Transcript MJO and the Record-Breaking East Coast Snowstorms in 2009/2010

MJO and the Record-Breaking East Coast Snowstorms in 2009/2010
Ja-Yeon Moon1, Bin Wang1, and Kyung-Ja Ha2
1IPRC, 2Pusan
National University
(a) OLR(Jan 31~Feb 7, 2010), GPH200 (+4days)
(b) SAT, GPH850 (+4days)
C
B
A
(c) OLR(A, B), Snowfall(C)
1DEC
2009
6
11
16
21
26
1JAN
2010
6
11
16
21
26
1FEB
6
11
16
21
26
Intraseasonal anomalies of (a) OLR (shading) and 200hPa GPH (geopotential height, contour), (b) Surface air temperature (SAT)
and 850hPa GPH, and (c) time series of area-averaged intraseaonal anomalies of OLR over “A”, “B”, and daily snowfall amount
(inches) averaged over eastern US (“C”) from 1 December 2009 to 28 February 2010.
The eastern United States saw several record-breaking snowfall events in the 2009/10 winter. They can be
traced to the central and eastern Pacific, which experienced unusually large swings in OLR and remarkable
wet-dry-wet cycles from late December to mid-February. Whenever the MJO convection reached the central
Pacific, a teleconnection pattern extended to North America, resulting in a westward-tilted deep anomalous
trough anchored over the eastern US, producing a low-level pressure dipole anomaly with an anticyclone
(cyclone) centered at the US west (east) coast. The warm moist air from the tropics, mixed with the cold air
from high-latitudes, resulted in favorable conditions for extremely heavy snowfall.