  Devastating floods in northeast Pakistan and northern India occurred in July
2010 and September 2014 as a consequence of extreme precipitation events. The
2010 and 2014 flood events had similar synoptic flow patterns that led to an
anomalously high moisture content in the flood region. The quasi-geostrophic
omega equation is inverted in order to attribute components of the large-scale
vertical motion profile to synoptic forcing, diabatic heating, and mechanically
forced orographic ascent. The results show that diabatic heating is the
dominant contributor to the large-scale vertical motion, and suggest that the
orographic forcing by flow over the Himalayas is the dominant mechanism by
which the convection that produces the heating is forced. Analysis of a longer
data record shows that instances of extreme precipitation in this region over
the last eleven years are closely associated with simultaneously large values
of orographic forcing and column-total precipitable water vapor.
