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?