December almost over...But City still Warm.

Mumbai is facing a winter , a "warm winter'' untypical of a normal December for the city.

It has been a hot start to Mumbai's winter, with the temperatures above normal throughout the period, especially in December, averaging around 3c above normal. 

Since 3rd December this year, Mumbai has seen day temperatures above 33c ( 2/3 c above normal) on all days )as  of 29th December). The top being 35.7c ( +4c)on 24th.

The nights have averaged 21/22c in December, around 4c above normal. The coolest this year seen is 18.9c on 24th.

Thus the daily day/night average for December works out to 27c..2c above normal.

But, as people's memory is short, let Vagaries remind all that, Mumbai had a much warmer December in in 1987 when Day was 39.8c on 4th December, the Monthly warmth was 4c above the normal. In 1990,  the temperature averaged 6c above normal !

Normally for Mumbai, the winter starts with the cold winds blowing from the North, generating from a Western Disturbance system in the Northern plains and Himalayas. . But this year an "anti Cyclone" system in Central India blocked the cold winds, and brought Easterlies and South Easterly winds, which are dry and warm.

A Western Disturbance System can approach Northern India around 6th January 2024. Mumbai can then get some pleasant weather after 7th, and cooler temperatures around 16/17c. Outer townships of Mumbai can go down to 15c.

29th December

 Cyclonic circulation seen over southern Arabian Sea...two regions of convection and vorticity. 

May organize over the next day or two and can move north. Monitoring for further development.

At 12 pm  29th December, widespread fog seen covering a larger stretch over IGP region from Pakistan to Bihar. 

Foggy day for the entire region. The entire is dry with temperature inversion seen near the surface and a highly stable atmosphere in terms of -e profile. 700 mb circulation shown.

Courtesy Vag. Gokul

 27th December 

Due to lesser frequency of W.D.s thus year, much reduced snow cover seen over the Himalayas. 

Compare with the December image of 2019

 23rd December..Konkan days hotter as mentioned 

Weather forecast from Friday 22nd to Monday 25th December

Plesant nights across Maharashtra, but hotter daytime weather for Konkan.

Mumbai: Day temperature will continue to be warmer than normal (around 33C) and can rise further on Sunday 24th/Monday 25th with max touching around 34-35C. Dry heat due to easterly winds, low humidity. Nights can be pleasant with minimum temperature around 19C over the weekend. 

Thane district and interior regions of Konkan belt will see cooler nights (around 15C-16C or slightly lower). Days will be very warm (unlike December).

Pune: Days to remain around 30C and night temperature to drop till around 12C. Outskirts and rural areas maybe slightly cooler. 

Marathwada and Vidarbha: Not much change in the weather. Days will be comfortable around 29C-30C. Minimum temperature in Marathwada region likley to be in the 11C-13C range. Vidarbha may continue to see cooler nights with temperatures dropping till 9C-10C, and even lower in rural regions.

Due to the absence of a moderate/strong intensity Western Disturbance for northern states and UTs, the cool northerlies are not expected along the west coast anytime soon.

 

  POLAR STRATOSPHERIC CLOUDS: See Vagaries extreme Blog...International Extreme Events Page

 Amazing Coincidence 100 years back...( sent by M.Krishnan

More on the Extreme Rainfall in Kayalpattinam...Some Explanations...

On Sunday (December 17), the Kayalpattinam locality within Tamil Nadu’s Thoothukudi district received a whopping 96 cm worth of rainfall in a single day, much higher than what the district receives in an entire year (up to 70 cm)! This intense soaking is down to several factors.

Typically, heavy rainfall of this magnitude is linked to well-defined systems like cyclones. However, in this instance, it was a mere upper-air cyclonic circulation over the Comorin area that triggered such substantial precipitation.

“There was more moisture inside the system which gave widespread rainfall, but usually upper air circulation doesn’t give this much rain. This (system) has given more rain than a cyclone,” S Balachandran, head of the Chennai-based Regional Meteorological Centre (RMC

This rainfall is both unusual and unprecedented especially when we are in the fag end of the northeast monsoon. Nothing like this has happened in more than 100 years,” said YEA Raj, the former deputy director general of the Indian Meteorological Department (IMD).

The torrential showers in Tamil Nadu's plains on Sunday and Monday constituted one of the highest-ever recorded rainfall episodes within a 24-hour period for the region. While such intense rainfall is more common in hilly regions, it is exceedingly rare in plain areas.

In spite of the unusual downpour, however, it is essential to acknowledge that additional factors may have contributed to this event. For instance, the slow movement of the rain-bearing system over the Comorin area—akin to Cyclone Michaung's stalling near Chennai on December 4—likely allowed repeated convergence at the same location.

Meanwhile, owing to the absence of an IMD observatory in Thoothukudi, the state government's observatory has provided this rainfall data to the National Data Centre in Pune. This data will undergo verification against previous years' records to gain further clarity on the significance of this single-day rainfall event and the records it may have broken.

