Alert archive / Virginia / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 192, NWS Baltimore/Washington

July 30, 2015Arlington County, Fairfax County, City of Alexandria, Virginia; Montgomery County, Prince George's County, Maryland

NWS Baltimore/Washington issued this severe thunderstorm warning at Jul 30, 2015, 1:57 PM EDT for Arlington County, Fairfax County, City of Alexandria, Virginia; Montgomery County, Prince George's County, Maryland. It was in force for 34 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
Jul 30, 2015, 1:57 PM EDT (17:57 UTC)
Expired
Jul 30, 2015, 2:31 PM EDT
In force
34 min
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon

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

The radar

The Sterling radar (KLWX), 35 km from the middle of the area, began a volume at 18:00 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.0 hours before the alert went out and 27 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 2015-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 283 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 2015-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 69 square meters per square second.1939Sfc1 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
283 J/kg
Mixed-layer CIN
-70 J/kg
Mixed-layer LCL
885 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
69 m²/s²
0-3 km storm-relative helicity
65 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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 Jul 29, 2:55 PM EDT, 23 hours 2 minutes earlier.

Area forecast discussion, Jul 29, 2:55 PM EDT, 23 hours 2 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
255 PM EDT WED JUL 29 2015

.SYNOPSIS...A COLD FRONT WILL CROSS THE AREA THU NIGHT. HIGH PRES
WILL BUILD FOR THE WEEKEND AND HOLD THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...VERY WARM AND HUMID TODAY WITH
DEWPOINTS IN THE MID 70S. SCT-NMRS SHOWERS AND ISOLD T-STORMS
ONGOING PRIMARILY OVER NE MD. SIMILAR TO LAST NIGHT CONVECTION IS
EXPECTED TO WIND DOWN DURING THE NIGHT WITH PATCHY DENSE FOG
DEVELOPING AGAIN. LOTS OF CLOUDS WILL KEEP THINGS VERY WARM AND
SULTRY WITH LOWS BARELY DROPPING BELOW 80F IN THE DISTRICT.

CDFNT CURRENTLY MOVING THROUGH THE MIDWEST WILL ENTER THE FCST
AREA AROUND 18Z THU AND SHOULD CLEAR THE FCST AREA BY 03Z FRI.
FRONT WILL BE LOSING MUCH OF ITS PUNCH BUT IT APPEARS THERE COULD
BE A QUICK BAND OF -SHRA/TSRA RIGHT ALONG OR JUST BEHIND THE
FRONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...12Z MODEL SUITE HAS THE
COLD FRONT PLACED JUST SOUTHEAST OF THE CWA BY 12Z FRIDAY. ANY
LINGERING PCPN WITH THE FRONT SHOULD REMAIN TO THE SOUTH AS THE
FRONTAL BOUNDARY STALLS AND EVENTUALLY DISSIPATES OVER THE
WEEKEND. SFC HIGH PRESSURE BUILDS IN FROM THE WEST IN THE WAKE.
THE REGION WILL REMAIN AT THE SOUTHERN FRINGE OF BROAD CLOSED LOW
OVER CANADA...WITH THE SHORTWAVE ENERGY ROUNDING THE LOW REMAINING
WELL TO THE NORTH. AS SUCH...EXPECTING DRY WX FRI AND FRI NIGHT.
12Z GFS SUGGESTING LIGHT PCPN OVER NORTHEASTERN AREAS OF THE CWA
SAT AFTN WITH A SHORTWAVE JUST TO THE NORTH. WILL KEEP THINGS DRY
FOR NOW THOUGH DURING THIS TIME WITH LACK OF SFC FORCING CURRENTLY
NOTED.

