Marine Forecast ProgramMarine Forecast Program

Alex Gibbs

Meteorologist National Weather Service,

Tallahassee

The Gulf of Mexico Last Week?

Outline-The NWS Marine Program Mission

-NWS Tallahassee Area of Responsibility

-Forecast Products available

-Wave generation sources for our area

-Tools that we utilize during the forecast process

-Basic marine definitions

-Forecasting seas

-The Gulf of Mexico bathymetry

-Feedback from the marine community

Marine Forecast ProgramMarine Forecast Program

• Meteorological Support to enhance:

– The Protection of Life and Property

– Efficiency of governmental, recreational, and commercial maritime operations.

Tallahassee Marine Forecast AreaTallahassee Marine Forecast Area

Forecast Products Issued by the NWS

Forecast Products Issued by the NWS

• Coastal Waters Forecast (Local NWS Office)

• Surf and Rip Current Forecast• AFD (Area Forecast Discussion) – Marine

• The Coastal Waters Forecast is tailored to a wide variety of marine users, including weekend fishermen to large ocean going ships. Now through 5 days.

Coastal Waters ForecastCoastal Waters Forecast

• Headlines- draws attention to the hazardous conditions described in the forecast.– Small Craft Exercise Caution: (15-20 kt or 5-6 ft seas)– Small Craft Advisory: (>= 20 kt or >= 7 ft seas)– Gale Warnings– Storm Warnings– Tropical Cyclone Watches and Warnings– Sea Fog (visibility less than 1 nm)– Winter Storm Watches and Warnings affecting coastal

waters

Coastal Waters ForecastCoastal Waters Forecast• The following is a list of the parameters

covered in the Coastal Waters Forecast – Winds– Sea Conditions– Significant Weather– Visibility– Icing – Air Temperatures– Sea Ice

The First ApproachThe First Approach

5-10KT KT 1 FT; < 2 FT Smooth10 KT 1-2 FT; 2 FT Light Chop10-15 KT 2 -3 FT; 2-4 FT Moderate Chop15 KT 3- 4 FT; 3-5 FT Moderate Chop15-20 KT 4-5 FT; 4-6 FT Choppy20 KT 5-7 FT Choppy20-25 KT 6-9 FT Rough25 KT 7-10 FT Rough 25-30 KT 8-12 FT Very Rough30 KT 8-12 FT Very Rough30-35 KT 10-15 FT Extremely Rough35 KT 10-15 FT Extremely Rough35-40 KT 12-18 FT Extremely Rough40 KT 14-20 FT Extremely Rough

Average Sea InlandWind Speed Height WatersForecast Forecast Forecast

Example of a Coastal Waters ForecastExample of a Coastal Waters Forecast

• FZUS52 KTAE 031539• CWFTLH

• COASTAL WATERS FORECAST• NATIONAL WEATHER SERVICE TALLAHASSEE FL• 1030 AM EST MON NOV 3 2003

• GULF COASTAL WATERS FROM THE SUWANNEE RIVER TO DESTIN OUT TO 60 NM

• GMZ700-032130-• SYNOPSIS APALACHICOLA TO DESTIN OUT TO 60 NM-• SYNOPSIS SUWANNEE RIVER TO APALACHICOLA OUT TO 60 NM-• 1030 AM EST (930 AM CST) MON NOV 3 2003

• .SYNOPSIS...A BROAD AREA OF LOW PRESSURE CENTER OFF THE FLORIDA COAST JUST• SOUTH WEST OF TAMPA WILL TRACK TO THE NORTHWEST TONIGHT AND TUESDAY AND MOVE• INLAND OVER SOUTH EAST LOUISIANA TUESDAY NIGHT. THIS LOW PRESSURE SYSTEM WILL• KEEP WINDS AND SEAS HIGH OVER THE MARINE AREA THROUGH TUESDAY ALONG WITH• INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS. WINDS AND SEAS WILL BEGIN TO• DIMINISH TUESDAY NIGHT. A WEAK COLD FRONT MAY MOVE THROUGH THE COASTAL WATERS• EARLY FRIDAY WITH THE CHANCE FOR SHOWERS AND POSSIBLY A FEW THUNDERSTORMS• CONTINUING THROUGH THE WEEK.

