IDENTIFICATION AND PREDICTION OF COLD AIR DAMMING IN THE NORTHEAST UNITED STATES: A COMPARISON OF NUMERICAL MODELS
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Authors
Vernon, Natalie
Date
2024-05
Type
Thesis
Language
en
Keywords
Alternative Title
Abstract
ABSTRACT
Cold air damming is a mesoscale phenomenon that occurs when a cold dome is
created along the lee side of mountain ranges. Cold air becomes trapped in part because
of low-level synoptic flow towards the lee side of mountains, preventing the cold dome
from escaping. When this condition occurs, temperatures are cooler on the inside of the
cold dome than those outside of the dome. Despite being a common weather
phenomenon, cold air damming has eluded accurate detection and prediction by most
numerical models. Common difficulties the models include: the timing of the event, the
degree to which the trapped air is colder than the surrounding air, the precise location of
the damming, and even failure of the model to detect cold air damming at all. Among the
explanations for these model difficulties is that the grid spacing of the model may not be
fine enough to resolve the phenomenon. Given the recognized limitations of past models,
the goal of this research is to determine if more recent versions of commonly used
weather models, such as the Global Forecast System (GFS) and the North American
Mesoscale Forecast System (NAM), can more accurately forecast cold air damming.
Twelve cold air damming events occurred over the winter of 2022 to 2023. The
observations from these events were compared to the associated model runs by looking at
the timing at the initiation of the damming, dissipation of the damming, and temperature
difference. The NAM was superior at predicting cold air at KCON than the other stations
compared to the GFS. On the other hand, the GFS had temperatures closer to the
observed temperatures than the NAM. However, just because the models were able to
predict cold air does not mean they were able to predict cold air damming occurring.
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Both models struggled to forecast cold air damming in the Northeast, having the colder
air over the mountains or not in the area. In the end, findings indicate that these current
models will need more refinement to substantially improve prediction of cold air
damming in the Northeast.