| Significant Weather Prognostic Chart |
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The low-level chart comes in two forms: the 12- and 24-hour forecast
chart, and the 36 and 48 surface only forecast chart. The first
chart is a four-panel chart that includes 12- and 24-hour forecasts
for significant weather and surface weather. Charts are issued four
times a day at 0000Z, 0600Z, 1200Z, and 1800Z. The valid time for
the chart is printed on the lower left-hand corner of each panel.
The upper two panels
show forecast significant weather, which may include nonconvective
turbulence, The lower two panels show the forecast surface weather and depicts the forecast locations and characteristics of pressure systems, fronts, and precipitation. Standard symbols are used to show fronts and pressure centers. Direction of movement
of the pressure center is depicted by an arrow. The speed, in knots,
is shown next to the arrow. In addition, areas offorecast
precipitation and thunderstorms are outlined. Areas of precipitation
that are shaded indicate at least one-half of the area is being
affected by the precipitation. Unique symbols indicate the type of
precipitationand the manner in which it occurs. |