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--- warm_nose [2017/04/14 01:29]
forsythsnow
+++ warm_nose [2017/04/17 13:14] (current)
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 ======Warm Nose======
-The killer of all SE snow events as described by many. The warm nose is a mid-level and low-level feature, which can be caused in many ways. One way is where a surface low pressure forms deep into where the cold area would be early on, and as a result, it draws warm air up from the south and into a region to produce rain, since this is a surface feature as well as a mid-level feature. Another way the warm nose wins is when warm air is established to start with a storm, and a [[cad|CAD]] event is in progress. In this situation, the cold air rushes in at the surface from the CAD, and the warm air remains, resulting in freezing rain in the areas that got sub-freezing, and cold rain in the rest of the areas.
+The killer of all SE snow events as described by many. A warm nose is a layer of warm air that usually appears between 875 and 750mb that switches snow to sleet, freezing rain, or rain during winter precipitation events.
+===== Cause =====
+The most typical cause of a warm nose is a NW tiled low pressure complex. In this case the 700mb and 850mb low centers are well to the NW of the surface low. While the winds in lowest levels have a northerly component as you increase with height these winds veer to a more southerly/easterly direction. This veering of wind aids in advancing warm air northward into the cold dome warming the mid layers causing a ptype transition.
+The thicker your warm nose and the thicker/colder the corresponding colder layer below the "nose" will determine your predominant ptype. A thin warm nose often leads to sleet being your dominant precip type, while a thick warm nose supports freezing rain or rain depending on your surface temp.
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