Storm Surge Products

John Cole

Warning Coordination Meteorologist

NWS Morehead City/Newport NC

Acknowledgements: Jamie Rhome and Rick Knabb (NHC), Mark Willis (WFO MHX),

Outline

• SLOSH (MOM’s and MEOW’s)• Operational SLOSH

(Deterministic Runs)• Probability Surge (P Surge)• Surge Product Timeline

The Storm Surge Threat

• An abnormal rise in water generated by a storm, over and above the astronomical tide

• A temporary rise in sea level that, in effect, moves the coastline inland

• Caused primarily by force of wind blowing across water surface

• Contribution by low pressure within center of storm is minimal• Influenced greatly by track, RMW, size, coastline

characteristics.

MEOW’s and MOM’s• Maximum Envelope of Water• Composite of maximum storm

surge heights at each grid cell using hypothetical hurricanes run with the same:

– Category– Forward Speed– Landfall Direction– Initial Tide Levels

• Composite achieved by reviewing parallel tracks that make landfall at different locations

• Over 80 MEOWs have been generated for some basins

• Maximum of MEOWs• Composite of the maximum

storm surge height for all hurricanes of a given category

• Disregards forward speed, landfall direction, landfall location, etc.

• Only 5 MOMs per basin, i.e. one per storm category

CAT 3 MEOW

Surge Inundation

SLOSH Tides

Maximum Storm Surge Potential for Cat 3 Storm (worst case scenario of all motions, sizes, etc)

Little Washington: We have a Hurricane Problem.

Deterministic Runs and SLOSH

• SLOSH will be run approximately 36 hours prior to arrival of TS winds– Why only 36 hours?

• NHC track/intensity errors• Run every 6 hours coinciding with full advisory package

– Animated gifs– Still images of Envelope of High Water (EOHW)– Rexfiles– Shapefiles (GIS)

• Output placed on FTP site:– ftp.nhc.noaa.gov– www.nhc.noaa.gov/ftp

• New SLOSH display program that incorporates GIS layer capabilities, the ability to show inundation (which will also be mentioned in the advisories), more control over fonts/colors, and better briefing capabilities.

Deterministic SLOSH Run

Rmax=25 mi(forecast)

Surge Based on NHC - 12 hr. Advisory

Actual Hurricane Track 30 mi. E of 12 hr. Advisory Forecast Track

TRACK FORECAST

ACTUAL TRACK

133 mph, 933 mb.

Rmax=40 mi

Surge Based on NHC Storm Best Track

Probabilistic Storm Surge takes this error into account

• Use an ensemble of SLOSH runs to create probabilistic storm surge (p-surge)

• Atlas of pre-computed surge maps based on:– Different directions of motion– Different landfall locations– Different intensities– Different storm sizes– Different forward speeds

• Based on statistics of NHC error including: along track error (timing), cross track (location), intensity, and Rmax error.

PSURGE for IVAN

• Similar probabilities near Mobile Bay as around Pensacola

• Beginning when the NHC issues a hurricane watch or warning for the continental US

• Available approx. 1-2 hours after the advisory release time

When and Where is P-Surge Available?

http://www.weather.gov/mdl/psurge/active.php

P-Surge Available in 1 foot increments from 2 to 25 feet.

Thank you…

• More details and products available at:• http://slosh.nws.noaa.gov/sloshPub/ (SLOSH)• www.hurricanes.gov (National Hurricane Center)• www.weather.gov (NWS homepage)

John Cole252-223-5122 ext 223John.Cole@noaa.gov