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Philadelphia/Mt Holly

Weather Forecast Office

2-3 November 2018 Severe Weather and Flooding

Weather.gov > Philadelphia/Mt Holly > 2-3 November 2018 Severe Weather and Flooding

Overview

A cold front slowly moved toward the East Coast on the evening of 2 November 2018. Substantial large-scale lift in advance of the front allowed for the generation of widespread precipitation during the evening hours in much of Pennsylvania and northern New Jersey. Then, as the front moved into the area, organized convection developed along the front. Instability was meager, which was apparent from the lack of lightning observed with the convection. Nevertheless, considerable deep-layer shear was present, allowing for storms to organize into a squall line with embedded bow echoes and mesovortices. These phenomena were strongly associated with localized wind damage that occurred in portions of Berks, Montgomery, and Chester Counties. Additionally, the convection developed in an environment of anomalously high moisture content. Combined with the slow movement of the front, this led to widespread heavy rainfall in much of the Lehigh Valley and the western suburbs of Philadelphia. Several reports of flash flooding were received in these areas during the overnight hours.

 

 

 

 

 Image
Radar Reflectivity Animation for the Event

Meteorological Environment/Setup

Synoptic Overview at 12z 2 Nov 2018 (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 3 Nov 2018 (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)

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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
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Figure 19: 12z Upton, NY 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 Nov 2018 to 12z 3 Nov 2018 Figure 2: Zoomed Preliminary Reports Figure 3: Prelim Reports vs. 1630z SPC Convective Outlook

Preliminary Local Storm Reports

 

NWUS51 KPHI 032239
LSRPHI

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
639 PM EDT SAT NOV 03 2018

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

0952 PM     TSTM WND GST     PALMER TWP.             40.69N  75.27W
11/02/2018  M48 MPH          NORTHAMPTON        PA   MESONET         

1000 PM     TSTM WND GST     WEST GROVE              39.87N  75.85W
11/02/2018  M40 MPH          CHESTER            PA   DEOS            

1006 PM     TSTM WND GST     READING REGIONAL AIRPOR 40.38N  75.97W
11/02/2018  M48 MPH          BERKS              PA   ASOS            

1033 PM     TSTM WND DMG     1 SE UNION TWP          40.21N  75.77W
11/02/2018                   BERKS              PA   SOCIAL MEDIA    

            DOWNED TREE AT INTERSECTION OF PARK ROAD AND CHESTNUT 
            STREET. TIME ESTIMATED FROM RADAR. 

1033 PM     TSTM WND DMG     3 W WEST POTTSGROVE TWP 40.26N  75.73W
11/02/2018                   BERKS              PA   SOCIAL MEDIA    

            A FEW TREES DOWN NEAR BENJAMIN FRANKLIN HIGHWAY IN 
            DOUGLASSVILLE. TIME ESTIMATED FROM RADAR. 

1037 PM     TSTM WND DMG     1 NNE WEST POTTSGROVE T 40.27N  75.67W
11/02/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            DOWNED TREE IN WIRES NEAR INTERSECTION OF MANATAWNY 
            STREET AND SELL ROAD. TIME ESTIMATED FROM RADAR. 

1039 PM     TSTM WND DMG     POTTSTOWN               40.25N  75.64W
11/02/2018                   MONTGOMERY         PA   911 CALL CENTER 

            LARGE TREE DOWN BLOCKING THE ROADWAY NEAR N WARREN ST 
            AND VIRGINIA AVE. 

1039 PM     TSTM WND DMG     POTTSTOWN               40.25N  75.64W
11/02/2018                   MONTGOMERY         PA   EMERGENCY MNGR  

            A ROOF WAS TORN OFF AT THE YORKSHIRE APARTMENTS IN 
            POTTSTOWN. 

1039 PM     TSTM WND DMG     1 E POTTSTOWN           40.25N  75.62W
11/02/2018                   MONTGOMERY         PA   SOCIAL MEDIA    

            PHOTOS SHOWING TWO HARDWOOD TREES DOWN IN A RESIDENTIAL 
            AREA. 

1039 PM     TSTM WND DMG     1 ENE POTTSTOWN         40.25N  75.63W
11/02/2018                   MONTGOMERY         PA   SOCIAL MEDIA    

            SEVERAL LARGE TREES DOWN AT BROOKSIDE COUNTRY CLUB. 
            TIME ESTIMATED FROM RADAR. 

