a. Terminal forecasts - any mention of low level wind sheer (LLWS) or the possibility of severe thunderstorm, heavy rain showers, hail, and wind gusts suggest the potential for LLWS and microbursts
b. METARs - inspect for ay indication of thunderstorms, rain showers, or blowing dust. Additional signs such as warming trends, gusty winds, cumulonimbus clouds, etc., hsould be noted.
c. Severe weather watch reports, SIGMETs, and convetive SIGMETs - severe convective weather is a prime source for wind shear and microbursts.
d. LLWAS (low level wind shear alert system) reports - installed at 110 airports in the US; designed to detect wind shifts between outlying stations and a reference centerfield station.
e. PIREPs - reports of sudden airspeed changes on departure or approach and landing corridors provide a real-time indication of the presence o wind shear.
a. TYPE OF REPORTS - the METAR, and the SPECI (aviation special weather report)
b. ICAO station identifier - 4-letter station identifiers; in the contiguous US, the 3-letter identifier is prefixed with K.
c. DATE AND TIME OF REPORT - a 6-digit date/time gropu appended with Z (UTC). First two digits are the date, then two for the hour, and two for minutes.
d. MODIFIER (as required) - if used, the modifier AUTO identifies the report as an automated weather report with no human intervention. If AUTO is shown in the body of the report, AO1 or AO2 will be encoded in the remarks section to indicate the type of precipitation sensor used at the station.
e. WIND - 5-digit group (6 digits if speed is over 99 KTS); first three digits = wind direction, in tens of degrees referenced to true north. Directions less than 100 degrees are preceded with a zero; next two digits are the average speed in knots, measured or estimated (or, if over 99 KTS, the next three digits).
f. VISIBILITY - surface visibility in statute miles, space, fractions of statute miles (as needed), and the letters SM.
g. RUNWAY VISUAL RANGE (RVR), as required
h. WEATHER PHENOMENA - broken into two categories: qualifiers and weather phenomena.
i. SKY CONDITION - amount/height/type (as required) or indefinite ceiling/height (vertical visibility). Heights are recorded in feet AGL.
j. TEMPERATURE/DEW POINT GROUP - 2 digit format in whole degrees Celsius, separated by a solidus (/). Temperatures below zero are prefixed with M.
k. ALTIMETER - 4-digit format representing tens, units, tenths, and hundredths of inches of mercury prefixed with A. The decimal point is not reported or stated.
l. REMARKS (RMK), as required - operational significant weather phenomena, location of phenomena, beginning and ending times, direction of movement.
A radar weather report (SD/ROB) contains information about precipitation observed by weather radar.
It is a textual product derived from the WSR-88D NEXRAD radar without human intervention.
Reports are transmitted hourly and contain the following: location ID, time, configuration (CELL, LN, and AREA), coverage, precipitation type and intensity, location, maximum tops, cell movement, and remarks.
The resolution of an SD/ROB is very coarse, up to 80 minutes old, and should only be used if no other radar information is available.
Winds and temperature aloft forecasts are computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. They are produced 4 times daily for specified locations in the continental US, Hawaii, Alaska, and coastal waters,and the western Pacific Ocean. Amendments are not issued to the forecasts. Wind forecasts are not issued for altitudes within 1,500' of a location's elevation.
Some of the features of FBs are:
a. Product header includes date and time observations collected, forecast valid date and time, and the time period during which the forecast is to be used.
b. Altitudes up to 15,000' referenced to MSL; altitudes at or above 18,000' are references to flight levels (FL).
c. Temperature indicated in degrees Celsius (two digits) for the levels from 6,000'-24,000'. Above 24,000', minus sign is omitted since temperatures are always negative at those altitudes. Temperature forecasts are not issued for altitudes within 2,500' of a location's elevation. Forecasts for intermediate levels are determined by interpolation.
d. Wind direction indicated in tens of degrees (two digits) with reference to true north and wind speed is given in knots (two digits). Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecaste wind speeds of 100-199 KTS are indicated by subtracting 100 from the speed and adding 50 to the coded direction. For example a forecast of 250 degrees, 145 knots, is encoded as 7545. Forecast wind speeds of 200 KTSor greater are indicated as a forecast speed of 199 KTS. For example, 779 is decoded as 270 degrees at 199 KTS or greater.
