Along the center, the cloud types are indicated. The top symbol is the high-level cloud type followed by the At the upper right is the In the upper left, the temperature mid-level cloud type. The lowest symbol represents low-level cloud over a number which tells the height of atmospheric pressure reduced to is plotted in Fahrenheit. In this the base of that cloud (in hundreds of feet) In this example, the high level cloud is Cirrus, the mid-level mean sea level in millibars (mb) A example, the temperature is 77°F. B C C to the nearest tenth with the cloud is Altocumulus and the low-level clouds is a cumulonimbus with a base height of 2000 feet. leading 9 or 10 omitted. In this case the pressure would be 999.8 mb. If the pressure was On the second row, the far-left Ci Dense Ci Ci 3 Dense Ci Cs below Cs above Overcast Cs not Cc plotted as 024 it would be 1002.4 number is the visibility in miles. In from Cb invading 45° 45°; not Cs ovcercast; not this example, the visibility is sky overcast increasing mb. When trying to determine D whether to add a 9 or 10 use the five miles. number that will give you a value closest to 1000 mb. 2 As Dense As Ac; semi- Ac Standing Ac invading Ac from Cu Ac with Ac Ac of The number at the lower left is the a/o Ns transparent Lenticularis sky As / Ns congestus chaotic sky Next to the visibility is the present dew point temperature. The dew weather symbol. There 95 point temperature is the symbols which represent the H temperature the air would have to E weather that is either presently cool to become saturated, or in 1 Cu Moderate Cu Cb no anvil Sc from Cu Sc NOT St Stfra or Cu ans Sc Cb w/anvil occurring or has ended within the other words reach a relative from Cu CuFra of different previous hour. In this example, a humidity of 100%. bad weather heights light rain shower was occurring at the time of the observation.
The circle symbol in the center represents the amount of total cloud cover These lines indicate wind direction and speed Calm wind This number and symbol tell how reported in eighths. This cloud cover includes all low, middle, and high rounded to the nearest 5 knots. The longest line, much the pressure has changed 5 knots level clouds. extending from the sky cover plot, points in the (in tenths of millibars) in the past F direction FROM which that wind is blowing. Thus, GG J 15 knots three hours and the trend in the in this case, the wind is blowing FROM the change of the pressure during No 1/8th 2/8th 3/8th 4/8th 5/8th 6/8th 7/8th 8/8th Sky 20 knots Clouds Obscured southeast. The shorter lines, called barbs, that same period. In this example, indicate the wind speed in knots (kt). The speed 25 knots the pressure was steady then fell of the wind is determined by the barbs. Each long (lowered) becoming 0.3 millibars 55 knots barb represents 10 kt with short barbs LOWER than it was three The lower right area is reserved representing 5 kt. A pennant is used to represent hours ago. for the past weather, which is the each 50 kt. In this example, one short barb and most significant weather that has 77 998 I one long barb means the wind speed is 15 kt. Rising, the falling occurred within the past six hours excluding the most recent hour. 5 -03 Rising, then steady; or Cold Front - a zone separating two air masses, of which the cooler, rising, then rising more slowly n/a Clear or Few Clouds (not plotted) denser mass is advancing and replacing the warmer. n/a Partly cloudy (scattered) or variable sky 71 Rising steadily, or unsteadily (not plotted) Warm Front - a transition zone between a mass of warm air and the cold air it is replacing. n/a Cloudy (broken) or overcast (not plotted) 20 Falling or steady, then rising; or
Occluded Front - a composite of two fronts, formed as a cold front Pressure higher than three hours ago rising, then rising more quickly Sandstorm or dust storm, or drifting or overtakes a warm or quasi-stationary front. Two types of occlusions can blowing snow form depending on the relative coldness of the air behind the cold front to Steady, same as 3 hours ago the air ahead of the warm or stationary front. A cold occlusion results Fog, or smoke, or thick dust haze when the coldest air is behind the cold front and a warm occlusion Falling, then rising, same or B3 results when the coldest air is ahead of the warm front. Drizzle lower than 3 hours ago A Stationary Front - a front between warm and cold air masses that is Falling, then steady; or B C moving very slowly or not at all. Rain 2 falling, then falling more slowly Snow, or rain and snow mixed, or ice pellets (sleet) D E F G Trough - No temperature difference across boundary Falling steadily, or unsteadily Shower(s) Dry Line - a boundary separating moist and dry air masses. It typically Steady or rising, then falling; or H B I lies north-south across the central and southern high Plains states Pressure lower than three hours ago falling, then falling more quickly Thunderstorm, with or without 1 during the spring and early summer, where it separates moist air from precipitation the Gulf of Mexico (to the east) and dry desert air from the southwestern J states (to the west).
