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Overview
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The last of a three-day period of severe weather in the National Weather Service Mount Holly county warning area (CWA) occurred on 30 May 2019. A low-amplitude shortwave trough in the Great Lakes region approached the northern Mid-Atlantic during the afternoon and evening hours, with fast midlevel flow downstream aiding in strong deep-layer shear. However, antecedent convection on 28-29 May weakened midlevel lapse rates sufficiently to lower the significant severe threat that existed the prior two days. Nevertheless, sufficient heating downstream of the aforementioned shortwave trough allowed for clusters of storms to develop from Pennsylvania southward to Virginia. A small but potent mesoscale convective system (MCS) developed near the DC area and spread eastward through Delmarva during the late afternoon hours. Widespread damaging winds were observed, with substantial tree damage in Caroline County in Maryland and Sussex County in Delaware reported. Meanwhile, in eastern Pennsylvania and New Jersey, instability was meager (limiting the severe-weather threat), but the environment proved favorable for heavy rainfall. Several instances of flooding were reported from Northampton County eastward to Morris and Somerset Counties in New Jersey.  Composite radar loop of the Delmarva mesoscale convective system on 30 May 2019. |
 Tree and roof damage near Milford, DE. Photo courtesy Lynn Wilkins. |
Synoptic Overview at 12z 30 May 2019 (courtesy of SPC)
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| Figure 1: 250-mb analysis | Figure 2: 300-mb analysis | Figure 3: 500-mb analysis |
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| Figure 4: 700-mb analysis | Figure 5: 850-mb analysis | Figure 6: 925-mb analysis |
Synoptic Overview at 00z 31 May 2019 (courtesy of SPC)
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| Figure 7: 250-mb analysis | Figure 8: 300-mb analysis | Figure 9: 500-mb analysis |
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| Figure 10: 700-mb analysis | Figure 11: 850-mb analysis | Figure 12: 925-mb analysis |
Surface Maps (courtesy of WPC)
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| Figure 13: 15z surface map | Figure 14: 18z surface map | Figure 15: 21z surface map |
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| Figure 16: 00z surface map | Figure 17: 03z surface map | Figure 18: 06z surface map |
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| Figure 19: 12z Upton, NY sounding | Figure 20: 12z Sterling, VA sounding | Figure 21: 12z Wallops Island, VA sounding |
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| Figure 22: 00z Upton, NY sounding | Figure 23: 00z Sterling, VA sounding | Figure 24: 00z Wallops Island, VA sounding |
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| Figure 1: National Preliminary Reports 12z 30 May 2019 to 12z 31 May 2019 | Figure 2: Zoomed Preliminary Reports for the same period. | Figure 3: Prelim Reports vs. 1630z SPC Convective Outlook |
Click here for a county warning area based plot of local storm reports and warnings/advisories issued for the 30 May 2019 event.
Flash Flood Watch 0005 Severe Thunderstorm Watch 0297 Severe Thunderstorm Warning 0103 Areal Flood Advisory 0064 Areal Flood Advisory 0065 Areal Flood Advisory 0066 Severe Thunderstorm Warning 0104 Severe Thunderstorm Warning 0105 Severe Thunderstorm Warning 0106 Severe Thunderstorm Warning 0107 Flash Flood Warning 0011 Areal Flood Advisory 0067 Special Marine Warning 0053 Areal Flood Advisory 0068 Severe Thunderstorm Warning 0108 Flash Flood Warning 0012 Severe Thunderstorm Warning 0109 Areal Flood Advisory 0069 Severe Thunderstorm Warning 0110 Special Marine Warning 0054 Severe Thunderstorm Warning 0111 Special Marine Warning 0055 Flash Flood Warning 0013 Flash Flood Warning 0014 Areal Flood Warning 0016 Areal Flood Warning 0017 Special Marine Warning 0056 Areal Flood Warning 0018
NWUS51 KPHI 021609
LSRPHI
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1209 PM EDT SUN JUN 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0430 PM TSTM WND GST CARVILLE 39.05N 76.01W
05/30/2019 M52 MPH QUEEN ANNES MD MESONET
0430 PM TSTM WND DMG QUEEN ANNE 38.92N 75.96W
05/30/2019 QUEEN ANNES MD 911 CALL CENTER
REPORTS OF TREES DOWN AND POWER OUTAGES NEAR
THE QUEEN ANNE AREA ALONG THE QUEEN ANNES
AND TALBOT COUNTY BORDER. TIME ESTIMATED
FROM RADAR.
