Weather Briefing Flashcards
Where does FF gets it weather information from?
National Weather Service
TAF- human
MOS- model
Daily- the weather channel
What are the two types of NOTAMS?
NOTAM (D)
Usually not included in a weather briefing unless specifically requested, NOTAM (D) outlines all local and distant (D) NOTAMs for all navigational facilities, public use airports, seaports, and heliports in the U.S. Chart supplement. For example, information regarding runway closures or obstructions can be found in this NOTAM.
FDC NOTAM
FDC, or Flight Data Center NOTAMs outline changes to instrument approach procedures and airways within the U.S. The next time you’re flying IFR, you should be checking them before you go.
METAR
Issued every 60min for local weather, but usually more frequent.
Meteorological Aerodrome Report
TAF
5 SM from airport,
issued 4Xs per day
valid for 24-30 hrs.
Terminal Aerodrome Forecast
Surface Prog Chart
Computer generated w/ frontal and pressure analysis
Provide snapshot for cross country flights
AIRMET
Bad news for small GA planes
An AIRMET is a weather advisory for pilots that alerts them to potential hazards in the air. The acronym “AIRMET” stands for “Airmen’s Meteorological Information.”
AIRMET SIERRA (Instrument Flight Rules or Mountain Obscuration): mountain obscuration or ceilings less than 1000 feet or visibility less than 3 miles affecting more than 50% of the stated area at one time
AIRMET TANGO (Turbulence): moderate turbulence, or continuous surface winds of 30 knots or more, or non-convective low−level wind shear.
AIRMET ZULU (Icing): moderate icing (AIRMET ZULU also provides freezing-level heights.)
What is a weather depiction chart?
Plots Wx, vis, sky cover, & ceiling height
8Xs per day (1, 4, 7, 10, 13, 16, 19, & 22)
Comes from NWS
What are the different types of fog?
Small temp/ dew point spreads… w/in 5 deg C
Radiation fog- forms when the ground cools to cool the air to the dew point, burns off in the morning, best conditions clear sky, no wind, high humidity
Advection fog- moist air moves over cooler ground or water, most common along the coast
Steam fog- cold and dry air moves over warm water, common during cold winter months over bodies of water
Upslope fog- moist, stable air moves up along terrain, it cools causing fog (common reason for Airmet Sierra)
Precipitation fog- warm rain falls through cool air, precipitation saturates the cool air, dense and long-lasting
Freezing fog- tiny droplets of water are supercooling in the air, needs to be very cold for freezing fog to form, ~15 deg F or cooler
Difference between AWOS, ATIS, and ASOS?
ATIS- human data, arrival, departing info updated hourly or when required
AWOS & ASOS- automated and provide realtime weather
AWOS- minute weather, FAA
ASOS- NOAA (not FAA),
AWOS-?
A- Altimeter
AV- Visibility & altimeter
-1 -wind, temp & dewpoint, altimeter, & DA
-2 - -1 + visibility
-3 - same as above, but reported as pertinent
ASOS contains
Wind, vis, temp/ dew point, altimeter, and DA
Stages of a thunderstorm?
Unstable air, lifting force, high moisture
Developing -updraft, build cumulus clouds building
Mature -turbulent conditions and wind shear, begin precip
Dissipating -severe downdrafts and heavy rainfall
How far do you stay away from a t-storm?
20 miles
What hazards do pilots face in LLWS or microburst?
Loss of lift
LLWS- take 1/2 gust factor to add to approach speed
Microburst downdrafts… full throttle and gradually but quickly pull full nose up
How do you know if the t-storm is in the mature stage?
Precip begins
What do we need for ice to form?
Temperature (0- -20 C), moisture, and droplet size
What do FDC NOTAM (flight data center) cover?
Regulatory changes, changes in instrument approach procedures,
What are NOTAM Ds?
Gives information about airports and airport facilities, temp outages, runways closed, etc
How do you receive NOTAMs w/ short effective period?
