Monthly Weather Report April 2019

Monthly Weather Report

April 2019

Director General Pakistan Meteorological Department

Prepared by: National Weather Forecasting Center Islamabad

Contents

SUMMARY ...... 1 INTRODUCTION ...... 2 FIRST SPELL ...... 3 SECOND SPELL ...... 5 THIRD SPELL ...... 7 FOURTH SPELL ...... 9 ACCUMULATIVE RAINFALL ...... 11 FORECAST VALIDATION ...... 13 TEMPERATURE ...... 14 DROUGHT CONDITION ...... 15 WEATHER OUTLOOK FOR MAY ...... 16 ACKNOWLEDGMENT ...... 17 REFERENCES ...... 17 ANNEX I ...... 18

List of Figures Figure 1 Synoptic situation on 10th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds...... 3 Figure 2 Rainfall (mm) distribution on 10th April 2019...... 4 Figure 3 Synoptic situation on 12th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds...... 5 Figure 4 Rainfall (mm) distribution on 12th April 2019...... 6 Figure 5 Synoptic situation from 16th to 18th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds...... 7 Figure 6 Rainfall (mm) distribution during 15th to 18th April 2019...... 8 Figure 7 Synoptic situation from 24th to 26th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds...... 9 Figure 8 Rainfall (mm) distribution during 24th to 26th April 2019...... 10 Figure 9 Rainfall (mm) distribution during April 2019...... 11 Figure 10 Rainfall departure in April 2019 ...... 12 Figure 11 Spatial distribution of rainfall (mm) departure in April 2019 ...... 12 Figure 12 Temperature comparison between normal and April 2019 maximum temperatures. . 14 Figure 13 Temperature anomaly in April w.r.t 1981-2010 ...... 14 Figure 14 Drought outlook during the month of April...... 15

List of Tables Table 1 Forecast verification contingency table ...... 13 Table 2 Percentage accuracy of each spell ...... 13

SUMMARY

1. In April 2019 area weighted rainfall of the country remained above normal +58 %.

2. On regional basis rainfall was above normal in Balochistan +184%, Punjab +146%, Khyber

Pakhtunkhwa +10%, and below normal in Gilgit Baltistan -68%, Azad Jammu and

Kashmir -20% and Sindh -4%.

3. Highest accumulated precipitation during the whole month was recorded in Dir, Khyber

Pakhtunkhwa, 190 mm.

4. Highest amount of rainfall during 24 hours was recoded in Jiwani, Balochistan, 89.0 mm.

5. Highest Maximum Temperature was recorded in Shaheed Benazirabad, 46.5℃.

INTRODUCTION

April is the first month in which summer conditions are settling in over most parts of the country. During April mean minimum temperature varies from 4.0℃ in Kalam to 23.0℃ in Karachi. While mean maximum temperature varies from 15.2℃ in Astore to 40.2℃ in Shaheed Benazirabad. Normal area weighted rainfall in April for Pakistan is 22.5 mm. For Khyber Pakhtunkhwa 73.9 mm, Punjab 20.6 mm, Balochistan 10.9 mm, Sindh 3.1 mm, Azad Jammu and Kashmir it is 45.2 mm and Gilgit Baltistan 38.8 mm. In April 2019 area weighted rainfall of Pakistan remained above normal +58%. On regional basis rainfall was above normal in Balochistan +184%, Punjab +146% and Khyber Pakhtunkhwa +10% below normal in Gilgit Baltistan -68%, Azad Jammu and Kashmir -20% and Sindh -4%. In this month highest maximum temperature was recorded in Shaheed Benazirabad (46.5℃). Highest accumulated precipitation during the whole month was reported from Dir, Khyber Pakhtunkhwa (190 mm). While highest amount of rainfall during 24 hours was recoded in Jiwani, Balochistan (89.0 mm). Pakistan experienced four rainfall spells during this month. Their detail is appended below.

