Study of few days METAR of Dehradun

By

Gp Capt (Dr) B Nandi

1. Introduction.

METARs of Dehradun from 11OCT2023 to 16OCT2023 were undertaken for the study to demonstrate how useful it is to understand the atmospheric processes. Following are the METARs:

• VIDN 160500Z 30010G27KT 2500 TSRA BKN020 FEW035CB OVC060 17/15 Q1018 NOSIG=
• VIDN 160430Z 30011G22KT 4000 HZ SCT020 BKN060 20/14 Q1018 NOSIG=
• VIDN 160400Z 29003KT 4000 HZ SCT030 BKN080 20/14 Q1016 NOSIG=
• VIDN 160330Z 35003KT 4000 BR SCT030 BKN080 20/16 Q1015 NOSIG=
• VIDN 160300Z 22003KT 4000 BR BKN080 20/13 Q1015 NOSIG=
• VIDN 160230Z 34003KT 4000 BR BKN080 19/16 Q1015 NOSIG=
• VIDN 160200Z 01003KT 3000 BR BKN080 18/16 Q1014 NOSIG=
• VIDN 160130Z 02003KT 3000 BR NSC 17/15 Q1014 NOSIG=
• VIDN 160100Z 03004KT 3000 BR NSC 16/14 Q1014 NOSIG=
• VIDN 160030Z 04003KT 3000 BR NSC 16/14 Q1013 NOSIG=
• VIDN 151430Z 06003KT 3000 HZ NSC 21/17 Q1012 NOSIG=
• VIDN 151400Z 05003KT 3000 HZ NSC 22/17 Q1012 NOSIG=
• VIDN 151330Z 04003KT 3000 HZ NSC 22/17 Q1012 NOSIG=
• VIDN 151300Z 05003KT 3000 HZ NSC 23/18 Q1011 NOSIG=
• VIDN 151230Z 02004KT 3000 HZ NSC 24/19 Q1011 NOSIG=
• VIDN 151130Z 36003KT 3000 HZ FEW030 28/18 Q1011 NOSIG=
• VIDN 151100Z 23004KT 3000 HZ FEW030 29/14 Q1011 NOSIG=
• VIDN 151030Z 23005KT 3000 HZ FEW030 29/16 Q1011 NOSIG=
• VIDN 151000Z 19004KT 3000 HZ FEW030 SCT060 30/15 Q1011 NOSIG=
• VIDN 150931Z 15004KT 3000 HZ FEW030 SCT060 30/17 Q1011 NOSIG=
• VIDN 150900Z 16004KT 3000 HZ FEW030 SCT060 30/16 Q1011 NOSIG=
• VIDN 150830Z 14004KT 3000 HZ FEW030 SCT060 30/16 Q1012 NOSIG=
• VIDN 150730Z 12004KT 3000 HZ FEW030 SCT060 28/16 Q1012 NOSIG=
• VIDN 150700Z 16003KT 3000 HZ FEW030 SCT060 28/16 Q1013 NOSIG=
• VIDN 150630Z 17003KT 3000 HZ FEW030 BKN060 28/15 Q1014 NOSIG=
• VIDN 150600Z 02004KT 3000 HZ FEW030 BKN060 27/14 Q1014 NOSIG=
• VIDN 150530Z 34005KT 3000 HZ FEW030 SCT080 26/14 Q1015 NOSIG=
• VIDN 150500Z 31011KT 3000 HZ FEW030 SCT080 25/14 Q1015 NOSIG=
• VIDN 150330Z 33003KT 3000 HZ FEW080 23/17 Q1015 NOSIG=
• VIDN 150300Z 30003KT 3000 HZ FEW080 21/16 Q1015 NOSIG=
• VIDN 150230Z 02003KT 3000 BR FEW080 20/16 Q1014 NOSIG=
• VIDN 150200Z 35003KT 3000 BR FEW080 19/15 Q1014 NOSIG=
• VIDN 150130Z 05003KT 3000 BR FEW080 19/14 Q1013 NOSIG=
• VIDN 150100Z 03003KT 3000 BR FEW080 16/15 Q1013 NOSIG=
• VIDN 150030Z 01003KT 3000 BR NSC 16/15 Q1012 NOSIG=
• VIDN 141500Z 04003KT 3000 BR NSC 21/19 Q1015 NOSIG=
• VIDN 141430Z 34003KT 3000 BR NSC 22/19 Q1014 NOSIG=
• VIDN 141400Z 04003KT 3000 HZ NSC 23/19 Q1014 NOSIG=
• VIDN 141330Z 04003KT 3000 HZ NSC 24/19 Q1014 NOSIG=
• VIDN 141300Z 04003KT 3000 HZ NSC 24/20 Q1014 NOSIG=
• VIDN 141230Z 03003KT 3000 HZ NSC 25/20 Q1013 NOSIG=
• VIDN 141200Z 08003KT 3000 HZ NSC 27/18 Q1013 NOSIG=
