La Niña, a phase of ENSO, is a periodic cooling of surface ocean waters in the eastern tropical Pacific along with a shift in convection in the western Pacific further west than the climatological average. These conditions affect weather patterns around the world. The preliminary CPC definition of La Niña is a phenomenon in the equatorial Pacific Ocean characterized by a negative sea surface temperature departure from normal.
- Browse Related Terms: AO, Arctic Oscillation, El Niño, INTSFY, La Niña, NAO Index, NEG, Negative-tilt Trough, NW, Oscillation, Pacific Decadal Oscillation, PDO, Positive-tilt Trough, Southern Oscillation
1) The measure of the time between the center of mass of precipitation to the center of mass of runoff (on the hydrograph); basin lag is a function of not only basin characteristics, but also of storm intensity and movement. Some hydrologic texts define lag from the center of mass of rainfall to the hydrograph peak.
2) The time it takes a flood wave to move downstream.
- Browse Related Terms: 100-year Flood, 100-year Flood Plain, Base Flood, Channel Routing, DNSTRM, Flood Frequency Curve, Flood Plain, Flood routing, Floodway, Lag, Lakeshore Flood Advisory, Lakeshore Flood Watch, Lakeshore Flooding, routing, Travel Time
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A thermally produced wind blowing during the day from the surface of a large lake to the shore, caused by the difference in the rates of heating of the surfaces of the lake and of the land.
- Browse Related Terms: Adiabatic, Bias, Fire Wind, Glacier Wind, Lake Breeze, Lake Effect Storm, Land Breeze, Psychrometer, Rain Induced Fog, Sea Breeze, Thermally Driven Circulation
Snow showers that are created when cold, dry air passes over a large warmer lake, such as one of the Great Lakes, and picks up moisture and heat.
- Browse Related Terms: Advection fog, CAA, CD, Cold Advection, Foehn Pause, Freezing Spray, Frostbite, Heavy Freezing Spray, Lake Effect Snow, Marine Inversion, Sea Fog, Stable, Stable Boundary Layer, Steam Fog, Thermal High, Thermal Wind, upwelling, WAA
This product is issued by the National Weather Service when pure lake effect snow (this is where the snow is a direct result of lake effect snow and not because of a low pressure system) may pose a hazard or it is life threatening. The criteria for this advisory varies from area to area.
- Browse Related Terms: Heavy Snow Warning, High Wind Advisory, High Wind Warning, High Wind Watch, Ice Storm Warning, Lake Effect Snow Advisory, Lake Effect Snow Warning, Snow Advisory, Wind Chill Advisory, Wind Chill Warning, Winter Storm Warning, Winter Storm Watch, Winter Weather Advisory
A local, intense, narrow band of moderate to heavy snow squall that can extend long distances inland. It may persist for many hours. It may also be accompanied by strong, gusty, surface winds and possibly lightning. Accumulations can be 6 inches or more in 12 hours.
- Browse Related Terms: ACPY, Downburst, Downdraft, DWNDFT, GSTY, Gust Front, Lake Effect Snow Squall, NRW, Plow Wind, Snow Squall, STG
This product is issued by the National Weather Service when pure lake effect snow (this is where the snow is a direct result of lake effect snow and not because of a synoptic storm or low pressure system) may pose a hazard or it is life threatening.
- Browse Related Terms: Heavy Snow Warning, High Wind Advisory, High Wind Warning, High Wind Watch, Ice Storm Warning, Lake Effect Snow Advisory, Lake Effect Snow Warning, Snow Advisory, Wind Chill Advisory, Wind Chill Warning, Winter Storm Warning, Winter Storm Watch, Winter Weather Advisory
A fall or winter storm that produces heavy but localized precipitation as a result of temperature differences between the air over snow-covered ground and the air over the open waters of a lake.
- Browse Related Terms: Adiabatic, Bias, Fire Wind, Glacier Wind, Lake Breeze, Lake Effect Storm, Land Breeze, Psychrometer, Rain Induced Fog, Sea Breeze, Thermally Driven Circulation
(L)ightning (A)ctivity (L)evels.
