Weather Information Flashcards
Most Wx occurs in what region of the atmosphere ?
Troposphere (up to 36,000 ft)
59F to -70F
What are standard temps and pressure at sea level ?
15C and 29.92 Hg
What are ISO Bars ?
areas of equal or constant barometric pressure
If ISO Bars close together on surface or pressure chart….
stronger pressure gradient
What does dew point mean ?
Temperature at which a column of air must be cooled to attain saturation.
When Temp and Dew point are close together (5 degrees F) what Wx is likely ?
Clouds, dew, or fog.
Ideal for Carb Icing
What factor determines the type and vertical extent of the clouds ?
Stability of the the atmosphere
Explain the difference between stable atmosphere and unstable atmosphere
depends on ability to resist vertical motion.
Stable atmosphere resists vertical motion.
Dampens out disturbances
How can you determine stability of atmosphere ?
When temperature decreases uniformly, approaching 3 degrees per 1000 ft, you have unstable air.
If temperature remains unchanged or decreases slightly, air tends to be stable.
What are the effects of stable and unstable air on clouds, turbulence, precipitation and visibility ?
Clouds Stratiform Cumuliform
Turb Smooth Heavy
Precip Steady Showery
Visibility Poor Good
What are characteristics of air flow around Low and High Pressure systems in Northern Hemisphere ?
Low: Inward, upward, counter-clockwise
High: Outward, downward, clockwise
What Wx can be expected flying towards a Low Pressure system ? A High Pressure system ?
Low pressure is characterized by rising air, conducive to clouds, precip, and bad Wx.
High pressure is characterized by descending air, favors good weather.
Describe different types of Fronts ?
Cold Front: Cold dense air replaces warm air
Occluded Front: Fast moving cold front catches up with Slow moving warm front
Warm Front: Boundary area when warm air mass contacts and flow over colder air mass
Stationary Front: Relatively Equal air masses boundary is stationary
What are general characteristics of Wx operating near a Cold Front ?
As Front passes, Cumulus, cumulonimbus, heavy rain lightning thunder hail tornadoes Temp/Dewpoint equal rapid pressure drops
What are general characteristics of Wx operating near a Warm Front ?
as front passes stratiform clouds drizzle low ceilings poor viz variable winds rise in temperature
What is a Trough ?
elongated area of relatively LOW pressure
What is a Ridge ?
elongated area of relatively HIGH Pressure
What is primary means of obtaining Wx ?
1-800-WX-Brief (24Hrs) FSS Briefer
What are examples of other sources of Wx ?
Foreflight, avaiationweather.gov, DUATS (Lockheed)
Does the Wx provided by 3rd party satisfy 91.103 requirements ?
It might not. May have different Quality Control. Would check with FAA Flight service specialist
What types of Wx briefings are available from FSS briefer ?
Standard (Request for Full report)
Abbreviated (request for supplemental)
Outlook (6+ hours or more)
Inflight (122.2)
What info should Wx preflight include ?
Adverse conditions VFR not recommended Synopsis Current Conditions Enroute Forecast Destination Forecast Winds Aloft Notices to Airmen ATC Delay Info on Special use Airspace
What is FIS-B ?
ground based Wx broadcast via ADS-B 978 MHz UAT
Can FIS-B be used to navigate TS ?
No, delayed info
What is HIWAS ?
inflight Wx on NAVAIDS for SIGMETS, Convective SIGMETS, CWAs, AIRMETS, URGENT Pireps.
What is ATIS ?
broadcast of repetitive info regarding aerodrome, terminal information service. (ATIS)
What’s included in ATIS broadcast ?
time of latest Wx ceiling viz obstructions to viz, temperature dew point wind (magnetic) velocity altimeter runway/approach in use
While enroute, how to obtain Wx info
FSS on 122.2 XM FIS-B ATIS HIWAS ATC workload permitting
What is a METAR ?
hourly routine Wx report
Describe types of Wx reporting.
Manual
AWOS (Automated Weather Observation_
ASOS (Automated Surface Observation)
What are PiReps ?
conditions from pilots in the air.
Two Types:
UA - Standard
UUA -Urgent
What are TAFs ?
Expected Wx issued 4 times a day.
What is Area Forecast (FA) ?
6 CONUS area forecasts issued 3 times a day.
Plans to discontinue and replace with GFA
What are graphically area forecasts (GFA) ?
aviationweather.gov to provide complete picture. 14 hrs in past to 15 hrs in future
What are the types of Wx advisories ?
SIGMET
Convective Sigment
Airmet
CWA
Convective SIGMET ?
Issued for Severe TS
1) due to Surface winds > 50 its
2) Hail > 3/4 inches
3) TS affecting 40% or more of area at least 3000 sq miles
4) Tornadoes
5) Embedded TS
6) Line of TS
7)Imply severe or greater turbulence, severe icing, LLWS
How long is a convective SIGMET valid ?