• VIDN 141130Z 27003KT 3000 HZ FEW030 28/17 Q1013 NOSIG=
• VIDN 141100Z 25004KT 3000 HZ FEW030 29/17 Q1013 NOSIG=
• VIDN 141030Z 24005KT 3000 HZ FEW030 29/16 Q1013 NOSIG=
• VIDN 141000Z 22003KT 3000 HZ FEW030 29/17 Q1013 NOSIG=
• VIDN 140930Z 29003KT 3000 HZ NSC 29/16 Q1013 NOSIG=
• VIDN 140900Z 22003KT 3000 HZ FEW030 29/17 Q1014 NOSIG=
• VIDN 140830Z 30003KT 3000 HZ FEW030 29/16 Q1014 NOSIG=
• VIDN 140800Z 23004KT 3000 HZ NSC 29/16 Q1014 NOSIG=
• VIDN 140730Z 22003KT 3000 HZ NSC 29/16 Q1015 NOSIG=
• VIDN 140700Z 18003KT 3000 HZ NSC 28/15 Q1015 NOSIG=
• VIDN 140630Z 17004KT 3000 HZ NSC 27/15 Q1016 NOSIG=
• VIDN 140600Z 17004KT 3000 HZ NSC 27/16 Q1016 NOSIG=
• VIDN 140500Z 22003KT 3000 HZ NSC 25/17 Q1017 NOSIG=
• VIDN 140430Z 19003KT 3000 HZ NSC 25/16 Q1017 NOSIG=
• VIDN 140400Z 18003KT 3000 HZ NSC 24/17 Q1017 NOSIG=
• VIDN 140330Z 20003KT 3000 HZ NSC 23/16 Q1017 NOSIG=
• VIDN 140300Z 33003KT 3000 BR NSC 21/17 Q1017 NOSIG=
• VIDN 140230Z 02003KT 3000 BR NSC 20/17 Q1017 NOSIG=
• VIDN 140200Z 02003KT 3000 BR NSC 18/17 Q1016 NOSIG=
• VIDN 140130Z 03004KT 3000 BR NSC 17/16 Q1015 NOSIG=
• VIDN 140100Z 02003KT 3000 BR NSC 17/16 Q1015 NOSIG=
• VIDN 140030Z 04003KT 3000 BR NSC 17/16 Q1014 NOSIG=
• VIDN 131430Z 03003KT 3000 HZ NSC 22/17 Q1015 NOSIG=
• VIDN 131400Z 06003KT 3000 HZ NSC 22/17 Q1015 NOSIG=
• VIDN 131330Z 06004KT 3000 HZ NSC 22/17 Q1015 NOSIG=
• VIDN 131300Z 04003KT 3000 HZ NSC 23/18 Q1014 NOSIG=
• VIDN 131230Z 04003KT 4000 HZ NSC 25/18 Q1014 NOSIG=
• VIDN 131200Z 07003KT 5000 HZ NSC 26/18 Q1014 NOSIG=
• VIDN 131130Z 24004KT 6000 FEW090 28/17 Q1014 NOSIG=
• VIDN 131100Z 18005KT 6000 FEW090 28/17 Q1014 NOSIG=
• VIDN 131030Z 21003KT 6000 FEW090 29/15 Q1014 NOSIG=
• VIDN 131000Z 16003KT 6000 FEW030 29/15 Q1014 NOSIG=
• VIDN 130930Z 19004KT 6000 FEW030 29/15 Q1014 NOSIG=
• VIDN 130901Z 22004KT 6000 FEW030 29/15 Q1015 NOSIG=
• VIDN 130830Z 26003KT 6000 FEW030 29/15 Q1015 NOSIG=
• VIDN 130730Z 21003KT 6000 FEW030 28/16 Q1016 NOSIG=
• VIDN 130700Z 23005KT 6000 NSC 28/16 Q1017 NOSIG=
• VIDN 130630Z 24005KT 6000 NSC 28/16 Q1017 NOSIG=
• VIDN 130531Z 18003KT 6000 NSC 27/15 Q1017 NOSIG=
• VIDN 130500Z 27003KT 5000 HZ NSC 26/15 Q1018 NOSIG=
• VIDN 130430Z 26003KT 5000 HZ NSC 25/15 Q1018 NOSIG=
• VIDN 130330Z 31003KT 5000 HZ NSC 23/15 Q1017 NOSIG=
• VIDN 130230Z 35003KT 5000 BR NSC 20/16 Q1017 NOSIG=
• VIDN 130200Z 02003KT 3000 BR NSC 18/17 Q1016 NOSIG=
• VIDN 130130Z 04003KT 3000 BR NSC 16/15 Q1016 NOSIG=
• VIDN 130100Z 35003KT 3000 BR NSC 16/15 Q1016 NOSIG=
• VIDN 130030Z 02003KT 3000 BR NSC 16/15 Q1015 NOSIG=
• VIDN 121430Z 04003KT 3000 BR FEW030 22/17 Q1015 NOSIG=
• VIDN 121400Z 07003KT 3000 BR FEW030 22/18 Q1015 NOSIG=
• VIDN 121330Z 06004KT 3000 BR FEW030 22/18 Q1015 NOSIG=
