A long duration flash flooding event occurred due a stalled frontal boundary in place helping to supply environmental lift along with ample Gulf moisture to produce slow-moving clusters of showers and thunderstorms. This event was not consistent, but came in waves beginning early July 6th lasting through early July 7th.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LIX wrote it up.
A long duration flash flooding event occurred due a stalled frontal boundary in place helping to supply environmental lift along with ample Gulf moisture to produce slow-moving clusters of showers and thunderstorms. This event was not consistent, but came in waves beginning early July 6th lasting through early July 7th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS New Orleans, LA wrote its last area forecast discussion before the first event at Jul 6, 2:30 AM CST, 2 hours 21 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service New Orleans LA 330 AM CDT Tue Jul 6 2021 .SHORT TERM (Today through Thursday)... A broad upper level low extends across the Gulf Coast from western Alabama to south Texas. There's even a weak surface inflection of this seen on radar with weak cyclonic flow across southeast LA and southern Mississippi. The amount of moisture in the atmosphere throughout the column remains high. PW's have been above 2 inches pretty much since July started. This, combined with general low level and upper level buoyance in place, is why at 3am there's scattered to numerous showers and thunderstorms across the CWA south of a Baton Rouge to Bogalusa line. GFS still shows deeper tropical moisture will be creeping in with PW's across the entire CWA running the 2.2 to 2.3" range mid morning onward. That's quite a bit above 90th percentile for reference. Although numbers that high don't mean widespread heavy rain is a given. Just that the potential is there. Would expect 1-3" per hour rainfall rates with a few or so locations possibly seeing 4-6" total today. Precisely where it falls will determine if any flash flooding occurs. Really not expecting much change rolling into Wednesday. The pattern looks the same with similar moisture levels and upper ridge center still far to the west and no apprecible influence locally from it. Therefore, should see another 80-90% coverage day with some locations possibly seeing quite heavy rainfall on a the scale of the size of a city. The only difference for Thursday is possibly some slightly "drier" air moving (drawn in from Elsa moving northeast). We may see a slight reduction in coverage but it might be hard to see the difference in the real world. At least the higher rain chances and cloud cover over the next few days will keep high temps below normal. MEFFER && .LONG TERM (Friday through Monday)... There has been a little bit of a shift in the extended models. Operational models and the ensemble means are diverging somewhat this weekend. ECMWF and the ECS are now suggesting the slight possibility of a drier pattern setting up or at least lower than normal for the Summer. One the other hand the GFS and GFES are not quite ready to bite on that and the GEM and CMCE are in between the two. The NBM is a little more in line with the GFS. With that confidence is a little lower in the extended forecast but given how the last few months have gone and poor performance of the ECMWF recently and more willing to stick closer to the GFES and NBM this forecast cycle. Friday and into the weekend...rain chances should begin to taper down just a tad but likely still abv climo thanks mainly to rather high PWs and still between the two ridges. Overall Friday should be far less active than Thursday as Thursday should have numerous to widespread convection. On Friday as Elsa quickly lifts across the east coast the western Atlantic ridge will try to build to the west and across the northern Gulf but likely not fast enough to keep scattered to numerous afternoon storms from developing. Now heading into the weekend is where the forecast gets a little tricky. Previous forecast had suggested that the ridge would struggle to build in over the area as another strong s/w drops into the Upper and Mid MS Valley Saturday eroding the western side of the Atlantic ridge Sunday. However, now there are some indications that the ridge may be a little stronger than previously thought and could build a good bit west. That would increase the subsidence and mid level temps across the region and help to knock down storm coverage some but given the amount of moisture in place not completely. This would also lead to a warmer forecast and with highs back in the lower 90s possibly we will have the possibility of seeing heat index values around 100 degrees. Now the other possibility and this is where the models disagree on and that is how far west the ridge does build. A few of the operational and ensemble means have the western periphery of the ridge rather close to the area and if that is right over or just a touch east then well enjoy the the scattered to numerous daily thunderstorms a bit longer. If the ECMWF and ECS is right then there is a chance we could see isolated storms this weekend and heading into next week. Again right now that is the first indication of that and the more of the solutions are in line with at least scattered convection each day. /CAB/ /CAB/ && .AVIATION... A lot of minor impacts again. First concern is low cigs again. These won't be all morning but there will be patches of low clouds likely causing tempo IFR cigs. Second will be convection as storms should begin to impact GPT, ASD, and possibly NEW and MSY from through 12z. After 12z convection will expand and likely across the area impacting most if not all terminals. /CAB/ && .MARINE... The wind field will remain fairly weak with prevailing onshore flow of 5 to 10 knots remaining in place through Thursday. Nocturnal increase to 10 to 15 will be possible. A swell train is expected to emanate from Tropical Storm Elsa beginning today and continuing through Wednesday. This swell will produce higher seas of 4 to 6 feet in the open Gulf waters. Otherwise, mainly 2 feet or less expected in the coastal waters. && .PRELIMINARY POINT TEMPS/POPS... MCB 87 72 86 71 / 80 50 90 30 BTR 89 73 87 73 / 90 60 90 30 ASD 88 74 87 74 / 90 70 90 40 MSY 89 76 88 77 / 90 70 90 30 GPT 87 74 87 75 / 90 70 90 40 PQL 87 73 88 74 / 90 70 80 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. &&
The Mobile radar (KMOB), 66 km away, was scanning. The volume nearest the first event began at 10:48 UTC.
6 flash flood, 1 flood. Local standard time, as filed.
Water reported entering buildings in the general area.
Numerous streets impassible and closed, some homes flooded in the neighborhood.
Flooding on I-10 between Canal Road Exit 31 and MS605 / Lorraine Cowan Road Exit 38 in Harrison County in both directions.
Flooding has reached inside the garage at a house in the area and is encroaching on other homes in the neighborhood.
Sheriffs office reported multiple roads beginning to flood and in the process of blocking and closing a few off.
Apartments beginning to take on water off of Oneal Road in North Gulfport.
Flooding occurring around the Palms Apartments in Gulfport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Mississippi in 2021Every state in 2021This day in weather historyWarnings in Mississippi, July 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 974421, 974428, 974423, 974424, 974425, 974426, 974427.