National Weather Service United States Department of Commerce

East Coast Flash Flood/Severe Thunderstorm Threat Monday

A cold front and waves of low pressure will slowly shift across the Mid-Atlantic and Southeast states Monday and Tuesday. Heavy thunderstorms along this front may produce heavy rain and flash flooding with the highest threat Monday from Tennessee into New England. A few strong to severe thunderstorms are also possible mainly from Northern Maryland to southern New Jersey. Read More >

Overview

An amplified trough centered in Ontario moved slowly eastward on 2 June 2019, with highly difluent mid/upper flow downstream across the northeastern U.S.  Strong diabatic heating contributed to the development of moderate instability during the afternoon across the northern Mid-Atlantic (1000-2000 J/kg MLCAPE).  Discrete storms developed rapidly along the I-95 corridor eastward into coastal New Jersey during mid-afternoon, with sufficient deep-layer shear combining with substantial instability to generate strong updrafts producing small to marginally severe hail in several locations across the area.  With time, convection began to organize into multicellular clusters and line segments, and the primary severe threat transitioned to damaging winds during the evening hours.  Several microbursts were observed across the area, including near Bear and Wilmington Manor in Delaware, the Croydon community in Bucks County in Pennsylvania, and portions of Somerset County in New Jersey.  These microbursts produced significant tree damage, with several instances of large trees falling onto and damaging property.  Fortunately, no injuries were reported.

Images of damage in Bucks County from a microburst on 2 June 2019.

Image
Image
Image

Meteorological Environment/Setup

Synoptic Overview at 12z 2 June 2019 (courtesy of SPC)

Environment Environment Environment
Figure 1: 250-mb analysis Figure 2: 300-mb analysis Figure 3: 500-mb analysis
 
Environment Environment Environment
Figure 4: 700-mb analysis Figure 5: 850-mb analysis Figure 6: 925-mb analysis

Synoptic Overview at 00z 3 June 2019 (courtesy of SPC)

Environment Environment Environment
Figure 7: 250-mb analysis Figure 8: 300-mb analysis Figure 9: 500-mb analysis
 
Environment Environment Environment
Figure 10: 700-mb analysis Figure 11: 850-mb analysis Figure 12: 925-mb analysis
 

Surface Maps (courtesy of WPC)

Environment Environment Environment
Figure 13: 15z surface map Figure 14: 18z surface map Figure 15: 21z surface map
 
Environment Environment Environment
Figure 16: 00z surface map Figure 17: 03z surface map Figure 18: 06z surface map

Observed Soundings
Environment Environment Environment
Figure 19: 12z Pittsburgh, PA sounding Figure 20: 12z Sterling, VA sounding Figure 21: 12z Wallops Island, VA sounding
Environment Environment Environment
Figure 22: 00z Upton, NY sounding Figure 23: 00z Sterling, VA sounding Figure 24: 00z Wallops Island, VA sounding

Preliminary Storm Reports

prelimreports prelimreports prelimreports
Figure 1: National Preliminary Reports 12z 2 June 2019 to 12z 3 June 2019 Figure 2: Zoomed Preliminary Reports for the same period. Figure 3: Prelim Reports vs. 1630z SPC Convective Outlook

Warning Information

prelimreports
Figure 1: Plot of local storm reports and storm-based warnings for the 2 June 2019 event. Click here for more information.

Preliminary Local Storm Reports

 

NWUS51 KPHI 030750
LSRPHI

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
350 AM EDT MON JUN 3 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0246 PM     HAIL             2 E WILLOWDALE          39.87N 75.68W
06/02/2019  E0.25 INCH       CHESTER            PA   PUBLIC           

            MPING REPORT. 

0247 PM     HAIL             KENNETT SQUARE          39.85N 75.71W
06/02/2019  E0.25 INCH       CHESTER            PA   PUBLIC           

             

0303 PM     HAIL             THORNBURY TWP           39.93N 75.53W
06/02/2019  M0.75 INCH       DELAWARE           PA   TRAINED SPOTTER  

             

0310 PM     HAIL             AUGUSTINE               39.77N 75.56W
06/02/2019  E0.75 INCH       NEW CASTLE         DE   PUBLIC           

            UP TO PEA SIZED HAIL REPORTED IN NORTH 
            WILMINGTON. 

0313 PM     HAIL             1 N NEWLIN TWP          39.92N 75.70W
06/02/2019  E0.75 INCH       CHESTER            PA   PUBLIC           

            MPING REPORT. 