• VIDN 121300Z 05003KT 3000 BR FEW030 23/19 Q1015 NOSIG=
• VIDN 121230Z 06003KT 5000 HZ FEW030 24/19 Q1015 NOSIG=
• VIDN 121200Z 27003KT 6000 FEW030 27/15 Q1014 NOSIG=
• VIDN 121130Z 26005KT 6000 FEW030 28/15 Q1014 NOSIG=
• VIDN 121100Z 26007KT 6000 FEW030 29/15 Q1014 NOSIG=
• VIDN 121030Z 26005KT 6000 FEW030 29/15 Q1014 NOSIG=
• VIDN 121000Z 26006KT 6000 FEW030 30/15 Q1014 NOSIG=
• VIDN 120930Z 22003KT 6000 FEW030 30/15 Q1014 NOSIG=
• VIDN 120900Z 22003KT 6000 FEW030 30/14 Q1014 NOSIG=
• VIDN 120830Z 20004KT 6000 FEW030 30/13 Q1014 NOSIG=
• VIDN 120800Z 20005KT 6000 FEW030 29/14 Q1015 NOSIG=
• VIDN 120730Z 25005KT 6000 FEW030 29/14 Q1015 NOSIG=
• VIDN 120700Z 24003KT 6000 NSC 29/14 Q1015 NOSIG=
• VIDN 120630Z 26003KT 6000 NSC 28/15 Q1016 NOSIG=
• VIDN 120600Z 26003KT 6000 NSC 27/14 Q1016 NOSIG=
• VIDN 120530Z 28003KT 6000 NSC 26/15 Q1016 NOSIG=
• VIDN 120500Z 29003KT 6000 NSC 26/14 Q1016 NOSIG=
• VIDN 120430Z 29003KT 6000 NSC 25/14 Q1016 NOSIG=
• VIDN 120400Z 31003KT 6000 NSC 23/15 Q1016 NOSIG=
• VIDN 120330Z 33003KT 6000 NSC 22/15 Q1016 NOSIG=
• VIDN 120230Z 33003KT 6000 NSC 19/15 Q1015 NOSIG=
• VIDN 120200Z 03003KT 6000 NSC 18/15 Q1015 NOSIG=
• VIDN 120130Z 02003KT 6000 NSC 16/14 Q1014 NOSIG=
• VIDN 120100Z 05003KT 6000 NSC 16/14 Q1014 NOSIG=
• VIDN 120030Z 03004KT 3000 BR NSC 16/14 Q1014 NOSIG=
• VIDN 120000Z 02003KT 3000 BR NSC 16/14 Q1013 NOSIG=
• VIDN 111400Z 04003KT 3000 BR NSC 22/17 Q1013 NOSIG=
• VIDN 111230Z 02003KT 4000 HZ NSC 26/18 Q1013 NOSIG=
• VIDN 111200Z 27003KT 6000 NSC 27/15 Q1012 NOSIG=
• VIDN 111130Z 26006KT 6000 NSC 28/15 Q1012 NOSIG=
• VIDN 111059Z 27006KT 6000 NSC 29/14 Q1012 NOSIG=
• VIDN 111030Z 27003KT 6000 NSC 28/15 Q1012 NOSIG=
• VIDN 111000Z 23003KT 6000 NSC 30/15 Q1012 NOSIG=
• VIDN 110930Z 23003KT 6000 NSC 31/14 Q1012 NOSIG=
• VIDN 110900Z 23003KT 6000 NSC 31/14 Q1012 NOSIG=
• VIDN 110830Z 29003KT 6000 NSC 31/17 Q1013 NOSIG=
• VIDN 110800Z 28003KT 6000 NSC 30/18 Q1013 NOSIG=
• VIDN 110730Z 02003KT 6000 NSC 30/18 Q1013 NOSIG=
• VIDN 110700Z 02003KT 6000 NSC 30/18 Q1014 NOSIG=
• VIDN 110630Z 29003KT 6000 NSC 29/18 Q1014 NOSIG=
• VIDN 110600Z 28003KT 6000 NSC 28/18 Q1014 NOSIG=
• VIDN 110530Z 29003KT 6000 NSC 27/14 Q1015 NOSIG=
• VIDN 110500Z 29003KT 6000 NSC 26/14 Q1015 NOSIG=
• VIDN 110430Z 25003KT 6000 NSC 25/14 Q1015 NOSIG=
• VIDN 110400Z 27003KT 6000 NSC 24/15 Q1015 NOSIG=
• VIDN 110330Z 30003KT 6000 NSC 23/14 Q1015 NOSIG=
• VIDN 110300Z 33003KT 5000 HZ NSC 21/15 Q1014 NOSIG=
• VIDN 110230Z 35003KT 5000 HZ NSC 20/15 Q1014 NOSIG=
• VIDN 110200Z 02003KT 5000 BR NSC 18/15 Q1013 NOSIG=
• VIDN 110130Z 03003KT 5000 BR NSC 16/14 Q1013 NOSIG=
• VIDN 110100Z 02003KT 5000 BR NSC 16/14 Q1013 NOSIG=
• VIDN 110030Z 03003KT 3000 BR NSC 16/15 Q1012 NOSIG=

