1. 28-29 July 2013 Philadelphia Heavy Rainfall Event
Colleen McHugh

2. Motivation
On 29 July 2013, Philadelphia International Airport (PHL) recorded a record breaking daily rainfall total of mm
The previous record was mm set on 16 September (Hurricane Floyd)
Made July 2013 the second wettest month on record behind August 2011 (Hurricane Irene) and ahead of September 1999
Record occurred in the presence of a frontal passage and heavy rainfall embedded in slow moving thunderstorms, not a tropical cyclone
186.7mm fell in a four hour period from 2000 UTC to 0000 UTC
203.7 mm =8.02”
168.4mm = 6.63”
186.7 mm = 7.35”

3. Methodology Synoptic conditions Surface analysis plots from WPC
Archived radar from NCAR MMM shows the rain fell between 2000 UTC 28 July and 0600 UTC 29 July
CFS reanalysis
Mesoscale conditions
SPC RAP archive
Soundings from University of Wyoming
Stage IV Precipitation Data
Analyzed conditions from 1200 UTC 28 July to 0600 UTC 29 July 2013

4. Key Findings
MUCAPE at 1800 on the 28th

5. Key Findings

6. Conclusions
Constant southerly flow due to a surface cyclone over the Great Lakes and 500 hPa heights that were -3.5 sigma
hPa mean wind was also southerly
PHL in a right entrance region of the jet
High PWAT values transported into the region by the southerly flow
Moderate MUCAPE values helped initiate convection and constant southerly flow and IVT helped to add to training effect and record breaking rainfall