Monsoon 2021 Outlook

Monsoon 2021 Outlook : The buzz is back as the Monsoon 2021 season nears. Already a bunch of predictions are pouring IN, so here’s one more to add to reader’s confusion!


MY PREDICTIONS (Unofficial):


TIMELY ONSET OF MONSOON (since ENSO generally doesn’t impact the onset) –

. Hits eastern belt of Sindh & Punjab ~ 3rd week of June
. Reach Karachi ~ June last week
. Covers whole country ~ July first week

OVERALL SWM 2021 – NORMAL (90% – 110% of the Long Period Average)

Lets move towards Monsoon 2021 map in the form of an IMAGE, which has all the key details incorporated.

MONSOON 2021 KEY FEATURES:

  1. Timely onset over the country that would be in June 3rd week & covers whole country by first week of July.
  2. Normal Countrywide Rainfall Performance (90-110% of the Long Period Average) with following distribution ;

Sindh: Normal
Punjab: Above Normal
KP: Below Normal
Baluchistan: Normal
North Pakistan: Deficit

  1. June & July will score well in terms of rains. These months could record above normal rainfall.
  2. August/September likely to perform slightly below normal.
  3. Due to Neutral conditions in Pacific & Indian Ocean, this year monsoon will be largely governed by Local dynamics + MISO

Basis of Forecast:

I am going to keep it simple this year. For predicting monsoon rainfall, two things matters the most.

  1. ENSO STATUS: Currently in “INACTIVE Mode”, means Neutral Effect (some areas of monsoon zones to get very good rains, some will face drought) & is forecasted to remain Neutral throughout monsoon season.
  2. Neutral Indian Ocean Dipole – Currently Neutral, means Neutral Effect (Walker circulation/ Moisture carrying Easterly trade winds, neither strong, nor weak) & it may turn weak negative during later half of monsoon season.

Since the present situation falls well under “Neutral Conditions”, which is a big problem in itself, as it is usually associated with high annual variability in rainfall pattern. A fully matured EL-Nino or La-Nina season is usually associated with below or above normal rainfall respectively and don’t have high variability when it comes to forecasting rainfall on a district wise scale, but with a Neutral conditions, local factors holds the key, hence rainfall patterns becomes very hard to predict on a city or a district wise scale. “That’s why rainfall map has been made on a provincial scale this time”


Few Positive & Negative Scenarios That Needs To Closely Watch :

A. Local factors such as Differential Heating b/Ocean & Land, Daytime Temperatures, Sea Breeze Intrusion, Topography etc could play a significant control in modifying the weather patterns on a microscale during this season. That could allow better progress/spread of monsoon currents over the country. (As of now it can be seen as Positive contributer)

B. High sea surface temperatures along the coast results in sustenance as well as increase in moisture came along with monsoon winds which helps strengthening of monsoon systems/circulations/offshore trough. (Another Positive Sign, as of now)

C. Strong MJO currents already start moving into Indian Ocean – (Positive sign)

D. Forecast of Weak Negative IOD development from various multi models pose threat for below par performance late in the season (Negative contributer)

E. Even though possibility of El-Nino development is very low, but even with 10% chances of weak Nino development (like a weak La-Nina emergence in MS 2020) is also a damper moving into monsoon season. (Negative contributer)


Moving Ahead In Monsoon 2021 :

Despite few worries, let’s hope the Monsoon2021 remains Normal and didn’t end up in a deficit. For me, August & September are the key months to be closely watched for.. if these fails than we might end up with below normal monsoon rainfall after two consecutive bumper seasons.

Stay safe everyone, see you all soon with more regular updates on Monsoon 2021

(Will post a separate update on KarachiMonsoon soon).

Feedbacks are always welcome.

Indeed Allah S.W.T knows the best.

Credits Yasar

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