1039 PM     TSTM WND DMG     2 ESE EARL TWP          40.34N  75.68W
11/02/2018                   BERKS              PA   SOCIAL MEDIA    

            SEVERAL REPORTS OF TREES DOWN IN EARL TWP, INCLUDING 
            NEAR MANATAWNY ROAD AND LONGVIEW ROAD AND ON POWDER MILL 
            HOLLOW ROAD. TIME ESTIMATED FROM RADAR. 

1042 PM     FLASH FLOOD      AMITY TWP               40.29N  75.76W
11/02/2018                   BERKS              PA   EMERGENCY MNGR  

            WATER RESCUE REPORTED ON BOYERTOWN PIKE. 

1042 PM     TSTM WND DMG     1 ESE LOWER POTTSGROVE  40.25N  75.57W
11/02/2018                   MONTGOMERY         PA   NEWSPAPER       

            DOWNED TREE SEVERELY DAMAGED A HOME ON WOODMERE ROAD. 

1042 PM     TSTM WND DMG     1 S LOWER POTTSGROVE TW 40.25N  75.59W
11/02/2018                   MONTGOMERY         PA   NEWSPAPER       

            DOWNED TREES ON CARS ON WELSH DRIVE. PORCH ROOF BLEW 
            OFF A HOME ON NORTH PLEASANTVIEW ROAD. TIME ESTIMATED 
            FROM RADAR. 

1044 PM     TSTM WND DMG     1 SE LOWER POTTSGROVE T 40.25N  75.58W
11/02/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            DONWED TREE IN WIRES ON SANATOGA ROAD BETWEEN CROWNVIEW 
            ROAD AND SNELL ROAD. ALL LANES CLOSED. TIME ESTIMATED 
            FROM RADAR. 

1045 PM     HAIL             2 W POTTSTOWN           40.25N  75.68W
11/02/2018  M1.00 INCH       MONTGOMERY         PA   TRAINED SPOTTER 

1046 PM     TSTM WND GST     POTTSTOWN LIMERICK AIRP 40.24N  75.56W
11/02/2018  M54 MPH          MONTGOMERY         PA   ASOS            

1057 PM     TSTM WND DMG     RICHLANDTOWN            40.47N  75.32W
11/02/2018                   BUCKS              PA   911 CALL CENTER 

            FEW TREES DOWN IN THE AREA. TIME ESTIMATED FROM RADAR. 

1059 PM     TSTM WND DMG     CHARLESTOWN TWP         40.09N  75.56W
11/02/2018                   CHESTER            PA   911 CALL CENTER 

            WIRES DOWN NEAR VALLEY HILL ROAD AND VALLEY BEECH LANE. 

1059 PM     TSTM WND DMG     1 ENE SALFORD TWP       40.35N  75.39W
11/02/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            DOWNED TREE IN WIRES ON MILLER ROAD BETWEEN RIDGE ROAD 
            AND SWAMP CREEK ROAD. ALL LANES CLOSED. TIME ESTIMATED 
            FROM RADAR. 

1104 PM     FLASH FLOOD      POTTSTOWN               40.25N  75.64W
11/02/2018                   MONTGOMERY         PA   911 CALL CENTER 

            WATER RESCUE REPORTED IN POTTSTOWN AT HIGH ST. AND 
            ARMAND HAMMER BLVD. 

1109 PM     TSTM WND DMG     EAST WHITELAND TWP      40.04N  75.56W
11/02/2018                   CHESTER            PA   EMERGENCY MNGR  

            8 RESIDENCES SUSTAINED DAMAGE FROM DOWNED TREES. 

1113 PM     TSTM WND DMG     MALVERN                 40.04N  75.52W
11/02/2018                   CHESTER            PA   BROADCAST MEDIA 

            SEVERAL TREES AND WIRES DOWN NEAR THE MALVERN SEPTA 
            STATION. TIME ESTIMATED FROM RADAR. 

1114 PM     FLASH FLOOD      UPPER POTTSGROVE TWP    40.28N  75.64W
11/02/2018                   MONTGOMERY         PA   911 CALL CENTER 

            WATER RESCUE REPORTED ON WILLOW ST. 