0319 PM     HAIL             1 NE PENNSAUKEN         39.96N 75.06W
06/02/2019  E0.25 INCH       CAMDEN             NJ   PUBLIC           

            ONE-QUARTER TO ONE-HALF INCH HAIL REPORTED 
            IN PENNSAUKEN. 

0319 PM     HAIL             GLEN MILLS              39.92N 75.49W
06/02/2019  E1.00 INCH       DELAWARE           PA   PUBLIC           

             

0321 PM     HAIL             POCOPSON TWP            39.91N 75.64W
06/02/2019  E1.00 INCH       CHESTER            PA   PUBLIC           

            TIME ESTIMATED FROM RADAR. 

0324 PM     HAIL             PHOENIXVILLE            40.13N 75.51W
06/02/2019  E0.75 INCH       CHESTER            PA   PUBLIC           

             

0326 PM     HAIL             MOORESTOWN              39.97N 74.94W
06/02/2019  E0.75 INCH       BURLINGTON         NJ   PUBLIC           

             

0329 PM     HAIL             KING OF PRUSSIA         40.09N 75.38W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0330 PM     HAIL             WEST CHESTER            39.96N 75.60W
06/02/2019  E0.75 INCH       CHESTER            PA   PUBLIC           

             

0330 PM     HAIL             2 WNW KING OF PRUSSIA   40.11N 75.42W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

            MPING REPORT. 

0335 PM     HAIL             2 SSW CHEYNEY           39.91N 75.54W
06/02/2019  E0.25 INCH       DELAWARE           PA   PUBLIC           

            MPING REPORT. 

0337 PM     HAIL             GLEN MILLS              39.92N 75.49W
06/02/2019  E0.75 INCH       DELAWARE           PA   TRAINED SPOTTER  

            DIME TO PENNY SIZE HAIL REPORTED IN GLEN 
            MILLS. 

0340 PM     HAIL             1 ESE RANCOCAS          40.01N 74.85W
06/02/2019  E0.75 INCH       BURLINGTON         NJ   TRAINED SPOTTER  

            UP TO PENNY SIZE HAIL REPORTED IN 
            WILLINGBORO. 

0349 PM     HAIL             LIMA                    39.92N 75.44W
06/02/2019  E0.88 INCH       DELAWARE           PA   TRAINED SPOTTER  

             

0350 PM     HAIL             MEDIA                   39.92N 75.38W
06/02/2019  E0.25 INCH       DELAWARE           PA   PUBLIC           

             

0351 PM     HAIL             NWS MOUNT HOLLY         40.01N 74.82W
06/02/2019  E0.25 INCH       BURLINGTON         NJ   OFFICIAL NWS OBS 

            PEA SIZED HAIL REPORTED AT THE NWS OFFICE. 

0353 PM     HAIL             GLEN MILLS              39.92N 75.49W
06/02/2019  E0.75 INCH       DELAWARE           PA   PUBLIC           

            TIME ESTIMATED FROM RADAR. 

0355 PM     HAIL             COLUMBUS                40.08N 74.72W
06/02/2019  E1.00 INCH       BURLINGTON         NJ   PUBLIC           

             

0355 PM     HAIL             EAST NORRITON           40.16N 75.34W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0356 PM     HAIL             1 N UPPER DUBLIN TWP    40.17N 75.20W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

            MPING REPORT. 

0405 PM     HAIL             BURLINGTON TWP          40.07N 74.83W
06/02/2019  E0.25 INCH       BURLINGTON         NJ   PUBLIC           

             

0408 PM     HAIL             WARMINSTER              40.21N 75.10W
06/02/2019  E0.25 INCH       BUCKS              PA   PUBLIC           

             

0414 PM     HAIL             WYNCOTE                 40.09N 75.15W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

            TIME ESTIMATED FROM RADAR. 

0415 PM     HAIL             GLENSIDE                40.10N 75.15W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0415 PM     HAIL             ABINGTON                40.12N 75.13W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0417 PM     HAIL             ABINGTON                40.12N 75.13W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0420 PM     HAIL             NORTHEAST PHILADELPHIA  40.09N 75.02W
06/02/2019  E0.25 INCH       PHILADELPHIA       PA   PUBLIC           

            TIME ESTIMATED FROM RADAR. 

