WFO Aviation Products & Services

1. WFO Aviation Products & Services By Nick Fillo WFO Shreveport, LA 2009 Regional Aviation Conference Shreveport, LA

2. Goals of this presentation: • Discuss how the Weather Forecast Office (WFO) develops a weather forecast. • What is a terminal aerodrome forecast (TAF). • Forecast Discussions: Laying out the reasoning of our forecasts. • Airport weather warnings: Protecting airport resources.

3. Forecast Process • Perform current weather analysis: Identify any weather features in the region which may impact airports. • Make use of radar, satellite, surface observations, weather balloons, etc. • Identify high and low pressure centers, fronts, troughs, outflow boundaries, upper level disturbances. • Use numerical weather models to aid in weather forecasting. Use knowledge of the local area to “fine tune” the forecast. • Coordinate with other forecasters within the office and from surrounding offices to ensure consistency.

4. Forecast Funnel Methodology • Start by analyzing features on a synoptic scale (North America). Doesn’t take much time. • Gradually work down to the • local scale, spending more time • focusing on weather features • that will pose an immediate • challenge to the forecast area. • Apply your knowledge of local • affects that model data doesn’t • pick up.

5. Terminal Aerodrome Forecast (TAF) • A TAF is an encoded weather forecast of conditions within the 5 mile vicinity of an airport. • TAFs are issued 4 times daily, at 00Z, 06Z, 12Z and 18Z. • Most TAFs cover weather conditions for a 24 hour period. However, a few major airports have TAFs which cover a 30 hour period (i.e. KDFW). • Once issued, TAFs may be amended as necessary to accommodate unforeseen changes in the weather. • 7 TAFs locations within the NWS Shreveport forecast region.

6. TAF Example 1: 24-Hour TAF • TAF • KXYZ 140520Z 1406/1506 16004KT 4SM BR BKN025 • FM141100 17003KT 2SM BR SCT009 BKN015 • TEMPO 1411/1414 1/2SM FG BKN003 • FM141600 18012KT P6SM SCT025 BKN040 • FM142300 18014G20KT 6SM –TSRA BKN030CB • FM150100 33015G25KT P6SM SCT090= • Breakdown of the first line: • TAF issued at 0520Z on the 14th • TAF is valid from 06Z on the 14th through 06Z on the 15th • Winds are from 160 degrees (SSE) at 4 knots • Prevailing surface visibility is 4 statute miles with misty (BR) conditions • A broken layer of clouds is expected around 2500 feet.

7. TAF Example 2: 30-Hour TAF TAF AMD (COR, RTD) KABC 050811Z 0508/0612 15006KT 3SM BR BKN020 TEMPO 0508/0510 1SM BR OVC003 FM051100 16010KT P6SM SCT040 WS016/17050KT FM051700 32015G22KT SCT050 BKN070 FM060100 VRB04KT P6SM SKC=

8. TAF Specification Criteria • Also, any time when significant weather affects the airport, including thunderstorms, freezing precipitation, snow etc.

9. TAF Benefits • An excellent planning/decision support tool. • Tower and airport staff can make preparations a day in advance of significant weather. • Helps airlines decide whether extra fuel is necessary, determine alternate airports, possibly whether to scrub the flight altogether. • More information about TAF coding is available at http://www.weather.gov/os/aviation/taf_testbed.shtml

10. Aviation Forecast Discussion • The Aviation Forecast Discussion provides the technical details and forecast reasoning as seen in the TAFs. • The discussion also provides information concerning our confidence in a weather event occurring. • Aviation Forecast Discussion is part of the more inclusive Area Forecast Discussion, which also includes the Public Forecast Discussion. • Discussions are usually issued around 3AM, 9AM, 3PM and 9PM local time.

