Meteorology · Synoptic Charts — Prognosis
A 500-millibar prognostic chart is used by forecasters and routers chiefly to:
- AGive exact tidal heights
- BDisplay surface wave heights directly
- CShow the upper-level flow pattern that steers surface lows and highs, indicating where systems will move✓ Correct
- DShow sea surface temperature
Explanation
The 500-mb level (~18,000 ft) depicts the mid-tropospheric flow — troughs and ridges — that steers surface systems. Reading the upper-level pattern helps anticipate the movement and development of surface lows, which is central to weather routing.
Authority: NOAA/NWS; WMO; Bowditch (Pub. No. 9), upper-air charts
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