1115 PM     TSTM WND DMG     WILLISTOWN TWP          40.00N  75.50W
11/02/2018                   CHESTER            PA   EMERGENCY MNGR  

            A GROUP HOME SUSTAINED DAMAGE BY DOWNED TREES. 

1122 PM     FLASH FLOOD      1 S AMITY TWP           40.27N  75.76W
11/02/2018                   BERKS              PA   EMERGENCY MNGR  

            TWO BUSINESSES SUSTAINED FLOODING DAMAGE NEAR U.S. 
            HIGHWAY 422 IN AMITY TWP. THE HIGHWAY WAS CLOSED FOR 
            SEVERAL HOURS. 

1129 PM     FLASH FLOOD      SOUTH POTTSTOWN         40.24N  75.64W
11/02/2018                   MONTGOMERY         PA   FIRE DEPT/RESCUE

            WATER RESCUE AT INTERSECTION OF WASHINGTON STREET AND 
            BRINGHURST ALLEY. 

1139 PM     FLASH FLOOD      2 SSW ALLENTOWN         40.56N  75.49W
11/02/2018                   LEHIGH             PA   DEPT OF HIGHWAYS

            INTERSTATE 78 CLOSED BETWEEN EXITS 57 AND 60 FROM FLASH 
            FLOODING. 

1149 PM     TSTM WND DMG     1 NNE WHITEMARSH TWP    40.11N  75.24W
11/02/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            DOWNED TREE IN WIRES ON STENTON AVENUE AND PENLLYN BLUE 
            BELL PIKE BETWEEN JOSHUA ROAD AND MILITIA HILL ROAD. ALL 
            LANES CLOSED. TIME ESTIMATED FROM RADAR. 

1228 AM     FLASH FLOOD      WASHINGTON TWP          40.39N  75.62W
11/03/2018                   BERKS              PA   EMERGENCY MNGR  

            WATER RESCUE REPORTED ON DALE ROAD. 

1230 AM     FLASH FLOOD      1 SE FOUNTAIN HILL      40.59N  75.39W
11/03/2018                   NORTHAMPTON        PA   EMERGENCY MNGR  

            LANDSLIDE ON SEIDERSVILLE ROAD NEAR FIRE LANE IN LOWER 
            SAUCON TWP. CONSIDERABLE FLOODING IN MUCH OF THE 
            TOWNSHIP, EXACERBATED BY CLOGGED DRAINS FROM FALLEN 
            LEAVES. TIME ESTIMATED BASED ON SURROUNDING REPORTS OF 
            FLOODING. 

1233 AM     FLASH FLOOD      EMMAUS                  40.53N  75.51W
11/03/2018                   LEHIGH             PA   NEWSPAPER       

            PORTIONS OF THE LOWER LEVEL OF EMMAUS HIGH SCHOOL WAS 
            FLOODED. 

1235 AM     TSTM WND GST     MORRISTOWN              40.80N  74.42W
11/03/2018  M48 MPH          MORRIS             NJ   AWOS            

1237 AM     HEAVY RAIN       NEFFS                   40.69N  75.61W
11/03/2018  M2.60 INCH       LEHIGH             PA   TRAINED SPOTTER 

1245 AM     TSTM WND DMG     1 NNE WATCHUNG          40.66N  74.44W
11/03/2018                   SOMERSET           NJ   SOCIAL MEDIA    

            PHOTOS SHOWING MULTIPLE BUT SPORADIC TREES AND LIMBS 
            DOWN IN A NEIGHBORHOOD. SOME DAMAGE TO SHINGLES 
            INCLUDING A SMALL SECTION THAT WAS PEELED OFF OF ONE 
            HOME. 

0100 AM     FLASH FLOOD      2 SSW MILFORD TWP       40.39N  75.42W
11/03/2018                   BUCKS              PA   DEPT OF HIGHWAYS

            SEVERAL ROADS CLOSED FROM FLASH FLOODING IN MILFORD 
            TWP...INCLUDING BROAD STREET, MAIN STREET, 
            TRUMBAUERSVILLE ROAD, AND SWAMP CREEK ROAD BETWEEN FELS 
            ROAD AND NURSERY ROAD. TIME ESTIMATED. 