FIRST SPELL

First rainfall spell in April was on 10th of the month. Synoptic situation during this day as obtained by NCEP/NCAR reanalysis dataset (Kalnay 1996) is shown in figure 1. A westerly wave is present over the central parts of the country and a trough of low pressure can also be seen at 850 hPa.

Figure 1 Synoptic situation on 10th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds.

Rainfall distribution during the first spell is shown in figure 2. This spell produced rainfall in upper and central parts of the country. Most of the southern parts of the country remained dry during this spell.

Figure 2 Rainfall (mm) distribution on 10th April 2019.

SECOND SPELL

Second wet spell of the month was on 12th April. The synoptic situation on this day was very similar to the previous wet spell. A westerly wave in upper air and a trough at lower level is present. An anticyclonic circulation is also present in South Arabian Sea

Figure 3 Synoptic situation on 12th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds.

Spatial distribution of rainfall on 12th April is shown in figure 4. It shows northern parts of the country received rainfall, while most of the southern parts of the country remained dry.

Figure 4 Rainfall (mm) distribution on 12th April 2019.

THIRD SPELL

Third wet spell of April was during 15th to 18th. The synoptic situation during these days is shown in figure 5. A strong cyclonic circulation on 16th April is seen gripping most of the central parts of the country. 850 hPa wind direction is also predominantly southwesterly transporting moisture from the Arabian Sea to upper parts of the country. This weather system latter on 17th and 18th April moved to upper parts of the country.

Figure 5 Synoptic situation from 16th to 18th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds.

Figure 6 represents the spatial distribution of rainfall during the spell. In this spell most parts of the country received rainfall. Upper parts of the country received more rainfall than rest of the country.

Figure 6 Rainfall (mm) distribution during 15th to 18th April 2019.

FOURTH SPELL

Third wet spell of April was during 24th to 26th. The synoptic situation during these days is shown in figure 7. A shallow cyclonic circulation gripped the country on 24th April and persisted for next two days producing rainfall in different parts of the country.

Figure 7 Synoptic situation from 24th to 26th April 2019. Shaded portion represents the geopotential height pattern at 500 hPa, solid line represents the geopotential height pattern at 850 hPa, while arrows indicate 850 hPa winds.

Figure 8 represents the spatial distribution of rainfall during the spell. In this spell most of the upper and central parts of the country received rainfall southeast parts of Sindh and southwest parts of Balochistan remained dry during this spell.

Figure 8 Rainfall (mm) distribution during 24th to 26th April 2019.

ACCUMULATIVE RAINFALL

In April most parts of the country received rainfall that is represented in figure 9. The center of maximum rainfall is near Dir, Khyber Pakhtunkhwa another center is present over Balochistan. Upper and western parts of the country received good rainfall. Details of rainfall are appended in annexure I.

Figure 9 Rainfall (mm) distribution during April 2019.

RAINFALL DEPARTURE During this month area weighted rainfall of the country remained above normal +58%. On regional basis rainfall was above normal in Balochistan +184%, Punjab +146% and Khyber Pakhtunkhwa +10% below normal in Gilgit Baltistan -68%, Azad Jammu and Kashmir -20% and Sindh -4% (CDPC 2019) represented in figure 10. Figure 11 shows the spatial distribution of rainfall departure in the month of April with respect to the base period of 1961-2010. It shows excess rainfall in most central and western parts of the country while below normal rainfall was recorded in northern parts of the country.

Figure 10 Rainfall departure in April 2019

Figure 11 Spatial distribution of rainfall (mm) departure in April 2019

FORECAST VALIDATION

An attempt is made to substantiate the accuracy of precipitation forecasts issued in April. This is done by using the contingency table 1, for each of the rainy spells. This table is used to find out the level of agreement between forecast and actual observation. The difference between forecast and observation is the error. The lower the errors, the greater the accuracy.