Excerpt From "The Weather Channel,"

18th December...NEM fury

Kayalpattinam in Thoothukudi records 932 mm in 24 hrs. (This is more than their annual rainfall falling in a day). 

This is the highest ever rainfall recorded in plains ever in Tamil Nadu in 24 hrs & the 2nd highest rainfall after the Kakkachi (manjolai) 965 mm recorded in 1992.

Information from Pradeep John.

18th December...Vigorous NEM

Kayalpattinam in south Tamil Nadu records extremely exceptional heavy rains of 950 mm in the past 24 hrs. 

A slow moving cyclonic circulation in Comorin sea and the associated large scale moisture transport from the east and south favored such extreme rains in much of south TN.

Post courtesy Vag. Gokul

 Lowest temperatin plains 3.5°c in

 plains. 👇

👆Major parts of India above normal at nights

Winter not yet established in peninsula  Indiaa due to poor precipitation and North Winds not setting in.

For proper winter conditions. Our wait is for a good W.D.

 

 17th December 

Interior Maharashtra gets a taste of winter like temperatures for the first time this season.

Temperatures have dropped close to the "Normal" for this time of year, as mentioned in our earlier post.

Minimum temperatures recorded today 15th December morning:

Pune Shivajinagar 12.3°C

Nagpur Airport 12.8°C

Chandrapur 13°C

Satara 13.2°C

Ahmednagar 13.3°C

Ch. Sambhajinagar 13.5°C

Nashik 14.2°C

Sangli 14.9°C

Outlook till Monday 18th December:

Mumbai: Night temperatures may rise a little from/after 17th December. Still no proper winter chill. Days to be warmer around 32-33°C and nights initially around 20°C but may rise to 22-23°C early next week. 

Outskirts in Thane/Raigad/Palghar districts may see minimum temperatures till 15-17°C for next 2 days, but rising early next week. 

Pune: Winter chill may be felt at night and early morning for another day or two. Minimum temperatures can rise by 2-3°C by Monday 17th December. 

Some regions in Pune/Raigad/Satara/Kolhapur/Ratnagiri/Sindhudurg districts may see increased cloudiness around Ghats during 17th-19th December. Some drizzles or isolated light shower cannot be ruled out.

Temperature may drop again later next week.

Interior Maharashtra including Marathwada and Vidarbha districts can also see some rise in minimum temperatures by Monday 17th December, but may drop again later next week. 

 A Dusting of Snow on Hawaii’s Tallest Peaks

see World Weather News Page

Mumbai/Pune to move around the "Normal" temperatures 11th Dec to 15th Dec (Next Week).

Mumbai:

* With the rains finally leaving Mumbai, and the humidity decreasing, City may get relief from the sweaty coastal weather. Currently at 65%, humid conditions may improve to 55%

* Coming week, Mumbai will see the nights getting cooler., with a "slight Nip". The best witnessed this season was 19.7c on 30th November. May get to around the "Normal" yellow line (around 18/19c).

* Days, already hovering around normal, will set at 31/32c.

*Panvel/Navi Mumbai/Karjat may get lower to17/19c.

Pune: 

* On 16th, Pune saw the lowest this season, 14.4c. 

*Coming week may hover around 12/14c, moving around the normal yellow Line.

Sambhajinagar: 

* Lowest has been 13.2c this season on 17th November. Now, with the cloudy conditions , the temperatures were around 16c.

* But with no rains and clear skies, the city may see nights at 12/14c again. May benefit standing "Channa" and Wheat.

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Mumbai: November 2023 Summery

Rainfall occurred on 26th and 27th due to Interaction of W.D/LWD/Induced Low

Summary

Temperature (°C)	Max	Average	Min
Max Temperature	37	34.5	30
Avg Temperature	32.15	29.87	26.73
Min Temperature	28	26.3	24
Dew Point (°C)	Max	Average	Min
Dew Point	26	19.51	11
Precipitation (mm)	Max	Average	Min

Weather forecast till Monday 11th December:

Mumbai: Warm days around 32°C, nights slightly pleasant around 20-21°C.

Interior konkan and Thane district can see cooler nights around 17-18°C. 

Pune: Daytime comfortable around 30°C, nights cool at 15°C. Pleasant weather but still missing the peak winter chill

Now, a UAC in the Arabian Sea. 

Due to poor support and slacking  MJO,may not strengthen. 

Animation of Chennai Doppler radar images before and during cyclone Michaung (compiled by Ponmar Ram)

6th December 

Cyclone Michaung nears the end of it's life cycle in Telangana. 

It will go into  records for causing extremely very heavy rainfall in Tamil Nadu and Andhra Pradesh. 

500 mm rainfall fell within 36 hours across several parts of Chennai and its suburbs. 

Mini Tornadoes were formed in AP. 

(Vag.Gokul)

In such emergencies, Nowcasts need to be accurate.

Cyclone Michaung : The strongest December cyclone in north India Ocean after 2016

Based on JTWC data, with a wind speed of 60 knots, Cyclone Michaung is the strongest December cyclone in the north Indian Ocean (including both the Arabian Sea and the Bay of Bengal) after 2016.

