2201 UTC 21 Sept 1989


1632 UTC 5 Sept 1996

Track of Hugo (1989)

Hugo’s track.

Fran’s track

Though Hugo and Fran were fairly similar in size,  they produced markedly dissimilar precipitation footprints in part because of the differences in how fast they moved.  Fran took two and a half days to track from the Carolina coast to a position near Buffalo, New York.  By contrast, Hugo took less than a day to move almost the same distance (see tracks below).  This certainly helps explains the differences of rainfall across the Piedmont of the Carolinas during the two storms. 

Hurricane Hugo

850-hPa geopotental height and RH analysis valid 00 UTC 7 Sept. 1996

500-hPa height and vorticity analysis valid 00 UTC 7 Sept. 1996

The NARR reanalysis data below is from The Pennsylvania State University

500-hPa height and vorticity analysis valid 12 UTC 6 Sept. 1996

The structure of the storms as they interacted with the mountains is another distinction between the two storms.  500-hPa and 850-hPa geopotential heights are shown for Fran below (the top three panels).  Fran still maintained a circulation at 850-hPa that was conducive to maintaining orographic lifting across the mountains of southern Pennsylvania on 00 UTC 7 September. 

Hurricane Fran

500-hPa analysis valid 12 UTC

22 Sept. 1999

500-hPa analysis valid 00 UTC

23 Sept. 1999

850-hPA geopotential height and RH analysis valid 00 UTC 23 Sept. 1999

Hugo’s 500– and 850-hPa patterns are shown on the three bottom panels.  Hugo was actually stronger than Fran at landfall but quickly lost its closed circulation at 500– and 850-hPa as it interacted with the strong trough digging into the Great Lakes region.  The lack of strong easterly flow by 00 UTC 23 Sept. limited the vertical motion as the flow quickly shifted to having a westerly component across the mountains which causes downsloping flow east of the mountains.  Hugo is a cautionary tale showing that a storms interaction with synoptic scale trough does not always result in a large areas of heavy rainfall associated with isentropic lift and frontogenesis.  In this case the shearing of the circulation center, the rapid movement, and the lack of a strong frontal boundary nearby kept Hugo from producing widespread heavy rainfall. 

Hurricane’s Hugo and Fran,  a quick comparison

Hugo storm total rainfall

Fran’s storm total rainfall