P-Surge Product Description
Product Description Documents
- 2011 - P-Surge (Datum; Probabilities; without tide): Operational "Tropical Cyclone Storm Surge Probabilities"
- 2011 - P-Surge (Datum; Exceedance; without tide): Operational "Probabilistic Tropical Cyclone Storm Surge Exceedance Products"
- 2013 - PHISH (AGL; Prob and Exceed; with and without tide): Experimental "Probabilistic Hurricane Inundation Surge Heights"
- 2013 - P-Surge (Datum; Prob and Exceed; with tide): Experimental "Probabilistic Tropical Cyclone Storm Surge and Tide above Datum"
Probabilistic Tropical Cyclone Storm Surge (P-Surge)
consists of two
suites of graphics in reference to above a vertical datum as follows:
- Probability of storm surge and tide above datum – Series of graphics which
show probabilities, in percent, of storm surge with tide exceeding 2 through 25
feet above North American Vertical Datum of 1988 (NAVD88), at 1 foot intervals.
- Exceedance height of storm surge and tide above datum – Series of graphics
which show heights of storm surge with tide, in feet above NAVD88, which will
be exceeded by a given percentage of storms. The suite of graphics range from
10 to 50 percent, at 10 percent intervals.
These products are provied as a single 0-78 hour cumulative probability defined as the
overall probability the event will occur at each grid cell from the start of
the run until 78 hours in the future. P-Surge was enhanced in 2013 to include tide and
there are long term plans to include waves and freshwater (i.e. precipiation runoff and
Probabilistic Hurricane Inundation Surge Height (PHISH)
consists of a similar
set of graphics but in reference to above ground level. They are:
- Probability of storm surge and tide above ground level – Series of graphics
which show probabilities, in percent, of inundation exceeding 0 through 20 feet
above ground level, at 1 foot intervals.
- Exceedance height of storm surge and tide above ground level – Series of graphics
which show heights of inundation, in feet above ground level, which will be
exceeded by a given percentage of storms. The suite of graphics range from 10
to 50 percent, at 10 percent intervals.
These products are provided as 13 cumulative probability products with 6 hour spacing
defined as the overall probability the event will occur at each grid cell from the start
of the run until some specified time (e.g. 0-6 hours, 0-12, 0-18, …,
0-78) and as 13 incremental probability products defined as the
probability the event will occur at each grid cell in a 6 hour window during
the next 78 hours (e.g. 0-6 hours, 6-12, 12-18, … 72-78).
Both P-Surge and PHISH are based upon an ensemble of Sea Lake and Overland
Surge from Hurricanes (SLOSH
model runs using the National Hurricane Center (NHC) official advisory and
accounts for track, size and intensity errors based on historical errors.
The graphics are intended to provide users with information which enhances
their ability to make preparedness decisions specific to their own situations.
The graphics originated from requests by users for additional tropical cyclone
probabilistic information, and the National Research Council’s Fair Weather
Report encouraging probabilistic products.
The emergency management community is the primary target audience. However,
this product will also be widely used by other federal, state, and local
government agencies; the media; maritime interests; and the general public.
Graphics are provided as a .png file and Google map interface at:
GRIB2, KMZ and ESRI shape files can also be downloaded from the website.
In addition, P-Surge Without Tide GRIB2 data is provided over NOAAPORT, and via the
National Digital Guidance Database
Feedback can be provided by completing a brief survey at:
Technical questions and comments may be addressed to firstname.lastname@example.org.
Policy questions and comments may be addressed to email@example.com.
Format & Science Basis
The graphics are a statistical output from an ensemble of Sea Lake and Overland Surges
from Hurricanes (SLOSH) model runs. All ensemble members are based on the current National
Hurricane Center (NHC)’s tropical cyclone advisory. Ensemble members take into account
historical error characteristics by varying input parameters such as forward speed,
cross track location, radius of maximum wind, and hurricane intensity.
Each ensemble member has a specific time associated with it, which allows SLOSH to calculate
a gridded tide which it combines with the surge thereby producing
overland flooding based on storm surge + tide (aka storm tide).
The products are available whenever a hurricane watch or warning is
in effect for any portion of the Gulf of Mexico or Atlantic coasts of the continental
United States. On a case by case basis, the graphics will also be available whenever
a tropical storm watch or warning is in effect. Updates are available about one hour
after the issuance of routine NHC tropical cyclone advisories (03, 09, 15, and 21
Coordinated Universal Time - UTC).