Receive w/ weather briefing
If longer, Notices to Airmen Publication (NTAP)
Where do you most likely encounter wind shear?
Temperature inversions
Fronts
Convective activity
Pilot math: Ground speed x 5 gives you..
~FPM to stay on a 3 deg glide path
during departure, under conditions of suspected low-level wind shear, a sudden decrease in headwind will cause
A loss in airspeed equal to the decrease in wind velocity
Light turbulence
Slight, erratic changes in altitude and/or attitude
Moderate turbulence
Changes in altitude and/or attitude occur but the aircraft remains in positive controls at all times
Severe turbulence
Large, abrupt changes in altitude and/or attitude.
It usually causes large variations in indicated airspeed.
Airplane could be momentarily out of control
Extreme turbulence
Aircraft is violently tossed about and is practically impossible to control
May cause structural damage
What is the standard lapse rate?
3.5 deg F / 2 deg C per 1000’
What is the standard air temp/ pressure at sea level?
15 deg C / 59 deg F
1013.2 mb / 29.92 Hg (inches of mercury)
The temp decrease w/ altitude continues until you reach the… and what altitude is the Tropopause…
Tropopause and 32k’
*the temp stops decreasing w/ altitude after the tropopause
What is the physical process of weather?
Result of a heat exchange
What creates wind?
Caused by pressure differences
High press to low press
What is a high pressure?
Air cools and then descends
Turns clockwise
Circulation- outward, Down and then out, clockwise
What is a low pressure?
Call a cyclone caused by coriolis force (counter clockwise circulation)
Turns counter clockwise
Circulation- Inward, upward, and counterclockwise
What does the coriolis force prevent?
Prevents air from flowing directly from high to low pressure
Counterbalancing the horizontal pressure gradient b/c wind turns to flow parallel to the isobars (once above surface friction)
What wind direction will you have flying into a lower pressure area?
Continuous left crosswind flying towards unfavorable weather
Closer to the center the higher the wind velocity
In the northern hemisphere, the wind is deflected to the
Right by Corilis force
Why does the wind have a tendency to flow parallel to the isobars above the friction level?
Coriolis force tends to counterbalance the horizontal pressure gradient
What prevents air from flowing directly from high pressure areas to low-pressure areas?
Coriolis force
Convective currents are most active on warm summer afternoons when the winds are
Light
In the development of convective circulation, will warm air rise on its own?
No… the more dense, cool air drawn to the ground by its greater gravitational force must sink to force the warm air upward.
Convective circulation patterns associated w/ sea breezes are caused by
Land absorbing and radiating heat faster than the water
To determine the stability of the air you need
A measure of the lapse rate
(Unstable ambient lapse rates produce unstable air)
((Stable air cools much slower than the standard lapse rate))
Condensation
Water vapor to liquid state
Evaporation
Liquid state to water vapor
Sublimation
Vapor state to frozen state or visa Versa
Evaporation and sublimation adds moisture to the air
Adding moisture to the air will decrease the stability of the air
What determines the structure and type of clouds which will form as a result of air being forced to ascend?
Stability of the air before lifting occurs
What are characteristics of an unstable atmosphere?
A warm, humid air mass
What do you need for cumuliform formation?
Lifting action
Moist air
Unstable air mass
Good visibility
Showery precip
Updrafts
Towering cumulus clouds
Produce convective turbulence
What happens when you have a cold air mass moving over a warm surface?
Heated from below, make the air rise,
Cumulifrm clouds
Turbulence
Good visibility
What type of conditions w/ Stable air (resists rising)?
Stratus-type clouds
Poor vis
Steady participation
Conditions necessary for the formation of state form clouds are a lifting action and
Stable, moist air
Characteristics of stable air are
Stratiform clouds and fog
Continuous precip
Smooth air
Fair to poor vis in haze and smoke
Which are characteristics of a cold air mass moving over a warm surface?
Cumuliform clouds, turbulence, and good vis
What weather do you expect after a cold front?