Note: Cyclone month distribution is defined based on the first day the cyclone attained cyclonic storm strength (wind speed 35 knots).

For the period 1982-2023, the maximum wind speed of cyclones in the north Indian Ocean in December is increasing at the rate of 2.8 knots/decade.

Attached is the maximum wind speed of the cyclones in December in north Indian Ocean for the period 1982-2023. Data: JTWC

1st Official Title by Vagaries...well deserving to Vineet Singh for his sincere and deep research 

*"Cyclone Man of Vagaries "*

-----------------

5th December

Estimated correctly by Vagaries on 3othNovember and again 2nd December with correct wind speeds

CycloneMichaung has moved very close to Nellore, Andhra Pradesh. Heavy to extremely heavy rains expected over coastal areas of south AP. 

Chennai rains will gradually decrease from early morning tomorrow and the situation will get better.

 

Very Heavy rains and water-logging reported across Chennai as western sector of Severe Cyclone Michaung batters north Tamil Nadu and south Andhra Pradesh coasts!

Chennai city 229.2 mm till 8:30 pm

Chennai Airport 180.2 mm till 8:30 pm

Rainfall will decrease significantly from tomorrow. 

Chennai, north TN flooded as cyclone inches closer to coast

Very heavy rain going on in Chennai since last night due to cyclone outer bands. The cyclone has now intensified to 45knots.

Due to very slow movement of cyclone Chennai is likely to keep getting heavy rain at least till 3-4pm. More flooding is expected.

Shriharikota very heavy rain is expected till night hrs of 4 Dec.

Nellore very heavy rain is expected to continue till early morning hrs of 5 December.

 

Cyclone Michanung will steadily intensify till 4 December, landfall on 5 December

Cyclone Michaung currently maintaining an intensity of 35 knots as per IMD.

Currently, low wind shear and robust poleward outflow supported by high SSTs and moderate ocean heat content will favor the cyclone to steadily intensify till the evening/night of 4 December. It is likely to reach a peak intensity of 90-100kmph by the night of 4 December. As of now, rapid intensification chances are low.

This is the 4th cyclone of the post-monsoon season in the north Indian Ocean. This is the highest number of cyclones in the north Indian Ocean post-monsoon season after 2019.

Figure: Ocean heat content (kJ/cm2) along with the forecasted path of the cyclone. Source: CIRA

Figure: Vertical wind shear as on 3 December 1130IST (Green lines indicate low shear which is favourable for cyclone intensification). Source: CIMSS

From 4 December night, due to land interaction and increased vertical wind shear, the cyclone is likely to stop intensifying. Latest model guidance suggests that coastal Andhra Pradesh is likely to get rain in excess of 200-250mm on 4-5 December.

Figure: Rainfall (mm) forecast by IMD-GFS model

3rd December......

Cyclone Michaung...!

Latest Synopsis :DVANCED DVORAK TECHNIQUE       

                    ADT-Version 9.1                
         Tropical Cyclone Intensity Algorithm       

             ----- Current Analysis ----- 
     Date :  03 DEC 2023    Time :   033000 UTC
      Lat :   11:42:18 N     Lon :   82:20:00 E

     
                CI# /Pressure/ Vmax
                2.6 /1005.5mb/ 37.0kt

     
             Final T#  Adj T#  Raw T# 
                2.6     2.7     2.8

 Center Temp : -34.9C    Cloud Region Temp : -63.1C

 Scene Type : CURVED BAND with 0.67 ARC in LT GRAY 
              Maximum CURVED BAND with 0.96 ARC in LT GRAY 
               at Lat:  12:18:00 N  Lon:  82:31:47 E 

Third cyclone of the season in Bay of Bengal

 A cyclone will form in the Bay of Bengal by the night of 2 Dec/morning of 3 dec.

This will be the third cyclone of the post-monsoon season in the Bay of Bengal.

For the 1st time after 2018, all the three months (Oct, Nov and Dec) of the post-monsoon season will have a cyclone in the Bay of Bengal.

Multi-model ensemble indicates that due to close proximity with land, this system can maximum intensify up to 90-95kmph. 

Due to weak steering the system is currently moving at a very low speed.

This system likley to hit central Andhra coast on 5 December with winds close to 90kmph.

SST in the south Bay of Bengal continue to remain 1-2C above normal.

Currently, the system is in a low wind-shear environment. However, from 4 December onwards high wind shear is likely to affect the system which will restrict the intensification of this system.

Weekend ( 2nd - 4th) Outlook:

Mumbai: Days warm around 31°c and nights around 21°c.

Partly cloudy skies possible with smoggy conditions ( due to atmospheric inversion trap). AQI average exp around 150.

 November Average 👇

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Gujarat: Localized showers or a thunderstorm possible in parts of Saurashtra and around Ahmedabad, Bharuch, Vadodara, Surat regions during Saturday 2nd and Sunday 3rd December. Rainfall will be unevenly spread