0423 PM     HAIL             MANAHAWKIN              39.69N 74.26W
06/02/2019  M0.75 INCH       OCEAN              NJ   TRAINED SPOTTER  

             

0428 PM     HAIL             SOMERTON                40.12N 75.01W
06/02/2019  E0.25 INCH       PHILADELPHIA       PA   PUBLIC           

             

0430 PM     HAIL             1 NE SOMERTON           40.13N 75.00W
06/02/2019  E0.25 INCH       BUCKS              PA   PUBLIC           

            MPING REPORT. 

0434 PM     HAIL             1 ENE LOWER MAKEFIELD T 40.23N 74.83W
06/02/2019  E0.25 INCH       BUCKS              PA   PUBLIC           

            MPING REPORT. 

0440 PM     HAIL             2 WSW EWING             40.26N 74.83W
06/02/2019  E0.25 INCH       MERCER             NJ   PUBLIC           

             

0440 PM     HAIL             3 S CLARKSBURG          40.15N 74.44W
06/02/2019  E0.25 INCH       MONMOUTH           NJ   PUBLIC           

             

0500 PM     HAIL             BARNEGAT                39.75N 74.22W
06/02/2019  M0.50 INCH       OCEAN              NJ   TRAINED SPOTTER  

             

0500 PM     HAIL             TUCKERTON               39.60N 74.34W
06/02/2019  E0.75 INCH       OCEAN              NJ   PUBLIC           

             

0602 PM     HAIL             LINCOLN UNIVERSITY      39.80N 75.92W
06/02/2019  M0.75 INCH       CHESTER            PA   PUBLIC           

             

0608 PM     HAIL             1 SE NEW LONDON TWP.    39.78N 75.86W
06/02/2019  E0.25 INCH       CHESTER            PA   PUBLIC           

            MPING REPORT. 

0614 PM     HAIL             1 S WEST GROVE          39.80N 75.83W
06/02/2019  E0.25 INCH       CHESTER            PA   COCORAHS         

             

0616 PM     TSTM WND DMG     WEST GROVE              39.82N 75.82W
06/02/2019                   CHESTER            PA   COUNTY OFFICIAL  

            DOWNED TREES NEAR AND ON THE RAILROAD TRACKS 
            NEAR RAILROAD AVENUE AND OAKLAND AVENUE. 
            TIME ESTIMATED FROM RADAR. 

0619 PM     HAIL             1 SE WEST GROVE         39.81N 75.81W
06/02/2019  E0.25 INCH       CHESTER            PA   TRAINED SPOTTER  

             

0630 PM     HAIL             2 S ODESSA              39.43N 75.66W
06/02/2019  E0.25 INCH       NEW CASTLE         DE   PUBLIC           

            MPING REPORT. 

0636 PM     TSTM WND DMG     WOODSHADE               39.65N 75.69W
06/02/2019                   NEW CASTLE         DE   PUBLIC           

            DOWNED WIRES ON CEDAR RIDGE COURT. TIME 
            ESTIMATED FROM RADAR. 

0639 PM     TSTM WND DMG     2 E WOODSHADE           39.65N 75.65W
06/02/2019                   NEW CASTLE         DE   PUBLIC           

            TREES DOWN AT THE CHRISTIANA MEADOWS 
            APARTMENT COMPLEX. 

0645 PM     TSTM WND DMG     1 E MIDVALE             39.66N 75.60W
06/02/2019                   NEW CASTLE         DE   PUBLIC           

            REPORT OF WIRES DOWN ON DUPONT HIGHWAY NEAR 
            WILMINGTON MANOR. TIME ESTIMATED FROM RADAR. 

0645 PM     TSTM WND GST     4 SSW ELSINBORO TWP     39.48N 75.54W
06/02/2019  M56 MPH          SALEM              NJ   MESONET          

            LOWER ALLOWAYS CREEK MESONET STATION. 

0647 PM     HAIL             WILMINGTON              39.75N 75.56W
06/02/2019  E1.00 INCH       NEW CASTLE         DE   TRAINED SPOTTER  

            DIME TO QUARTER SIZE HAIL REPORTED IN 
            WILMINGTON. 

0647 PM     TSTM WND DMG     1 SW MIDVALE            39.65N 75.62W
06/02/2019                   NEW CASTLE         DE   DEPT OF HIGHWAYS 

            DOWNED WIRES HAVE CLOSED U.S. HIGHWAY 13 
            SOUTH OF U.S. HIGHWAY 40. TIME ESTIMATED 
            FROM RADAR. 

