Hurricane Michael) as well as the US eastern Seaboard (Major Hurricane Florence) BDA Despite some agencies forecasting an average or below average season, there were no less than 15 named storms, compared to an average of 12 However, for Bermuda, it was another welcome quiet season, with NO Tropical watches/warnings issued Image courtesy of NOAA/NHC Review of 2018 Hurricane Season September 12th - HURCN Florence Cat 3 HURCN Helene Cat 1 TS Isaac STS Joyce Joyce Florence BDA Helene Isaac Hurricane Florence – forecast challenges Atlantic Hurricane Season Summary 2018(& 2017) ATLANTIC SEASONAL HURRICANE FORECAST FOR 2015 Forecast Climatology Last year’s tally, Previous year, 2017 Parameter (average 1981- 2018 2010) Named Storms 12 15 17 Hurricanes 6 8 10 Major Hurricanes 3 2 6 WHY increased activity? Despite forecasting agency projections suggesting near or just below average, last year was above average, largely due to poorly forecasted warming SSTs in August, as well as a slower than expected El Nino development. 2017 was very active due to a developing La Nina. Despite these two active years, Bermuda was not directly impacted by any tropical cyclones, with no watches/warnings issued for first time since 2007! 2019 Hurricane Season 1. 2019 Seasonal Forecast - season so far & latest August update 2. Atlantic & Bermuda Tropical Climatology 3. BWS communications with EMO before, during and after a tropical system affecting BDA 2019 Hurricane Season – current stats ACE is the measure of all the energy associated with a Tropical cyclone. It stands for: Accumulated Cyclone Energy Current ACE is 5 compared with seasonal average of 20 Image courtesy of Colorado State 2019 Hurricane Season – current stats STS Andrea caught BWS’s attention ahead of official start of season – no impact Hurricane Barry caused extensive damage to Lafayette, Lake Charles, and Baton Rouge All systems rather short- lived, not generating much ACE Image courtesy of Wikipedia Atlantic Seasonal Hurricane Forecast 2019 ATLANTIC SEASONAL HURRICANE FORECAST FOR 2015 Forecast Climatology Tropical Colorado NOAA CPC UK Met Office Parameter (average Storm Risk State issued issued issued 1981-2010) issued 5 August 8 August 21 May 6 August Named 12 13 14 14 13 Storms Hurricanes 6 6 7 7 7 Major 3 2 2 3 3 Hurricanes Why are forecast numbers slightly above average for this season? Recent El Nino event has now ended. El Nino typically suppresses Atlantic hurricane activity but now that’s gone, we are likely to see a slightly above average season ahead. This is coupled with the current on-going era of more conducive conditions (positive phase of the AMO – warmer SSTs) since 1995. REMEMBER, what ever the projections are, it only takes one storm to make it an active season for us! E.g. Hurricane Nicole The very fact that NO tropical watches/warnings were issued by BWS in the last two seasons makes it increasingly likely BWS will issue some this season! Tropical Climatology of Atlantic - August BDA Images courtesy of NOAA Tropical Climatology of Atlantic - September BDA Images courtesy of NOAA Tropical Climatology of Atlantic - October BDA Images courtesy of NOAA Tropical Climatology of Atlantic - November BDA Images courtesy of NOAA Historical Record For Atlantic Basin 12-13 October 2016 Major Hurricane Nicole 4-5 October 2015 Hurricane Joaquin 17 October 2014 Major Hurricane Gonzalo 12 October 2014 Hurricane Fay Historical Record For Bermuda (Hurricanes) Historical Record For Bermuda (Tropical Storms & Hurricanes) 44 34 Timeline for Threats, Watches and Warnings Creation of TUBs Threat consideration Email to EMO Cessation of executive Issuance of Cessation of Final POTENTIAL TS force Likely Issuance hurcn force communication THREAT Potential for winds. TS convening of of Onset of winds. HURCN between BWS & (400nm) or Issuance of strongest WARNING EMO as TS/HURCN