0103 AM     FLASH FLOOD      1 NW EAST GREENVILLE    40.42N  75.52W
11/03/2018                   MONTGOMERY         PA   FIRE DEPT/RESCUE

            WATER RESCUE AT INTERSECTION OF MILL HILL ROAD AND 
            GRAVEL PIKE. 

0114 AM     HEAVY RAIN       GILBERTSVILLE           40.32N  75.61W
11/03/2018  M2.12 INCH       MONTGOMERY         PA   TRAINED SPOTTER 

0210 AM     HEAVY RAIN       SUCCASUNNA              40.86N  74.65W
11/03/2018  M2.75 INCH       MORRIS             NJ   SOCIAL MEDIA    

0354 AM     FLOOD            2 ENE MARLBOROUGH TWP   40.37N  75.42W
11/03/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            FLOODING ON MILLER ROAD AND WHITES MILL ROAD BETWEEN 
            RIDGE ROAD AND SWAMP CREEK ROAD. ALL LANES CLOSED. 

0357 AM     HEAVY RAIN       NORTH CATASAUQUA        40.66N  75.48W
11/03/2018  M3.62 INCH       NORTHAMPTON        PA   SOCIAL MEDIA    

            3.07 INCHES FELL FROM 8:30PM - MIDNIGHT. 

0433 AM     FLOOD            1 SSE WEST EASTON       40.67N  75.24W
11/03/2018                   NORTHAMPTON        PA   DEPT OF HIGHWAYS

            FLOODING ON LARRY HOLMES DRIVE, IRON STREET, LEHIGH 
            DRIVE, AND WASHINGTON STREET BETWEEN KEYSTONE STREET AND 
            ADAMSON STREET. ALL LANES CLOSED. 

0447 AM     FLOOD            2 WNW STEUBEN           40.70N  75.39W
11/03/2018                   NORTHAMPTON        PA   DEPT OF HIGHWAYS

            STATE HIGHWAY 512 CLOSED BETWEEN LOCUST ROAD AND 
            JACKSONVILLE ROAD. 

0527 AM     FLOOD            SCHWENKSVILLE           40.26N  75.46W
11/03/2018                   MONTGOMERY         PA   DEPT OF HIGHWAYS

            FLOODING ON NEIFFER ROAD, SCHWENKSVILLE ROAD, AND GAME 
            FARM ROAD BETWEEN MAIN STREET AND PENNYPACKER ROAD. ALL 
            LANES CLOSED. 

0611 AM     HEAVY RAIN       BETHLEHEM TWP           40.66N  75.31W
11/03/2018  M3.52 INCH       NORTHAMPTON        PA   TRAINED SPOTTER 

0749 AM     HEAVY RAIN       BELVIDERE               40.83N  75.07W
11/03/2018  M3.15 INCH       WARREN             NJ   CO-OP OBSERVER  

0800 AM     HEAVY RAIN       PLAINFIELD TWP          40.81N  75.26W
11/03/2018  M2.46 INCH       NORTHAMPTON        PA   TRAINED SPOTTER 

            24-HOUR TOTAL. 

0845 AM     HEAVY RAIN       FORKS TWP               40.73N  75.22W
11/03/2018  M4.09 INCH       NORTHAMPTON        PA   PUBLIC          

0900 AM     HEAVY RAIN       JEFFERSON TWP           40.96N  74.59W
11/03/2018  M3.65 INCH       MORRIS             NJ   TRAINED SPOTTER 

0946 AM     HEAVY RAIN       4 SW WANTAGE            41.24N  74.65W
11/03/2018  M3.01 INCH       SUSSEX             NJ   NWS EMPLOYEE    

            2.71 INCHES FROM 7:00PM - 9:45AM. 

0947 AM     FLOOD            COLLEGEVILLE            40.19N  75.46W
11/03/2018                   MONTGOMERY         PA   EMERGENCY MNGR  

            FOUR HOMES EVACUATED NEAR PERKIOMEN CREEK. SEVERAL 
            VEHICLES NEEDED TO BE TOWED FROM FLOODED AREAS. 

0351 PM     FLOOD            2 S HACKETTSTOWN        40.82N  74.82W
11/03/2018                   MORRIS             NJ   BROADCAST MEDIA 

            FLOODING OF THE MUSCONETCONG RIVER WITH WATERS 
            BEGINNING TO FLOW OVER EAST AVENUE. 