2. DEWPOINT JUMP

• VIDN 111230Z 02003KT 4000 HZ NSC 26/18 Q1013 NOSIG=
• VIDN 111200Z 27003KT 6000 NSC 27/15 Q1012 NOSIG=

On 11OCT2023, in half an hour (1200Z to1230Z) 3°C jump of dewpoint temperature from 15°C to 18°C has taken place along with change in wind direction from Wly to NNEly and with no significant clouds.

• VIDN 121230Z 06003KT 5000 HZ FEW030 24/19 Q1015 NOSIG=
• VIDN 121200Z 27003KT 6000 FEW030 27/15 Q1014 NOSIG=

On 12OCT2023, in half an hour (1200Z to1230Z) 4°C jump of dewpoint temperature from 15°C to 19°C has taken place along with change in wind direction from Wly to NEly and few low clouds.

• VIDN 131100Z 18005KT 6000 FEW090 28/17 Q1014 NOSIG=
• VIDN 131030Z 21003KT 6000 FEW090 29/15 Q1014 NOSIG=

On 13FEB2023, in half an hour (1030Z to1100Z) 2°C jump of dewpoint temperature from 15°C to 17°C has taken place along with change in wind direction from SSWly to Sly and few medium clouds.

• VIDN 141230Z 03003KT 3000 HZ NSC 25/20 Q1013 NOSIG=
• VIDN 141200Z 08003KT 3000 HZ NSC 27/18 Q1013 NOSIG=

On 14OCT2023, in half an hour (1200Z to1230Z) 2°C jump of dewpoint temperature from 18°C to 20°C has taken place along with change in wind direction from Ely to NEly and with no significant clouds.

• VIDN 151130Z 36003KT 3000 HZ FEW030 28/18 Q1011 NOSIG=
• VIDN 151100Z 23004KT 3000 HZ FEW030 29/14 Q1011 NOSIG=

On 15OCT2023, in half an hour (1100Z to1130Z) 4°C jump of dewpoint temperature from 14°C to 18°C has taken place along with change in wind direction from SWly to Nly and few low clouds.

Westerlies to Easterlies wind change brings lager dewpoint jump of the order of 3⁰C to 4⁰C. The proximity of Song River (about 3km) to the eastern side of airfield brings moist air along with temperature reduction with time, puts moisture saturation level to higher side helping rise in dew point.

