AVIATION VERIFICATIONAVIATION VERIFICATION

NWS KEY WESTNWS KEY WEST

20052005

Bill South

Aviation Program Leader

OBJECTIVESOBJECTIVES

• Present KEYW and KMTH TAF statistics Present KEYW and KMTH TAF statistics for 2005 using TAF Stats on Demand. for 2005 using TAF Stats on Demand.

• Present TAF writing philosophies for Present TAF writing philosophies for improving verification results while improving verification results while providing quality service to our providing quality service to our customers.customers.

TAF WRITING TAF WRITING PHILOSOPHYPHILOSOPHY

Many pilots find TAFs are often Many pilots find TAFs are often written with a level of complexity that written with a level of complexity that they lose utility.they lose utility.

Verification statistics prove that Verification statistics prove that PROB and TEMPO groups are PROB and TEMPO groups are overused, and can hurt the value of overused, and can hurt the value of the forecast.the forecast.

TAF WRITING TAF WRITING PHILOSOPHYPHILOSOPHY

Important thresholds, with large Important thresholds, with large impacts on traffic do not necessarily impacts on traffic do not necessarily occur at the thresholds of flight occur at the thresholds of flight categories. categories.

Federal Air Regulations (FAR) 91.167 Federal Air Regulations (FAR) 91.167 states that +/- 1 hr, LT 2000 ft, LT 3SM states that +/- 1 hr, LT 2000 ft, LT 3SM requires the filing of an alternate requires the filing of an alternate airport for IFR traffic.airport for IFR traffic.

Major impact is that it costs Major impact is that it costs approximately 10% of the cost of approximately 10% of the cost of extra fuel just to carry that extra fuel. extra fuel just to carry that extra fuel.

*Extra weight=Extra Fuel Burn*Extra weight=Extra Fuel Burn

TAF STATS ON DEMANDTAF STATS ON DEMAND

TAF Stats on Demand breaks each TAF and TAF Stats on Demand breaks each TAF and observation into 288 discrete 5 minute observation into 288 discrete 5 minute blocks.blocks.

For this presentation, only the first six For this presentation, only the first six hours of scheduled TAFs (00Z, 06Z, 12Z, hours of scheduled TAFs (00Z, 06Z, 12Z, and 18Z) are verified. and 18Z) are verified.

Forecasts within TEMPO groups are verified.Forecasts within TEMPO groups are verified.

TEMPO GROUPSTEMPO GROUPS

TAF Stats on Demand checks TAF Stats on Demand checks TEMPO groups for justification.TEMPO groups for justification.

A TEMPO group is considered A TEMPO group is considered justified if conditions change twice justified if conditions change twice or more during a period of three or more during a period of three hours or less.hours or less.

TEMPO GROUPSTEMPO GROUPS

If the TEMPO group is justified, each 5 If the TEMPO group is justified, each 5 minute interval is evaluated with the minute interval is evaluated with the forecast from either the prevailing or forecast from either the prevailing or TEMPO condition, which ever condition TEMPO condition, which ever condition produces the most favorable verification produces the most favorable verification score.score.

If the TEMPO group is not justified, each 5 If the TEMPO group is not justified, each 5 minute interval is evaluated with the minute interval is evaluated with the forecast representing the lowest (worst) forecast representing the lowest (worst) condition, the condition for which the pilot condition, the condition for which the pilot must plan.must plan.

AVIATION GPRA GOALSAVIATION GPRA GOALS

The aviation GPRA goals for TAFs are The aviation GPRA goals for TAFs are Instrument Flight Rules (IFR) and Instrument Flight Rules (IFR) and Thunderstorm (TS) Probability of Detection Thunderstorm (TS) Probability of Detection (POD) and False Alarm Ratio (FAR) in the (POD) and False Alarm Ratio (FAR) in the first six hours of the TAF.first six hours of the TAF.

The NWS is required to share these The NWS is required to share these statistics with the FAA.statistics with the FAA.

(Government Performance & Results Act)

Remember…Remember…

All verification results are based on one All verification results are based on one verification point. The TAF area verification point. The TAF area encompasses a circle within 5 statute encompasses a circle within 5 statute miles of the airport.miles of the airport.

Quality control of observations by the Quality control of observations by the tower can be inconsistent at best. tower can be inconsistent at best.

Our verification system is not nearly a Our verification system is not nearly a perfect system, but it is what it is.perfect system, but it is what it is.

2005 TS POD2005 TS POD

0.272

0.560.584

0.25

0.3

0.5

0

0.1

0.2

0.3

0.4

0.5

0.6

POD

Key West Miami Florida NWS Current NWS FY07Goal

NWS FY12Goal

Office

0 to 6 hour TS POD (January 1, 2005 - December 31, 2005)

+4.5%

+3.7%+0.9%

2005 TS FAR2005 TS FAR

0.9160.885

0.863

0.71

0.6

0.4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

FAR

Key West Miami Florida NWS Current NWS FY07Goal

NWS FY12Goal

Office

0 to 6 hour TS FAR (January 1, 2005 - December 31, 2005)

+0.6%-1.2%

+4.5%

2005 IFR POD2005 IFR POD

0.504

0.399

0.565

0.45

0.55

0.7

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

POD

Key West Miami Florida NWS current NWS FY07Goal

NWS FY12Goal

Office

0 to 6 hour IFR POD (January 1, 2005 - December 31, 2005)

+20.0%

+13.1%

+4.4%

2005 IFR FAR2005 IFR FAR

0.656

0.737

0.617

0.71

0.64

0.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

FAR

Key West Miami Florida NWS Current NWS FY07Goal

NWS FY12Goal

Office

0 to 6 hour IFR FAR (January 1, 2005 - December 31, 2005)

+26.9%

+16.1%

+8.2%

WHAT ARE WE DOING WHAT ARE WE DOING RIGHT?RIGHT?

