2007 Hurricane Season Briefing

Dr. Mark Guishard Director, Weather Service An Effective End-to-End Warning System

Predict / monitor TC development/progress using best science available

Produce / deliver timely and accurate warnings in well understood formats via different channels

A receptive, prepared and resourceful community

Background - Intensity

„ Tropical Storm — winds 39-73 mph (34-63 kt) e.g. Karen, Oct. 2001

„ Category 1 Hurricane — winds 74-95 mph (64-82 kt) e.g. Florence, Sept. 2006, Emily, Sept. 1987

„ Category 2 Hurricane — winds 96-110 mph (83-95 kt)

„ Category 3 Hurricane — winds 111-130 mph (96-113 kt) e.g. Fabian, Sept. 2003

„ Category 4 Hurricane — winds 131-155 mph (114-135 kt)

„ Category 5 Hurricane — winds 156 mph and up (135+ kt)

The Saffir-Simpson Scale

„ Tropical Storm — winds 39-73 mph (34-63 kt)

– e.g. Franklin, Harvey 2005

TS Franklin July 26 2005

Source: NOAA The Saffir-Simpson Scale

„ Tropical Storm — winds 39-73 mph (34-63 kt)

– e.g. Franklin, Harvey 2005

45 1016 TS Harvey, August 4 2005 40 1014 TS Harvey, August 4 2005

35 1012

30 1010

Speed

25 1008 Gust

SLP

20 1006

15 1004

10 1002

5 1000 032355Z 040152Z 040355Z 040618Z 040707Z 040755Z 040824Z 040855Z 040942Z 041055Z 041155Z 041336Z 041455Z 041655Z 041855Z 042055Z 042255Z 040507Z Source: BWS The Saffir-Simpson Scale

„ Category 1 Hurricane — winds 74-95 mph (64-82 kt)

„ Hurricane Emily September 27 1987 „ Rapidly turned towards Bermuda and intensified to a Hurricane. „ Direct hit, with passing over the island. „ Tornadoes embedded: Widespread roof damage & power outages

Source:Unisys.com

Source: NOAA The Saffir-Simpson Scale

„ Category 1 Hurricane — winds 74-95 mph (64-82 kt)

„ September 11, 2006 „ Another recurving hurricane „ Very large wind field „ Evidence of damage

Bermuda

Source: BWS The Saffir-Simpson Scale

„ Category 2 Hurricane — winds 96-110 mph (83-95 kt)

„ Category 3 Hurricane — winds 111-130 mph (96-113 kt) e.g. Fabian, Sept. 2003 „ Hurricane Fabian- Friday, September 5, 2003 „ Yet another recurving hurricane „ Widespread heavy damage „ Four Lives lost

Bermuda

Source: UW-CIMSS Source: Royal Gazette The Saffir-Simpson Scale

„ Category 4 Hurricane — winds 131-155 mph (114-135 kt)

„ Category 5 Hurricane — winds 156 mph and up (135+ kt)

Mitch 1998: Cat 5

Katrina 2005: Cat 5

Source: NOAA Fabian 2003: Cat 4 Significance of Category

„ Potential for Hurricane Category vs. Windspeed and Damage damage is an Source: Gray and Landsea, 1992 exponential 0 function of 160 7000 140 6000 120 Category. 5000 100 4000 80 60 3000 40 2000 20 1000 Median normalized U.S. destruction in $ millions 1949-199 Wind Speed (knots) Speed Wind 0 0

12345 Saffir-Simpson Category

SS Category Windspeed Damage Losses Normalised 1 64 minimal 24 1 2 83 moderate 218 10 3 96 extensive 1108 50 4 114 extreme 2274 100 5 135 catastrophic 5933 250 Mean Atlantic Basin activity :

Hurricane Season: Jun. 1- Nov. 30

Probabilities

Probability that a hurricane will come within 1° (60nm) of a given location within the hurricane season, based on data from 1944 to 1999. (NOAA Hurricane Research Division). ~16% for Bermuda.

Caveat – Hurricanes don’t remember where their predecessors have been!

Typical season storms to watch

Tropical advisories, watches and warnings

„ Potential Threat: The centre of a tropical system is forecast to come within 400 nautical miles of Bermuda within 72 hours.

„ Threat: The centre of a tropical system is forecast to come within 100 nautical miles of Bermuda within 72 hours.

„ Hurricane Watch: 36 hours or less prior to possible onset of hurricane force (64 knots or more) winds.

„ Hurricane Warning: Hurricane force winds within 24 hours.

„ Tropical Storm Watch: 36 hours or less prior to possible onset of tropical storm force (34 knots or more) winds.

„ Tropical Storm Warning: Tropical storm force winds within 24 hours.

Timeline case study 1: Fabian

„ Potential Threat: The centre of a tropical system is forecast to come within 400 nautical miles of Bermuda within 72 hours.

