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
|
|
|
|
|
|
|
|
|
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. |