Using ASCAT Wind and Other Data in Marine Forecasting

5.0 Closing the Case, 25 November » 5.1 Observational Data

We’ll finish the lesson by looking at the position of the cold front on 25 November and see what the weather and marine conditions were like.

The daytime Natural Color RGB image shows the position of vessel relative to the cold front. As you can see, the cold front is well to the east of the vessel, although there is still activity south of its position.

MSG Daytime Natural Color RGB showing the southern South Africa region on 25 Nov 2013 12 UTC

The photograph from the ship at 12 UTC shows mostly clear skies. The sea state is still fairly choppy, with white caps on the ocean surface. The sea swell is up to 4.5 m and the wind waves on top of that are at 2.5 m.

Photograph taken from the Polarstern vessel on 25 Nov 2013

The corresponding SYNOP report from 12 UTC on November 25 shows cumulonimbus cloud, mid-level altocumulus cloud, and upper-level cirrus cloud.

SMVX01 EDZW 251200 DBLK 25121 99523 30133 41597 62613 11009 21037 49950 52010 72782 84931 22221 04001 20605 326// 41109 =

The table summarizes the sea conditions observed at this time.

Parameter

Observation

Wind speed

13 m/s

Wind direction

W’ly

Wind waves (height)

2.5 m

Swell (height)

4.5 m

Pressure tendency

Increasing steadily

Atmospheric temperature

-0.9°C

The observations are in line with the weather and sea conditions expected behind a cold front, where pressure is rising, temperatures are colder, and sea conditions are unsettled.