A cold front is where colder air replaces warmer air and its passage is associated w/ clearing skies, with gusty turbulent winds, and cooler temps.
Radiation fog
Restricted to land areas
surface based temp inversion
On clear, cool nights
W/ calm or light wind
Steam fog
Forms over a water surface
Evaporating water adds moisture to the air above it
Advection fog
Typically in coastal area
VECtor- moist air moves over a colder surface, air cools off to the dew point
Air mass moving inland from the coast during the winter
Can appear suddenly day or night
More persistent than radiation fog
Surface winds of 15kts or stronger
Can dissipate advection fog or lift it into a layer of stratus clouds
Precipitation induced fog
Associated w/ warm fronts
Raining out of warm fronts into colder air below, evaporates and saturates the air
Result of saturation
Cold front occlusion occurs
Air ahead of warm front is warmer than the air behind the overtaking cold front
((Cold fronts sometimes move faster than warm fronts))
Warm front occlusion
Cool air is not as called as the retreating cold air
Warm front rides over top if it all
Occluded fronts
Most likely to have freezing precip
Rain falls from air warmer than 32 deg F
Into air w/ temp of 32 deg F or less
What is a cold-front occlusion?
The air ahead of the warm front is warmer than the air behind the overtaking cold front.
In a cold front occlusion, the coldest air is under the cold front. When it overtakes the warm front, it lifts the warm front aloft, and cold air replaces the cool air at the surface.
When does frost form
Surface temp below dew point
Dew point below freezing
Frost causes early airflow separation of the wing
Freezing rain
Water instantly goes from liquid to a solid on contact
Highest rate of structural ice accumulation
(Must be warmer temperatures above)
Ice pellets
Frozen rain turned solid
Prob freezing rain at a higher altitude above you
Wet snow
Temperature is above freezing at your altitude
Ice pellets encountered during a flight are evidence that
A warm front is about to pass
Rain falling through colder air may become supercooled, freezing on impact as freezing rain, or it may freeze during descent.
Ice pellets always indicate there exists a layer of warmer air above which is normally is evidenced that a warm front is about to pass
Thunderstorm stages
Cumulus stage (Building, updrafts)
Mature -rain begins to reach the ground, rain at surface, updrafts and downdrafts (Updrafts- enhance growth rate of precip)
Dissipating -dominated by downdrafts, decrease over time as the storm loses moisture
What are the greatest threats in vicinity of thunderstorms?
Hail
Turbulence
What are the hazards associated w/ squall lines?
Most intense weather hazards to aircraft
Destructive winds
Heavy hail
Tornadoes
-narrow bands of active t-storms ahead of a cold front
-non-frontal
-contain severe steady state thunderstorms
What are signs of extreme turbulence in a thunderstorm?
Cumulonimbus clouds
Very frequent lightening
Roll clouds
Where can wind shear turbulence w/ thunderstorms occur?
Outside the clouds
20 miles literally from a severe storm
Where is hail most likely?
To be associated w/ cumulonimbus clouds
In clear air
Several miles from the t-storm (thrown out the top and dropped on your from the anvil)
Do squall lines form slowly?
No, squall lines usually form rapidly.
Squall lines may develop far from any front (I.e. non-frontal)
Weather avoidance radar
Provides no assurance of avoiding IFR weather
It only shows precip, you dont get any return from the clouds
Use it to avoid areas of hazards weather.
Avoid t-storms by 20miles
What min distance between intense radar echoes before any attempt to fly inbetween them?
40 miles
Wind shear?
Suddenly or abrupt change in the wind direction and/or wind speed over a very short distance
Any any altitude
Horizontal and vertical direction
In areas of temp inversions
Near t-storms
What is a temp inversion?
Warm air above and cold air above
Windward side?
Wind blowing into the mountain
Leeward side
Wind coming over the mountain
greatest danger from turbulence in mountains terrain?
