A wake low developed behind a line of showers and thunderstorms. The low produced high winds which caused damage in southwest Alabama.
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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 MOB wrote it up.
A wake low developed behind a line of showers and thunderstorms. The low produced high winds which caused damage in southwest Alabama.
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 Mobile, AL wrote its last area forecast discussion before the first event at May 4, 3:43 AM CST, 17 minutes earlier.
Area Forecast Discussion
National Weather Service Mobile AL
443 AM CDT Thu May 4 2017
.DISCUSSION...See updated information for land areas below.
&&
.UPDATE...We have been monitoring a tightening pressure gradient
on the back side of the rain shield that is currently moving
across the area. Winds just to the west and north of our forecast
area have responded to the tightening gradient, gusting up to 35
or 40 mph at times and there have been a few reports of trees
blown down. Hi-Res models indicate this gradient will move east
across our Mississippi counties and interior southwest Alabama
counties (west of I-65) through around 9 am or so this morning.
With this, we have issued a Wind Advisory for those areas through
10 AM, where we expect southeasterly winds associated with the
gradient to be in the 15 to 25 mph range, with frequent gusts to
around 35 mph. We will have to monitor and see if the tight
gradient persists as it moves east, and it's possible we may have
to extend the advisory further east a little later this morning.
The Wind Advisory and the resultant updated Zone Forecast have
already been issued. 12/DS
&&
.PREV DISCUSSION... /issued 414 AM CDT Thu May 4 2017/
NEAR TERM /Now Through Thursday night/...Vigorous positive tilt
upper level trof exits the southern Plains today. On the eastern
periphery of the trof axis, deep layer ascent operating on deep
layer moisture from 1.75 to 1.9 inches results in an eastward
moving and ongoing large shield of showers and embedded storms.
The deepest convection was moving east over the coastal waters.
Surface front was positioned from the Lower MS River Valley and
will track eastward across the region today. Bulk of ongoing showers
and storms will shift east this morning with potential return of
numerous storms forming out ahead of eastward moving cold front
late morning into mid afternoon. As atmospheric instability
recovers, there is some potential for strong to marginally severe
storms to re-develop generally over the eastern half of the local
area. Localized damaging wind gusts and perhaps instances of
large hail look to be the main threats in any isolated severe
storms. Will leave flash flood watch as is, in effect thru 10 AM,
but will likely be able to cancel early if ongoing morning rains
continue good eastward progression. Steady eastward progress in
storms that redevelop today look to limit widespread flash
flooding potential in these. High surf continues along the beaches
and latest forecast calls for breakers and potential of high surf as
well. Went with the cooler guidance for today's highs due to frontal
passage and lingering clouds. Numbers look to range well below
seasonable levels for early May standards, at a cool mid to upper
60s over the northwest zones in the wake of frontal passage. Lower
to mid 70s elsewhere. May be dealing with wrap around clouds tonight
as we see cyclonic curvature in the height field aloft progressing
east over the local area. Clouds would act to keep overnight lows
from getting as cool as they could and will trend these to the
warmer side of the guidance envelope, ranging from the upper 40s
interior to mid 50s beaches. /10
SHORT TERM /Friday Through Saturday night/...Deep upper low/trof
over the TN/OH river valleys early Fri morning will drift
northeast to the eastern Great Lakes region and New England
states by late Sat evening. South and west of the broad cyclonic
flow a large area of cloudiness or wrap around moisture will
continue to stretch south towards the northern gulf coast leading
to mostly cloudy conditions for most locations in the forecast
area early Fri gradually shifting northeast through late fri
night. By Friday night skies become mostly clear as a broad
surface ridge of high pressure shifts southeast and east over Tx
and the lower Ms river valley fri night through early sun. this
pattern is a reflection of a sharp upper ridge drifting east over
the central plains late Friday through early Sunday.
As for temps highs will be on the cool side on Fri, running 5 to
10 degrees below seasonal averages, due to good cold air
advection in the wake of a cold front combined with more clouds
than sun. Highs Fri will range from the upper 60s to lower 70s
generally over the northern half of the forecast area and the
lower to middle 70s to the south. Lows Fri night will range from
the upper 40s to near 50 for most inland areas and the lower to
middle 50s close to the coast. For Sat with plenty of sunshine,
lower wind speeds and increased subsidence in the boundary layer
high temps on Sat will be warmer climbing to the mid 70s for most
areas.
LONG TERM /Sunday Through Wednesday/...The sharp upper ridge
over the central plains over the weekend will slowly shift
eastward towards the Mississippi river valley through midweek. At
the surface high pressure will continue to reflect east of the
upper ridge settling over the north central gulf states and
adjacent gulf waters late Sun through midweek. This pattern will
lead to mostly sunny conditions each day and clear skies at night
with temps gradually rebounding to near seasonal levels. Some
patchy fog will also be likely near sunrise each day due to the
slightly better moisture in the lower levels combined with good
radiational cooling each night.
