Storm Surge Training
Post on 30-Dec-2015
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Storm Surge TrainingStorm Surge Training
• Pre-generated 1. Parallel runs of Similar intensity storms2. Worst Case Scenario Maps
• Real-time SLOSH 3. Probabilistic storm surge (online for public)4. Real-Time SLOSH runs (NWS Only)
SLOSH Storm Surge ModelBehind the scenes
Winds 120 mphEye Diameter 25nmMoving NW 5 mph
Winds 120 mphEye Diameter 25nmMoving WNW 15 mph
• STRONGLY dependent on accurate track forecast!
• Very inaccurate more than a day in advance of landfall
• Use with extreme caution!
Realtime SLOSH Limitations
Hurricane Advisory – Approximately 12 hr. before landfall
NHC TRACK ERROR 12 hr. OUT
133 mph, 933 mb.
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
Uses an ensemble of SLOSH runs
• Intended to be used operationally so it is based on NHC’s official advisory
• Based on statistics of past performance of the advisories
• Based on size, intensity, of current and past storms rather than a random sampling
Probabilistic Storm Surge
Cross-Track Error
Other Parameters
Size: Small (30%), Medium (40%), Large (30%)
Forward Speed: Fast (30%), Medium (40%), Slow (30%)
Intensity: Strong (30%), Medium (40%), Weak (30%)
When is it Available?
• Initiated whenever a hurricane watch is issued!
• Available ~20-30 minutes after advisory release
Available Surge Products
ProbabilisticProbabilistic: This graphic shows the overall chance that storm surges will be greater than x feet above normal tide levels during the next 3 days.
Exceedance: Exceedance: This experimental graphic shows storm surge heights, in feet above normal tide level, which have a x percent chance of being exceeded during the next 3 days.
Rmax=25 mi(forecast)
Surge Based on NHC -12 hr. Advisory
Deterministic SLOSH run shows limited surge threat to Pensacola area
Actual storm caused highest surge in Pensacola area
Probabilistic product shows considerable surge threat to Pensacola area
Questions???
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