Degree of Certainty
| Rain will be isolated/scattered/widespread… | Degree of certainty is 80-100% | 
| Likelihood of isolated/scattered/widespread rain…. | Degree of certainty is 60% | 
| Possibility of isolated/scattered/widespread rain…. | Degree of certainty is 40% | 
Rain categories for Areawise forecast
| Isolated | Rain will be at 30% of the State/ Division. Especially it can be during the period of weak monsoon. (eg. Out of 10 stations in a State/Division, 3 stations got rain amount) | 
| Scattered | Rain will be at 50% of the State/ Division. Especially it can be during the period of weak monsoon. (eg. Out of 10 stations in a State/Division, 5 stations got rain amount) | 
| Fairly widespread | Rain will be at 80% of the State/ Division. Especially it can be during the period of moderate monsoon. (eg. Out of 10 stations in a State/Division, 8 stations got rain amount) | 
| Widespread | Rain will be all the State/ Division. Especially it can be during the period of strong/vigorous monsoon. (eg. Out of 10 stations in a State/Division, all stations got rain amount) | 
Rain categories according to intensity
| Light rain | During the 24 hours, rain will be below (0.5) inch for Central area and below (1.0) inch for the remaining areas. | 
| Moderate rain | During the 24 hours, rain will be between (0.5) and (1.5) inches for Central area and between (1.0) and (3.0) inches for the remaining areas. | 
| Torrential rain | During one hour, rain will be (1.0) inch and above it. | 
| Heavy rain | During the 24 hours, rain will be (1.5) inches and above for Central area and (3.0) inches and above for the remaining areas. | 
Rain categories according to Duration and frequency
| Intermitted rain | Frequent rain and it may occur when monsoon is in strong condition/ if there is storm in the Bay of Bengal. | 
| Temporary rain | Rain will be in a few hours and it may occur when thunderstorm, cumulonimbus climbed down closely to ground and pass the area. | 
| At times / One or two rain | One or two rain has been occurred during 24 hours especially moderate and moderate to strong monsoon period. | 
| Occasional rain | One or two rain with more frequent. | 
Rain categories according to the combination of Area and intensity
| Isolated heavy fall | Rain have been heavy at 30% of the State/Division during 24 hours. The amount will be (1.5) inches and above for Central area and (3.0) inches and above for the remaining areas. | 
| Locally heavy fall | Rain have been heavy at 50% of the State/Division during 24 hours. The amount will be (1.5) inches and above for Central area and (3.0) inches and above for the remaining areas. | 
Portions of the Bay of Bengal
| North (or) Head Bay | Latitude ……18.5ºN and above | 
| West Central Bay | Latitude…….between 13.0ºN and 18.5º N Longitude…..88.5ºE and its western portion | 
| East Central Bay | Latitude…….between 13.0ºN and 18.5º N Longitude…..88.5ºE and its eastern portion | 
| South West Bay | Latitude…….13.0ºN and its southern portion Longitude…..86ºE and its western portion | 
| South East Bay | Latitude…….13.0ºN and its southern portion Longitude…..between 86ºE and 93ºE | 
| Andaman Sea | Latitude……Deltaic coast, Gulf of Mottama and its southern lower latitudes Longitude…..between 93ºE and Taninthayi coast | 
Categories of storms in the Bay of Bengal according to wind speed (NMC)
| (1) Low Pressure Area | ≤ 32 mph | 
| (2) Tropical Depression | 33-38 mph | 
| (3) Tropical Storm | 39-55 mph | 
| (4) Cyclonic Storm | 56-72 mph | 
| (5) Severe Cyclonic Storm | ≥ 73 mph | 
| (6) Very Severe Cyclonic Storm | ≥ 100 mph | 
| (7) Very Severe Cyclonic Storm with Hurricane wind force | ≥ 120 mph | 
The Definition of Normal, Above Normal & Below Normal (NMC, Myanmar)
| Normal | : Average amount of previous 30 years (at least) meteorological data | 
| Above Normal | : > 20% of the Normal | 
| Below Normal | : < 20% of the Normal | 
The Definition of Normal, Above & Below Normal Temperature (NMC, Myanmar)
| No. | Above / Below from Normal Temperature | Maximum /Minimum Temperature Definition | 
| 1. | +3°C to +4°C | Slightly Warm | 
| 2. | +5°C to +6°C | Markedly Warm | 
| 3. | +7°C to +8°C | Heat Wave | 
| 4. | +9°C and above | Severe Heat Wave | 
| 5. | -3°C to -4°C | Slightly Cold | 
| 6. | -5°C to -6°C | Markedly Cold | 
| 7. | -7°C to -8°C | Cold Wave | 
| 8. | -9°C and above | Severe Cold Wave | 
State of the Sea
| Slight | Sea will be slight with height of about (0.5-1.25) meters | 
| Moderate | Sea will be moderate with height of about (1.25-2.5) meters | 
| Rough | Sea will be rough with height of about (2.5-4.0) meters | 
| Very Rough | Sea will be very rough with height of about (4-6) meters | 
Monsoon Intensity
(∆P) stands for mean sea level pressure difference between Sittwe(STW) and Mawlamyine(MLM)
For Rakhine coast(STW-MLM)
| ΔP ≤ 1.5 hPa | Feeble | 
| 1.5 < ΔP ≤ 3.0 hPa | Weak | 
| 3.0 < ΔP ≤ 4.0 hPa | Moderate | 
| 4.0 < ΔP ≤ 5.5 hPa | Strong | 
| ΔP > 5.5 hPa | Vigorous | 
For Taninthayi coast (MLM-KTW)
| ΔP ≤ 0.5 hPa | Feeble | 
| 0.5 < ΔP ≤ 1.5 hPa | Weak | 
| 1.5 < ΔP ≤ 2.0 hPa | Moderate | 
| 2.0 < ΔP ≤ 2.5 hPa | Strong | 
| ΔP > 2.5 hPa | Vigorous | 
For Whole coast (STW-KTW)
| ΔP ≤ 2.0 hPa | Feeble | 
| 2.0 < ΔP ≤ 4.0 hPa | Weak | 
| 4.0 < ΔP ≤ 6.0 hPa | Moderate | 
| 6.0 < ΔP ≤ 8.0 hPa | Strong | 
| ΔP > 8.0 hPa | Vigorous | 
Key terms used in hydrological forecast
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Earthquake Glossary
| Earthquake An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. | 
| Richter Magnitude Scale The Richter magnitude scale, also known as the local magnitude (ML) scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. | 
| Moment Magnitude Scale The moment magnitude scale (Mw) is used by seismologists to measure the size of earthquakes in terms of the energy released. | 
| Mercalli Intensity Scale The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake. The scale quantifies the effects of an earthquake on the Earth's surface, humans, objects of nature, and man-made structures on a scale of I through XII, with I denoting not felt, and XII total destruction. | 
| Primary Wave (P-wave) P-waves are type of elastic wave, also called seismic waves, that can travel through gases, solids and liquids, including the Earth. P-waves are produced by earthquakes and recorded by seismometers. | 
| Secondary Wave (S-wave) A type of seismic wave, the S-wave, secondary wave, or shear wave (sometimes called an elastic S-wave) is one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. | 
| Tsunami A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, usually an ocean, though it can occur in large lakes. | 

