Weather 14th Annual Hot Air Balloon Safety Seminar Rick Davis Senior Meteorologist National Weather...

Weather14th Annual Hot Air Balloon Safety Seminar

Rick DavisSenior Meteorologist

National Weather Service - Tampa Bay Area

Observing the WeatherObserving the WeatherASOS - Automated Surface Observing SystemASOS - 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 locati

on nearb

y.

ASOSASOSFacts and FiguresFacts and Figures

▪569 FAA sponsored sites▪313 NWS sponsored sites

▪Provides nonstop weather info, updating every minute if needed

▪Computer generated voice broadcasts gives pilots updates critical to safe landings

▸Using FAA VHF ground-to-air radio or appended to ATIS broadcast▪Information is also available through the phone or on the

internet

AWOSAWOSAutomated Weather Observing SystemAutomated 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

ASOS/AWOS LocationsASOS/AWOS LocationsFloridaFlorida

Decoding METARsDecoding METARsWinter ObservationsWinter Observations

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

Aviation ForecastsAviation ForecastsTafs/TwebsTafs/Twebs

From NWS in RuskinFrom NWS in Ruskin

KFMYKRSW

Decoding TAF ForecastsDecoding TAF ForecastsSome InsightsSome Insights

TAF AMDKFMY 141542Z 141612 33030G40KT 2SM RA B KN010

TEMPO 1618 32035G44KT 3/4SM +TSRA SQ BKN008 OVC015CB FM1800 32025G32KT P6SM BKN020

TEMPO 1821 ....

- Most detail is in first 12 hours, generalized outlook after 12 hours

- Issued four times a day at 06Z, 12Z, 18Z, and 00Z

- Format of each forecast group is wind, weather, clouds

- Naming of present weather has a strong French influence

- GR is hail >1/4 inch

- GS is hail < 1/4 inch

- FU is smoke

Weather BalloonsWeather BalloonsThe RadiosondeThe Radiosonde

▪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 DataRadiosonde DataStation Map and Data PlotStation Map and Data Plot

Doppler RadarDoppler Radar

Doppler VAD Wind ProfilesDoppler VAD Wind ProfilesVelocity Azimuth Display

General WindsGeneral Winds

Large-scale winds caused by the Large-scale winds caused by the pressure patterns associated with pressure patterns associated with high and low pressure areas.high and low pressure areas.

Fronts & InstabilityFronts & InstabilityIR satellite image overlaid with radar and frontsIR satellite image overlaid with radar and fronts

Wind Flow Associated With Wind Flow Associated With Pressure Systems and Pressure Systems and

FrontsFrontsWind direction ahead of an approaching Wind direction ahead of an approaching

low pressure system and cold front will low pressure system and cold front will generally be southerly. Wind Speed will generally be southerly. Wind Speed will normally increase ahead of approaching normally increase ahead of approaching systems.systems.

Wind direction behind a cold front and low Wind direction behind a cold front and low pressure system will become northerly. pressure system will become northerly. Wind speed will normally be stronger just Wind speed will normally be stronger just behind the front, then will slowly decrease.behind the front, then will slowly decrease.

Sources of LiftSources of LiftFronts and Low Pressure SystemsFronts and Low Pressure Systems

LH80s

70s60s

Cold air weighs more than warm air

Local WindsLocal Winds

Smaller-scale winds caused by Smaller-scale winds caused by local temperature differences.local temperature differences.

SeabreezesSeabreezes

During a clear day. . . sunshine heats the During a clear day. . . sunshine heats the land to a greater extent than the water.land to a greater extent than the water.

Warm air over the land rises and is replaced Warm air over the land rises and is replaced by cooler, moister, marine air.by cooler, moister, marine air.

Sea Breezes (cont’d)Sea Breezes (cont’d)

An area experiencing a sea breeze An area experiencing a sea breeze will seewill see::

A temperature decrease 5-7A temperature decrease 5-7oo F. F.

An RH increase of 10-15 %.An RH increase of 10-15 %.

A possible change in wind speed and A possible change in wind speed and

direction.direction.

