Alert archive / Virginia / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 33, NWS Baltimore/Washington

May 12, 2002Arlington County, Fairfax County, Virginia; Montgomery County, Prince George's County, Maryland

NWS Baltimore/Washington issued this severe thunderstorm warning at May 12, 2002, 8:58 PM EDT for Arlington County, Fairfax County, Virginia; Montgomery County, Prince George's County, Maryland. It was in force for 47 min. 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 12, 2002, 8:58 PM EDT (00:58 UTC)
Expired
May 12, 2002, 9:45 PM EDT
In force
47 min
Issued by
NWS Baltimore/Washington
Area
Whole counties

Counties Montgomery County, MD, Prince George's County, MD, Arlington County, VA, Fairfax County, VA

The radar

The Sterling radar (KLWX), 33 km from the middle of the area, began a volume at 00:59 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
May 12, 5:15 PM EDTSevere Thunderstorm WatchSPC5 hr
May 12, 3:30 PM EDTSevere Thunderstorm WatchSPC6 hr

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at May 12, 2:20 PM EDT, 6 hours 38 minutes earlier.

Area forecast discussion, May 12, 2:20 PM EDT, 6 hours 38 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
220 PM EDT SUN MAY 12 2002

TONIGHT...

SHORTWAVE WILL MOVE EWD PASSING JUST N OF THE AREA 00Z-06Z. THE
ASSOCD SFC WAVE WILL TRACK EWD ALG THE FNT WHICH WILL BE POSITIONED
JUST N OF THE AREA. FNT WILL SAG SWD TOWARD THE PA BORDER
LATER TNGT AND ANOTHER SFC WAVE WILL MOVE EWD ALG THE SAGGING FNT.

DEWPOINTS ARE RISING NICELY OVR THE AREA AS S FLOW IS ADVECTING
MOISTURE NWD. IN ADDTN...SOME AFTRN HEATING HAS RESULTED IN
INCREASING CAPE AND LOWERING OF THE LIS FROM SW AND W WORKING ITS
WAY NEWD. UNSTABLE AIR MASS NOW  MOVING INTO THE AREA WITH THE
LAST OF THE STABLE AIR EXITING NE MD. SO FAR...ONLY SCT CONVECTION
OVR WRN AREAS IN AREA OF HIGHEST CAPES/LOWEST LIS.

12Z ETA HAS A 70KT WIND MAX AT 700MB CROSSING THE MD/PA BORDER
AROUND 00Z IN ASSOCN WITH VORT MAX. IN ADDTN...ETA SHOWING GOOD PRES
FALLS THIS EVE OVR THE AREA. EXPECT CONVECTION THIS EVENING AS SFC
WAVE MOVES ALG THE FNT AND FNT SAGS SWD A BIT SWD. BIGGEST THREAT
WILL BE STRAIGHT LINE DAMAGING WINDS THANKS TO SPEED MAX AND HIGHEST
THREAT OF SVR WILL BE NEAR THAT SPEED MAX OVR THE NRN ZNS. WILL HAVE
ENHANCED WORDING IN NRN 2/3 CWA FOR THIS EVENING. OVER THE SRN 1/3
OF THE AREA...DYNAMICS ARE LACKING AND WIND PROFILES NOT AS
IMPRESSIVE. HOWEVER...THAT IS THE MOST UNSTABLE AREA SO CANT RULE
OUT ISOLD SVR IN THAT AREA....BUT AGAIN...MAIN FOCUS SHOULD BE ACRS
THE N.

INITIAL ROUND OF CONVECTION WILL PASS BY 06Z BUT GIVEN THE PROXIMITY
OF THE FNT AND THE FACT THAT ANOTHER WAVE WILL MOVE ALG IT...CANT
RULE OUT SHRA/TSRA ALL NIGHT. HOWEVER...DO NOT EXPECT THE ACTIVITY
LATER AT NIGHT TO BE SEVERE SINCE AIR MASS SHOULD BE WORKED OVER
FROM INITIAL CONVECTION...AIR MASS WILL NOT BE AS UNSTABLE.

WILL HAVE LIKELY POPS TONIGHT ACRS THE N 2/3 OF AREA...CLOSEST TO
THE SFC AND UPR LVL SYSTEMS. FURTHER S...WILL GO WITH CHC POPS.

PWS CLIMB FAIRLY HIGH TNGT SO TSTMS COULD CONTAIN HEAVY RAIN.
HOWEVER...FFG VALUES NOT TOO LOW ATTM OVR CWA AND STORMS SHOULD BE
MOVING AT A FAIRLY GOOD CLIP. WILL HOLD OFF ON ANY FFA FOR TNGT.

