Alert archive / Maryland / Flash Flood Warnings in 2001

Flash Flood Warning 50, NWS Baltimore/Washington

August 30, 2001Howard County, Maryland

NWS Baltimore/Washington issued this flash flood warning at Aug 30, 2001, 7:03 PM EDT for Howard County, Maryland. It was in force for 117 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.

The facts

Issued
Aug 30, 2001, 7:03 PM EDT (23:03 UTC)
Expired
Aug 30, 2001, 9:00 PM EDT
In force
117 min
Issued by
NWS Baltimore/Washington
Area
Whole counties; the outline is the Mesonet’s reconstruction

County Howard County, MD

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.1 hours before the alert went out and 62 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, Washington/Dulle, VA at 12:00Z on 2001-08-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1915 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2001-08-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 51 square meters per square second.193958Sfc1 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
1915 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
517 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
51 m²/s²
0-3 km storm-relative helicity
95 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KLWX 302305
FFWLWX
MDC027-310100-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON
703 PM EDT THU AUG 30 2001

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  HOWARD COUNTY IN CENTRAL MARYLAND

* UNTIL 900 PM EDT

* AT 700 PM EDT...A RAIN GAUGE IN ELKRIDGE HAS RECORDED OVER TWO AND 
THREE QUARTER INCHES OF RAIN IN THE LAST HOUR AND FIFTEEN MINUTES.

* AT 700 PM EDT...EMERGENCY MANAGERS REPORT FLASH FLOODING IN
  ELKRIDGE.

IF WATER IS FLOWING ACROSS A ROADWAY TURN YOUR VEHICLE AROUND AND 
FIND AN ALTERNATE ROUTE. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW 
YOUR CAR TO CROSS SAFELY. VEHICLES CAUGHT IN RISING WATER SHOULD BE 
ABANDONED QUICKLY. MOVE TO HIGHER GROUND.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE. IF YOUR VEHICLE STALLS, ABANDON IT IMMEDIATELY AND SEEK
HIGHER GROUND.

LAT...LON 3927 7686 3917 7673 3925 7674 3928 7678

ABW

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 Baltimore/Washington wrote its last area forecast discussion before this flash flood warning went out at Aug 30, 10:15 AM EDT, 8 hours 48 minutes earlier.

Area forecast discussion, Aug 30, 10:15 AM EDT, 8 hours 48 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
1015 AM EDT THU AUG 30 2001

WEAK HI PRES ACRS THE AREA ATTM ALONG WITH A WEAK FRNTL BNDRY XTNDG
FM NEAR FDK TO BTWN IAD AND DCA THEN E OF EZF. SCT SHWRS AND A FEW
TSTMS HAVE BEEN ACTIVE AHEAD OF THE BNDRY. SAT IMAGERY DEPICTS GNRL
CLDINS E OF THE BLUE RDG WITH PATCHES OF DENSE FOG RMNG TO THE WEST
OF THE RDG WHICH WL DISSIPATE BY ARND NOON. OTW ERLR FCST PKG
APPEARS ON TARGET FOR THE RMNDR OF THE DAY. SLT OR 30 POP CHC WL DO
FOR ANY CONV ACTVTY WHICH WL BE DIURNALLY DRIVEN WITH LTL OR NO UPR
SUPPORT. FOG AND CONV BEING HANDLED WITH NOWS.

THATS IT FOR NOW...LATER.

FCSTID = 13...PAP
DCA   86  72  86  69 /  20  10  30  50
BWI   86  69  86  67 /  20  10  30  50
MRB   85  67  85  65 /  20  10  30  60
IAD   86  67  86  65 /  20  10  30  50
CHO   85  68  85  67 /  30  20  40  50
HGR   85  66  85  64 /  20  10  30  60
NHK   86  69  86  67 /  20  10  30  50
W99   86  68  86  66 /  20  10  30  60

.LWX...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.

In the hours before

Special weather statement, Aug 30, 4:50 PM EDT, 2 hours 13 minutes before
DCZ001-MDZ002>006-009>011-013-014-016>018-VAZ021-025>031-036>042-
050>057-WVZ048>055-302345-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON
450 PM EDT THU AUG 30 2001

...THUNDERSTORMS WITH HAIL AND TORRENTIAL RAINS AFFECTING THE AREA...

SHOWERS AND THUNDERSTORMS...SOME WITH HAIL AND HEAVY RAINS WERE
AFFECTING A LARGE PORTION OF NORTHERN AND CENTRAL VIRGINIA...EASTERN
WEST VIRGINIA...AND CENTRAL AND SOUTHERN MARYLAND THIS AFTERNOON.
THUNDERSTORMS WERE MOST NUMEROUS OVER CENTRAL AND NORTHERN VIRGINIA
ESPECIALLY OVER THE SHENANDOAH VALLEY AND THE PIEDMONT AREAS. PARTS
OF ROCKINGHAM ALBEMARLE AND ORANGE COUNTIES WERE ESPECIALLY HARD
HIT. SEVERE THUNDERSTORM WARNINGS HAD BEEN ISSUED FOR THESE AREAS
LATE THIS AFTERNOON. HAIL TO DIME SIZE OR LARGER WAS REPORTED IN
CHARLOTTESVILLE JUST AFTER 4 PM.

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO AFFECT MUCH OF
THE AREA INTO EARLY THIS EVENING...THEN GRADUALY WEAKEN AFTER
NIGHTFALL. THE STRONGER THUNDERSTORMS MAY BE ACCOMPANIED BY HAIL AND
STRONG GUSTY WINDS. TORRENTIAL RAINS WITH 1 TO 2 INCHES POSSIBLE IN
A SHORT PERIOD MAY RESULT IN LOCALIZED FLOODING. RESIDENTS SHOULD
SEEK INDOOR SHELTER AND MOTORISTS SHOULD NOT ATTEMPT TO DRIVE INTO
WATER ON ROADS.

THE THUNDERSTORMS WERE THE RESULT OF A MOIST AND UNSTABLE AIR MASS
OVER THE AREA AND TRIGGERED PRIMARILY BY DAYTIME HEATING. THUS A
GRADUAL WEAKENING TREND IS EXPECTED AFTER DARK.

JLW

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 30, 1:31 PM EDTSevere Thunderstorm WarningLWXAnne Arundel29 min
Aug 30, 1:38 PM EDTFlash Flood WarningLWXAnne Arundel2 hr
Aug 30, 5:57 PM EDTFlash Flood WarningLWXAnne Arundel2 hr
Aug 30, 7:46 PM EDTFlash Flood WarningLWXCharles119 min

Nearby

Flash Flood Warnings in Maryland, 2001Every flash flood warning in 2001

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.