Computer-generated graphical display of a collection of automated radar weather reports (SDs). The chart displays areas of precipitation as well as information about type, intensity, configuration, coverage, echo top, and cell movement of precipitation. Severe weather watches are plotted if they are in effect when the chart is valid. The chart is available hourly with a valid time of 35 minutes past each hour.
This chart aids in pre-flight planning by identifying general areas and movement of precipitation and/or thunderstorms. Displays drops or ice particles of precipitation size only; it does not display clouds and fog. Therefore, since the absence of echoes does not guarantee clear weather, and cloud tops will most likely be higher than the tops of the precipitation echoes detected by radar, the radar summary chart must be used along with other charts, reports, and forecasts for best effectiveness.
It is a "Day One" forecast of significant weather for the conterminous U.S., pertaining to the layer from surface to FL240 (400mb).
With two forecast periods, 12 hours and 24 hours, the chart is composed of four panels. The two lower panels depict the 12- and 24-hour surface progs, and the two upper panels depict the 12- and 24-hour significant weather progs.
Issued 4 times a day at 0Z, 06Z, 12Z, and 18Z.
Covered are forecast positions and characteristics of pressure systems, fronts, and precipitation.
Much insight can be gained by evaluating the individual fields of pressure patterns, fronts, precipitation, weather flying categories, freezing levels, and turbulence displayed on the chart.
Any surface of equal pressure in the atmosphere is constant pressure surface.
A constant pressure analysis chart is an upper air weather map where all information depicted is at the specified pressure of the chart.
From these charts, a pilot can approximate the observed air temperature, wind, and temperature-dew point spread along a proposed route.
They also depict highs, lows troughs, and ridges aloft by the height contour patterns resembling isobars on a surface map.
Twice daily, five constant pressure charts are issued from observed data obtained at 00Z and 12Z:
850 mb .......... 5,000 ft
700 mb ........ 10,000 ft
500 mb ........ 18,000 ft
300 mb ........ 30,000 ft
200 mb ........ 39,000 ft
En Route Flight Advisory Service (EFAS)
c. Contact flight watch by useing the name of the ARTCC facility identification serving the area of your location, followed by your aircraft identification, and the name of the nearest VOR to your position. The specialist needs to know this approximate location to select the most appropriate transmitter/receiver outlet for communications coverage.
d. Charts depicting the location of the flight watch control stations (parent facility) and the outlets they use are contained int he A/FD. If you do not know in which flight watch area you are flying, initiate contact by using the words "Flight Watch," your aircraft ID, and the name of the nearest VOR. THe facility will respond using the name of the flight watch facility.
[A service specifically designed to provide enroute aircraft with timely and meaningful weather advisories pertinent to the type of flight intended, route of flight, and altitude.
In conjunction with this service, EFAS is also a central collection and distribution point for pilot reported weather information (PIREPs).
EFAS provides communications capabilities for aircraft flying at 5,000' AGL to 17,000' MSL on a common frequency of 122.0 MHz.
It is also known as "Flight Watch."]
a. Microbursts are small scale intense downdrafts which, on reaching the surface, spread outward in all directions from the downdraft center.
This causes the presence of both vertical and horizontal wind shears that can be extremely hazardous to all types and categories of aircraft, especially at low altitudes.
Due to their small size, short life span, and the fact that they can occur over areas without surface precipitation, microbursts are not easily detectable using conventional weather radar or wind shear alert systems.
b. Parent clouds producing microburst activity can be any of the low or middle layer convective cloud types. However, microbursts commonly occur within the heavy rain portion of thunderstorms, and in much weaker, benign appearing convective cells that have little or no precipitation reaching the ground.
Microbursts can be found almost anywhere that there is convective activity.
-heavy rain associated with a thunderstorm
-light rain in benign appearing virga
Can last 15 minutes to an hour.
e. Microburst wind shear may create a severe hazard for aircraft within 1,000ft of the ground, particularly during landing and takeoff.