Windy
Leeward side
Flying into the wind
And you are flying into rising terrain
Mountain wave formation
Stable air (resists lifting)
Wind at least 20 kts
*if you have unstable air, you would end up w/ tall buildups or t-storms
Standing lenticular altocumulus clouds are an indication of
Strong turbulence
Found on the leeward side of the mountain ridge
What is the most danger mountain wave turbulence
In and below rotor clouds
Forms at ridge top level
What type of turbulence is associated w/ the Jet stream
Clear air turbulence
Above 15k’ AGL
Not associated w/ cumuliform clouds
Common location is on the polar side of the Jetstream when you have an upper trough (low pressure system)
Expect moderate or greater turbulence in the jet stream
6 knots vertical shear per 1k’
How do you recognize the jet stream?
Long streaks of cirrus clouds
When is the jet stream the strongest?
In winter- moves south/ stronger (wild in winter)
((In summer- moves north/ weaker (stop))
A strong wind shear can be expected in a jet stream?
On the low pressure side of a Jetstream core where the speed at the core is stronger than 110 knots
Tell the weather briefer the following
Pilot
Aircraft ID or pilots name
VFR only or IFR
Route
Destination
Type of aircraft
Standard weather briefing type
Complete weather briefing, need everythibng
What is a abbreviated Wx briefing?
Supplement mass disseminated data
Update a previous weather briefing
What is outlook briefing?
6 or more hours in the advance of the departure time
Most current source for Wx enroute
Flight service station
What is the Wx Forecast Office (WFO) good for?
Out of ordinary requests (maritime forecast)
Is NEXRAD is up to date?
It’ could be 15-20 min late in addition to the age you see in the cockpit
What wind conditions would anticipate when squalls are reported at your destination?
Sudden wind increase of at least 16 kts
Sustained speed of 22 kts or more
for at least 1 min
What is virga
streamers of precip trailing beneath clouds but Evaporating before it hits the ground
Could be microburst
METAR
Regular routine hourly observation… normally updated at 55min past the hour
If labeled speci report then
Substantial change in Wx from regular observation
METAR RMK
RMK RAB35
Rain started 35 past the hour
(1835 is correct)
METAR Remarks: FZDZB42 WSHFT 30 FROPA
Freezing drizzle 42 min past the previous hour
Wind shift occurred 30min past the hour due to Frontal passage
METAR ceilings are measured in AGL
Field elevation 1,300’ MSL
Tops reported 3,800’ MSL
OVC020 is 2k’ AGL
2000 + 1300= 3300
3800-3300= 500’
In a convective atmosphere, temperature and dew point converge at
2.5 deg C per 1k’
Temp @2k’ MSL 10 deg C
Minus DP @2k’ MSL 1 deg C
Temp spread = 9 deg c
Base of cumulus clouds AGL
9 deg * 1000 / 2.5 = 3,600’ AGL
Surface in MSL = 2000
Based of clouds AGL = 3600
Based of clouds MSL= 5600 ft
How to find bases w/ temp and dew point spread?
Temp spread * 1000 / 2.5 = ? AGL
PIREPS (pilot reports)
UA -routine pirep
UUA -urgent pirep
What is listed in UUA pireps?
Tornadoes
Funnel clouds
Waterspouts
Severe icing
Hail
Low-level wind shear
PIREP breakdown
SK OVC 025/ =means tops at 2500
045 OVC 090/ =means 4500 bottoms and 9000 tops
Look at FSS on information box
Look at your VOR box, upper left,
Give your tail number, give free #, location to closest VOR
Note- If line under frequency then there is no voice available
What is the meaning of the terms PROB40 1321/1402 +TSRA as seen in a TAF?
Between 2100z and 0200z there is a 40% probability of t-storms w/ heavy rain
TAF, what does VRB mean?