0435 PM TSTM WND DMG 1 ESE OAKLAND 38.98N 75.87W
05/30/2019 CAROLINE MD PUBLIC
STRAIGHT-LINE WINDS ESTIMATED BETWEEN 60 AND
70 MPH UPROOTED OR SNAPPED LARGE LIMBS FROM
15 TREES. DELAYED REPORT FROM THURSDAY
AFTERNOON.
0435 PM TSTM WND DMG RIDGELY 38.95N 75.89W
05/30/2019 CAROLINE MD 911 CALL CENTER
TREES AND WIRED DOWN IN RIDGELY. TIME BASED
ON RADAR.
0440 PM TSTM WND DMG GREENSBORO 38.98N 75.81W
05/30/2019 CAROLINE MD 911 CALL CENTER
TREES AND WIRES DOWN IN GREENSBORO. TIME
ESTIMATED BY RADAR.
0445 PM TSTM WND DMG GOLDSBORO 39.04N 75.79W
05/30/2019 CAROLINE MD 911 CALL CENTER
TREES AND WIRED DOWN IN GOLDSBORO. TIME
ESTIMATED BY RADAR.
0450 PM TSTM WND GST 2 N EASTON 38.80N 76.07W
05/30/2019 M47 MPH TALBOT MD ASOS
EASTON, MD ASOS GUST.
0454 PM TSTM WND GST OXFORD 38.69N 76.17W
05/30/2019 M58 MPH TALBOT MD MESONET
0455 PM TSTM WND DMG ALBRIGHTSVILLE 41.01N 75.60W
05/30/2019 CARBON PA PUBLIC
DOWNED TREES AND POWERLINES IN
ALBRIGHTSVILLE.
0502 PM TSTM WND DMG 1 NE FELTON 39.02N 75.56W
05/30/2019 KENT DE 911 CALL CENTER
TREE DOWN INTO WIRES IN FELTON. TIME
ESTIMATED FROM RADAR.
0504 PM FLOOD 1 ENE BRASS CASTLE 40.76N 75.00W
05/30/2019 WARREN NJ DEPT OF HIGHWAYS
KINNAMAN AVE FLOODED.
0505 PM TSTM WND DMG PRESTON 38.72N 75.91W
05/30/2019 CAROLINE MD 911 CALL CENTER
WIRES DOWN IN PRESTON. TIME ESTIMATED BY
RADAR.
0510 PM TSTM WND DMG ALLAMUCHY-PANTHER VALLE 40.91N 74.83W
05/30/2019 WARREN NJ COUNTY OFFICIAL
SOME REPORTS OF A FEW TREES DOWN IN
ALLAMUCHY TWP. TIME ESTIMATED FROM RADAR.
0514 PM TSTM WND DMG 4 WSW BIG STONE BEACH 38.97N 75.39W
05/30/2019 KENT DE 911 CALL CENTER
MULTIPLE REPORTS OF TREES ACROSS ROADWAYS
AND TREES INTO WIRES IN SOUTH BOWERS. TIME
ESTIMATED FROM RADAR.
0520 PM FLOOD 1 W ROXBURG 40.78N 75.13W
05/30/2019 WARREN NJ DEPT OF HIGHWAYS
FLOODING ON HUTCHINSON RIVER RD.
0520 PM TSTM WND DMG 1 SW SEAFORD 38.64N 75.62W
05/30/2019 SUSSEX DE FIRE DEPT/RESCUE
DOWNED WIRES AT INTERSECTION OF BRADFORD
STREET AND PENNSYLVANIA AVENUE. TIME
ESTIMATED FROM RADAR.
0526 PM TSTM WND DMG GEORGETOWN 38.69N 75.39W
05/30/2019 SUSSEX DE 911 CALL CENTER
DOWNED TREES IN GEORGETOWN. TIME ESTIMATED
FROM RADAR.
0530 PM FLASH FLOOD FORKS TWP 40.73N 75.19W
05/30/2019 NORTHAMPTON PA NEWSPAPER
DELAYED REPORT. NUMEROUS ROADS FLOODED AND
IMPASSABLE IN FORKS TWP, INCLUDING
KESSLERSVILLE ROAD AT HUNTER ROAD, RICHMOND
ROAD AT SHORT ROAD, GLOVER ROAD AND PADULA
ROAD, WEST NEWLINS ROAD AT SULLIVAN TRAIL,
AND KLEIN ROAD. PHOTOS INDICATE INUNDATION
OF 2 TO MORE THAN 4 FEET ON SOME ROADS. TIME
ESTIMATED FROM NEARBY REPORTS AND RADAR.
