What is Atmospheric Mixing? Evolution through the Day Local Example Aviation Weather Hazards Influenced by Mixing o Dryline o Nocturnal Low Level Jet o Nocturnal Low Clouds & Fog o Wildfire Smoke o Rio Grande Valley East Canyon Winds (if time) Interruptions to the Typical Cycle of Atmospheric Mixing

The transfer of momentum from stronger flow aloft to the surface by buoyant and mechanical processes o Buoyant Processes – Large thermals including their associated descending couplets o Mechanical Processes – Vigorous turbulence resulting from strong wind shears (ie. advancing cold fronts)

0°c10°c20°c-10°c-20°c-30°c 0 ft 5,000 ft 10,000 ft 15,000 ft 20,000 ft AGL

0°c10°c20°c-10°c-20°c-30°c 0 ft 5,000 ft 10,000 ft 15,000 ft 20,000 ft

0°c10°c20°c-10°c-20°c-30°c 0 ft 5,000 ft 10,000 ft 15,000 ft 20,000 ft

The stronger the atmospheric mixing, the better strong winds aloft mix down to the surface.

Adapted from Stull, R. B., 2000: Meteorology for Scientists and Engineers Top of the Inversion Surface Note the nearly calm surface winds at the bottom of the inversion and the region of wind shear at the top of the inversion

Adapted from Stull, R. B., 2000: Meteorology for Scientists and Engineers The descending couplet in the thermal circulation transfers stronger momentum aloft downward causing surface winds to strengthen

EZ = Entrainment Zone Elevated Capping Inversion (ECI) 1 km Free Atmosphere Stable Air Mixing Air WRM ECI EZ 1 km Free Atmosphere Weaker Residual Mixing (WRM) Stable Air Stable Air Mixing Air WRM ECI EZ Height Time Adapted from Stull, R.B.,2000: Meteorology for Scientists and Engineers

Dry Line Nocturnal Low Level Jet Nocturnal Low Clouds & Fog Wildfire smoke Rio Grande Valley East Canyon Winds (if time) E NM/W TX Haboob October 17, 2011 ~3 PM MDT

USATODAY.COM Dewpoints Dry/moist convergence zone Flying hazards o Thunderstorms o Low Level Wind Shear Most common and intense in spring and early summer Daytime advances east Nighttime usually retreats west

A stream of stronger winds (25-50 KT) centered around 2-3K FT AGL Most frequent in Spring & Summer Peaks in strength before sunrise, then weakens during the day Flight Impacts o Low level wind shear o Varies the approach speed; may cause short or long landing o Fuel savings or increased expense due to tail or headwind Detection o WSR-88D VAD Wind Profile o Texas Tech Sodar Wind Profile: o Plot of AWC/ADDS Flight Level Winds ~ 3000 FT ( o PIREPS indicating Low Level Wind Shear Surface Analysis Including Nocturnal Low Level Jet (Red Arrow)

Monitor Nighttime IFR using these satellite images Go to Choose ‘Fog Image’ or ‘Low Cloud Base (LCB) Image’ & loop them. High clouds (blue) obscure satellite view of low level moisture (see E TX/OK) GOES Low Cloud Base ProductGOES Fog Image

6/24/ Z 6/23/ Z NWS ABQ Website: Mogollon Rim Wildfire

* Santa Fe Tijeras Canyon Tijeras Canyon ABQ Airport X 1200 FT drop Sandia Mtns Sandia Mtns High on ABQ Sunport & Santa Fe Airport. Stronger events also reach Double Eagle (KAEG), Taos (KSKX), & Grants (KGNT) Airports. Develop most often at night, then taper off during mid to late morning Over-the-top events can cause hurricane-force winds in Albuquerque o 124 mph (base of the tram) o 108 mph – 1990 (Glenwood Hills) o 90 mph Sustained – 1943 (ABQ Airport)

Clouds o Inhibit mixing during the day by decreasing the amount of solar energy that reaches the ground o Inhibit the growth of the nocturnal temperature inversion by weakening radiational cooling Cold fronts o Can cause strong winds during cloudy days and also at night when they have strong surface pressure gradients o Can mechanically induce vertical mixing day or night helping to transfer stronger momentum aloft to the surface even in the absence of thermals

What is Atmospheric Mixing? Evolution through the Day Local Example Aviation Weather Hazards Influenced by Mixing o Dryline o Nocturnal Low Level Jet o Nocturnal Low Clouds & Fog o Wildfire Smoke o Rio Grande Valley East Canyon Winds (if time) Interruptions to the Typical Cycle of Atmospheric Mixing

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Hourly Weather Graph o Hourly graph of wind, mixing height, transport wind, temperature, & more at a point location o NWS Aviation Forecast Discussions o Forecaster reasoning behind TAFs & discussion of aviation weather hazards for next 24 hours o METAR Plot from the Aviation Weather Center o Zoomable plot of surface weather observations that updates automatically o Flight Path Tool from the Aviation Weather Center o Application that draws a cross-section through the atmosphere along your flight path with a plethora of wind and other weather information at various levels o Observed Atmospheric Soundings (Skew-T Log-P Diagrams) o Weather-balloon-sampled vertical profile of temperature and winds updated after 00Z & 12Z o (click your local star b/c soundings default to OUN) Forecast Soundings, Windgrams & Balloon Flight Forecasting Tools from NOAA Air Resources Laboratory o Choose a weather model to forecast a sounding or hourly vertical wind profiles over a specific location o (Enter location, then select Sounding or Windgram) o Or, choose ‘Balloon Flight Forecasting Tools’ from the left column menu National Satellite & Information Service o Nighttime Fog & Low Cloud Images o Smart Phone Weather o Free forecasts, graphical forecasts, forecast discussions, warnings, radar, satellite, TAF/METAR o