Source: BWS Timeline case study 1: Fabian

„ Potential Threat: The centre of a tropical system is forecast to come within 400 nautical miles of Bermuda within 72 hours.

„ Potential Threat: The centre of a tropical system is forecast to come within 400 nautical miles of Bermuda within 72 hours.

Source: BWS Typical Timeline – case study 1: Fabian

„ Threat: The centre of a tropical system is forecast to come within 100 nautical miles of Bermuda within 72 hours.

Source: BWS Typical Timeline – case study 1: Fabian

„ Hurricane Watch: 36 hours or less prior to possible onset of hurricane force (64 knots or more) winds.

Source: BWS „ Hurricane Warning: Hurricane force winds within 24 hours.

Source: BWS Timeline case study 2: Karen

Source: UW-CIMSS

Timeline case study 2: Karen

Source: UW-CIMSS

Timeline case study 2: Karen

Source: BWS Peak Gusts 78 kt. Hurricane-force Karen, 2001 Max 10 min. mean 58 kt.

Source: BWS

Source: The Royal Gazette

989 mb NHC now issue advisories on Subtropical Storms Coordination in advance of a storm

„ NHC Hurricane Specialists in charge of forecast track and intensity

Source: US Navy

Source: CSU USAF C-130 Hercules Source: NOAA

NOAA GULFSTREAM IV-SP JET

NOAA P-3 Orion

Source: US Navy

Source: NOAA Coordination in advance of a storm

„ BWS in charge of local conditions and warnings

Source: NOAA Source: BWS

Source: BWS

Source: BWS Source: NOAA

Source: NOAA

Coordination in advance of a storm

„ EMO in charge of coordinating preparations…

Source: The Royal Gazette

…and response

Forecast Track valid 15 UTC (12 noon ADT) Saturday Sept. 9, 2006

TROPICAL STORM FLORENCE is a threat to Bermuda. Currently: 24.7N 63.7W 465nm S of Bermuda Recent Movement: WNW at 11 kt Central Pressure: 992 mb / 29.29 in Max Sustained Winds: 60kt gusts 75kt

Closest point of approach to Bermuda within 72 hrs: Date: 11 am Mon, Sep 11, 2006 Distance: 15 nm to the west Source: BWS

Before, during and after the storm

Source: The Royal Gazette 2005 season - 28 named storms

„ Several subtropical storms

„ Local effects from tropical cyclones in each month from July through October.

„ Warnings issued for Bermuda: – Gale Warnings: 1 – Tropical Storm Watches: 2 – Tropical Storm Warnings: 3 – Hurricane Watch: 1

Source: NOAA 2006 season – 9 named storms

„ Cat. 1 Hurricane Florence

„ Direct hit Sept. 11 2006

„ Warnings issued for Bermuda: – Tropical Storm Watches: 1 – Tropical Storm Warnings: 1 – Hurricane Watch: 1 – Hurricane Warning: 1

Source: NOAA Forecasting the season: Number, intensity

„ Colorado State (Klotzbach and Gray)

„ Tropical Storm Risk

„ NOAA

„ Parameters used: – El Nino Southern Oscillation Indices – SST, Sea Level Pressure Anomalies – Wind Shear – Sahel Rainfall

Forecasting the season: Tracks

„ North Atlantic Oscillation

„ Bermuda/Azores High

Source: AMS

Forecasting the season: Tracks

„ North Atlantic Oscillation

„ Bermuda/Azores High

Source: AMS

Colorado State University (Klotzbach and Gray, 2007) ATLANTIC SEASONAL HURRICANE FORECAST FOR 2007 Issue Date Forecast Parameter and 1950-2000 2006 2005 Climatology (in parentheses) 3 April 2007 Named Storms (9.6) 17 10 27 Hurricanes (5.9) 9 5 15

Intense Hurricanes (2.3) 5 2 7

Named Storm Days (49.1) 85 53 125

Hurricane Days (24.5) 40 21 51

Intense Hurricane Days (5.0) 11 2 17 Net Activity (100%) 185 85% 263%

Non-tropical warnings

„ Typically associated with winter marine weather systems

„ Storm Warning: Storm force winds (48 knots or more) within 36 hours

„ Gale Warning: Gale force winds (34 knots or more) within 36 hours

„ Severe Watch: Severe may develop and/or approach the island within 6 hours.

„ Severe Thunderstorm Warning: Severe thunderstorms have developed and are approaching the island, possibly as much as 1 hour lead time.

„ VHF Marine Channel 2

„ www.weather.bm

„ WOW / CableVision

„ VSB TV nightly weather

„ Radio soundbites, live interviews, DJ readings

„ Phone tapes (soon to be replaced and upgraded)

Source: BWS Wed. May 16th : 6:30pm, BUEI

Five things you never knew about hurricanes

Any Questions?