Thunderstorms in unstable air.Thunderstorms in unstable air.

cumulus cloud thatmay form due to rising air reaching dewpoint

cumulus cloud thatmay form due to rising air reaching dewpoint

Bubble of

Warm Air

Localized Thermals

Cooler SinkingAir

Air MotionAir Motion

Stability = Vertical MotionWind = Horizontal Motion

Wind ShearWind ShearTwo Types of Wind ShearTwo Types of Wind Shear

Directional Shear - Wind direction Directional Shear - Wind direction varies with height. varies with height.

Speed Shear – Wind speed significantly Speed Shear – Wind speed significantly increases with height. increases with height.

BOTH ARE IMPORTANT TO AVIATION!!!BOTH ARE IMPORTANT TO AVIATION!!!

InstabilityInstabilityParcel TheoryParcel Theory

●A parcel is a small bag of air (size of cubic foot)

●Acts like a hot air balloon-Doesn’t let air in or out-The bag will rise if it is warmer than the

surrounding air-The bag will sink if it is colder than the

surrounding air

Parcel TheoryParcel TheoryParcels act like bags of airParcels act like bags of air

50̍� at 10̍,0̍0̍0̍ ft

70̍� at 50̍0̍0̍ ft

90̍� at surface

AIr

Temperature

70̍��

70̍��

Will this parcel rise or sink?

The parcel will rise because the air inside the parcel > air outside

(70L > 60L)

Will this parcel rise or sink?

The parcel will sink because the air inside the parcel < air outside

(70L < 80L)

InstabilityInstabilityRelating to Temperature InversionsRelating to Temperature Inversions

50̍�

60̍�

85�

80̍�

90̍��Surface

10,000 feet

Stable Layer 82̍̍��

92̍̍��

What happens when temperatures warm with height?(a temperature inversion)

InstabilityInstabilitySea Breeze and Outflow BoundariesSea Breeze and Outflow Boundaries

50̍�

60̍�

70̍�

85�

80̍�

90̍��Surface

10,000 feet

Stable Layer

72̍̍��

82̍̍��

92̍̍��

50̍�

60̍�

80̍�

88��

63̍̍��

55��

Sea Breeze

Need lifting mechanism to get parcel above inversion

Unstable AtmosphereUnstable Atmosphere

Stable AtmosphereStable Atmosphere

Unstable, But No Storms?Unstable, But No Storms?Why is that?Why is that?

Need additional lift to get thunderstorms to develop

Stable Layer

Atmospheric StabilityAtmospheric Stability

Stability is a measure of the equilibrium Stability is a measure of the equilibrium of the atmosphere to vertical motion.of the atmosphere to vertical motion.

Stable Air - Resists Vertical MotionStable Air - Resists Vertical Motion

Unstable Air - Encourages Vertical Unstable Air - Encourages Vertical MotionMotion

Stability ContinuedStability Continued

Paramount to the concept of Paramount to the concept of stability is:stability is:

–Relative to the surrounding Relative to the surrounding environment: environment: hot air rises and hot air rises and cold air sinks.cold air sinks.

Remember that indicators of stable and unstable atmospheres are

instantaneous indicators. Changes in stability can be extremely rapid.

Stability is a function of the Stability is a function of the Lapse RateLapse Rate

Change in temperature with Change in temperature with heightheight

Average Lapse RateAverage Lapse Rate

Decrease of 3.5 degrees F per

1000 feet of altitude

H

T70o

1,000’ 66.6o

Lapse Rate and StabilityLapse Rate and Stability

If the measured lapse rate is greater than 5.5° F per 1000 ft, the atmosphere is

unstable.If the measured lapse rate is less than 5.5° F

per 1000 ft, the atmosphere is stable.If the measured lapse rate is equal to 5.5° F

per 1000 ft, the atmosphere is neutral.

InversionsInversionsLayer of air in which the temperature rises Layer of air in which the temperature rises

with height.with height.

3 Types3 Types

Radiation or Nighttime InversionRadiation or Nighttime Inversion

Marine InversionMarine Inversion

SubsidenceSubsidence

Temperature InversionsTemperature Inversions

As you go aloft, temperature As you go aloft, temperature normally decreases at a rate of normally decreases at a rate of 5.55.5°° F. per 1000 feet. F. per 1000 feet.