Table 1 Forecast verification contingency table

Observed

Yes No Total

Forecast Yes Hits False Alarms Forecast Yes

No Misses Correct Negatives Forecast No

Total Observed Yes Observed No Total

Hits means when the precipitation was forecasted and it occurred. Miss is used when the precipitation was not forecasted and it occurred. False alarm means when the precipitation was forecasted and it did not occur. Correct negatives are when the precipitation was not forecasted and also it did not happen. Accuracy of forecast is calculated by using formula in equation 1. Table 2 describes the accuracy in each of the spells

퐴푐푐푢푟푎푐푦 = 퐻푖푡푠 + 푐표푟푟푒푐푡 푛푒푔푎푡푖푣푒푠/푇표푡푎푙 (1)

Table 2 Percentage accuracy of each spell

Rainfall spells Percentage accuracy First Spell 84 Second Spell 90 Third Spell 90 Fourth Spell 87 Average 88

TEMPERATURE

During the month of April slightly above average maximum temperatures were recorded Pakistan. Maximum temperatures in Gilgit Baltistan and Azad Jammu Kashmir remined almost 2.0 degree above normal. Sindh, Punjab and Khyber Pakhtunkhwa recorded slightly above normal maximum temperatures while in Balochistan it remained slightly below normal. Figure 12 represents the comparison of April 2019 and mean maximum temperatures over the country. Spatial distribution of anomaly of mean temperature is shown in figure 13. It Indicates that parts of Gilgit Baltistan, South Punjab, Southeastern Sindh and Central Balochistan were warmer as compared to the mean temperatures. While parts of Punjab, Khyber Pakhtunkhwa and coastal areas of Sindh and Balochistan were cooler than normal.

Figure 12 Temperature comparison between normal and April 2019 maximum temperatures.

Figure 13 Temperature anomaly in April w.r.t 1981-2010

DROUGHT CONDITION

According to the latest drought analysis done by National Drought Monitoring Center of PMD,

Wet conditions prevailed over most places in the northern parts of the country. During the month of April, the rains in the agricultural plains of Khyber Pakhtunkhwa and Punjab gave relief to the crops. Some districts in Sindh are under moderate drought conditions due to no or very less precipitation and persistent dry conditions over there.

Figure 14 Drought outlook during the month of April.

WEATHER OUTLOOK FOR MAY

Normal Indian Ocean Dipole (IOD) and positive El Nino are forecasted to persist throughout the month. While North Atlantic Oscillation (NAO) is swinging along the neutral values during the forecast period. Based upon the regional and global weather conditions as stated above, weather outlook for the May 2019 is as follows:

❖ Normal or slightly above normal rainfall is expected in the country during the current month of May. ❖ The average temperature is likely to remain normal throughout the country during the month. However, there may be above normal temperature in Southern parts of the country. ❖ Heat wave conditions are likely to develop in plain areas of the country during last two weeks (2nd fortnight) of this month.

ACKNOWLEDGMENT

This work is the combined effort of all the forecasting team. Special thanks to Mr. Farooq Dar, Ms. Ruqiya Mehmood and Mr. Muhammad Safdar, National Weather Forecasting Center (NWFC), Islamabad. Mr. Nadeem Faisal, Climate Data Processing Center (CDPC), Karachi. Mr. Ibrar Qureshi, Flood Forecasting Division (FFD), Lahore. Mr. Nassir Yaseen, National Drought Monitoring Centre (NDMC), Islamabad

REFERENCES

CDPC, Pakistan Meteorological Department. 2019. “Winter Rainfall Update.” 2019. http://www.pmd.gov.pk/cdpc/winter2019_rainfall_update.htm. Kalnay, E. 1996. “The NCEP/NCAR 40-Year Reanalysis Project.” Bull. Am. Meteorol. Soc. 77 (3): 437–71. https://doi.org/10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2.

ANNEX I

Accumulative rainfall (mm) in April 2019, and their deviation from the normal rainfall.