0652 PM     HAIL             MONROE PARK             39.78N 75.53W
06/02/2019  M1.00 INCH       NEW CASTLE         DE   TRAINED SPOTTER  

             

0653 PM     HAIL             CARRCROFT               39.78N 75.50W
06/02/2019  E0.75 INCH       NEW CASTLE         DE   PUBLIC           

            OBSERVED AT BELLEVUE STATE PARK. 

0654 PM     TSTM WND DMG     1 ENE BRECKNOCK TWP.    40.24N 75.97W
06/02/2019                   BERKS              PA   FIRE DEPT/RESCUE 

            REPORTS OF TREES DOWN ON GILL ROAD, KURTZ 
            MILL ROAD, AND CANDY ROAD IN BRECKNOCK TWP. 
            TIME ESTIMATED FROM RADAR. 

0654 PM     HAIL             1 N NEW MORGAN          40.21N 75.89W
06/02/2019  M0.25 INCH       BERKS              PA   COCORAHS         

             

0655 PM     TSTM WND GST     READING REGIONAL AIRPOR 40.37N 75.96W
06/02/2019  M48 MPH          BERKS              PA   ASOS             

             

0705 PM     TSTM WND GST     1 WNW CEDARVILLE        39.63N 75.36W
06/02/2019  M46 MPH          SALEM              NJ   MESONET          

            NJWXNET GAUGE. 

0715 PM     TSTM WND GST     POTTSTOWN               40.25N 75.65W
06/02/2019  E50 MPH          MONTGOMERY         PA   TRAINED SPOTTER  

            ESTIMATED 40 TO 50 MPH WIND GUST. TIME 
            ESTIMATED FROM RADAR. 

0715 PM     HAIL             POTTSTOWN               40.25N 75.65W
06/02/2019  M0.25 INCH       MONTGOMERY         PA   TRAINED SPOTTER  

             

0717 PM     TSTM WND DMG     1 ESE UPPER PITTSGROVE  39.61N 75.22W
06/02/2019                   SALEM              NJ   DEPT OF HIGHWAYS 

            U.S. HIGHWAY 40 CLOSED BETWEEN STATE HIGHWAY 
            77 AND COUNTY ROAD 648 OWING TO DOWNED POWER 
            CABLES. TIME ESTIMATED FROM RADAR. 

0722 PM     TSTM WND DMG     3 E GILBERTSVILLE       40.31N 75.54W
06/02/2019                   MONTGOMERY         PA   PUBLIC           

            MPING REPORT OF TREES AND POWER LINES DOWN. 
            TIME ESTIMATED FROM RADAR. 

0725 PM     HAIL             GILBERTSVILLE           40.32N 75.61W
06/02/2019  M0.25 INCH       MONTGOMERY         PA   TRAINED SPOTTER  

             

0729 PM     HAIL             2 SW CLAYTON            39.64N 75.12W
06/02/2019  E0.25 INCH       GLOUCESTER         NJ   PUBLIC           

            MPING REPORT. 

0730 PM     TSTM WND DMG     FRANKLINVILLE           39.62N 75.08W
06/02/2019                   GLOUCESTER         NJ   FIRE DEPT/RESCUE 

            SEVERAL TREES AND POWER LINES DOWN. TIME 
            ESTIMATED FROM RADAR. 

0732 PM     HAIL             SEWELL                  39.77N 75.15W
06/02/2019  E0.25 INCH       GLOUCESTER         NJ   TRAINED SPOTTER  

             

0737 PM     TSTM WND DMG     3 E CHURCH HILL         39.14N 75.93W
06/02/2019                   QUEEN ANNES       MD   DEPT OF HIGHWAYS 

            U.S. HIGHWAY 301 CLOSED AT STATE HIGHWAY 302 
            FROM WIND DAMAGE AND DEBRIS. TIME ESTIMATED 
            FROM RADAR. 

0737 PM     HAIL             PINE HILL               39.79N 74.99W
06/02/2019  E0.25 INCH       CAMDEN             NJ   PUBLIC           

             

0738 PM     HAIL             2 SSW MONROE TWP        39.63N 74.98W
06/02/2019  E0.25 INCH       GLOUCESTER         NJ   PUBLIC           

            MPING REPORT. 