0531 PM TSTM WND DMG 2 NNE LAKESIDE MANOR 38.59N 75.54W
05/30/2019 SUSSEX DE DEPT OF HIGHWAYS
U.S. HIGHWAY 9 CLOSED BETWEEN FIRE TOWER
ROAD AND KAYE ROAD OWING TO DOWNED TREES AND
POWER LINES. TIME ESTIMATED FROM RADAR.
0538 PM TSTM WND DMG LEWES 38.78N 75.13W
05/30/2019 SUSSEX DE 911 CALL CENTER
SEVERAL DOWNED TREES IN LEWES. TIME
ESTIMATED FROM RADAR.
0540 PM FLOOD 1 SE ROXBOROUGH 39.99N 75.21W
05/30/2019 PHILADELPHIA PA TRAINED SPOTTER
UP TO FOUR FEET OF WATER UNDER AN OVERPASS
ON FAIRMOUNT PARK DR.
0540 PM TSTM WND GST 2 WNW LEWES 38.79N 75.16W
05/30/2019 M53 MPH SUSSEX DE MESONET
MEASURED BY WXFLOW GAUGE.
0542 PM MARINE TSTM WIND CAPE HENLOPEN BEACH 38.81N 75.10W
05/30/2019 M46 MPH ANZ431 DE MESONET
DELAYED REPORT FROM THURSDAY.
0542 PM MARINE TSTM WIND 1 ENE LEWES 38.78N 75.11W
05/30/2019 M46 MPH SUSSEX DE MESONET
0545 PM MARINE TSTM WIND 1 WNW LEWES 38.79N 75.15W
05/30/2019 M43 MPH SUSSEX DE MESONET
0546 PM FLOOD 1 S PORT MURRAY 40.77N 74.92W
05/30/2019 WARREN NJ COUNTY OFFICIAL
CHANGEWATER ROAD FLOODED FROM ASBURY
ANDERSON ROAD TO THE HUNTERDON COUNTY LINE.
0548 PM MARINE TSTM WIND DEWEY BEACH 38.69N 75.07W
05/30/2019 M51 MPH ANZ455 DE MESONET
DELAYED REPORT FROM THURSDAY.
0548 PM TSTM WND GST INDIAN BEACH 38.68N 75.08W
05/30/2019 M52 MPH SUSSEX DE MESONET
MEASURED BY WXFLOW GAUGE.
0548 PM FLOOD 1 ESE TACONY 40.02N 75.03W
05/30/2019 PHILADELPHIA PA DEPT OF HIGHWAYS
FLOODING ON INTERSTATE 95 AT EXIT 30. RAMP
CLOSURE IN PLACE.
0548 PM MARINE TSTM WIND INDIAN BEACH 38.68N 75.08W
05/30/2019 M52 MPH SUSSEX DE MESONET
MEASURED BY WXFLOW GAUGE.
0548 PM MARINE TSTM WIND 1 SSW NORTH CAPE MAY 38.97N 74.96W
05/30/2019 M42 MPH CAPE MAY NJ MESONET
CMAN4 NOS GAUGE.
0550 PM MARINE TSTM WIND 2 WNW LEWES 38.79N 75.16W
05/30/2019 M53 MPH SUSSEX DE MESONET
MEASURED BY WXFLOW GAUGE.
0552 PM TSTM WND DMG 1 ENE MILLVILLE 38.55N 75.09W
05/30/2019 SUSSEX DE 911 CALL CENTER
SEVERAL DOWNED TREES IN THE MILLVILLE AND
OCEAN VIEW AREA. TIME ESTIMATED FROM RADAR.
0558 PM FLOOD 1 NE MANSFIELD TWP 40.81N 74.90W
05/30/2019 WARREN NJ COUNTY OFFICIAL
FLOODING REPORTED ON ROCKPORT ROAD IN
MANSFIELD TWP.
0603 PM MARINE TSTM WIND INDIAN BEACH 38.68N 75.08W
05/30/2019 M47 MPH SUSSEX DE MESONET
MEASURED BY WXFLOW GAUGE.
0611 PM FLOOD 1 NNE LAWRENCE PARK 39.98N 75.34W
05/30/2019 DELAWARE PA DEPT OF HIGHWAYS
FLOODING ON INTERSTATE 476 NEAR THE BROOMALL
EXIT. LANE RESTRICTIONS IN PLACE.