Wind direction (not speed) is variable
AIRMET
Airmen’s meteorological advisory
Small aircraft/ inexperienced pilots
IFR
Mountain obscurantism
Moderate turbulence
Surface winds over 30 kts
Moderate icing
Issued every 6 hrs and valid for no more than 6 hrs
SIGMET
Significant Meteorological Advisory: observation and a forecast or just a forecast
*potentially hazardous to all aircraft
Unscheduled
Period not to exceed 4 hours
May be reissued
SIGMETS – Significant Meteorological Information
SIGMETs (abbreviated WSs) are notices issued for non-convective weather that is potentially hazardous to all aircraft. SIGMETs are unscheduled forecasts that are valid for 4 hours unless the SIGMET relates to a hurricane, in which case it is valid for 6 hours. They are issued to report severe weather such as:
Severe icing not associated with thunderstorms
Severe or extreme turbulence or clear air turbulence (CAT) not associated with thunderstorms
Dust storms or sandstorms that lower surface or in-flight visibilities to below three miles
Volcanic ash
Convective SIGMET
Reported or forecasted t-storm
Severe or greater turbulence
Server icing
LLWS
Embedded t-storms
Lines of t-storms
T-storms w/ widespread heavy precip
Issued hourly
Updated every 2 hours
Special convective SIGMETs
Severe t-storms
Hail 3/4” or larger
Tornadoes
Issued hourly
Normally valid for 2 hours
What are CWAs?
CWAs are advisories issued by the Center Weather Service Units (CWSUs) that are for conditions just below severe criteria.
CWAs are issued for:
Thunderstorms
Turbulence
Icing
Ceiling & Visibility (IFR)
What are Weather Advisory Broadcast in flight?
Severe Wx forecasts alert (AWWs)
Convective SIGMETs
SIGMETs
CWAs
AIRMETs
WABs, including AWW, convective SIGMETs, and SIGMETs are provided by
ARTCCs on all freqs, except emergency, when any part of the area described is w/in 150 miles of the airspace under their jurisdiction.
What does ADS-B stand for?
Automatic Dependent Surveillance - Broadcast
ADSB- out & in?
Out- aircraft location, direction, speed, altitude to other aircraft and ATC
In- allows you to display weather information, traffic, etc via data linking FIS-B (flight info system broadcast), I.e. data linked.
Data linked weather is a advisory only.
Datalink weather: NEXRAD- C, Age- 8 min
C means conus
8 min means how long since it has been created. Images depicted on the image is always older than this time as much as 15-20min older.
Surface Analysis Chart
Observed frontal positions
Pressure centers
@the valid time of the chart
What are isobars?
(Surface analysis chart)
Solid lines
Show sea leave pressure patterns
Connect points of equal pressure
Closer together the isobars the strong pressure gradient and stronger the winds are…
*dashed line to weak pressure gradient, “trough”
Surface analysis charts show
Actual frontal positions, pressure patterns, temperatures, dew point, wind, weather, and obstructions to vision at the valid time of the chart
What values are used for Winds Aloft Forecasts?
True direction and knots
Which provides a graphic display of both VFR and IFR weather?
Weather Depiction Chart by outlines and hatching
When total sky cover is few or scattered, the height shown on the Weather depiction chart is
Base of the lowest layer
Hatching on a constant pressure analysis chart indicates
Wind speed 70 knots to 110 knots
What flight planning info can a pilot derive from a Constant Pressure Analysis charts?
Winds and temperatures aloft
@each reporting station are the observed temp, temp-dew point spread, wind, height of the pressure surface, as well as height changes over the previous 12-hr period
High level prog chart?
Flight level 250- 630
Low level prog chart?
SFC up to 400 MB (24k’)
Valid for specific time
Valid for 12 hours
Prognostic charts
Help determine areas to avoid
High level sig Wx prog chart
Issued 0800, 1400, 2000, 02z
Valid for 24hrs
Fl 250-630
What is the height of the tropopause?
Look at the BOX on the high level prog chart
What Wx phenomenon is implied w/in an area enclosed by small scalloped lines on a U.S. High-Level Significant Wx Prog chart?
CB, icing, and moderate or greater turbulence