• $$

Example of a Coastal Waters ForecastExample of a Coastal Waters Forecast• GMZ750-770-032130-• APALACHICOLA TO DESTIN 20 TO 60 NM OFFSHORE-APALACHICOLA TO DESTIN OUT TO 20 M-• 930 AM CST MON NOV 3 2003

• ...SMALL CRAFT EXERCISE CAUTION...

• .THIS AFTERNOON...NORTHEAST WIND 15 TO 20 KNOTS. SEAS 3 TO 4 FEET NEARSHORE• AND 4 TO 6 FEET WELL OFFSHORE. PROTECTED WATERS CHOPPY. SCATTERED SHOWERS.• .TONIGHT...EAST WIND 20 KNOTS. SEAS 4 TO 6 FEET. PROTECTED WATERS• CHOPPY. SCATTERED SHOWERS.• .TUESDAY...SOUTHEAST WIND 20 TO 25 KNOTS. SEAS 5 TO 7 FEET. PROTECTED WATERS• ROUGH. SCATTERED SHOWERS AND THUNDERSTORMS.• .TUESDAY NIGHT...SOUTH WIND 20 KNOTS. SEAS 4 TO 6 FEET. PROTECTED WATERS CHOPPY.• SCATTERED SHOWERS AND THUNDERSTORMS.• .WEDNESDAY...SOUTHEAST WIND 10 KNOTS. SEAS 2 TO 3 FEET. PROTECTED WATERS A LIGHT• CHOP. ISOLATED RAIN AND SCATTERED SHOWERS AND THUNDERSTORMS.• .THURSDAY...SOUTHEAST WIND 10 KNOTS. SEAS 2 FEET OR LESS.• PROTECTED WATERS A LIGHT CHOP. SCATTERED RAIN.• .FRIDAY...EAST WIND 10 KNOTS. SEAS 2 TO 3 FEET. PROTECTED WATERS A LIGHT CHOP.• ISOLATED RAIN.

• $$

Example Surf Zone Forecast

000FZUS52 KTAE 050750

CCASRFTAE

SURF ZONE FORECAST FOR FLORIDA

.NATIONAL WEATHER SERVICE TALLAHASSEE

237 AM EST TUE FEB 5 2008.

SYNOPSIS...EXPECT THE GRADIENT TO TIGHTEN AS A COLD FRONTAPPROACHES THE AREA FROM THE WEST TODAY. THE SOUTHERLY WINDS AHEADOF THE FRONT WILL REACH MODERATE TO FRESH LEVELS ACROSS THECOASTAL WATERS LATER TODAY AND TONIGHT. THE SURF WILL STEADILYINCREASE THROUGH THE DAY AND WILL RESULT IN STRENGTHENING RIPCURRENTS...ESPECIALLY ALONG THE PANHANDLE BEACHES. ONWEDNESDAY...THE WINDS WILL REMAIN FAIRLY STRONG AND SLOWLY VEERAROUND TOWARD THE WEST-SOUTHWEST IN THE LATE AFTERNOON HOURS.WEDNESDAY EVENING AND INTO THE NIGHT...THE COLD FRONT WILL PUSHTHROUGH THE AREA FROM WEST TO EAST WITH MODERATE NORTHERLY WINDSFILLING IN ACROSS THE AREA. ALTHOUGH THE SURF WILL BE ON THEDOWNWARD TREND LATE WEDNESDAY NIGHT...THERE WILL LIKELY BE SOMELEFT OVERS EARLY THURSDAY MORNING AROUND DAYBREAK. AIR TEMPERATURESSHOULD REMAIN IN THE UPPER 40S EARLY THURSDAY MORNING.

