F ti S W th L kF ti S W th L kForecasting Severe Weather over Lake Forecasting Severe Weather over Lake Victoria region in Uganda Victoria region in Uganda

Khalid Y. MuwembeUGANDA NATIONAL METEOROLOGICAL

AUTHORITY(UNMA)

Outline

• Backgroundg• Set-up of forecasting/alert service• Diurnal circulation of convection over the Lake• Diurnal circulation of convection over the Lake• Using satellite data for monitoring convection

A li ti f t llit d NWP d t• Application of satellite and NWP products• Other critical applications of satellite data• A case study

Background

• The frequent recurrence of severe storms continues to threaten the safety of marine navigation over Lake Victoria since a large number of boats use the lake on a daily basis to sustain a thriving fishing industry.

• Hundreds of people lose their lives on the lake each year with a significant proportion of these related toyear, with a significant proportion of these related to hazardous storm conditions.

• Given the rough weather conditions common over the lake, there was need for regular weather warnings to

f f i iensure safety of marine operations.

Setting up of Forecast/Alert serviceSetting up of Forecast/Alert service

• Taking advantage of significant improvement of weather monitoring, forecasting and communication technology in recent yearstechnology in recent years.

• It is now possible to access necessary tools to routinely f / fdeliver forecasts/alerts of dangerous weather over the

lake.

• UNMA set-up mobile weather alert Service designed as easy to use: daily forecasts sent by SMS to registered users each morning; and alerts whenever the weatherusers each morning; and alerts whenever the weather situation worsens significantly

The alert service The alert service ObjectiveObjective

Utilise mobile phone ptechnology to develop a sustainable warning service gthat reduces the vulnerability of communities in the Lake Victoria Region to weather hazards.

Mobile Weather Alert: Community weather information via mobile technology

Green Al t

No alert: No hazardous weather expected. Take normal precautions.

Alert

Be aware: There might be changes in the

YellowAlert

Be aware: There might be changes in the weather. Be watchful and look out for signs of storm such as clouds, wind gusts, higher

Alert waves.

Be prepared: The weather is likely to changeAmber Alert

Be prepared: The weather is likely to change. Consider moving to safer areas and be prepared to take necessary actions.

RedTake action: The weather will change soon. Take the necessary actions to get to a safeRed

AlertTake the necessary actions to get to a safe area.

Focus area

Fig 2: Major Islands with active fisheries over Lake

Fig 1: Topographic map of Uganda and location within Africa. Source: Wileyonlinelibrary.com/journal/met

Fig 2: Major Islands with active fisheries over Lake Victoria.

Source: Google Maps

Diurnal cycle of convection over the Lake

• Deep convection peaks over the lake in the early hours of the morning and dissipates in the afternoon

Chamberlain and Bain (2012)

g p

• Evening peak in convection over land north-east of the lake and to the east.

Using satellite data for monitoring convection

Using Single channel: IR 10.8

*** Forecasters able t id tif ithto identify areas with cold (high) tops –Deep convection andDeep convection and

***Areas with warm tops – Low level clouds on the IR10.8 image

Monitoring using Vis Channel

From the Vis Ch lChannel more details on the l d f tcloud features

can be observed

Colour enhanced images are useful:Convection over Lake Victoria

Mid Level Clouds

KenyaKenya

C

DemocraticRepublic of

"Lake" Convection

Tanzania

pthe Congo

Using Channel IR10.8: Deep convection can be easily distinguished from mid level clouds and Low level clouds

Monitoring using RGB 05-06, 04-09, 03-01: Colour Interpretation

Deep precipitating cloud(precip. not necessarilyreaching the ground)

Thin Cirrus cloud

(large ice particles)

Deep precipitating cloud(Cb cloud with strongupdrafts and severeweather)*

reaching the ground)

- high-level cloud- large ice particles

- high-level cloud- small ice particles

*or thick, high-level lee cloudiness with small ice

ti lparticles

Thin Cirrus cloud

(small ice particles)

RGB HRV, HRV, IR10.8

Identification of different cloud features

Application of Satellite and NWP Products

Predicted strong onshore winds causing deep convection over L. Victoria and Kyoga

Model-derived sounding parameters associated with severe convective storms

High CAPE means storms will build vertically very quickly. The updraft speed depends on the CAPE environment.C

ADowndraft: An intense updraft often produces an intense downdraft since an intense updraft will condense out a large

CA

P

APE

p gamount of moisture.

Forecasters normally expect isolated i f h i h t f

PELI

regions of very heavy rain when storms form in a large or extreme CAPE environment.

Lightning: Large and extreme CAPE willLightning: Large and extreme CAPE will produce storms with abundant lightning.

Model-derived sounding parameter for lightning and thunderEarth networks total lightning detection

Model-derived sounding t lightning detectionparameters

Corresponding satellite image

Other critical application of satellite d tdataContinuous monitoring of weather conditions across the

tcountryPreparation of TS SIGMETs for aviation

Preparation of low-level significant weather charts for aviation

Now casting and issuance of severe weather alerts

Daily forecast verification

R i f i ifi t t diReview of significant case studies

Forecast verification using satellite data

Observed convective storms 24-hrs cumulative ppn Forecast from 4-km L. Vic model

Case studyS t 1st M h 2012Severe storm on 1st March, 2012

in Buvuma area (L. Victoria)in Buvuma area (L. Victoria)

*** Th (3) B t i d*** Three (3) Boats capsized*** Fifty (50) travelers lost lives Fifty (50) travelers lost lives

Satellite imagery on 1st March

4-km Lake Victoria model T+12

Global unified model T+12

Chamberlain and Bain (2012)

They look keen on our service

Accurate and reliable weather information saves lives

The EndThe EndThe EndThe EndThank o for o rThank o for o rThank you for your Thank you for your

attentionattentionattentionattention

MerciMerciMerciMerci