Alert archive / North Carolina / Flash Flood Warnings in 2021

Flash Flood Warning 20, NWS Raleigh, NC

September 9, 2021Wake County, North Carolina

NWS Raleigh, NC issued this flash flood warning at Sep 9, 2021, 11:21 AM EDT for Wake County, North Carolina. It was in force for 3 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Sep 9, 2021, 11:21 AM EDT (15:21 UTC)
Expired
Sep 9, 2021, 2:30 PM EDT
In force
3 hr
Issued by
NWS Raleigh, NC
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Wake County, NC

The radar

The Raleigh/Durham radar (KRAX), 32 km from the middle of the area, began a volume at 15:26 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.

What was reported inside it

TimeReportWhereRemark
Sep 9, 11:34 AM EDTFLASH FLOOD3 E Raleigh, NCWATER RESCUE IN PROGRESS IN THE 3200 BLOCK OF ATLANTIC AVENUE.
Sep 9, 12:00 PM EDTFLASH FLOOD1 Nnw Raleigh, NCMULTIPLE LANES OF I-440 WEST BLOCKED BY STANDING WATER.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 3.4 hours before the alert went out and 105 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, Greensboro/Hi Pt, NC at 12:00Z on 2021-09-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 309 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, Greensboro/Hi Pt, NC at 12:00Z on 2021-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 square meters per square second.1939587897Sfc1 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
309 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
579 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
171 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.9

Open this sounding in Storm Lab

The text

As transmitted.

740 
WGUS52 KRAH 091521
FFWRAH
NCC183-091830-
/O.NEW.KRAH.FF.W.0020.210909T1521Z-210909T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Raleigh NC
1121 AM EDT Thu Sep 9 2021

The National Weather Service in Raleigh has issued a

* Flash Flood Warning for...
  Central Wake County in central North Carolina...

* Until 230 PM EDT.

* At 1121 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Raleigh, Cary, Garner, RDU International, Apex, Morrisville, 
  Knightdale, William B Umstead State Park, Lake Wheeler, Research 
  Triangle and Carpenter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3591 7877 3589 7852 3576 7849 3570 7863
      3570 7878 3578 7892 3587 7888 3587 7885
      3587 7884 3587 7883 3588 7882 3589 7882
      3590 7882

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Green
3 follow-up statements
481 
WGUS72 KRAH 091545
FFSRAH

Flash Flood Statement
National Weather Service Raleigh NC
1145 AM EDT Thu Sep 9 2021

NCC183-091830-
/O.CON.KRAH.FF.W.0020.000000T0000Z-210909T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wake NC-
1145 AM EDT Thu Sep 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 230 PM EDT THIS 
AFTERNOON FOR CENTRAL WAKE COUNTY...

At 1145 AM EDT, Doppler radar indicated thunderstorms producing 
heavy rain across the warned area. Between 1 and 2 inches of rain 
have fallen. Additional rainfall amounts of 1 to 2 inches are 
possible in the warned area. Flash flooding is already occurring, 
and a water rescue has occurred on Atlantic Avenue in Raleigh.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Raleigh, Cary, Garner, RDU International, Apex, Morrisville, 
  Knightdale, William B Umstead State Park, Lake Wheeler, Research 
  Triangle and Carpenter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3591 7877 3589 7852 3576 7849 3570 7863
      3570 7878 3578 7892 3587 7888 3587 7885
      3587 7884 3587 7883 3588 7882 3589 7882
      3590 7882

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Green
614 
WGUS72 KRAH 091756
FFSRAH

Flash Flood Statement
National Weather Service Raleigh NC
156 PM EDT Thu Sep 9 2021

NCC183-091830-
/O.CON.KRAH.FF.W.0020.000000T0000Z-210909T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wake NC-
156 PM EDT Thu Sep 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 230 PM EDT THIS 
AFTERNOON FOR CENTRAL WAKE COUNTY...

At 156 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain have moved out of the warned area. Between 1 and 3 inches of 
rain fell. Flash flooding is occurring, and may continue to occur as 
water recedes.

HAZARD...Life threatening flash flooding.

SOURCE...Radar and public reports.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Raleigh, Cary, Garner, RDU International, Apex, Morrisville, 
  Knightdale, William B Umstead State Park, Lake Wheeler, Research 
  Triangle and Carpenter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3591 7877 3589 7852 3576 7849 3570 7863
      3570 7878 3578 7892 3587 7888 3587 7885
      3587 7884 3587 7883 3588 7882 3589 7882
      3590 7882

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

JJT
563 
WGUS72 KRAH 091824
FFSRAH

Flash Flood Statement
National Weather Service Raleigh NC
224 PM EDT Thu Sep 9 2021

NCC183-091834-
/O.EXP.KRAH.FF.W.0020.000000T0000Z-210909T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wake NC-
224 PM EDT Thu Sep 9 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 230 PM EDT THIS AFTERNOON FOR 
CENTRAL WAKE COUNTY...

Flood waters are receding and the heavy rain has ended. Flooding is 
no longer expected to pose a threat at this time. Please continue to 
heed remaining road closures.

LAT...LON 3591 7877 3589 7852 3576 7849 3570 7863
      3570 7878 3578 7892 3587 7888 3587 7885
      3587 7884 3587 7883 3588 7882 3589 7882
      3590 7882

$$

JJT

The office that day

Everything else NWS Raleigh, NC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 8, 8:02 PM EDTSpecial Weather StatementRAHWarren58 min
Sep 9, 10:29 AM EDTAreal Flood AdvisoryRAHMoore3 hr
Sep 9, 12:11 PM EDTSpecial Weather StatementRAHWarren64 min
Sep 9, 12:20 PM EDTSpecial Weather StatementRAHWake55 min
Sep 9, 12:51 PM EDTAreal Flood AdvisoryRAHVance, Warren3 hr
Sep 9, 1:08 PM EDTSpecial Weather StatementRAHWake67 min
Sep 9, 2:33 PM EDTAreal Flood AdvisoryRAHHalifax92 min
Sep 9, 2:46 PM EDTSpecial Weather StatementRAHEdgecombe, Wilson59 min

Nearby

Flash Flood Warnings in North Carolina, 2021Every flash flood warning in 2021

Sources

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