FLZ008-012-014-015-GMZ750-061000-

SOUTHERN WALTON-BAY-GULF-FRANKLIN-C

OASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM-INCLUDING THE BEACHES OF...SANDESTIN...PANAMA CITY BEACH...APALACHICOLA...ST GEORGE ISLAND237 AM EST TUE FEB 5 2008 /137 AM CST TUE FEB 5 2008/TODAY.

.BEACH WINDS.........SOUTHEAST AROUND 10 MPH INCREASING TO AROUND 15 MPH WITH HIGHER GUSTS IN THE AFTERNOON

.UVI INDEX...........6 OR HIGH EXPOSURE

.WATER TEMPERATURE...59 DEGREES AT PANAMA CITY BEACH

.SURF................2 TO 3 FEET BUILDING TO 3 TO 4 FEET IN THE AFTERNOON

.RIP CURRENT RISK....MODERATE INCREASING TO HIGH IN THE AFTERNOON

.WIND AND SURF CONDITIONS WILL SUPPORT DANGEROUS RIP CURRENTS LATER TODAY. RIPCURRENTS ARE LIFE THREATENING TO ANYONE ENTERING THE WATER.

.&&

LOCAL TIDE PREDICTIONS FOR TODAY...

SAINT MARKS RIVER ENTRANCE...

TODAY: HIGH/ 12:26 AM...LOW/ 07:30 AM...HIGH/ 01:59 PM...LOW/ 07:14 PM:

APALACHICOLA...TODAY: HIGH/ 12:59 AM...LOW/ 09:40 AM...HIGH/ 04:57 PM...LOW/ 09:02 PM:

SAINT ANDREW BAY AT PANAMA CITY...TODAY: LOW/ 06:54 AM...HIGH/ 08:46 PM:

NOTE THAT THE TIMES OF HIGH AND LOW TIDE ARE 3 MINUTES EARLIER ATSHELL POINT THAN AT THE SAINT MARKS RIVER ENTRANCE.

$$

GIBBS

Coastal Waters Forecast Issuance Times

Coastal Waters Forecast Issuance Times• 3:30 AM CST/CDT

• 9:30 AM CST/CDT

• 3:30 PM CST/CDT

• 9:30 PM CST/CDT

Wave Generation Sources for the Gulf of Mexico

-Cold Fronts

-Tropical Cyclones-Yucatan Channel

-Easterly Regime

Cold Fronts

42002

4203942040

4200342001

42036

L

20-30 kts

Fetch Region: Generally 250nm X 100 nm

Strongest Cold Fronts typically occur from November through March

Cold FrontsQuikSCAT – Surface Wind Speed and Direction

-1800 km (~1000 NM) Swath-Coverage – twice per day (00z and 12z roughly)

What time of year is this?

Tropical Cyclones

CASE #1Dean 04L (8/2007): CAT 5 just before landfallMotion: 17knots WNWRadius of TS winds ~ 175nm

Easterly flow across the waters

Easterly Regime

H

Tools utilized for the forecast:Tools utilized for the forecast:

- Global Wave/Wind Models-Tabular Output

- NOGAPS Ensemble Model (16 components)

- SWAN Model – Simulated WAves Nearshore

Verification and Initialization:

- Buoys- Ship Reports- QuikSCAT - Scatterometry- Altimetry - Wave Height

Global Wind / Wave Model ForecastsGlobal Wind / Wave Model Forecasts

- Produced by 16 WW3 model forecasts (members), each driven by the corresponding NOGAPS EFS member.- Products consist of probability models specifically for the GOMEX.

- Probability of 4, 6, and 12 foot waves.- https://www.fnmoc.navy.mil/efs/efs_ww3.html

Wave Watch III (WW3) ENSEMBLE FORECAST SYSTEM (EFS) DISPLAYS

SWAN – Simulating Waves Nearshore Model

https://oceanography.navy.mil/legacy/web/ops.htm

A Simulating Waves Nearshore (SWAN) model is a third generation wave model for use in coastal areas (Booij et. al., 1999). It includes wave generation by winds, propagation, shoaling, refraction, bottom friction and breaking. It uses a 50 m horizontal grid.

