This project uses GLOBE data: GLOBE Task Team and others (Hastings, David A., Paula K. Dunbar, Gerald M. Elphingstone, Mark Bootz, Hiroshi Murakami, Hiroshi Maruyama, Hiroshi Masaharu, Peter Holland, John Payne, Nevin A. Bryant, Thomas L. Logan, J.-P. Muller, Gunter Schreier, and John S. MacDonald), eds., 1999. The Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0. National Oceanic and Atmospheric Administration, National Geophysical Data Center, 325 Broadway, Boulder, Colorado 80305-3328, U.S.A. Digital data base on the World Wide Web (URL: http://www.ngdc.noaa.gov/mgg/topo/globe.html) and CD-ROMs.
https://www.ngdc.noaa.gov/mgg/topo/globe.html
https://www.ngdc.noaa.gov/mgg/topo/report/globedocumentationmanual.pdf

Elevation Code: elevations.py

This analysis counts landfalling hurricanes and calculates their slowest six hour movement within a 36 hour period before and after landfall. Then divides the number of slow moving landfalling storms by the total landfalling storms (slow or not).

The analysis now tracks all landfalls. Claudette made two landfalls and the second one was slow with the US 24 hour rainfall record. Mitch had three landfalls, the first of which was slow and deadly. Dorian had one landfall with only one data point (7 meters). There will be missed storms that move slowly past smaller islands due to the limitations of using 6 hour positions only (for long term consistency).

The analysis shows storms that that stall or do very small loops like Harvey (2017) and Florence (2018) are relatively rare events with some natural variation. But storms like most recently Imelda (2019) are increasing by percentage, and as the Post article for Imelda points out, there's more moisture to work with leading to higher rainfall totals. These storms can move slowly 4-6 mph without stalling but still dump more rainfall like Imelda without even becoming hurricanes.

The trend since 1950 in landfalling storms moving 6 mph or less is 0.157 percent per year. Using that trend for 70 years gives an 11 percentage point rise. In other words the percentage of landfalling storms <= 6 mph has risen from about 40% in 1950 to 50% today. With the increase in available moisture, it's no suprise that 6 of the 10 wettest US storms have occurred since 1997. However they remain relatively rare especially the stalled storm events, <= 3 mph.

Here's a list of the slowest moving landfalling storms since 1950 that moved 6 mph or less for 6 hours, except Amelia 1978 as noted. The highlighted storms moved 3 mph or less for 6 hours. Ranking US wettest column is from Wettest storms in the US (Wikipedia)

(Note: auto-generated table is under construction)

Year	Name	speed mph	rank US	Rain 24 hr	Rain total	Notes
1992	DANIELLE	5.29
1993	ARLENE	1.02
	GERT	3.97
1994	ALBERTO	1.5			27.85	GA state record
	BERYL	1.52
	GORDON	3.61
1995	DEAN	0.0
	ERIN	1.02
	JERRY	3.8
	OPAL	1.15
	ROXANNE	3.2
1996	DOLLY	5.87
	FRAN	2.3
	HORTENSE	4.43
1997	DANNY	1.52	8	32.52	36.71	AL state record
1998	BONNIE	5.96
	FRANCES	2.3
	GEORGES	0.99	7		38.46	FL/MS MS state record (32.21)
	HERMINE	2.3
	MITCH	0.0			62.87	Honduras, Nicaragua 11,000 fatalities
1999	BRET	5.26
	DENNIS	2.25
	FLOYD	1.15
	LENNY	1.59
2000	GORDON	4.73
	KEITH	1.1			32.67	Belize record
2001	ALLISON	1.15	6			LA 2nd highest
	BARRY	5.76
	CHANTAL	4.53
	GABRIELLE	4.16
	MICHELLE	4.1
2002	BERTHA	2.51
	EDOUARD	1.0
	FAY	2.3
	HANNA	3.46
	ISIDORE	2.54
2003	BILL	3.62
	HENRI	3.07
	LARRY	1.15
2004	FRANCES	3.85
	GASTON	2.95
	IVAN	2.3
	JEANNE	4.9
2005	ARLENE	5.86
	BRET	5.54
	DENNIS	0.89			42.99	Cuba 2nd highest
	EMILY	1.08
	JOSE	5.9
	STAN	5.88
	WILMA	2.54		64.33		record 24h Western Hemisphere
	BETA	2.52
	GAMMA	1.15
2007	HUMBERTO	5.85
	LORENZO	3.97
	NOEL	4.06			29.43	Bahamas record
2008	ARTHUR	4.52
	DOLLY	0.0
	FAY	0.0
	GUSTAV	1.5
	HANNA	3.16
	PALOMA	1.57
2009	ERIKA	3.32
	IDA	4.12
2010	ALEX	3.62
	HERMINE	5.76
	KARL	2.18
	PAULA	5.08
	RICHARD	1.1
2011	ARLENE	3.21
	LEE	1.15
	NATE	4.33
	RINA	5.1
2012	BERYL	2.29
	DEBBY	3.02
	HELENE	5.09
	ISAAC	4.58
2013	BARBARA	1.6
	ANDREA	5.85
	BARRY	5.43
	INGRID	4.7
2014	GONZALO	1.51
	HANNA	4.6
2015	ANA	3.01
2016	BONNIE	1.51
	DANIELLE	4.91
	JULIA	5.87
	MATTHEW	5.76
2017	HARVEY	2.32	1		60.58	TX TX and US record
	IRMA	5.46
	KATIA	3.42
	NATE	5.67
2018	ALBERTO	5.03
	FLORENCE	2.24	9		35.93	NC/SC state records
	GORDON	2.49
	KIRK	1.12
2019	BARRY	4.66				AR state record (16.59)
	DORIAN	1.54			22.84	Bahamas 2nd highest
	IMELDA	4.72	5
2020 *	AMANDA:CRISTOBAL	1.59
	FAY	0.0
	KYLE	4.46
	SALLY	2.51
	BETA	2.86
	GAMMA	1.15
	ZETA	5.13
	ETA	2.52

* 2020 data from IBTRACS is provisional and missing some storms

The analysis shows a long term trend towards slowing. The shorter term trends show the slowest or stalled storms as flat or varying as a larger number of those stalled patterns occurred in the 1990s and 2000s.

Code: hurricanes.py | Data: hurdat.csv | Instructions: README