Highs Sun will climb to the lower 80s for most areas then the mid
to upper 80s Tue and Wed. Lows Sun night will be a tad warmer
than previous nights ranging from the lower to middle 50s for
inland areas and lower 60s closer to the coast. Slightly warmer
temps are expected Mon and Tue nights ranging from the mid to
upper 50s to near 60 inland and the lower to middle 60s near the
coast Mon night then the lower to middle 60s for all areas Tue
night. 32/ee
MARINE...Cold front makes passage, bringing resultant wind shift
across the coastal waters today. Strong winds and high seas will
maintain small craft advisories in the short term. Strong west to
northwest flow looks to continue over the open Alabama and northwest
Florida coastal waters thru Friday night. Strong west to northwest
flow looks to continue over the open Alabama and northwest Florida
coastal waters thru Saturday morning and have extended the small
craft advisory to account for latest wind speeds and seas heights
meeting criteria. High pressure moves across the coastal waters late
in the weekend bringing lower winds and decreased seas. /10
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Flash Flood Watch until 10 AM CDT this morning for ALZ052-
261>266.
Wind Advisory until 10 AM CDT this morning for ALZ051>055.
High Rip Current Risk through this evening for ALZ265-266.
High Surf Advisory until 6 PM CDT this evening for ALZ265-266.
FL...Flash Flood Watch until 10 AM CDT this morning for FLZ201>204.
High Rip Current Risk through this evening for FLZ202-204-206.
High Surf Advisory until 6 PM CDT this evening for FLZ202-204-
206.
MS...Flash Flood Watch until 10 AM CDT this morning for MSZ075-076-
078-079.
Wind Advisory until 10 AM CDT this morning for MSZ067-075-076.
GM...Small Craft Advisory until 7 AM CDT Saturday for GMZ631-632-650-
655-670-675.
Small Craft Advisory until midnight CDT tonight for GMZ630-
633>635.
&&
This product is also available on the web at:
http://weather.gov/mobHazardous Weather Outlook...UPDATED National Weather Service Mobile AL 346 PM CDT Wed May 3 2017 ALZ051>060-261>266-FLZ201>206-MSZ067-075-076-078-079-042100- Choctaw-Washington-Clarke-Wilcox-Monroe-Conecuh-Butler-Crenshaw- Escambia-Covington-Mobile Inland-Baldwin Inland-Mobile Central- Baldwin Central-Mobile Coastal-Baldwin Coastal-Escambia Inland- Escambia Coastal-Santa Rosa Inland-Santa Rosa Coastal- Okaloosa Inland-Okaloosa Coastal-Wayne-Perry-Greene-Stone-George- 346 PM CDT Wed May 3 2017 This Hazardous Weather Outlook is for portions of south central Alabama...southwest Alabama...northwest Florida and southeast Mississippi. .DAY ONE...This Afternoon and Tonight There is a high risk of rip currents along area beaches through tonight. Strong to potentially severe storms are possible tonight into early Thursday morning. There is a Slight Risk for severe thunderstorms across portions of southeast Mississippi and southwest Alabama, with a Marginal Risk across much of the remainder of the area. Storms will enter southeast Mississippi late this evening and move eastward across the area overnight, exiting the area by late Thursday morning. Damaging winds will be the primary threat. A Flash Flood Watch is also in effect for portions of southeast Mississippi, southwest Alabama and the western Florida panhandle tonight, beginning at 7 pm this evening and continuing through Thursday morning. Overnight rainfall totals of 2 to 3 inches will be possible, with locally higher totals possible. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday There is a High Risk of rip currents along area beaches through Thursday. There will remain a Marginal Risk of severe storms, mainly east of I-65 in Alabama and parts of the western Florida panhandle early Thursday morning, with the severe threat ending by late morning. Damaging winds will be the primary threat. .SPOTTER INFORMATION STATEMENT... Activation of SkyWarn Severe Storm Spotter networks may be required tonight through early Thursday. GMZ630>635-650-655-670-675-042100- Northern Mobile Bay-Southern Mobile Bay-Mississippi Sound- Perdido Bay-Pensacola Bay System-Choctawhatchee Bay- Coastal waters from Pensacola FL to Pascagoula MS out 20 NM- Coastal waters from Destin to Pensacola FL out 20 NM- Waters from Pensacola FL to Pascagoula MS from 20 to 60 NM- Waters from Destin to Pensacola FL from 20 to 60 NM- 346 PM CDT Wed May 3 2017 This Hazardous Weather Outlook is for portions of the coastal waters of Alabama and northwest Florida. .DAY ONE...This Afternoon and Tonight Strong winds over the marine area will likely create hazardous conditions for small craft beginning tonight. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Strong winds over the marine area will continue to create hazardous conditions for small craft Thursday through late Friday.
The national radar mosaic for the moment the first event began.
1 strong wind. Local standard time, as filed.
Winds estimated at 40 to 50 mph associated with a wake low produced widespread tree and power line damage across the county.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alabama in 2017Every state in 2017This day in weather historyWarnings in Alabama, May 2017
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: 701837.