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Weather Information for the Ballooning
CommunityJennifer McNattLead Forecaster
National Weather Service Tampa Bay Office
Today’s Overview
• Meteorology Review• Forecasting 101– Current data (soundings, observations,
radar)–Model data– Forecasts (TAFs, meteograms)
• Sources for Weather Information
Meteorology Review
• Upper Level Patterns –What “drives” weather systems
Highs and Lows
• Determine surface wind direction and speed
• Precip chances• Cloud cover
Meteorology Review - Winds
• Pressure gradient– Tight = faster
winds
• Follow isobars, but also flow from higher to lower pressures
Local Winds
• Smaller-scale winds caused by local effects.– Seabreezes– Differential Heating– Convective Outflow– Inversions/Boundary Layer
Seabreezes
• During a clear day. . . sunshine heats the land to a greater extent than the water.
• Warm air over the land rises and is replaced by cooler, moister, marine air.
At Night…Opposite processes occur
Differential Heating
Convective Outflows
• Doesn’t have to be from a thunderstorm
• Range from an increase in a few knots to 100+kts– Rapid change
in wind direction
Inversions/Boundary Layer
• Especially pertinent to early AM flights– Colder layer near the surface– Gets “cut-off” from layer above it• Leads to stronger winds in layer above• Winds mix down to surface after sunrise
TemperatureDewpoint
Forecasting 101
To know what’s going to happen in the future, you
have to know what’s going on now…
Observing the Weather
ASOS - Automated Surface Observing System
Rain
Temp & Dew Point
Precip type and intensity
Wind Direction and Speed
Data Unit
Visibility
Pressure measured at the Tower or other location nearby.
ASOS
• 569 FAA sponsored sites• 313 NWS sponsored sites• Non-stop weather information• Computer generated voice broadcasts• Using FAA VHF ground-to-air radio or
appended to ATIS broadcast• Also available through the phone or on the
internet
AWOSAutomated Weather Observing System
▪AWOSs cost about $94,000 and are much less expensive than ASOSs
▪Who owns them▸Federal AWOSs are maintained by the FAA▸Most AWOSs are owned and maintained by
states, airports, or other local interest▪There are three main types of AWOSs▸AWOS I - temp, dew point, pressure, wind,
density altitude▸AWOS II - adds visibility▸AWOS III - adds cloud information
–AWOS IIIp - adds precipitation type sensor
Decoding METARs
METAR KTPA 101955Z 33015G22KT 1/2SM FG VV002 19/19 A2955 RMK A02 PK WND 32035/1915 TWR VIS 3/4 SLP028 P0004 T01920188
Remarks
Automated precipitation reporting
Peak wind northwest at 35kts at 1915Z
Tower visibility 3/4 mile
Sea level pressure 1002.8 MB00.04" rain in last hour
Temp = 19.2 CDew = 18.8 C
Weather Balloons
▪Launched at the same time across the world (11Z & 23Z)
▪Rises 1000 feet per minute
▪Reaches 90,000 ft in 1.5 hours
▪Balloon expands to 35 feet before exploding
▪Measures:▸Temperature▸Dew Point▸Wind direction and speed▸Pressure
Radiosonde Data
Station Map and Data Plot
WSR-88D Radar
• 154 WSR-88D sites• About a 250nm range• Detects precip and velocity data• An additional 45 TDWR Sites– Higher resolution data
Composite vs. Base Reflectivity
Forecasting 101 – Model Data
• Ballooning = mesoscale models– Or models that take into account local effects
• WRF– Run at NWS offices– Small scale model– Data hourly– Check with your local office for availability on the web
Model Data Continued…
• RUC– Designed for aviation community– Rapid update (hourly)– 1hr time steps
• MOS Guidance– Model Output Statistics
• Takes model data and interprets it for specific points (airports, METAR sites, etc)
• Also uses statistics…or climatology for that site
– Run every six hours
MOS Bulletins
Model Data Continued…
• LAMP (Localized Aviation MOS Guidance)–Will probably be the most helpful to
balloonists!!– Updates GFS MOS on an hourly basis– Forecasts elements every hour
LAMP Guidance
Forecasting 101 - Forecasts
• The NWS does the work for you!– Text Forecasts– Discussions– Aviation Forecasts– Graphical Forecasts
www.weather.gov
NWS Products
• Forecast discussions– Out to 7 days– Include aviation section
• 7-day point and click forecast• Graphical forecasts– Hourly weather graphs based on
graphics
Terminal Aerodrome Forecasts (TAFs)
• Most used aviation forecast• Valid for 24-30hrs• Issued every 6hrs– Amended/updated as needed
• “Magic” threshold for winds = 12kts– Too high for balloonists?
Decoding TAF Forecasts
• Slightly different time format now• TEMPO groups = <50% of the time• Difference between CB, VCTS and
TS?
How can you access all of this data?
RUC Soundings/Windshttp://rucsoundings.noaa.gov/gifs/
Text Bulletins
• LAMP guidance (listed by state/site):http://www.nws.noaa.gov/mdl/gfslamp/
bullform.html• MOS Bulletins:http://www.weather.gov/mdl/synop/products.php
Decoding Observations
http://www.ncdc.noaa.gov/oa/climate/conversion/swometardecoder.html
Dialing ASOS Siteshttp://www.faa.gov/air_traffic/weather/asos/
Other useful websites
• Aviation Weather Center:http://www.aviationweather.govhttp://adds.aviationweather.gov/
Other Useful Websites
• Check with your local NWS office– Aviation Section on website– Aviation Focal Point• Can give talks, provide more information,
etc.
http://www.weather.gov
Radar Data http://www.weather.gov/radar_tab.php
• Can toggle:– Warnings– Topography– Cities– Highways
Questions?