Hurricane Force Low Pressure System In the Central Pacific Ocean? (credit: NWS Ocean Prediction Center)
DISCUSSION: Although most do not even consider to think about this type of meteorological phenomena, often times during the Winter season, hurricane-force low pressure systems can develop over large expanses of the central/eastern Pacific Ocean as well as a very large percentage of the central/northern Atlantic Ocean. During the more conventionally recognized hurricane season periods for the various Pacific and Atlantic Ocean basins, tropical cyclones which form are fueled by the presence of particularly warm sea surface temperatures which fuel the inner core (a.k.a., the internal "heat engine") of strengthening tropical cyclones. However, during the Winter-time when we observe low pressure systems with measured maximum sustained wind speeds at or sometimes well-above hurricane intensity, this unfolds as a consequence of profoundly unique circumstances.
As many people around the world have come to fundamentally understand, extra-tropical cyclones which impact large coastal (and often semi-inland) regions around the world are triggered by horizontal changes in temperature with distance over some given region. Thus, it is what is referred to as a "frontogenetic forcing" measuring or an atmospheric low pressure intensification mechanism which is driven by changes in temperature at or near the surface. This surface-based temperature gradient subsequently affects the temperature and therefore the wind field distribution in the vicinity of developing extra-tropical low pressure system at the surface as well as points higher up in the atmosphere. Thus, this deep-layer horizontal change in temperature over some horizontal difference provides the critical energy/fuel needed to sustain Winter-time low pressure system.
Colloquially, when these types of Winter-time low pressure systems impact populated areas, we conventionally refer to these types of storms as "Nor'easters" since they are identified as coastal low pressure systems which typically move in a northeasterly direction with time and deliver cold northeasterly winds to the area they impact as they move through. As shown in the brief satellite footage attached above, this same process can happen over larger oceanic basins as well such as this hurricane-force low which just recently strengthened significantly over the northeastern Pacific Ocean. This just goes to show that intense Winter-time low pressure systems can form and intensify while under the influence of many different types of atmospheric environmental conditions.
To learn more about other high-impact weather events occurring across the central and/or eastern Pacific Ocean, be sure to click here!
©2017 Meteorologist Jordan Rabinowitz