0740 PM     HAIL             UPPER SALFORD TWP       40.29N 75.45W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0741 PM     HAIL             WILLIAMSTOWN            39.69N 75.00W
06/02/2019  M0.50 INCH       GLOUCESTER         NJ   TRAINED SPOTTER  

             

0743 PM     HAIL             2 ESE MEDFORD LAKES     39.85N 74.77W
06/02/2019  E1.00 INCH       BURLINGTON         NJ   TRAINED SPOTTER  

             

0745 PM     HAIL             1 SW MEDFORD LAKES      39.85N 74.81W
06/02/2019  E0.25 INCH       BURLINGTON         NJ   PUBLIC           

            MPING REPORT. 

0746 PM     HAIL             FRANCONIA TWP           40.30N 75.36W
06/02/2019  E0.25 INCH       MONTGOMERY         PA   PUBLIC           

             

0756 PM     TSTM WND DMG     2 ENE KENTON            39.24N 75.63W
06/02/2019                   KENT               DE   PUBLIC           

            REPORT OF DOWNED WIRES ON MASSEYS MILLPOND 
            ROAD IN SMYRNA. TIME ESTIMATED FROM RADAR. 

0758 PM     HAIL             2 NW CHESWOLD           39.24N 75.61W
06/02/2019  E0.75 INCH       KENT               DE   PUBLIC           

            TIME AND LOCATION APPROXIMATED. 

0800 PM     TSTM WND DMG     CROYDON                 40.09N 74.90W
06/02/2019                   BUCKS              PA   PUBLIC           

            TREES DOWN INCLUDING ONE LARGE TREE 
            UPROOTED. PART OF A ROOF PEELED OFF OF A 
            BUILDING. TIME ESTIMATED FROM RADAR. 

0802 PM     HAIL             1 SSE BENSALEM          40.10N 74.92W
06/02/2019  E0.25 INCH       BUCKS              PA   PUBLIC           

            MPING REPORT. 

0805 PM     TSTM WND DMG     BRISTOL TWP             40.12N 74.87W
06/02/2019                   BUCKS              PA   FIRE DEPT/RESCUE 

            SEVERAL REPORTS OF TREES DOWN AROUND THE AREA, A FEW 
            OF WHICH FELL ON HOUSES, MAINLY IN THE CROYDON COMMUNITY.
            RAMP RESTRICTIONS AT EXIT 37 OF INTERSTATE 95 AT STATE
            HIGHWAY 132 ARE IN PLACE FROM DOWNED TREES. TIME ESTIMATED 
            FROM RADAR. 

0815 PM     TSTM WND DMG     BROWNS MILLS            39.97N 74.58W
06/02/2019                   BURLINGTON         NJ   PUBLIC           

            DELAYED REPORT. LARGE TREES DOWN AT A FEW 
            RESIDENCES. TIME ESTIMATED FROM RADAR. 

0818 PM     MARINE TSTM WIND 6 ESE WOODLAND BEACH    39.31N 75.38W
06/02/2019  M43 MPH          ANZ430             DE   MESONET          

            SHIP JOHN SHOAL NOS GAUGE. 

0834 PM     MARINE TSTM WIND 2 E WARETOWN            39.79N 74.17W
06/02/2019  M61 MPH          ANZ451             NJ   MESONET          

            WEATHERFLOW GAUGE. 

0834 PM     TSTM WND GST     WARETOWN                39.79N 74.20W
06/02/2019  M61 MPH          OCEAN              NJ   MESONET          

             

0840 PM     TSTM WND DMG     2 NW MILLSTONE          40.52N 74.61W
06/02/2019                   SOMERSET           NJ   PUBLIC           

            SOME TREES DOWN WHICH TOOK DOWN WIRES ON A 
            PORTION OF SUNNYMEADE ROAD IN HILLSBOROUGH. 
            TIME ESTIMATED FROM RADAR. 

0844 PM     HAIL             2 WSW FOLSOM            39.59N 74.88W
06/02/2019  E0.25 INCH       ATLANTIC           NJ   PUBLIC           

            MPING REPORT. 

0844 PM     TSTM WND GST     2 N BARNEGAT LIGHT      39.78N 74.11W
06/02/2019  M56 MPH          OCEAN              NJ   MESONET          

             

0845 PM     TSTM WND GST     2 SSW SEASIDE PARK      39.91N 74.09W
06/02/2019  M58 MPH          OCEAN              NJ   MESONET          

            CWOP SENSOR. 