Squal Line - a line of active thunderstorms, either continuous or with National Weather Service breaks, including contiguous precipitation areas resulting from the Building a Weather-Ready Nation existence of the thunderstorms. https://www.weather.gov/media/jetstream/synoptic/sfc_plot_key.pdf
Present Weather Symbols 00 01 02 03 04 05 06 07 08 09 ( ) Cloud development NOT Clouds generally State of sky on the whole Clouds generally forming Visibility reduced by Haze Widespread dust in Dust or sand due to wind Well developed dust whirl Dust storm or sandstorm observed during past becoming less unchanged during past or developing during past smoke the air, not raised by at or near the station but and/or sand whirl but no within sight or at the hour (not plotted) developed (not plotted) hour (not plotted) hour (not plotted) wind at or near station no dust whirl/sandstorm dust storm/sandstorm station during past hour 10 11 12 13 14 15 16 17 18 19 ) ) ( ( )
Mist Patches of shallow fog More or less continuous Lighting visible, no Precipitation within sight, Precipitation within sight, Precipitation within sight, Thunder heard, but no Squall(s) within sight Funnel cloud(s) and/or at station, NOT deeper shallow fog at station, thunder heard but NOT reaching the reaching the surface, but reaching the surface precipitation at the station during past hour Tornado(es) during the than 6 feet on land NOT deeper than 6 feet ground more than 3 miles away within 3 miles preceding hour 20 21 22 23 24 25 26 27 28 29
Drizzle (not freezing) or Rain (not freezing) not Snow not falling as Rain and snow or ice Freezing drizzle or freez- Shower(s) of rain ended Shower(s) of snow, or Shower(s) of hail, or Fog or ice fog ended Thunderstorm (with or snow grains, not as falling as shower(s) , shower(s) ended in pellets, not as shower(s) ing rain, not as shower(s) in the past hour of rain and snow ended of rain and hail ended in the past hour without precipitation) shower(s), has ended ended in the past hour the past hour ended in the past hour ended in the past hour in the past hour in the past hour ended in the past hour 30 31 32 33 34 35 36 37 38 39
Slight or moderate dust Slight or moderate dust Slight or moderate dust Severe dust storm or Severe dust storm or Severe dust storm or Slight or moderate Heavy drifting snow Slight or moderate Heavy blowing snow storm or sandstorm (has storm/sandstorm (no storm or sandstorm (has sandstorm, decreased sandstorm, has no sandstorm has begun drifting snow (generally (generally below blowing snow (generally (generally above eye decreased in past hour) change during past hour) begun or increased) during the past hour change during past hour or increased below eye level) eye level) above eye level) level) 40 ( ) 41 42 43 44 45 46 47 48 49
Fog at a distance, but Fog in patches Fog, sky visible Fog, sky obscured Fog, sky visible (no Fog, sky obscured (no Fog, sky visible (has Fog, sky obscured (has Fog, depositing rime Fog, depositing rime not at the station during (has become thinner (has become thinner appreciable change appreciable change begun or has become begun or has become ice, sky visible ice, or ice fog, sky the preceding hour during preceding hour) during preceding hour) during the past hour) during the past hour) thicker during past hour) thicker during past hour) obscured 50 51 52 53 54 55 56 57 58 59
Drizzle, not freezing, Drizzle, not freezing, Drizzle, not freezing, Drizzle, not freezing, Drizzle, not freezing, Drizzle, not freezing, Drizzle, freezing, slight Drizzle, freezing, Drizzle and rain, slight Drizzle and rain, intermittent (slight at continuous (slight at intermittent (moderate at continuous (moderate at intermittent (heavy at continuous (heavy at moderate or heavy moderate or heavy time of observation) time of observation) time of observation) time of observation) time of observation) time of observation) 60 61 62 63 64 65 66 67 68 69
Rain, freezing, Rain, not freezing, Rain, not freezing, Rain, not freezing, Rain, not freezing, Rain, not freezing, Rain, not freezing, Rain, freezing, slight Rain or drizzle and Rain or drizzle and moderate or heavy intermittent (slight at continuous (slight at intermittent (moderate at continuous (moderate at intermittent (heavy at continuous (heavy at snow, slight snow, moderate time of observation) time of observation) time of observation) time of observation) time of observation) time of observation) or heavy 70 71 72 73 74 75 76 77 78 79
Intermittent fall of Continuous fall of Intermittent fall of Continuous fall of Intermittent fall of Continuous fall of Ice needles (with Snow grains (with Isolated star-like Ice pellets (sleet) snowflakes (slight at snowflakes (slight at snowflakes (moderate snowflakes (moderate snowflakes (heavy at snowflakes (heavy at or without fog) or without fog) snow crystals (with time of observation) time of observation) at time of observation) at time of observation) time of observation) time of observation) or without fog) 80 81 82 83 84 85 86 87 88 89
Rain shower(s), slight Rain shower(s), Rain shower(s), violent Shower(s) of rain and Shower(s) of rain and Snow shower(s), slight Snow shower(s), Shower(s) of snow pellets Shower(s) of snow pellets Shower(s) of hail, slight, moderate or heavy snow mixed, slight snow mixed, moderate moderate or heavy or small hail, slight with or or small hail, moderate or w/ or w/o rain or rain/ or heavy without rain or rain/snow heavy w/ or w/o rain/snow snow mixed, no thunder 90 91 92 93 94 95 96 97 98 99
Shower(s) of hail, w/ or Thunderstorm during past Thunderstorm during past Thunderstorm ended w/ Thunderstorm ended w/ Thunderstorm, slight or Thunderstorm, slight or Thunderstorm, heavy, Thunderstorm combined Thunderstorm, heavy, w/o rain or rain/snow, no hour w/ slight rain at time hour w/ current moderate/ current slight snow, rain/ current moderate/heavy moderate, w/o hail but w/ moderate, with hail at w/o hail but with rain with dust storm or with hail at time of thunder, mod. or heavy of observation heavy rain snow mixed, or hail snow, rain/snow, or hail rain and/or snow time of observation and/or snow sandstorm observation
National Weather Service Building a Weather-Ready Nation https://www.weather.gov/media/jetstream/synoptic/sfc_plot_key.pdf