EL NINO – A warmer than normal sea surface in the east equatorial Pacific Ocean, resulting in a stronger storm track at 28-40N near and west of California in the normal wet season (November – March), but drier than normal in the Pacific Northwest and far N California. This anomalous pattern Normally persists for an entire winter rain season.
LA NINA – A colder than normal sea surface in the east equatorial Pacific Ocean, resulting in a weak or intermittent storm track at 28-40N in the eastern North Pacific, and a drier than normal wet season November-March). It associates with a wetter than normal rain season in the Pacific Northwest and far N California. It normally persists for an entire winter rain season.
MJO – Madden Julian Oscillation – Similar to the El Niño-La Niña patterns except that it persists for only about 30 days.
- Active MJO – Simulates an El Niño to produce a midwinter period of active rains and fronts.
- Inactive MJO – Simulates a La Niña pattern. It produces periods of fair, dry weather and often mild conditions within the usual rainy season, i.e. (November – March).
FRONT – A zone of transition between two different airmasses, often associated with rain or winter snow.
- Cold Front – cold dry air pushes against warm moist air.
- Warm Front – warm moist air pushes against cold dry air.
ATMOSPHERIC RIVER (AR) – A long stream in the atmosphere, consisting of a moist storm track. These used to be called "pineapple express," having been identified in California with tropical moisture arriving from Hawaii during the winter rainy season. To put it very simply, an Atmospheric River is like “a very large warm front on steroids…a lot of rain, a lot of wind, and heavy rains in foothills and mountains." ARs can be as long as 2000 miles and about 100-200 miles wide.
RIDGE – An area of high pressure and lack of precipitation.
IVT – Literally “integrated vapor transport”. Lay term: Storm Track Moisture. So, when you see the map of forecasted IVT from the Scripps Center for Western Weather and Water Extremes (CW3E), what you are really looking at is “Storm Track Moisture”, including clouds, water vapor, and precipitation.
Sea Surface Temperature Anomaly (SSTA) – Observed sea surface temperature minus the 30 year climatological (mean).
IVTinit™ - Fox Weather’s predicted IVT, based on Sea Surface Temperature Anomaly (SSTA) only, using Fox Weather’s proprietary application (app). This is used to indicate tendency for development of troughs, lows, and fronts that move across the predicted pattern from the west or southwest into California or west coastal United States.
Prepared by Alan Fox
Fox Weather, LLC
Copyright (c) 2021 Fox Weather, LLC