0846 PM     MARINE TSTM WIND 1 E BARNEGAT LIGHT      39.76N 74.09W
06/02/2019  M44 MPH          ANZ451             NJ   MESONET          

            WEATHERFLOW GAUGE. 

0847 PM     TSTM WND DMG     2 WSW MANVILLE          40.54N 74.62W
06/02/2019                   SOMERSET           NJ   PUBLIC           

            DOWNED TREE ON U.S. HIGHWAY 206 SOUTH OF 
            BROOKS BLVD. ALL LANES CLOSED. TIME 
            ESTIMATED FROM RADAR. 

0853 PM     TSTM WND DMG     1 S SOUTH BOUND BROOK   40.55N 74.53W
06/02/2019                   SOMERSET           NJ   PUBLIC           

            TREE INTO A HOUSE AND WIRES DOWN ON MAPLE 
            AVENUE IN FRANKLIN TWP. TIME ESTIMATED FROM 
            RADAR. 

0856 PM     MARINE TSTM WIND 2 W BRICK               40.01N 74.09W
06/02/2019  M41 MPH          ANZ451             NJ   MESONET          

            WEATHERFLOW GAUGE. 

0910 PM     HAIL             MATAWAN                 40.41N 74.23W
06/02/2019  E0.25 INCH       MONMOUTH           NJ   PUBLIC           

             

0920 PM     TSTM WND DMG     1 WNW HAZLET            40.43N 74.20W
06/02/2019                   MONMOUTH           NJ   DEPT OF HIGHWAYS 

            DOWNED TREE ON NJ 36 NORTHBOUND IN THE AREA 
            OF MAIN STREET. ALL LANES CLOSED. TIME 
            ESTIMATED FROM RADAR. 

0927 PM     MARINE TSTM WIND 1 WNW MONMOUTH BEACH    40.34N 73.99W
06/02/2019  M45 MPH          MONMOUTH           NJ   MESONET          

            WEATHERFLOW GAUGE. 

0936 PM     TSTM WND GST     2 S SANDY HOOK          40.45N 74.00W
06/02/2019  M58 MPH          MONMOUTH           NJ   C-MAN STATION    

             

0942 PM     MARINE TSTM WIND 5 SE MYSTIC ISLAND      39.51N 74.32W
06/02/2019  M47 MPH          OCEAN              NJ   MESONET          

            HADS SENSOR. 

0945 PM     MARINE TSTM WIND 4 SE MYSTIC ISLAND      39.52N 74.32W
06/02/2019  M44 MPH          OCEAN              NJ   MESONET          

            WEATHERFLOW GAUGE. 

0946 PM     MARINE TSTM WIND 2 SSE TUCKERTON         39.58N 74.32W
06/02/2019  M43 MPH          ANZ451             NJ   MESONET          

             

0946 PM     MARINE TSTM WIND 2 SW BEACH HAVEN        39.54N 74.26W
06/02/2019  M43 MPH          OCEAN              NJ   MESONET          

             

&&

$$

CMS/GORSE

Radar Interrogation

Microburst in Croydon, PA (GR2Analyst and AWIPS)

Environment Environment
Figure 1: Loop of KDIX radar reflectivity factor (top left), base velocity (top right), correlation coefficient (bottom left), and differential reflectivity (bottom right) from 2353 UTC 2 June 2019 to 0007 UTC 3 June 2019. An area of stronger radar reflectivity factor moves over the Croydon area during this time, coinciding with the reported wind damage to the area (including numerous trees down and property damage). However, the presentation on radar is not overly suggestive of such a strong microburst. A primary reason for this is that the storm is traveling generally perpendicular to the direction of the radar pulse. Thus, the base velocities measured by the radar (which only measure velocities parallel to the beam) are fairly low (generally below 25 kts). Detection of severe winds is much more difficult with storms moving perpendicular to the radar pulse. Additionally, storms on this evening were low-topped (i.e., did not extend high into the atmosphere), which makes identification of severe storms more difficult as well. Figure 2: Loop of TPHL base velocities from 2353 UTC 2 June 2019 to 0001 UTC 3 June 2019. The Philadelphia Terminal Doppler radar is located in western New Jersey across the Delaware River from Philadelphia International Airport. In this case, the radar detects the Croydon microburst far better, since the winds are generally parallel to the radar pulse. Measured velocities here are above 50 kts around 750 feet above ground level (AGL), a strong suggestion of a severe storm.
Environment Environment
Figure 3: Cross section of the Croydon microburst using KDIX radar reflectivity factor valid at 2348 UTC (top left), 2353 UTC (top right), 2359 UTC (bottom left), and 0004 UTC (bottom right) 2-3 June 2019. The highest reflectivities are tilted (generally toward the east) with height, but the strongest cores generally reach around 10,000 feet AGL, an indication of the low-topped nature to the convection. However, the storm did have >50 dBZ echoes to around 20,000 feet AGL shortly before the microburst occurred (not shown). There is a general appearance of the strongest echo descending with time, indicative of a downdraft reaching the surface (overwhelming the updraft). Figure 4: Same as Fig. 1, valid at the 6.4 degree elevation angle (around 17,000 feet AGL near Croydon) at 0003 UTC 3 June 2019. There is a core of 60+ dBZ radar reflectivity factor at this level, suggesting a strong updraft is lofting rain and hail to this level. This is one of the indications this storm was at least capable of producing severe weather.

