Struthwolf

Slide 1: 

Communication between NWSFO and FAA Mitigates Effects of Microbursts at Salt Lake City International Airport Mark Struthwolf Aviation Focal Point WFO Salt Lake City 12th Annual Intermountain Workshop

Overview: 

Overview Synoptic Pattern Radars Available Time Line of Events Forecaster Dilemma FAA Operational Structure Actions and Results How to Strengthen Communications 12th Annual Intermountain Workshop

Slide 3: 

500 mb winds 1200 UTC 09 July 2004 SLC 12th Annual Intermountain Workshop

Slide 4: 

500 mb winds 0000 UTC 10 July 2004 SLC 12th Annual Intermountain Workshop

Slide 5: 

Stable above this level

Slide 6: 

Stable above This level Inverted-V

Relationship of Radar Locations to Salt Lake City (SLC): 

Relationship of Radar Locations to Salt Lake City (SLC) TDWR SLC Promontory Point (KMTX) 12th Annual Intermountain Workshop

Radars: 

Radars KMTX Elevation - 6574 ft MSL Distance from SLC 41 miles Lowest Beam Height over SLC - 5380 ft TDWR Elevation - 4300 ft MSL Distance from SLC 12 miles Lowest Beam Height over SLC - 840 ft 12th Annual Intermountain Workshop

Slide 9: 

Grantsville SLC LGU OGD HIF 2208 UTC TDWR

Slide 10: 

12th Annual Intermountain Workshop

Slide 11: 

Grantsville SLC 2256 UTC Inbound Velocities of 36 to 50 KTs LGU 2230 UTC 70 mph Gust TDWR

Slide 12: 

Grantsville SLC SVR – Issued at 2341 UTC >50 mph wind gust reported at 2330 UTC But actually occurred at about 2300 UTC 2332 UTC HIF OGD TDWR 36 min later TAF updated 2342 UTC

Slide 13: 

SLC Inbound Velocities of 36 to 50 KTs 0033 UTC TDWR One hour later First Microburst missed SLC Another Microburst develops OGD and HIF 0010 UTC >60 mph Gust

Slide 14: 

SLC Inbound Velocities of 36 to 50 KTs 0045 UTC TDWR 12 min later

Slide 15: 

SLC 2345 UTC 0025 UTC Forecaster Dilemma

Forecaster Dilemma: 

Forecaster Dilemma QUESTION: HOW DOES THE AVIATION FORECASTER HANDLE THIS SITUATION? CALL ATCT WHO? Can’t use more than one TEMPO per hour Could use multiple FM groups… but unsure of exact timing of microbursts Without TEMPOs will lose the temporal resolution of the event What should you do? 12th Annual Intermountain Workshop

FAA Operational Structure: 

FAA Operational Structure T M U Air Traffic Control System Command Center - Oversees all air traffic control and regulates problematic air traffic situations - NAS Air Route Traffic Control Center – Managing IFR traffic in the en route phase of flight (beyond 50 miles) Terminal Radar Approach Control – Departure/Arrival phase of flight (>5 to 50 miles) Air Traffic Control Tower – Takeoff, Landing, and ground traffic (<5 miles) Traffic Management Unit Coordinates efforts between the other 4 divisions Monitors and balances traffic flow 12th Annual Intermountain Workshop

Communication and Actions: 

Communication and Actions WFO NOTIFICATION OF MICROBURSTS ATCT COLLABORATIVE DECISION TRACON ATCSCC REQUEST ARRIVAL RATE DECREASE TMU Coordinates ATCT Efforts TRACON ARTCC Honored Request to Decrease Arrival Rate From 80 to 48 For Following 1 Hour Adjust Air Traffic En Route to SLC For This New Rate Update TAF

FAA Actions Summarized: 

FAA Actions Summarized Initiated strategic plan to mitigate effects of microburst on air traffic operations through… Reduced arrival rate Established 3 different runway configuration plans for various wind directions Advanced the landing of some aircraft Delayed the landing of others 12th Annual Intermountain Workshop

Results: 