3.  Wind oscillation

On light wind days of 925hPa, Dehradun has diurnal oscillation of wind. After 1200 -1230Z winds are NEly and it continues to 0230-0300Z through night. Thereafter wind changes to Sly/SWly till evening. This indicates the dominance of Katabic/Anabatic wind of the high hill ranges to NE of Dehradun

4. Temperature Increase jump in morning.

• VIDN 110330Z 30003KT 6000 NSC 23/14 Q1015 NOSIG=
• VIDN 110300Z 33003KT 5000 HZ NSC 21/15 Q1014 NOSIG=
• VIDN 110230Z 35003KT 5000 HZ NSC 20/15 Q1014 NOSIG=
• VIDN 110200Z 02003KT 5000 BR NSC 18/15 Q1013 NOSIG=
• VIDN 110130Z 03003KT 5000 BR NSC 16/14 Q1013 NOSIG=

On 11OCT2023, every half an hour  2°C jump of temperature during 0130Z to 0330Z has taken place .

• VIDN 120200Z 03003KT 6000 NSC 18/15 Q1015 NOSIG=
• VIDN 120130Z 02003KT 6000 NSC 16/14 Q1014 NOSIG=

On 12FEB2023, in half an hour  2°C jump of temperature during 0130Z to 0200Z has taken place.

• VIDN 130200Z 02003KT 3000 BR NSC 18/17 Q1016 NOSIG=
• VIDN 130130Z 04003KT 3000 BR NSC 16/15 Q1016 NOSIG=

On 13OCT2023, in half an hour  2°C jump of temperature during 0130Z to 0200Z has taken place.

• VIDN 140230Z 02003KT 3000 BR NSC 20/17 Q1017 NOSIG=
• VIDN 140200Z 02003KT 3000 BR NSC 18/17 Q1016 NOSIG=

On 14OCT2023, in half an hour  2°C jump of temperature during 0200Z to 0230Z has taken place.

• VIDN 150130Z 05003KT 3000 BR FEW080 19/14 Q1013 NOSIG=
• VIDN 150100Z 03003KT 3000 BR FEW080 16/15 Q1013 NOSIG=

On 15OCT2023, in half an hour  3°C jump of temperature during 0100Z to 0130Z has taken place.

• VIDN 160200Z 01003KT 3000 BR BKN080 18/16 Q1014 NOSIG=
• VIDN 160130Z 02003KT 3000 BR NSC 17/15 Q1014 NOSIG=

On 16OCT2023, in half an hour  3°C jump of temperature during 0100Z to 0130Z has taken place.

It can be concluded that after about an hour of sun rise (around 0619IST or 0049Z) temperature tends to jump 2°C without much of change in wind direction.

5. Temperature decrease jump in evening

• VIDN 121230Z 06003KT 5000 HZ FEW030 24/19 Q1015 NOSIG=
• VIDN 121200Z 27003KT 6000 FEW030 27/15 Q1014 NOSIG=

On 12OCT2023, in half an hour  3°C decrease in temperature during 1200Z to 1230Z has taken place with wind shift Wly to NEly.

• VIDN 131300Z 04003KT 3000 HZ NSC 23/18 Q1014 NOSIG=
• VIDN 131230Z 04003KT 4000 HZ NSC 25/18 Q1014 NOSIG=

On 13OCT2023, in half an hour  2°C decrease in temperature during 1200Z to 1230Z has taken place with nil wind shift.

• VIDN 141230Z 03003KT 3000 HZ NSC 25/20 Q1013 NOSIG=
• VIDN 141200Z 08003KT 3000 HZ NSC 27/18 Q1013 NOSIG=

On 14OCT2023, in half an hour  2°C decrease in temperature during 1200Z to 1230Z has taken place with wind shift Ely to NEly.

The wind shift to NEly indicates that cooler katabatic wind onset takes place somewhere around 1200-1230Z coinciding with the sunset time (1757IST or 1227Z).

6. Final conclusion

• Over Dehradun Katabatic/anabatic wind dominates during low synoptic winds. Katabatic wind sets in somewhere between 1200-1230Z coinciding with sunset and continues till 0200-0230Z. During the day anabatic wind dominates.
• During the setting in of katabatic wind that is NElies, atmosphere becomes more moist with dewpoint jump, due to the proximity of Song River in the east.
• Usually with the onset of anabatic wind during 0200-0230Z temperature tends to sudden increase.
• It appears that RH is maintained as temperature decreases in the morning, dewpoint also decreases maintaining the dewpoint depression. So, evening dewpoint need not represent the moisture in the morning.
• Katabatic circulation has upward branch over the valley. So, it is unlikely to favour the fog formation.