LAL 1 - No thunderstorms.
LAL 2 - Few building cumulus with isolated thunderstorms.
LAL 3 - Much building cumulus with scattered thunderstorms. Light to moderate rain.
LAL 4 - Thunderstorms common. Moderate to heavy rain reaching the ground.
LAL 5 - Numerous thunderstorms. Moderate to heavy rain reaching the ground.
LAL 6 - Dry lightning (same as LAL 3 but without the rain).
- Browse Related Terms: Banner Cloud, Cap Cloud, ISOL, ISOLD, LALs
Smooth, non-turbulent. Often used to describe cloud formations which appear to be shaped by a smooth flow of air traveling in parallel layers or sheets.
- Browse Related Terms: Baroclinic leaf shield, Billow Cloud, Catalina Eddy, Cloud Streets, Comma Cloud, Inflow Stinger, Laminar, Lenticular Cloud, Microscale, Morning Glory, Rope Cloud, Stratocumulus, Striations, Tail Cloud
Streamline flow in which successive flow particles follow similar path lines and head loss varies with velocity to the first power.
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A coastal breeze at night blowing from land to sea, caused by the difference in the rates of cooling of their respective surfaces.
- Browse Related Terms: Adiabatic, Bias, Fire Wind, Glacier Wind, Lake Breeze, Lake Effect Storm, Land Breeze, Psychrometer, Rain Induced Fog, Sea Breeze, Thermally Driven Circulation
The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely at the center, it is possible for a cyclone's strongest winds to be experienced over land even if landfall does not occur. Similarly, it is possible for a tropical cyclone to make landfall and have its strongest winds remain over the water. Compare direct hit, indirect hit, and strike.
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The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely at the center, it is possible for a cyclone's strongest winds to be experienced over land even if landfall does not occur. Similarly, it is possible for a tropical cyclone to make landfall and have its strongest winds remain over the water. Compare direct hit, indirect hit, and strike.
- Browse Related Terms: Center / Vortex Fix, Central North Pacific Basin, Direct Hit, Eastern North Pacific Basin, Eye, Eyewall / Wall Cloud, Hurricane Season, Indirect Hit, Invest, Landfall, Major Hurricane, Radius of Maximum Winds, Strike, Synoptic Track, Tropical Cyclone Plan of the Day
[Slang], a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar). Landspouts typically are observed beneath Cbs or towering cumulus clouds (often as no more than a dust whirl), and essentially are the land-based equivalents of waterspouts.
- Browse Related Terms: Condensation Funnel, D, Debris Cloud, Dry Microburst, Dust Devil, Dust Plume, Dust Whirl, funnel cloud, Gunge, Landspout, Multiple Vortex Tornado, Obscuration, Obscuring Phenomena, ROTG, SUF, Tornado, Waterspout, Whirlwind
The rate of change of an atmospheric variable, usually temperature, with height. A steep lapse rate implies a rapid decrease in temperature with height (a sign of instability) and a steepening lapse rate implies that destabilization is occurring.
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(Synoptic Scale) Size scale referring generally to weather systems with horizontal dimensions of several hundred miles or more. Most high and low pressure areas seen on weather maps are synoptic-scale systems.
- Browse Related Terms: ARSI, Baroclinic Zone, Deepening, Dry Slot, Filling, General Wind, Gradient High Winds, Large Scale, Mesolow, Saturation Vapor Pressure, Subtropical Cyclone, SYNOP, Synoptic-scale, Vapor Pressure, Vertically Stacked System
The time and date in which the forecast was issued or updated. The forecast may be updated at any time as weather conditions warrant.
- Browse Related Terms: Flash flood warning, Flash Flood Watch, Flood Watch, Last Update, PTWC, River Ice Statement, Tidal Wave, Tsunami Advisory, Tsunami Information Statement, Tsunami Warning, Tsunami Watch