IRFP-01
Metro Review
B. Prognostic charts 21.1.1.3.4
Fig 22: Low-Level
Prognostic Chart
NOTE: Remember to correlate forecast flight conditions to scheduled
flight time.
1. Low-Level Significant Weather Prognostic Chart
a. Manually produced facsimile prognostic charts providing
depictions of various surface and low-level (up to 24,000 ft
MSL) significant weather features out to 48 hours
b. The 12- and 24-hour forecasts are produced on one chart,
4 times a day
NOTE: Separate panels depict the surface weather prognosis,
and a second panel depicts the “significant weather” for each
forecast time.
c.
The 36- and 48-hour forecasts are on a separate chart
produced twice daily
NOTE: A single panel depicts both surface features and
significant weather. Underneath the panel, a forecast
discussion about which guidance was used to prepare the
chart and why it was used, is written in plain language with
many abbreviations.
d. Chart intended for general flight planning, see specific TAFs
for terminal aerodrome forecasts
e. Chart shares some symbology and coloration with the Surface
Analysis (SA) chart
f.
Frontal type and position shown using standard symbols
(1) High- and low-pressure centers indicated by Hs and Ls
with the pressure value (underlined) to the nearest whole
millibar
(2) Pressure center movement is indicated by an arrow for
direction, and the forecast speed of movement at the valid
time of the chart is entered in knots at the head of the
arrow
NOTE: The term “STNRY” is used to indicate little
movement.
(3) Isobars will be depicted with a thin, solid line at an
8-millibar interval, labeled in tens and units of millibars
(8-97) Original
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