Alert archive / Alabama / Flash Flood Warnings in 2017

Flash Flood Warning 13, NWS Mobile, AL

May 20, 20174 counties in Alabama

NWS Mobile, AL issued this flash flood warning at May 20, 2017, 5:57 PM CDT for 4 counties in Alabama. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
May 20, 2017, 5:57 PM CDT (22:57 UTC)
Expired
May 21, 2017, 12:00 AM CDT
In force
6 hr
Issued by
NWS Mobile, AL
Area
Storm-based polygon
Flood severity
None

Counties Baldwin County, AL, Clarke County, AL, Mobile County, AL, Washington County, AL

The radar

The Mobile radar (KMOB), 72 km from the middle of the area, began a volume at 22:57 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.0 hours before the alert went out and 204 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2017-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2399 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2017-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
2399 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
567 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
64 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

294 
WGUS54 KMOB 202257
FFWMOB
ALC003-025-097-129-210500-
/O.NEW.KMOB.FF.W.0013.170520T2257Z-170521T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mobile AL
557 PM CDT SAT MAY 20 2017

The National Weather Service in Mobile has issued a

* Flash Flood Warning for...
  Northern Mobile County in southwestern Alabama...
  Northwestern Baldwin County in southwestern Alabama...
  Southeastern Washington County in southwestern Alabama...
  South central Clarke County in southwestern Alabama...

* Until midnight CDT Sunday

* At 554 PM CDT, Doppler radar indicated thunderstorms producing 
  very heavy rain across the warned area. Radar estimates that 2 to 
  4 inches of rain, with isolated amounts approaching 5 inches has 
  fallen across much of the warned area. Additional thunderstorms 
  will produce additional heavy rainfall and flash flooding is 
  expected to begin shortly.

* Some locations that will experience flooding include...
  Citronelle, Mount Vernon, Blacksher, Calvert, McIntosh and 
  Carlton. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.

&&

LAT...LON 3103 8834 3137 8813 3141 8774 3136 8775
      3136 8777 3135 8777 3133 8779 3131 8778
      3130 8777 3099 8786

$$

The office that day

Everything else NWS Mobile, AL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 4:57 PM CDTAreal Flood AdvisoryMOBBaldwin, Clarke, Mobile, Washington3 hr
May 20, 5:30 PM CDTSpecial Weather StatementMOBMobile, Washington45 min
May 20, 5:42 PM CDTAreal Flood AdvisoryMOBMobile, Washington3 hr
May 20, 6:17 PM CDTSpecial Weather StatementMOBWashington43 min
May 20, 6:27 PM CDTSpecial Weather StatementMOBMobile48 min

Nearby

Flash Flood Warnings in Alabama, 2017Every flash flood warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.