Significantly below normal
temperature anomalies over the Carolinas were observed on the morning of
December 22 with morning temperatures in the teens and lower 20s and with
the center of a strong Arctic high pressure system over the central Plains
(Figure 2), temperatures as low as -36 degrees Fahrenheit was observed over
northern Nebraska (Figure 3). This supported snow as the predominant
precipitation type as this event unfolded. As a 500 mb trough dug into the
Mississippi Valley on the morning of December 23, and started to gradually
take on a more neutral tilt (Figure 4), a surface low pressure system
developed off the Georgia coast (Figure 5). By the morning of December 24,
the 500 mb trough had taken on a negative tilt and started to show signs of
closing off over the Eastern Carolinas (Figure 6). As both the surface and
850 mb low pressure (Figure 7) intensified by 12Z on December 24, 1989,
easterly winds resulted in moisture advection off the Atlantic Ocean.
Low-level convergence and enhancement of low-level frontogenesis,
resulted in increased precipitation production and a large area of heavy
snow along the North Carolina coast.
Figure 2. Strong Arctic high pressure over
the Central United States (1054 mb) at 12Z December 22, 1989.
Figure 3. Another surface map
from 12Z December 23, 1989 showing temperatures as low as -36F in Nebraska.
Figure 4. The 500 mb trough
digs and gradually starts to take on a more neutral tile at 12Z December
Figure 5. Low pressure develops
off the Georgia coast as of 12Z December 23, 1989 as Arctic high pressure
Figure 6. 500 mb Analysis at
12Z December 24, 1989 showing upper low showing signs off cutting off as it
moves across the Eastern Carolinas.
Figure 7. 850 mb low
strengthening off the North Carolina coast at 12Z December 24, 1989 leading
to bands of heavy snow along the North Carolina coast.
Weather Service, Raleigh, NC