Weather Services

FSS/AFSS

continuous recording of meteorological and/or aeronautical information available by telephone

continuous broadcast of inflight weather advisories

contacting flight watch, using the name of the ARTCC facility identification in your area, your aircraft identification, and name of nearest VOR, on 122.0 MHz below 17,500 feet MSL

weather forecast office (WFO)

a TWEB on a low-frequency and/or VOR receiver

ARTCCs on all frequencies, except emergency, when any part of the area described is within 150 miles of the airspace under their jurisdiction

8,800 feet

The top of the lower overcast is 2,500 feet; base and top of second overcast layer is 4,500 and 9,000 feet, respectively

Wind shift at three zero due to frontal passage

3,500 feet

Rain and mist obstructing visibility; rain began at 1812Z

The maximum tops of the cells is 57,000 feet located 65 NM southeast of the station

isobars

actual frontal positions, pressure patterns, temperature, dew point, wind, weather, and obstructions to vision at the valid time of the chart

weak

strong pressure gradient

Surface Analysis Chart

Winds and temperatures aloft

Constant Pressure Analysis Charts

windspeed 70 knots to 110 knots

Between 2100Z and 0200Z there is a forty percent (40%) probability of thunderstorms with heavy rain

Wind direction is variable

SKC in the valid period indicates no significant weather and sky clear

6 statute miles

Four times daily and are usually valid for a 24 hour period

three times each day

VFR Clouds and Weather (VFR CLDS/WX)

sky condition, cloud heights, visibility, obstructions to vision, precipitation, and sustained surface winds of 20 knots or greater

In-Flight Weather Advisories

Forecasts for potentially hazardous flying conditions for en route aircraft

AIRMETs and Center Weather Advisories (CWA)

to all aircraft

They consist of either an observation and a forecast or just a forecast for tornadoes, significant thunderstorm activity, or hail greater than or equal to 3/4 inch in diameter

Sudden increases in windspeed of at least 16 knots to a sustained speed of 22 knots or more for at least 1 minute

12-hour Significant Weather Prognostic Chart

24,000 feet

Cumulonimbus clouds, icing, and moderate or greater turbulence

24,000 feet to 63,000 feet

pilot reports

base of the lowest layer

Weather Depiction Chart

Lines and cells of hazardous thunderstorms

True direction and knots

observed freezing level data from upper air observations