WALSTON

...LONGER TERM...MON THRU SUN...

BY MON MORNING...ORGANIZED CONVECTION FROM SUN NIGHT WILL HAVE COME
TO AN END AND ATMOS WILL HAVE STABILIZED A BIT. MODELS SHOW ONLY
WEAK LIFT S AND E OF SFC BOUNDARIES FCST TO BE NEAR W AND N CWA
BORDERS BY SUNRISE. MOST OF CWA WILL BE IN WARM SECTOR SO THIS WILL
ALLOW SOME SUN TO PEEK THRU DURING AM CAUSING SOME DEGREE OF
INSTABILITY TO REDEVELOP.

WARM FRONT JUST N OF CWA FCST TO PUSH SWARD BY EARLY AFT MAKING
DEVELOPING SFC LOW TRACK ACROSS N CWA. COLD FROPA EXPECTED 00Z-06Z
FROM W TO E. MODELS CONTINUE TO SHOW GOOD VVEL IN ADDITION TO LLJET
AND WEAK VORT DYNAMICS ALONG THESE BOUNDARIES SO LIKELY POPS
WARRENTED. SPC PUT ENTIRE CWA IN SLIGHT RISK DAY 2 /MAINLY MON
EVE/ FOR WIND GUSTS DUE TO SIG SPEED SHEAR FROM LLJET AHEAD OF COLD
FRONT. TSTM SEVERITY WILL DEPEND ON HOW MUCH SUN WE GET DURING DAY
MON.

ANOTHER CONCERN IS PRECIP WATER VALUES AVG 1.75 INCH 18Z-00Z MON
WHICH COULD CAUSE HEAVY DOWNPOURS.  IF ANY AREA RECEIVES HVY
RAINFALL TONIGHT ANOTHER ROUND OF PRECIP MON/MON NIGHT MIGHT CAUSE
PROBLEMS. WILL LET MID SHIFT DECIDE IF ANY PART OF CWA NEEDS FLOOD
WATCH BASED ON WHAT HAPPENS THIS EVE.

SHRA/TSRA WILL COME TO AN END WITH FROPA MON NIGHT BUT LOW WILL
BECOME CUTOFF OVER NEW ENGLAND TUE KEEPING CWA IN PATH OF VORTICITY
ROTATING AROUND FEATURE. THIS WILL KEEP CONSIDERABLE CLDS AND LLRH
IN CWA...ESPECIALLY IN MTNS TUE AND TUE NIGHT. THERE IS A SMALL
THREAT OF UPSLOPE SHRA WITH FEATURE IN FAR W RIDGES SO WILL HAVE
SILENT 20 POP THERE. CWA ALSO IN SIG PRES GRAD AS HIGH TRIES TO
APPROACH. WILL MENTION BREEZY COND MON NIGHT THROUGH TUE
NIGHT...EXCEPT WILL GO WINDY ON RIDGES MON NIGHT DUE TO STRENGTH OF
CAA /850MB TEMPS DROP 12 DEGREES IN 12 HRS/ AND SIG PRESSURE
FALLS.

HIGH PRES ARRIVES WED CLEARING REMAINING CLDS...AND LINGERS THROUGH
FRI. ECMWF AND AVN EXTENSION NOW AGREE COLD FRONT WILL APRROACH CWA
FROM NW FRI NIGHT AND CROSS CWA SAT. GRADUAL CLEARING EXPECTED SUN
AS LOW PUSHES OFFSHORE.

REGARDING TEMPS...STAYED CLOSE TO GUIDANCE MON. MON NIGHT THRU
WED...UNDERCUT GUIDANCE A BIT BECAUSE DO NOT BELIEVE WITH SUCH
STRONG CAA AND 850MB TEMPS DROPPING TO NEAR ZERO THAT WE WILL REACH
HIGHS NEAR 70. TEMPS WED A FEW DEGREES BELOW GUIDANCE FOR TRENDING
PURPOSES. GUIDANCE TEMPS LOOKED GOOD FRI THRU SUN.

THANKS FOR COORD RNK.

MMARGRAF

.LWX...NONE.