Results Microburst hits SLC (45-50 mph) / visibility < 2 miles SLC airport closed down for 13 min SLC arrival/departure rate remained below normal operations for 30-40 min Net result “NO DIVERSIONS” and “SAFE LANDINGS” for all arrivals Received KUDOS from ATCT 12th Annual Intermountain Workshop

How to Build Communications Between WFO and ATCT: 

Develop a working relationship with ATCT through verbal communication Foster this relationship by making visits to each other’s facility Build their confidence in your forecast Anticipate changes in the weather Respond with proactive TAF updates Notify ATCT with reasons for update How to Build Communications Between WFO and ATCT

Questions ?: 

Questions ?

: 

The End Thank You for Your Time

Time Line of Observations and Events: 

Time Line of Observations and Events 2230 UTC - 70 mph wind gust Logan, 65 miles N of SLC) 2330 UTC - >50 mph wind gust Grantsville, 30 miles WSW of SLC 2341 UTC - Severe Thunderstorm Warning issued for Davis and Weber Counties (southern boundary within 8 miles of SLC) 2342 UTC – TAF updated and ATCT notified 12th Annual Intermountain Workshop

Time Line of Observations and Events (continued): 

Time Line of Observations and Events (continued) 0000-0015 UTC - >60 mph wind gusts at both Ogden (OGD), 30 miles N of SLC Hill Air Force (HIF), 22 miles N of SLC 2340 – 0035 UTC…Sustained south winds 15- 20 mph (Microburst missed SLC) 0035 – 0045 UTC…Wind Gusts 45-50 mph …Visibility < 2 miles temporarily 12th Annual Intermountain Workshop

Forecaster Actions Summarized: 

Forecaster Actions Summarized Situational awareness Alert radar monitoring Proactive TAF update Verbal communication with ATCT 12th Annual Intermountain Workshop

Forecaster Dilemma: 

Forecaster Dilemma Microburst winds likely to affect SLC from at least 2 directions during next hour, maybe 3 directions Stringent TAF format allows only one TEMPO group per hour 12th Annual Intermountain Workshop

TAF Forecast Challenges: 

TAF Forecast Challenges Wind (speed and direction) Visibility Weather Obstruction to vision (if any) Clouds (vertical visibility in to surface-based obscuration) Low Level Wind Shear (LLWS) Any expected significant changes to one or more of these elements

Slide 29: 

Weather Radar Limitationsin the Mountainous Western U.S.

Observations at SLC: 

Observations at SLC 0035 – 0045 UTC…Wind Gusts 45-50 mph …Visibility < 2 miles temporarily 2340 – 0035 UTC…Sustained south winds 15- 20 mph (Microburst missed SLC) SLC airport was effectively closed down for 13 min SLC arrival/departure rate remained below normal operations for 30-40 min

Communication and Actions: 

ATCT and TRACON devised 3 Strategic Plans according to most likely timing and direction of microburst winds 1 for Cross and 1 for North – during initial 30 min as a microburst moved past to the NW of SLC 1 for South – during next 30-60 min for potential microbursts from new radar returns that had developed to the south southwest of SLC Communication and Actions

Conclusion: 

Conclusion Aviation Forecasters must – Remain astute during their weather watch Anticipate changes in weather Respond with proactive TAF update Notify ATCT with reasons for update Establish an exemplary working relationship with ATCT or TRACON Develop a level of confidence

summary: 

summary Shallow Convection Developed – innocuous looking radar returns Several Severe Wind Gust reports - >58 kt TAF updated Verbal Update to ATCT Reduction of aircraft in SLC airspace Microburst winds of 45-50 mph Visibility reduced to under 2 miles Net result “No Diversions” and “SAFE landings” SUMMARY

SUMMARY: 

SUMMARY Situation Awareness - Meteorology of the day Anticipate changes in the weather What are the impacts on Aviation? Be Proactive in updating TAF Verbally notify ATCT VARIOUS DIVISIONS OF FAA BECAME INVOLVED IN THE COLABORRATIVE DECISION PROCESS AIR TRAFFIC SAFETY WAS NEVER COMPROMISED