Marine Verification at WFO Key West Where to go and how to get there… Andy Devanas, SOO and Matt Parke, Verification Focal Point. There are three kinds of lies: lies, damned lies, and statistics. Benjamin Disraeli (1804 - 1881). Figure 1. USF Buoy Not Operational. X. X. X. X. X.
Marine Area approx.
22000 square miles
10555 square miles
X– No Surface Data Available
NO WAVE DATA AT ALL
Need to integrate verification into the forecast process
Need to provide meaningful, frequent and timely verification data to forecasters ( e.g. Percent Correct vs. ESS)
Need to identify forecast and guidance biases
Enhanced discrimination in critical categories
APPLICATION OF THE NATIONAL MARINE VERIFICATION PROGRAM (NMVP) TO LOCAL MARINE VERIFICATION
What’s wrong with this picture??
Before Matched Sets at NMVP Site Customers…
EYW Forecasts: January 2004 Customers…
This Forecast Was Never Made
Where Did This Number Come From?
This Will Severely Skew ESS Score. As Well As Other Statistical Measures.
Percent Correct Customers…Definition From
Marine Verification Program Glossary
Definition: Percentage of the correct forecasts (hits) from the total number of events. Formula:
In Other Words: A/(A+B+C+D)
Some EYW verification results: Customers…
Gridded Verification at EYW…. Customers…
Otherwise known as…
What are you Kidding me??
From Murphy 1993… Customers…
“Since Forecasters’ judgments necessarily contain an element of uncertainty, their forecasts must reflect this uncertainty accurately in order to satisfy the basic maxim of forecasting. In general, then, forecastsmust be expressed in probabilistic terms.”
Melbourne’s ADAS Customers…
Closer to grid verification
*Supported by relatively dense surface data network over land
*Buoy in Marine Zones
Winds in this region most likely NE 10-15 knots.
We do not have ANY guidance to forecast wave height inside the reef at this resolution and detail, and little skill – therefore we do not attempt to forecast this region in our grids and zero out this region – but do include in our CWF.
Wavewatch III is poor at best outside of the reef – and does not account for gulf stream interactions.
AND NOT ONE WAVE HEIGHT DATA POINT!!
So How Do You Verify Wave Height??
Answer: You don’t.
Marine Forecast the reef at this resolution and detail, and little skill – therefore we do not attempt to forecast this region in our grids and zero out this region – but do include in our CWF.
730 PM EST SUN MAR 14 2004
SMALL CRAFT ADVISORY
TONIGHT: EAST WINDS AROUND 20 KNOTS. SEAS OUTSIDE THE REEF 5 TO 7 FEET...EXCEPT HIGHER IN THE GULF STREAM. SEAS INSIDE THE REEF 2 TO 3 FEET. NEARSHORE WATERS CHOPPY TO ROUGH. SCATTERED SHOWERS.
MONDAY: EAST WINDS 15 T0 20 KNOTS...DECREASING TO 10 TO 15 KNOTS BY NOON. SEAS OUTSIDE THE REEF 4 TO 7 FEET...EXCEPT HIGHER IN THE GULF STREAM. SEAS INSIDE THE REEF 2 TO 3 FEET. NEARSHORE WATERS CHOPPY. SCATTERED SHOWERS.
MONDAY NIGHT: SOUTHEAST WINDS NEAR 15 KNOTS. SEAS OUTSIDE THE REEF 3 TO 5 FEET. SEAS INSIDE THE REEF 2 TO 3 FEET. NEARSHORE WATERS A MODERATE CHOP. ISOLATED SHOWERS.
GRID VERIFICATION “THOUGHTS”… the reef at this resolution and detail, and little skill – therefore we do not attempt to forecast this region in our grids and zero out this region – but do include in our CWF.
Given the current state of model guidance and surface data available for the EYW marine area –
- It is entirely possible that our forecasters will have to DEGRADE our forecasts to match verification fields…