Temperature inversion occurs Temperature inversion occurs when the temperature increases when the temperature increases with height instead of decreasing. with height instead of decreasing.

Temperature InversionsTemperature Inversions

TemperatureDewpoint

InversionsInversionsInversions normally dissipate as the Inversions normally dissipate as the

surface temperature rises and mixing surface temperature rises and mixing of the atmosphere begins, unless of the atmosphere begins, unless inversion is strong.inversion is strong.

Inversions frequently occur near the Inversions frequently occur near the center of high pressure systems where center of high pressure systems where winds are light and skies are clear.winds are light and skies are clear.

Mixing HeightMixing Height

The height below which relatively The height below which relatively vigorous mixing in the atmosphere is vigorous mixing in the atmosphere is taking placetaking place

Winter Daytime 2- 4 Thousand FeetWinter Daytime 2- 4 Thousand Feet Summer Daytime 4-6 Thousand FeetSummer Daytime 4-6 Thousand Feet

Nighttime/early morning 100-500 feet Nighttime/early morning 100-500 feet when stable to 1000 feet in unstablewhen stable to 1000 feet in unstable

Transport WindsTransport Winds

Average horizontal wind speed and Average horizontal wind speed and direction between the surface and direction between the surface and the mixing height.the mixing height.

Determines the rate of horizontal Determines the rate of horizontal movement.movement.

Dispersion IndexDispersion Index

A forecast tool used to estimate daytime and A forecast tool used to estimate daytime and nighttime stability.nighttime stability.

Incorporates the stability, transport winds Incorporates the stability, transport winds and mixing heights.and mixing heights.

Daytime DI: 50-75 = unstableDaytime DI: 50-75 = unstable Nighttime DI: 1-4 = stableNighttime DI: 1-4 = stable

ThunderstormsThunderstorms

Thunderstorms significantly effect the Thunderstorms significantly effect the local environmentlocal environment

Gusty erratic windsGusty erratic winds Cooler temps/Higher RHCooler temps/Higher RH Rain - Possible Hail/TornadoesRain - Possible Hail/Tornadoes Lightning as far as 10 miles from the Lightning as far as 10 miles from the

stormstorm

Safety Above All ElseSafety Above All ElseLightning SafetyLightning Safety

▪#1 Florida weather killer

▪Average 10 fatalities and 40 injuries each year

▪Can strike over 10 miles away from the

storm

When is Lightning Most Dangerous?When is Lightning Most Dangerous?June through SeptemberJune through September

NOAA Weather RadioNOAA Weather RadioAutomated Automated All-HazardsAll-Hazards Warning Information Warning Information

▪Warns of natural and man made hazards▪Alerts you even when you’re sleeping

▪New radios can be programmed just for your county

Visit Us on the Web!Visit Us on the Web!http://weather.govhttp://weather.gov

Local NWS OfficeLocal NWS Office

Aviation Weather CenterAviation Weather Centerhttp://aviationweather.govhttp://aviationweather.gov

▪AIRMETs, SIGMETs, SIGWX Progs, etc.▪Aviation Digital Data

Service▪Standard unofficial

briefing▪Experimental products

▪Training

Useful Web SitesUseful Web Sites1.1. www.srh.noaa.gov/tbwwww.srh.noaa.gov/tbw -- National Weather Service, Tampa -- National Weather Service, Tampa

Bay, FloridaBay, Florida

2.2. www.srh.noaa.govwww.srh.noaa.gov -- National Weather Service, Southern -- National Weather Service, Southern Region Headquarters, Ft. Worth, TXRegion Headquarters, Ft. Worth, TX

3.3. www.aviationweather.govwww.aviationweather.gov -- Aviation Weather Center, Kansas -- Aviation Weather Center, Kansas City, MissouriCity, Missouri

4.4. www.weather.govwww.weather.gov -- National Weather Service Headquarters, -- National Weather Service Headquarters, Washington, D.C.Washington, D.C.

5.5. www.spc.noaa.govwww.spc.noaa.gov – Storm Prediction Center, Norman, OK – Storm Prediction Center, Norman, OK

QUESTIONS AND/OR QUESTIONS AND/OR COMMENTS???COMMENTS???

THE END!

Norman, OK 06/28/99 (Todd Lindley)