Delaware Severe Storms (GR2Analyst)

Environment Environment
Figure 5: Same as Fig. 1, using KDOX and valid from 2229 UTC to 2247 UTC on 2 June 2019. Similar to the Croydon microburst, the storm's motion in this case was generally easterly. This is perpendicular to the direction of the radar pulse from KDOX (located at Dover Air Force Base). As such, base velocities are once again rather low and not overly suggestive of a severe storm. However, note the tendency for the storm to bow (bend eastward) with time. This is an indication of strong winds reaching the surface, forcing the storm forward faster where the strongest winds are occurring. Figure 6: Same as Fig. 5, valid from 2351 UTC 2 June 2019 to 0001 UTC 3 June 2019. This storm was a little easier to diagnose as severe, as its radar reflectivity factor was much higher than other convective cores that produced wind damage during the event. Hail to the size of pennies was reported with this storm, as well as wind damage in a swath from Queen Anne's County in Maryland to the Kent County shores of Delaware Bay. The most significant damage was reported in Kenton, which was well-timed with the storm exhibiting its highest radar reflectivities. This storm also featured a three-body scatter spike (low CC to the northwest of the storm) and bowing characteristics. Note that base velocities are once again fairly low, owing to the storm's track perpendicular to the radar pulse.

Somerset County Microburst (GR2Analyst)

Environment
Figure 7: Same as Fig. 1, valid from 0039 to 0053 UTC on 3 June 2019. Here is another instance of a microburst generally occurring perpendicular to the radar pulse. There is some hint of bowing with this storm at the time wind damage was reported near Manville and South Bound Brook. Note also that radar reflectivity factor was above 60 dBZ at times near and just northwest of the bowed portion of the storm. These are subtle indications the storm may be producing damaging winds. In this case, the Terminal Doppler radar from Newark, NJ (TEWR), identified stronger winds close to the surface (not shown).

Pocopson Large Hail (GR2Analyst)

Environment Environment
Figure 8: Same as Fig. 1, valid from 2210 to 2221 UTC on 2 June 2019. Before the storms became primarily wind-damage producers, they generated a lot of hail across the area. Hail up to quarter size was observed with this storm in Chester County, in Pocopson Twp. Radar indicated a three-body scatter spike with this storm (note the very low CC and varying ZDR extending west of the storm); this is strongly indicative of large hail. The storm also exhibits a slight right turn during the animation (fairly common with supercells). Hail sizes were generally kept to around one inch in diameter or less because of two factors: (1) Most of the instability was in the layer of air above freezing, and (2) the depth of above-freezing air was substantial (generally above 10,000-12,000 feet). Thus, although the storms generated a lot of hail, hailstones melted considerably before reaching the surface. Figure 9: Cross section of the Pocopson hail storm, using KDIX radar reflectivity factor valid at 2210 UTC (left) and 2228 UTC (right) on 2 June 2019. The relatively deep layer of >60 dBZ radar reflectivity factor at 2210 UTC indicated an intense storm producing large hail. However, the storm was ultimately collapsing twenty minutes later, as indicated by the much shallower nature of the high reflectivity at 2228 UTC. This was a common characteristic of storms during the afternoon. They became briefly intense, producing small to marginally severe hail. Then, the storm weakened as the downdraft overwhelmed the updraft (an indication that shear was probably too weak to maintain separation between updrafts and downdrafts).  In this case, a new updraft appeared to be developing on its west side.  Indeed, a new storm developed and produced small hail a few minutes later.