QUICK SHOT OF CAA IN THE WAKE OF THE FRONT ON FRIDAY DROP 850MB
TEMPS TO AROUND 15 DEGREES CELSIUS...RESULTING IN HIGHS GENERALLY IN
THE 80S. THE COOLER AIRMASS WILL BE SHORT LIVED AS THE HIGH BUILDS
IN...WITH 850MB TEMPS REBOUNDING BACK TO NEAR 20 DEGREES CELSIUS BY
SAT AFTN. LOWS FRIDAY NEAR NORMAL...WITH HIGHS NEARING 90 ON
SATURDAY. DEW PTS IN THE 60S SAT SHOULD KEEP HEAT INDICES WELL BELOW
ADVISORY LVLS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...QUIET WEATHER PATTERN
FOR SUN INTO MON WITH HIGH PRESS DOMINATING CONDITIONS BEHIND A
COLD FRONT. THE FRONT LINGERS OFF THE DELMARVA COAST AS IT
WEAKENS... THEREFORE CANNOT RULE OUT SOME SHOWERS TO THE SE AND E
OF OUR CWA. SHORTWAVE TROUGH COULD BRING SOME AFTN SHOWERS ON MON
AND TUE... BUT CONFIDENCE WITH IT IS LOW ATTM... SO HAVE KEPT LOW
POPS. ANOTHER FRONT APPROACHES ON WED INCREASING THE CHANCE OF
SHOWERS AND TSTMS FOR THIS DAY. TEMPS WILL NEAR NORMAL SUN AND
GRADUALLY INCREASING INTO HE LOW 90S FOR WED.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...CHANCE OF A SHOWER OR
T-STORM UNTIL 00Z TONIGHT. PATCHY DENSE FOG DEVELOPING LATE
TONIGHT AT THE USUAL TROUBLE SPOTS. CDFNT WILL CROSS THE AREA THU
AFTERNOON

VFR CONDITIONS FRIDAY AND SATURDAY. WINDS GENERALLY 10 KTS OR
LESS...SHIFTING FROM THE NW FRIDAY TO A WESTERLY FLOW SAT.

&&

.MARINE...SRLY WINDS EXPECTED TO INCREASE TONIGHT OVER THE BAY AND
CONTINUE THROUGH THE DAY THU. SCA WAS EXPANDED TO COVER THE ENTIRE
LENGTH OF THE BAY.

BRIEF PERIOD OF SCA GUSTS EARLY FRIDAY MORNING ON THE CHESAPEAKE
BAY...WITH ALL WATERS BCMG SUB-SCA BY FRI AFT. SUB-SCA CONDITIONS
THEN LASTING INTO THE WEEKEND.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 7 PM EDT
     THURSDAY FOR ANZ530>534-537-539>541-543.

&&

SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...SEARS
LONG TERM...IMR
AVIATION...SEARS/IMR/LFR
MARINE...SEARS/IMR/LFR

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 30, 1:30 AM EDTSmall Craft AdvisoryLWX18 hr
Jul 30, 12:59 PM EDTSpecial Marine WarningLWX91 min
Jul 30, 1:05 PM EDTSpecial Marine WarningLWX85 min
Jul 30, 2:02 PM EDTSpecial Marine WarningLWX88 min
Jul 30, 2:06 PM EDTSpecial Marine WarningLWX84 min
Jul 30, 2:25 PM EDTSpecial Marine WarningLWX20 min
Jul 30, 3:18 PM EDTSpecial Marine WarningLWX87 min
Jul 30, 3:26 PM EDTSpecial Marine WarningLWX49 min
Jul 30, 3:46 PM EDTSpecial Marine WarningLWX29 min
Jul 30, 4:12 PM EDTSpecial Marine WarningLWX63 min
Jul 30, 4:42 PM EDTSpecial Marine WarningLWX93 min
Jul 30, 5:32 PM EDTSpecial Marine WarningLWX88 min
Jul 29, 9:54 PM EDTCoastal Flood AdvisoryLWXAnne Arundel11 hr

Nearby

Severe Thunderstorm Warnings in Virginia, 2015Severe Thunderstorm Warnings in Maryland, 2015Every severe thunderstorm warning in 2015

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.