Model Wind ForecastsModel Wind Forecasts

42002

4203942040

4200342001

42036

Gulf of Mexico Buoys

Real-Time Data for the Tallahassee Coastal Waters

Real-Time Data for the Tallahassee Coastal Waters

http://www.ndbc.noaa.gov/rmd.shtml-DIAL-A-BUOY – 888-701-8992

- when prompted – punch in the station ID (ex: 42039)

K tower

National Data Bouy Center webpage

National Data Bouy Center webpage2

Definitions Definitions - Wind Waves - Local short period waves generated from the local wind stress on the surface of the water. Periods typically range from 4-8 seconds.

- Swell - Wind generated waves that have traveled out of their generating area. Swells are characterized as having smoother and more regular and uniform crests and a longer period than wind waves. These periods are typically >8 seconds.

- Seas - A term used to describe the combination of wind waves and swells. Mathematically, this is just the sum of the squares of the wind waves and swell components.

- Shoaling - When the water is less than half the height of the wavelength in depth, the wave begins to feel the bottom (water depth < ½ (wavelength). Interaction with the ocean floor slows the wave. Waves behind it continue toward the shore at the original rate. Wavelength therefore decreases, but the period remains conserved.

(Average highest 1/3)

Sig. Wave Height X 1.25

(1/2 the Significant Wave Height)

(5/8 of the Significant Wave Height)

Forecasting SeasForecasting Seas

• Three factors generate seas

• Any one of them can be a limiting factor

– Wind Speed– Wind Duration– Wind Fetch

Feedback from Marine UsersFeedback from Marine Users

• Since buoys are very expensive, having a dense network of buoys to collect data is usually not possible.

• Therefore the NWS has to rely on feedback and input from local marine users such as:– Commercial Fishermen– Government Patrolling Agencies– Other Frequent Boaters

• NWS Tallahassee Public Line 850-942-8833• alex.gibbs@noaa.gov

Graphical ForecastsGraphical Forecasts

USEFUL LINKS & NUMBERS

NWS Tallahassee: http://www.srh.noaa.gov/tlh/ Buoys: http://www.ndbc.noaa.gov/rmd.shtml QuikSCAT: http://manati.orbit.nesdis.noaa.gov/quikscat/ Models: http://polar.ncep.noaa.gov/waves/viewer.shtml?-gmex-

PHONE NUMBERS: NWS Tallahassee - 850-942-8833 (24/7) Dial-A-Buoy - 888-701-8992 (Buoy ID: ex: 42039) NWR 850-942-8851

EMAIL: Meteorologist/Forecaster alex.gibbs@noaa.gov Warning Coordination Met. bob.goree@noaa.gov

Thank You!Thank You!

If everyday could only be like this:

Wind/Swell Wave Characteristics

Cdeep = √(gL/2π) (Where L = wavelength = 1.56(Period)²) (typical ocean wind/swell wavelengths range from 200-500 m)

Cshallow = √gh (Where h is equal to the depth the wave begins to break)

When the water is less than half the height of the wavelength in depth, The wave begins to feel the bottom. (water depth < ½ (wavelength)Ex: 17s period….L=1.56(17)^2 = 450 m…therefore, water depth < ½(450) = <225 m

13s period…L=1.56(13)^2 = 265m…therefore, water depth < ½(265) = <132.5 m

7s period….L=1.56(7)^2=76m…water depth <76/2=38 m

Interaction with the ocean floor slows the wave. Waves behind it continuetoward the shore at the original rate. Wavelength therefore decreases,but the period remains conserved.

Since the energy in the wave remains the same, the shortening of thewavelength results in an increase in amplitude or wave height. This process Is called shoaling.

A wave will break at about a 3:4 ratio of wave height to water depth.(example: a 3 m wave will break in 4 m of water.)