In the hours before

Local storm report, May 12, 5:26 PM EDT, 3 hours 32 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
526 PM EDT SUN MAY 12 2002

TIME(EDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0428 PM    MOUNT AETNA               MD   .75 INCH HAIL
05/12/02   WASHINGTON                     REPORTED BY
SPOTTERS

0452 PM    GERMANTOWN                MD   WIND DAMAGE
05/12/02   MONTGOMERY                     TREES DOWNREPORTED BY LAW
                                          ENFORCEMENT

0500 PM    ROCKVILLE                 MD   WIND DAMAGE
05/12/02   MONTGOMERY                     WIND BLEW ROOF OFFREPORTED
                                          BY SPOTTERS

DMW
Local storm report, May 12, 5:47 PM EDT, 3 hours 11 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
547 PM EDT SUN MAY 12 2002

TIME(EDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0428 PM    MOUNT AETNA               MD   .75 INCH HAIL
05/12/02   WASHINGTON                     REPORTED BY SPOTTERS

0452 PM    GERMANTOWN                MD   WIND DAMAGE
05/12/02   MONTGOMERY                     TREES DOWN REPORTED BY LAW
                                          ENFORCEMENT

0500 PM    ROCKVILLE                 MD   WIND DAMAGE
05/12/02   MONTGOMERY                     WIND BLEW ROOF OFF REPORTED
                                          BY SPOTTERS

0500 PM    COUNTY WIDE               MD   WIND DAMAGE
05/12/02   HOWARD                         TREES DOWN REPORTED BY LAW

0630 PM    MANASSAS                  VA   .75 INCH HAIL
05/12/02   MANASSAS CITY                  REPORTED BY SPOTTERS

0635 PM    3S MANASSAS              VA   .75 INCH HAIL
05/12/02   PRINCE WILLIAM                 REPORTED BY SPOTTERS

DMW
Special weather statement, May 12, 6:00 PM EDT, 2 hours 58 minutes before
MDZ004>007-122330-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
600 PM EDT SUN MAY 12 2002

A LINE OF THUNDERSTORMS STRETCHES FROM SOUTHEASTERN PENNSYLVANIA
BACK THROUGH NORTHERN FREDERICK COUNTY MARYLAND. THESE STORMS ARE
MOVING SOUTHEAST AT 40 MPH...AND WILL EFFECT THE MARYLAND COUNTIES
OF FREDERICK EASTWARD TO HARFORD THROUGH 730 PM. IF YOU SEE OR HEAR
ONE OF THESE STORMS APPROACHING MOVE TO SHELTER IMMEDIATELY. THESE
STORMS WILL CONTAIN STRONG GUSTY WINDS...LIGHTNING...AND SMALL HAIL.

STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER
DETAILS OR UPDATES.
Local storm report, May 12, 6:49 PM EDT, 2 hours 9 minutes before
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Local storm report, May 12, 6:50 PM EDT, 2 hours 8 minutes before
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Special weather statement, May 12, 8:16 PM EDT, 42 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
May 13, 12:51 PM EDTSevere Thunderstorm WarningLWXRockingham, City of Harrisonburg39 min
May 13, 12:59 PM EDTSevere Thunderstorm WarningLWXPage31 min
May 13, 1:12 PM EDTSevere Thunderstorm WarningLWXMadison, Page, Rappahannock, Shenandoah, Warren48 min
May 13, 1:22 PM EDTSevere Thunderstorm WarningLWXClarke, Frederick23 min
May 13, 1:47 PM EDTSevere Thunderstorm WarningLWXLoudoun43 min
May 13, 2:21 PM EDTSevere Thunderstorm WarningLWXFairfax, Loudoun, Prince William39 min
May 13, 3:30 PM EDTSpecial Marine WarningLWX2 hr
May 13, 3:30 PM EDTSpecial Marine WarningLWX2 hr
May 13, 3:32 PM EDTSpecial Marine WarningLWX43 min
May 13, 4:06 PM EDTSpecial Marine WarningLWX39 min
May 13, 7:02 PM EDTSevere Thunderstorm WarningLWXClarke, Frederick, City of Winchester43 min
May 13, 3:11 PM EDTTornado WarningLWXMontgomery34 min
May 13, 3:14 PM EDTTornado WarningLWXHoward31 min
May 13, 3:21 PM EDTTornado WarningLWXBaltimore, City of Baltimore24 min
May 13, 3:46 PM EDTTornado WarningLWXBaltimore, Harford, City of Baltimore29 min
May 13, 4:36 PM EDTSevere Thunderstorm WarningLWXHarford24 min
May 13, 7:20 PM EDTSevere Thunderstorm WarningLWXFrederick40 min
May 13, 7:57 PM EDTSevere Thunderstorm WarningLWXSaint Mary's33 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2002Severe Thunderstorm Warnings in Maryland, 2002Every severe thunderstorm warning in 2002

Sources

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