2 hrs
When (time) are convective SIGMET issued ?
55 min past the hour.
SIGMET ?
Severe or extreme Turbulence NOT associated with TS
widespread Dust/Sand storms
Volcanic ash
What time are convective SIGMETS issued ?
unscheduled, as needed. Valid for 4 hrs.
Ash/Volcano = 6hrs
What is an AIRMET ?
Wx Advisory IFR Mountain obscuration turbulence strong surface winds icing freezing levels
How often are AIRMETs issued ?
Every 6 hrs.
What are the different types of AIRMETS ?
Sierra - IFR and Mountain obscurations
Tango - Turbulence
Zulu - Moderate Icing and provides freezing levels
What is a winds and temperature aloft forecast (FB) ?
4 digit codes for wind and direction, 2 digit codes for temps.
issued 4 times a day
What info can be obtained from winds aloft forecasts (FB) ?
Favorable altitude
Areas of icing
Temperature Inversions
Turbulence
What is a CWA ?
Warning of adverse conditions valid for Max of 2 hrs
What is a Convective Outlook ?
outlook for severe (tornado, 50kts gusts, 1” hail) and non-severe convection
What is a surface analysis chart ?
highs lows ridges and troughs fronts issued 8 times a day
Describe Ceiling and Visibility analysis.
real-time analysis of observed and estimated ceilings in CONUS
What does a Wx depiction chart provide ?
Plot of selected METAR stations for IFR, MVFR, VFR conditions
What info do short-range surface prognostic charts provide ?
Forecast of surface pressure systems and precip for 2 1/2 day period. 4 times a day.
Describe low-level significant Wx chart (SIGWX).
12 to 24 hr forecasts of
Wx categories
turbulence
Freezing levels
What are NOTAMS ?
Time critical info on runway closures navaids approaches radar availability essential to enroute, terminal or landing operations.
NOTAMS (D)
Distributed widely (ie.runway closures etc)
FDC NOTAM
Regulatory, I.e. IFR Chart mods
Pointer NOTAMS
Refer to other NOTAMS
Military NOTAM
Military
SAA NOTAM
Special Airspace
FICON NOTAM
Field Conditions
Give examples of NOTAM keywords
RWY, TWY, RAMP, NAV, COM, U = unverified
Where to obtain NOTAMS ?
Foreflight, FSS, FAA pilot webiste
What are the 3 principle types of TS ?
Single Cell
Multi-Cell
Super Cell
When attempting to avoid TB around TS, explain operational procedures Pilots should never attempt…
Never TOL with approaching TS (wind sheer)
Never Fly Under TS
Never Fly under Anvil
Never Fly without Radar into a cloud mass (embedded)
Never Trust visual appearance
Never assume ATC will offer guidance
Never use NEXRAD for tactical … to thread needle through TS (delayed)
What procedures can be performed when flying without TS detection equipment ?
1) Strategic Spacing VIA NEXRAD (shows where it was)
2) Ask ATC radar guidance
3) Avoid 20 NM
4) Avoid entire area if TS cover 60% of area
5) Recall vivid and frequent lighting = SEVERE TS
Can ATC provide inflight assistance to avoid Wx ?
yes, to the extent possible. Primary responsibility is traffic separation.
What charts are useful for Preflight planning of TS avoidance ?
1) Convective Outlook
2) Significant weather chart SIGWX
3) Wx Radar observations
4) Convective SIGMETS
5) Pilot Reports
What are microbursts ?
Intense downdrafts which spread outward when reaching surface causing vertical and horizontal sheers
Where are microbursts most likely to occur ?
anywhere convective activity, Virga, TS
What are basic characteristics of a microburst ?
< 1 mile in Diameter near top, 2.5 miles near ground
downdrafts or 6000 FPM
can last up to 15 min
What type of Wx info will you examine to see microburst conditions ?
1) TAFS for convective activity
2) METARS for WSHR clues (TS, rain showers, blowing dust)
3) LLWAS reports
4) TDWR (Doppler radar)
5) SIGMETS
What is wind sheer and when most likely to occur ?
rapid rate of wind change per unit of distance.
a) low-level temp inversion
b) Fronts
c) CAT (clear air turbulence)
Why is wind sheer a concern for pilots ?
Rapid changes in wind speed an direction are hazardous at low altitudes
What airplane characteristics will be observed with sudden increase/decrease of headwind ?
Tailwind sheers to HW = increase in AS, ALT, PITCH
HW sheers to TW = decrease in AS, ALT,PITCH
What is LLWAS ?
Low-Level Windshear Alert System at some airports
What are 2 classifications of thunder storms ?
Airmass TS = single cell, pop-up
Steady State = Associated with Frontal systems.
Describe properties of a steady state TS.
associated with Frontal system
converging winds and troughs aloft force upward motion
precipitation falls outside of updraft allowing TS to continue for many hours