From 2003-2005, we showed gradual From 2003-2005, we showed gradual improvement in TS POD, IFR POD improvement in TS POD, IFR POD and IFR FAR for 0 to 6 hours. and IFR FAR for 0 to 6 hours.

Right now, we are better than the Right now, we are better than the NWS current skill scores for TS POD, NWS current skill scores for TS POD, IFR POD and IFR FAR for 0 to 6 IFR POD and IFR FAR for 0 to 6 hours.hours.

WHERE CAN WE WHERE CAN WE IMPROVE?IMPROVE?

From 2003-2005, we showed little From 2003-2005, we showed little to no improvement in TS FAR for 0 to no improvement in TS FAR for 0 to 6 hours.to 6 hours.

Right now, we are 20.6% worse Right now, we are 20.6% worse than the NWS current skill score for than the NWS current skill score for TS FAR for 0 to 6 hours.TS FAR for 0 to 6 hours.

WHAT TO DO?WHAT TO DO?

So, it would seem statistically that it would So, it would seem statistically that it would behoove us to forecast TS rarely, if ever. behoove us to forecast TS rarely, if ever.

BUT, we want to provide quality service to BUT, we want to provide quality service to our customers and present the realm of our customers and present the realm of possibilities.possibilities.

We need to find a way to balance service We need to find a way to balance service and verification as much as possible.and verification as much as possible.

SOME SUGGESTIONSSOME SUGGESTIONS

For the first 3 hours of a TAF, if you feel that TS For the first 3 hours of a TAF, if you feel that TS are likely, pick the “most likely” hour and use a FM are likely, pick the “most likely” hour and use a FM or TEMPO group during that hour. Otherwise, use or TEMPO group during that hour. Otherwise, use CB and/or VCTS.CB and/or VCTS.

This strategy will inform pilots of the risk, yet This strategy will inform pilots of the risk, yet somewhat minimize the impact to our stats if there somewhat minimize the impact to our stats if there is a miss. Possible drawback is implied precision.is a miss. Possible drawback is implied precision.

Yes, you may pick the wrong hour, but that is what Yes, you may pick the wrong hour, but that is what amendments are for, AND at least the presence of amendments are for, AND at least the presence of such convection in the TAF will inform the users.such convection in the TAF will inform the users.

SOME SUGGESTIONSSOME SUGGESTIONS

Between 3-6 hours of a TAF, use of TEMPO Between 3-6 hours of a TAF, use of TEMPO groups for TS is discouraged, unless you groups for TS is discouraged, unless you have clear justification (e.g. squall line). have clear justification (e.g. squall line). Even then, be “brief”, monitor trends and Even then, be “brief”, monitor trends and amend if necessary.amend if necessary.

Preferred method, use CB and/or VCTS for Preferred method, use CB and/or VCTS for situations where there is no clear situations where there is no clear justification.justification.

SOME SUGGESTIONSSOME SUGGESTIONS

Beyond 6 hours of a TAF, use of TS is Beyond 6 hours of a TAF, use of TS is STRONGLY discouraged (even though STRONGLY discouraged (even though doing so would not affect our stats).doing so would not affect our stats).

Preferred method, use CB and/or VCTS. In Preferred method, use CB and/or VCTS. In rare instances, TEMPO groups are alright rare instances, TEMPO groups are alright (well-timed strong cold front, for (well-timed strong cold front, for example).example).

AMENDMENTSAMENDMENTS

NEVER write the unamendable TAF.NEVER write the unamendable TAF.

Give it your best shot the first time, if Give it your best shot the first time, if you have to amend the forecast, you you have to amend the forecast, you have to amend the forecast.have to amend the forecast.

Amendments MUST be proactive (2-6 Amendments MUST be proactive (2-6 hours) as often as possible, not reactive. hours) as often as possible, not reactive. NOWTAFing should be avoided if at all NOWTAFing should be avoided if at all possible.possible.

BOTTOM LINE…BOTTOM LINE…

• Focus on what WILL happen, not what COULD Focus on what WILL happen, not what COULD happen.happen.

• Use TEMPO and PROB groups sparingly and Use TEMPO and PROB groups sparingly and smartly, keep them short and specific. Don’t smartly, keep them short and specific. Don’t simply use them “just in case”. All FM groups simply use them “just in case”. All FM groups are preferred in the first six hours of the TAF.are preferred in the first six hours of the TAF.

• Be ESPECIALLY careful with TS usage. Consider Be ESPECIALLY careful with TS usage. Consider using VCTS or a “stand-alone” CB in the cloud using VCTS or a “stand-alone” CB in the cloud group.group.