11. Example Aviation Forecast Discussion AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 900 PM CDT TUE APR 15 2008 .AVIATION... VFR CONDITIONS WILL REMAIN FOR ANOTHER 24 HRS ALTHOUGH PATTERN WILL BE CHANGING RAPIDLY THERAFTER. SURFACE RIDGE WILL SLOWLY DRIFT E INTO THE LOWER MS VALLEY TONIGHT RESULTING IN SSW WINDS OF 4-7 KTS FOR MOST LOCATIONS WITH LGT/VRBL WINDS EXPECTED OVER THE ELD/MLU TERMINALS. DESPITE LGT/ VRBL WINDS TONIGHT... SHALLOW FOG WILL BE PATCHY AT BEST THUS WILL NOT INCLUDE IN THE ELD/MLU TAFS ATTM. WINDS WILL SHIFT TO NORTH AND NORTHWEST AND INCREASE TO 15-20 KTS WITH GUSTS TO NEAR 30KTS AFTER 15Z WEDNESDAY AHEAD OF A COLD FRONT THAT WILL EXTEND ACROSS CENTRAL OK AND NORTH CENTRAL TX. EXPECTING 10 KFT AC DECK TO TRAVERSE SE INTO THE AREA AS EARLY AS DAYBREAK OVER E TX… SW AR... AND ACROSS THE REMAINDER OF THE TERMINALS OF N LA BY MID TO LATE MORNING... POSSIBLY LOWERING SOME BUT REMAINING VFR. ISOLATED SHOWERS COULD DEVELOP AHEAD OF THE FRONT AFTER 28/00Z OVER SW AR AND NW LA.

12. TAF & Aviation Discussion Together TAF KSHV 050530Z 0506/0606 15004KT 3SM BR BKN020 TEMPO 0508/0510 1SM BR OVC003 FM051100 16010KT P6SM BKN040 WS016/17050KT FM051700 32015G22KT SCT050 BKN070 FM060100 VRB04KT P6SM SKC= .AVIATION... LOW STRATUS AND AREAS OF FOG WILL BE THE MAIN CONCERNS EARLY IN THE 05/06Z TAF PACKAGE. GULF MOISTURE MAKES A RAPID RETURN TO THE AREA AS SURFACE HIGH OVER COASTAL AL SLIDES QUICKLY EAST. THEREFORE STRATUS WILL BE BELOW 2KFT FOR PARTS OF THE FOUR STATE REGION AFTER 08Z. PATCHY FOG WILL ALSO DEVELOP WITH VISIBILITIES AS LOW AS 1 STATUE MILE POSSIBLE FROM S CENTRAL LA ACROSS NE TX TO SE OK.AS THE PRESSURE GRADIENT TIGHTENS ACROSS THE SOUTHERN PLAINS…A LOW LEVEL JET WILL INTENSIFY TO NEAR 50KT ACROSS THE AREA. HOWEVER… WITH A SURFACE INVERSION EXPECTED TO HOLD TOGETHER DURING THE PREDAWN HOURS…WIND SHEAR CONDITIONS ARE LIKELY AT AREA AIRPORTS. THESE CONDITIONS WILL DIMINISH AS DAYTIME HEATING BREAKS THE INVERSION…ALLOWING STRONGER WINDS TO MIX DOWN TO THE SURFACE.A COLD FRONT WILL MOVE THROUGH THE REGION BY EARLY AFTERNOON…SHIFTING WINDS TO A NW DIRECTION. THE TIGHTENED PRESSURE WILL SUPPORT GUSTY WINDS THROUGH SUNSET…WHEN AN INVERSION DEVELOPS ALLOWING WINDS TO BECOME LIGHT AND VARIABLE.

13. Aviation Forecast Discussion Benefits • Goes into a detailed explanation about a forecast that might not be obvious on a TAF alone. • TAF=location while aviation discussion=location and/or region specific. • Another decision support tool; Allows for better coordination among aviation services. • The Shreveport Aviation Discussion may be viewed at: http://forecast.weather.gov/product.php?site=SHV&product=AFD&issuedby=SHV

14. Airport Weather Warning • In the NWS Shreveport forecast region, the airport weather warning is issued only for Shreveport Regional Airport. • Issued whenever winds (convective or non-convective) are expected to be GTE 35kts. • AIRPORT WEATHER WARNING • NATIONAL WEATHER SERVICE SHREVEPORT LA • 704 AM CDT FRI AUG 21 2009 • ...AIRPORT WEATHER WARNING FOR SHV THROUGH 735 AM... • THUNDERSTORMS WITH WIND GUSTS IN EXCESS OF 35 KNOTS AS WELL AS LIGHTNING WITHIN 10 NM OF THE AIRPORT. STORMS LOOK TO CONTINUE AROUND SHV FOR ANOTHER HALF HOUR. GUSTS ABOVE 35 KTS LOOK LIKELY AT THIS TIME.

15. Airport Weather Warning Benefits • Gives the tower time to prepare for hazardous weather and possibly dangerous crosswinds. • Allows airport staff to take shelter before the onset of dangerous winds and/or hail. • Allows airport personnel time to protect property. • Shreveport Airport Weather Warnings may be viewed at: http://forecast.weather.gov/product.php?site=SHV&product=AWW&issuedby=SHV

16. Questions? or Comments? Thanks for your time.