No. IV-18.4 - (IMD), Pune

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44 marked in the moisture field. The wind and the humidity fields tied with the realised rainfall. The pressure changes as well as the deep easterly field in which the low was embedded indicated a continued westerly movement. 16.6 By llth morning, the low moved to central and adjoining southeast Arabian Sea, off Coastal Mysore and continued to be well-marked (Fig. 16.8). The associated north-south trough also moved westwards into the Arabian Sea off south Maharashtra and Mysore coasts (Fig. 16.9). However, the east-west trough persisted across south Peninsula. With the westward movement of the low, pressures rose over the whole Peninsula, the maximum rise being about 3 mb in the eastern half. As the low and the associated trough moved west, moist southeasternes spread over the whole Peninsula and rainfall extended into western portion of the Peninsula; it generally decreased in the eastern half, though isolated heavy falls occurred in Coastal Andhra Pradesh where monsoon continued vigorous. 6.7 Subsequently the well—marked low moved away further westwards in the Arabian Sea and rainfall also decreased further in the Peninsula, being mostly confined to the western half. 16.8 This sequence brings out the following chief features: i) The low pressure area was marked, being seen in the surface and in the upper air, with a well-defined cyclonic circulation; it could be traced from South Andaman Sea to East Arabian Sea. In the upper air, the associated cyclonic circulation was well-marked extending upto the mid-troposphere (400 mb) with a southwestward slope with height. The seasonal east-west trough across the south Peninsula was also well-marked extending to midtropospheric level, with a general tilt towards the south. ii) There was also a north-south oriented trough extending from the low northwards, which also sequentially moved westwards along with the well-marked low. linen the north—south trough moved across the Peninsula, radiosonde
45 data showed that though there was no temperature discontinuity across the trough line, the southeasteries to the east of the trough line, were considerably moist and the northeasterlies to the west of the trough were dry. Rainfall was confined to the moist southeasterlies on the eastern side of the trough line. iii) Though initially when the low pressure area was out at sea in the Bay, the westerlies over the Peninsula Were moderate to strong, subsequently when the system moved inland, the easterlies to the north of the low became quite strong (reaching upto 35 kts) in the lower troposphere while the westerlies were relatively weak. iv) Rainfall extended far to the north of the low in the field of the moist easterlies and the significant amounts were close to the low or to the north of it, in the field of the southeasterlies. Coastal Andhra Pradesh which was well to the north of the low got vigorous monsoon on two consecutive days and heavy falls upto 12 cms were recorded there. The rainfal to the north of the low was confined to the area of cyclonic shear in the easterlies. v) The contrast in the rainfall and wind patterns on 7th and 8th when compared to 10th and llth show the differences between the two situations: a) linen the low was out at sea with only a east-west oriented trough line across the south Peninsula and b) when the well-marked low moved across the Peninsula. vi) Rainfall was generally accompanied by thunder. vii) The vertical time sections of Port Blair (Fig. 16.10) and Madras (Fig. 16.11) showed the passage of the low. The forward slope of the axis of the low with height, in both the sections, may be noted. Similarly, the strengthening of the southeasterlies after the low passed over the station is also noteworthy. viii).The isobaric field, 24 hr. pressure changes and the changes in the upper winds gave good indications of the movement of the low; similarly the
Page 2 and 3: FORECASTING MANUAL REPORTS Ho. 1-1
Page 4 and 5: Contents: 1. Introduction 2. Genera
Page 6 and 7: 2 1.3 In this report, we will deal
Page 8 and 9: 4 TABLE - I Mean Monthly, seasonal
Page 10 and 11: 6 iv)South Interior Mysore:— For
Page 12 and 13: 8 TABLE - II Division *Large excess
Page 14 and 15: 10 tions between 0300 and 0900 IST.
Page 16 and 17: temporarily shift north and come ov
Page 18 and 19: 14 Coastal Andhra Pradesh. 9.4 In a
Page 20 and 21: 16 The percentage frequencies of oc
Page 22 and 23: 11.2 Some details of the rainfall c
Page 24 and 25: ii) Depression and storms affect th
Page 26 and 27: 22 the incidence of storms in this
Page 28 and 29: 24 iv) Phenomenally heavy rains may
Page 30 and 31: 26 change chart or as a region of n
Page 32 and 33: 28 tilt usually towards a direction
Page 34 and 35: 30 rainfall is mostly along and to
Page 36 and 37: 32 south Peninsula. Rainfall was ge
Page 38 and 39: 34 even after the storm had moved i
Page 40 and 41: south Orissa coasts where speeds re
Page 42 and 43: 38 useful indications to prognostic
Page 44 and 45: 40 15.5 The main features in this s
Page 46 and 47: 42 Port Blair and also in the press
Page 50 and 51: 46 cloud configuration in the APT p
Page 52 and 53: 48 though it was still widespread (
Page 54 and 55: 50 area) than in the surface isobar
Page 56 and 57: 52 between the moist easterlies and
Page 58 and 59: 54 i) During this period, the antic
Page 60 and 61: 56 REFERENCES AND SELECTED BIBLIOGR
Page 62 and 63: 58 35. Raghavondra, V.K. and Rao, K
Page 64 and 65: 6"€. Venkiteshwaran, S.P. 1933: T
Page 66 and 67: FIG. 3.1 MEAN RAINFALL (Cm)
Page 68 and 69: FIG. 9.1 VERTICAL PROFILE OF MONTHL
Page 70 and 71: Fig. 10.2 Mean Tephigrams of Madras
Page 72 and 73: FIG. Il.l RAINFALL FOR 24 HRS. ENDI
Page 74 and 75: FIG. 12.1 TYPICAL DAY'S ISOHYETAL C
Page 77: FIG 13.2 UPPER WINDS 00 GMT 2 NOV.
Page 81: FIG. 13.6 UPPER WINDS 00 GMT 4 NOV.
Page 85: FIG. 14-2 UPPER WINDS 0 0 GMT 5 NOV
Page 88: FIG. 14.5 1200 GMT 6 NOV. 69 24 HR.
Page 92: FIG. 14.10 UPPER WINDS 00 GMT 8 NOV
Page 96: F1G.15. 4 UPPER WINDS 00 G M T 11 N
Page 99 and 100:
FIG. 15.7 SYNOPTIC CHARTS 0300 GMT
Page 102:
FIG. 16.2 UPPER WINDS OO GMT 7 OCT.
Page 107:
FIG. 16.7 UPPER WINDS 00 GMT 10 OCT
Page 110 and 111:
FIG. 16.10 TIME CROSS SECTION CHART
Page 113:
FIG. 17-2 UPPER WINDS 6 D E C . 7 1
Page 117:
FIG. 17-6 UPPER WINDS OO GMT 8 DEC.
Page 121:
FIG. 18-3 UPPER WINDS OOGMT 25 OCT.
Page 124 and 125:
Page 126 and 127:
FIG.195 SPACE CROSS-SECTION 9 N0V.
Page 128 and 129:
Page 130 and 131:
FIG. 19.9 TEPHIGRAM OF BANGALORE &
Page 132:
No. IV-13 Rainfall of India - P. Ja
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No. IV-18.4 - (IMD), Pune

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