Alert archive / Tennessee / Flash Flood Warnings in 1998

Flash Flood Warning 69, NWS Morristown, TN

May 21, 1998Knox County, Tennessee

NWS Morristown, TN issued this flash flood warning at May 21, 1998, 6:52 PM EDT for Knox County, Tennessee. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 21, 1998, 6:52 PM EDT (22:52 UTC)
Expired: May 21, 1998, 9:00 PM EDT
In force: 2 hr
Issued by: NWS Morristown, TN
Area: Whole counties

County Knox County, TN

The radar

The Knoxville radar (KMRX), 52 km from the middle of the area, began a volume at 23:09 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

Nashville Metro, TN (KBNA), launched 12:00Z, 10.9 hours before the alert went out and 240 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1382 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 1095 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 139 m²/s²
0-3 km storm-relative helicity: 162 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KMRX 212251
FFWMRX
TNC093-220100-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE KNOXVILLE/TRI-CITIES TN
652 PM EDT THU MAY 21 1998

THE NATIONAL WEATHER SERVICE IN KNOXVILLE/TRI-CITIES HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  KNOX COUNTY IN EASTERN TENNESSEE

* UNTIL 900 PM EDT

* AT 652 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  THAT CLUSTERS OF THUNDERSTORMS WITH VERY HEAVY RAIN WERE LOCATED
  ACROSS ALL OF KNOXVILLE AND SOUTHERN PORTIONS OF KNOX COUNTY...
  MOVING SOUTHEAST AT 10 MPH.

* EXCESSIVE RAINFALL AT THE RATE OF 2 TO 3 INCHES PER HOUR WILL
  PRODUCE FLOODING ACROSS KNOXVILLE AND SOUTHERN PORTIONS OF
  KNOX COUNTY THROUGH 900 PM EDT.

zDON'T DRIVE INTO AREAS WHERE WATER COVERS THE ROAD!

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Morristown, TN wrote its last area forecast discussion before this flash flood warning went out at May 21, 2:35 PM EDT, 4 hours 17 minutes earlier.

Area forecast discussion, May 21, 2:35 PM EDT, 4 hours 17 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KNOXVILLE/TRI-CITIES TN
235 PM EDT THU MAY 21 1998

...MAIN FCST CHLG IS PRECIP CHCS THRU FCST PRD...

CRNT SFC ANALYSIS SHOS CLD FRNT NR KY/TN BRDR ATTM. LTL CONV HAS FIRED
ALNG FRNT DUE TO WEAK CAP OVR AREA. CRNT IR PIC SHOS 3 DIST MCSS OVR
MO..AND NE ATTM. THCKNS PATTERNS INDIC THAT MCSS SHUD CONT A SE
MOVMNT.  CRNT ADAP PRODS SHO LIS -10 TO -15 AND 0 CAP ATTM. SO AS UPR
LVL S/W MOVS INTO THE AREA W/ A LTL MORE SFC WARMING SHUD SEE SCT TSRA
OVR THE AREA THRU THIS EVENING.

TONITE...W/ MCSS MOVING TWRDS SW VA/AND NE TN WOULD LIKE TO SEE A
GOOD CHC OF TSRA OVERNIGHT (50%) FOR THE REMAINDER OF THE AREA WOULD
LIKE TO SEE A CHC OF TSRA (30%). AS FAR AS TEMPS GO...FWC/FAN NUMBERS
LOOK GOOD.  (60 TO 65) WK THETA-E RIDGE BUILDS INTO THE NE PORTION OF
THE CWA WHICH WOULD INDICATE CRNT MCS SHUD REMAIN OVER THAT AREA.

FRIDAY...THCKNS PATTERNS TURN MOR SE OVR CWA AND UPR LVL S/WS MOV
INTO THE AREA UNDER WK NW FLOW...SO MCSS OVR NORTHERN MO AND NEBRASKA
SHUD MOV INTO THE AREA. UPR LVL DYNAMICS LUK WK ATTM HOWEVER THETA-E
RIDGE BUILDS OVR THE AREA SO PRECIP CHCS SHUD BE PRESENT...SO WOULD
LIKE TO INTRODUCE A 40 PERCENT CHC OF TSRA DURING THE DAY.  FWC/FAN
TEMPS LUK GOOD.  PARTLY CLOUDY SHUD PREVAIL ACRS CWA.  (80 TO 85)

FRIDAY NITE...ENTIRE CWA STAYS UNDER WK NW FLOW AND WK S/WS CONT TO
MOV THRU THE AREA SO WOULD LIKE TO GO PARTLY CLOUDY W/ A 30 PERCENT
CHC OF SHRA AND TSRA.  FWC/FAN TEMPS LUK GOOD. (60 TO 65)

SAT...UPR LVL RIDGE BEGINS TO MOV INTO THE AREA AND SHUD PUSH PRECIP
CHCS OFF TO THE EAST OF THE CWA. SO WOULD LIKE TO GO PARTLY CLOUDY
WITH HIGHS 80 TO 85.

PDK

The office that day

Everything else NWS Morristown, TN issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 9:32 PM EDT	Severe Thunderstorm Warning	MRX	Carter, Johnson	33 min
May 20, 10:14 PM EDT	Severe Thunderstorm Warning	MRX	Johnson, Sullivan	46 min
May 21, 4:55 PM EDT	Severe Thunderstorm Warning	MRX	Roane	35 min
May 21, 5:45 PM EDT	Severe Thunderstorm Warning	MRX	Loudon	35 min
May 21, 5:55 PM EDT	Severe Thunderstorm Warning	MRX	Knox	50 min
May 21, 6:32 PM EDT	Severe Thunderstorm Warning	MRX	Roane	33 min
May 21, 6:45 PM EDT	Severe Thunderstorm Warning	MRX	Knox	30 min
May 21, 6:48 PM EDT	Severe Thunderstorm Warning	MRX	Jefferson, Sevier	47 min
May 21, 7:14 PM EDT	Severe Thunderstorm Warning	MRX	Knox	31 min
May 21, 7:29 PM EDT	Severe Thunderstorm Warning	MRX	Roane	31 min
May 21, 7:39 PM EDT	Severe Thunderstorm Warning	MRX	Cocke	36 min

Nearby

Flash Flood Warnings in Tennessee, 1998 Every flash flood warning in 1998

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.