Alert archive / North Carolina / Flash Flood Warnings in 2011
Flash Flood Warning 39, NWS Raleigh, NC
NWS Raleigh, NC issued this flash flood warning at Aug 20, 2011, 6:16 PM EDT for Forsyth County, North Carolina. It was in force for 88 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2011, 6:16 PM EDT (22:16 UTC)
- Expired
- Aug 20, 2011, 7:44 PM EDT
- In force
- 88 min
- Issued by
- NWS Raleigh, NC
- Area
- Storm-based polygon
- Flood severity
- None
County Forsyth County, NC
The radar
The Roanoke radar (KFCX), 104 km from the middle of the area, began a volume at 22:16 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
Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 10.3 hours before the alert went out and 30 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.
- Mixed-layer CAPE
- 606 J/kg
- Mixed-layer CIN
- -65 J/kg
- Mixed-layer LCL
- 1004 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- -1 m²/s²
- 0-3 km storm-relative helicity
- 39 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted, in the capitals the NWS used until 2016.
563
WGUS52 KRAH 202216
FFWRAH
NCC067-210115-
/O.NEW.KRAH.FF.W.0039.110820T2216Z-110821T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE RALEIGH NC
616 PM EDT SAT AUG 20 2011
THE NATIONAL WEATHER SERVICE IN RALEIGH HAS ISSUED A
* FLASH FLOOD WARNING FOR...
FORSYTH COUNTY IN CENTRAL NORTH CAROLINA
* UNTIL 915 PM EDT
* AT 612 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH VERY HEAVY RAIN PRODUCING FLOODING OVER CENTRAL
FORSYTH COUNTY. DOPPLER RADAR ESTIMATED THAT ONE TO ONE AND A HALF
INCHES OF RAIN HAS FALLEN OVER THE CITY OF WINSTON SALEM.
* LOCATIONS THREATENED WITH FLOODING INCLUDE WINSTON-SALEM.
AN ADDITIONAL ONE INCH OF RAIN IS STILL POSSIBLE...WHICH WILL RESULT
IN URBAN FLOODING.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
EXCESSIVE RUNOFF FROM THE HEAVY RAIN WILL CAUSE FLASH FLOODING OF
CREEKS AND STREAMS...ROADS...LOW LYING AND POOR DRAINAGE AREAS. DO
NOT DRIVE YOUR VEHICLE INTO AREAS WHERE WATER COVERS THE ROAD. MANY
ROADS AND INTERSECTIONS IN THE AREA WILL QUICKLY FLOOD. WHEN
ENCOUNTERING FLOODED ROADS TURN AROUND...DONT DROWN.
PLEASE REPORT FLOODING TO THE NATIONAL WEATHER SERVICE BY CALLING...
1...8 7 7...6 3 3...6 7 7 2 OR NOTIFY YOUR LOCAL LAW ENFORCEMENT
AGENCY.
&&
LAT...LON 3619 8029 3618 8021 3613 8014 3606 8017
3602 8020 3602 8021 3601 8022 3602 8031
3609 8034
$$
MWS2 follow-up statements
302
WGUS72 KRAH 202310
FFSRAH
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
710 PM EDT SAT AUG 20 2011
NCC067-210115-
/O.CON.KRAH.FF.W.0039.000000T0000Z-110821T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
FORSYTH NC-
710 PM EDT SAT AUG 20 2011
...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM EDT FOR
CENTRAL FORSYTH COUNTY...
AT 706 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THE
THUNDERSTORM THAT PRODUCED THE EARLIER HEAVY RAIN HAD DISSIPATED.
HOWEVER...MULTI-SENSOR PRECIPITATION ANALYSES INDICATE TWO TO AS
MUCH AS THREE AND A HALF INCHES OF RAIN FELL OVER THE CITY WINSTON
SALEM BETWEEN 545 AND 645 PM.
WHILE NO ADDITIONAL HEAVY RAIN IS EXPECTED...THE EARLIER RAINFALL
WILL POSE A CONTINUED RISK OF FLASH FLOODING.
LOCATIONS THREATENED BY FLOODING INCLUDE BUT ARE NOT LIMITED TO
WINSTON-SALEM
PRECAUTIONARY/PREPAREDNESS ACTIONS...
EXCESSIVE RUNOFF WILL CAUSE FLOODING OF SMALL CREEKS AND STREAMS...
URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER
DRAINAGE AREAS AND LOW LYING SPOTS.
PLEASE REPORT FLOODING TO THE NATIONAL WEATHER SERVICE BY CALLING...
1...8 7 7...6 3 3...6 7 7 2 OR NOTIFY YOUR LOCAL LAW ENFORCEMENT
AGENCY.
&&
LAT...LON 3619 8029 3618 8021 3613 8014 3606 8017
3602 8020 3602 8021 3601 8022 3602 8031
3609 8034
$$
MWS192
WGUS72 KRAH 202344
FFSRAH
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
744 PM EDT SAT AUG 20 2011
NCC067-202350-
/O.CAN.KRAH.FF.W.0039.000000T0000Z-110821T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
FORSYTH NC-
744 PM EDT SAT AUG 20 2011
...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL FORSYTH
COUNTY...
AT 740 PM EDT...THERE HAD BEEN NO REPORTS OF HIGH WATER OR FLASH
FLOODING IN THE CITY OF WINSTON SALEM...AND NO SIGNIFICANT RAIN HAD
FALLEN IN OVER AN HOUR. THEREFORE THE FLOODING THREAT HAS ENDED...
AND THE WARNING HAS BEEN CANCELLED.
LAT...LON 3619 8029 3618 8021 3613 8014 3606 8017
3602 8020 3602 8021 3601 8022 3602 8031
3609 8034
$$
MWSThe office that day
Everything else NWS Raleigh, NC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 6:00 PM EDT | Special Weather Statement | RAH | Forsyth | 45 min |
| Aug 20, 6:08 PM EDT | Areal Flood Advisory | RAH | Forsyth | 97 min |
Nearby
Flash Flood Warnings in North Carolina, 2011Every flash flood warning in 2011
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.