0629 PM FLOOD 1 NW LOWER FREDERICK TW 40.29N 75.48W
05/30/2019 MONTGOMERY PA PUBLIC
SALFORD STATION ROAD CLOSED NEAR STATE
HIGHWAY 29 DUE TO FLOODING.
0636 PM FLOOD 1 SE ROXBOROUGH 39.99N 75.21W
05/30/2019 PHILADELPHIA PA PUBLIC
MARTIN LUTHER KING JR. DRIVE CLOSED NEAR
MONTGOMERY DRIVE FROM FLOODING.
0656 PM FLASH FLOOD 2 ENE SOMERVILLE 40.58N 74.58W
05/30/2019 SOMERSET NJ DEPT OF HIGHWAYS
U.S. HIGHWAY 22 CLOSED AT NORTH ADAMSVILLE
ROAD FROM FLASH FLOODING.
0657 PM FLASH FLOOD 1 N BOUND BROOK 40.58N 74.53W
05/30/2019 SOMERSET NJ DEPT OF HIGHWAYS
U.S. HIGHWAY 22 CLOSED AT MOUNTAIN AVENUE
FROM FLASH FLOODING.
0700 PM FLOOD 2 NNE BASKING RIDGE 40.73N 74.54W
05/30/2019 MORRIS NJ DEPT OF HIGHWAYS
FLOODING ON INTERSTATE 287 NORTHBOUND NEAR
EXIT 30. LANE RESTRICTIONS IN PLACE.
0702 PM FLOOD 2 SSW MARTINSVILLE 40.58N 74.57W
05/30/2019 SOMERSET NJ DEPT OF HIGHWAYS
FLOODING ON INTERSTATE 287 NORTHBOUND AT
EXIT 14. RAMP CLOSURE IN PLACE.
0712 PM FLOOD 2 NW WHITE HOUSE STATIO 40.64N 74.79W
05/30/2019 HUNTERDON NJ DEPT OF HIGHWAYS
FLOODING ON U.S. HIGHWAY 22 NEAR POTTERSTOWN
ROAD IN READINGTON TWP. LANE RESTRICTIONS IN
PLACE.
0736 PM FLOOD 1 E MADISON 40.76N 74.39W
05/30/2019 MORRIS NJ DEPT OF HIGHWAYS
STATE HIGHWAY 24 NEAR EXIT 7 FLOODED WITH
LANE RESTRICTIONS IN PLACE.
0738 PM FLOOD 3 WSW PLEASANT VALLEY 40.73N 75.06W
05/30/2019 WARREN NJ DEPT OF HIGHWAYS
STATE HIGHWAY 57 FLOODED NEAR ASBURY
BROADWAY ROAD IN FRANKLIN TWP. LANE
RESTRICTIONS IN PLACE.
&&
$$
CMS
Delmarva MCS (GR2Analyst)
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| Figure 1: Loop of KDOX radar reflectivity factor (top left), base velocity (top right), correlation coefficient (CC; bottom left), and differential reflectivity (ZDR; bottom right) valid from 2028 UTC to 2047 UTC on 30 May 2019. During this portion of the event in Delmarva, several instances of wind damage occurred in northern Caroline County (MD) between Ridgely and Goldsboro. The loop suggests velocities around 1500 feet above ground level (AGL) were well in excess of 50 kts. The storm was also exhibiting characteristics of bowing (bending downstream, as in the extension of a bow). This is strongly indicative of an intense rear-inflow jet (horizontal stream of air coming into the storms from behind) that is forced downward to the surface as the flow of air reaches the downdraft. The loop indicates these strong winds were fairly widespread across the area where wind damage occurred. Note the base velocities markedly change appearance in the last two frames; this is because of a change in the configuration of the radar that allowed for less velocity folding (increased the scale of the velocities). Base velocities were actually similar in magnitude throughout this loop. | Figure 2: Same as Fig. 1, valid from 2105 to 2117 UTC on 30 May 2019. Several reports of wind damage occurred between Ellendale and Frederica, and radar is strongly suggestive of a bowing segment within the broader line of storms (near and north of Milford, in particular). Note that velocities are not particularly impressive, but this is because the winds are mostly perpendicular to the radar beam at this time (which are not picked up by the radar). In the last frame of the loop, stronger velocities begin to appear near Slaughter Beach, since the beam becomes more parallel to the motion of the winds again (and imply magnitudes 70+ kts around 1500 ft AGL). |
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