Punjab

Stations April-19 Normal Deviation Murree 92.22 131.8 -39.6 Islamabad, Zeropoint 91.02 59.6 31.4 Noorpur Thal 86.2 ** ** Gujranwala 85.43 ** ** Chakwal 84.9 ** ** Joharabad 83.02 ** ** Layyah 81.41 ** ** Khanewal 78.01 ** ** Islamabad, New Airport 76.4 ** ** Kasur 69.43 ** ** Bahawalnagar 62.04 10.8 51.2 Jhang 60.51 ** ** Lahore, City 54.53 21.6 32.9 Mandibahauddin 53.02 ** ** Bhakkar 53.01 ** ** Jhelum 52.81 40.2 12.6 Lahore, Airport 50.44 21.1 29.3 D.G. Khan 50.22 ** ** Sargodha City 48.03 ** ** Sahiwal 47.51 ** ** Hafizabad 45.75 ** ** Gujrat 44.22 ** ** Bahawalpur, Airport 43.63 ** ** Mangla 41.61 ** ** Sialkot Airport 37.85 ** ** Faisalabad 37.83 23.7 14.1 Narowal 36.94 ** ** Sialkot Cantt 34.03 33.5 0.5 T.T. Singh 31.53 ** ** Okara 27 ** ** Kot Addu 25.93 ** ** Multan 19.92 14.2 5.7 Bahawalpur, City 18.04 10.5 7.5 Khanpur 11.2 4.3 6.9 Rahim Yar Khan 11 ** **

Kashmir Gilgit-Baltistan Stations April-19 Normal Deviation Garidopatta 112 119 -7.4 Rawalakot 110 ** ** Muzaffarabad 78 107.1 -29.1 Bagrote 36.7 ** ** Astore 33.9 85.5 -51.6 Kotli 32 72.8 -40.8 Gupis 14 51.6 ** Bunji 7.55 26.8 -19.3 Skardu 5.02 37.2 -32.2 Chilas 4.85 38.2 -33.4 Gilgit 4.44 25.5 -21.1 Hunza 2 ** ** Khyber Pakhtunkhwa Stations April-19 Normal Deviation Dir 190 166 24 Mirkhani 182 ** ** Kalam 172 ** ** M.Jabba 147 ** ** Drosh 122 97.7 24.7 Parachinar 116 87.8 28.2 Pattan 107 ** ** Chitral 99.4 78.7 20.7 Lower Dir 94 ** ** Balakot 83.7 117.6 -33.9 Bannu 69.1 21.2 47.9 Saidu Sharif 67.5 125 -57.5 Kakul 66 111.9 -45.9 D.I. Khan 63 23.9 39.1 Peshawar City 57.7 ** ** Cherat 57 66.4 -9.4 Sindh Stations April-19 Normal Deviation Padidan 32 2.1 29.9 Dadu 12 ** ** Hyderabad 7.2 7 0.2 Rohri 2.4 4.9 -2.5 19

Jacobabad 2.02 2.7 -0.7 Sukkur 2 5.7 ** Tando Jam 2 ** ** Badin 1.01 1.7 -0.7 Mirpur Khas 1 ** ** Mohenjo-Daro 0.03 2.9 -2.9 Larkana 0.02 4.5 -4.5 Chhor 0 2.3 -2.3 Karachi A/P 0 3 -3 Mithi 0 ** ** Shaheed Benazirabad 0 2.8 -2.8 Thatta 0 ** ** Balochistan Stations April-19 Normal Deviation Barkhan 138 31.3 106.7 Jiwani 94 3.4 90.6 Sibbi 72 7.1 64.9 Zhob 68 31.9 36.1 Quetta 50.3 ** ** Turbat 49.3 1.6 47.7 Gwadar 33.5 ** ** Kalat 25 8.4 16.6 Pasni 20 1.8 18.2 Khuzdar 17.9 16.2 1.7 Lasbela 6.01 7.2 -1.2 Ormara 4.2 0 4.2 Dalbandin 3.02 5.6 -2.6 Panjgur 3 7.2 -4.2 Nokkundi 2.04 1.7 0.3