Occluded front

[JenBayles]

Not sure exactly where to ask this question, but since this forum seems to be the most active these days, I'll put it here.

Since I am an uneducated weather amateur, can someone please explain what exactly is an occluded front? I get the cold front and the warm front concepts, but the occluded eludes me. Oooh! I'm a poet & don't know it!

[GalvestonDuck]

Jen, I'm sliding this up to the Weather forums for ya.

[Brent]

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/af/frnts/ofdef.rxml

http://www.usatoday.com/weather/tg/wofront/wofront.htm

[Guest]

An occluded front is simply when the cold front catches up with the warm front around a low pressure system. The there is a boundary between cool and cold instead of warm and cold. It happens with Pacific storms alot.

[senorpepr]

An occluded front is simply when the cold front catches up with the warm front around a low pressure system. The there is a boundary between cool and cold instead of warm and cold. It happens with Pacific storms alot.

It also happens a lot over any maritime region. Therefore, in the Northern Hemisphere they're found most often along the west coasts of continents and vice versa in the Southern Hemisphere.

Bottom line, the occluded front is the seperation of cold and cool air and the weather associated with it is normally like that of warm fronts (drizzle and steady, slow rains, but unlike warm fronts, colder air is found behind the front).

[Fred Gossage]

It is also very important to note that in most cases, when a storm system has an occluded front associated with it, it has reached maturity...and soon after....may begin to weaken...(most of the time)....

[Aslkahuna]

Actually occlusions can occur over land as well. There are two types of occlusions-cold type and warm type. In the former the cold air behind the cold front is colder than the air ahead of the warm front and thus it undercuts the warm front and lifts it. Weather with this will feature initially a warm frontal pattern with a period of heavy precipitation just ahead of the front followed by rapid clearing. This type of occlusion is most common overland and off the east coasts of continents. The warm type is where the air behind the cold front is warmer than the air ahead of the warm front and thus the cold front rides up over the warm front. Again you start with a warm frontal type weather pattern with heavy precipitation and even thunderstorms when the cold front aloft passes overhead followed by low clouds/fog/drizzle until the occluded front comes through. This type of occlusion is most common along west coasts of continents where the cold front has mP/mA behind it with cP/cA air ver land ahead of the warm front. Generally the cold type occlusion is the most common since even over the oceans fresh cold maritime air will be colder than the modified cold air ahead of the warm front.

Steve

[george_r_1961]

It is also very important to note that in most cases, when a storm system has an occluded front associated with it, it has reached maturity...and soon after....may begin to weaken...(most of the time)....

These lows with occluded fronts in them over the subtropical or tropical Atlantic during the latter part of the hurricane season often transform into warm core systems if conditions are right