&&

EVENT NUMBER PHI1801789 PHI1801788 PHI1801787 PHI1801818 PHI1801835 
PHI1801817 PHI1801792 PHI1801800 PHI1801827 PHI1801829 PHI1801838 
PHI1801796 PHI1801822 PHI1801823 PHI1801837 PHI1801786 PHI1801794 
PHI1801821 PHI1801790 PHI1801836 PHI1801791 PHI1801795 PHI1801826 
PHI1801793 PHI1801799 PHI1801819 PHI1801803 PHI1801805 PHI1801816 
PHI1801797 PHI1801806 PHI1801832 PHI1801801 PHI1801830 PHI1801824 
PHI1801804 PHI1801802 PHI1801814 PHI1801834 PHI1801808 PHI1801833 
PHI1801809 PHI1801807 PHI1801815 PHI1801810 PHI1801811 PHI1801825 
PHI1801813 PHI1801828 PHI1801831 PHI1801820 PHI1801839  


$$

SFJ

Public Information Statement

 

NOUS41 KPHI 031946
PNSPHI
DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-
055-060>062-070-071-101>106-040800-

Public Information Statement
National Weather Service Mount Holly NJ
346 PM EDT Sat Nov 3 2018

...NWS DAMAGE SURVEY FOR 11/02/18 THUNDERSTORM WIND EVENT...

.Pottstown...

Location...Pottstown in Montgomery County, Pennsylvania
Date...2 Nov 2018
Estimated Time...10:30-10:50 PM EDT
Estimated Maximum Wind Speed...70-80 mph
* Fatalities...None
* Injuries...None

...Summary...
A convective microburst formed along a line of strong to severe 
thunderstorms west of Pottstown, PA. Damage occurred along a track 
extending through much of the center of Pottstown. Though there
aren't any indications that a tornado occurred, this event is
evidence that straight line winds, including downburst events such
as this one, can produce similar damage to some tornadoes.

.East Whiteland Township...

Location...East Whiteland Township in Chester County, Pennsylvania
Date...2 Nov 2018
Estimated Time...11:00-11:30 PM EDT
Estimated Maximum Wind Speed...70-80 mph
* Fatalities...None
* Injuries...None

...Summary...
A convective microburst formed along a line of strong to severe 
thunderstorms over portions of Chester County. There were numerous
downed trees throughout portions of East Whiteland Township and 
neighboring Willistown, Pennsylvania. Damage to 9 structures, 
including a group home, occurred. Though there aren't any 
indications that a tornado occured, this event is evidence that 
straight line winds, including downburst events such as this one, 
can produce similar damage to some tornadoes.

* The information in this statement is preliminary and subject to
change pending final review of the events and publication in NWS
Storm Data.

$$

CMS/Davis/Johnson/Miketta/Ruh

Radar Interrogation

Pottstown Downburst (GR2Analyst)

Environment Environment Environment
Figure 1: Base radar reflectivity factor (top left), base velocity (top right), correlation coefficient (CC; bottom left), and differential radar reflectivity (ZDR; bottom right) valid at 0239 UTC 3 Nov 2018. Figure 2: Same as Fig. 1, valid at 0244 UTC 3 Nov 2018. Note the high radial velocities observed near and just east of Pottstown, where several occurrences of wind damage were reported. Figure 3: Same as Fig. 1, valid at 0248 UTC 3 Nov 2018.

 

Malvern Downburst (GR2Analyst)

Environment Environment Environment
Figure 4: Same as Fig. 1, valid at 0309 UTC 3 Nov 2018. A strong bow echo was approaching Malvern. Figure 5: Same as Fig. 1, valid at 0313 UTC 3 Nov 2018. Note the increasing velocity signatures near and north of Malvern. Figure 6: Same as Fig. 1, valid at 0317 UTC 3 Nov 2018.

Radar-Derived Storm Total Rainfall

Environment
Figure 7: Storm-total rainfall as estimated using polarimetric radar. Widespread 3-4 inch rainfall was observed in portions of the Lehigh Valley and adjacent portions of northern New Jersey. The radar noticeably underestimated rainfall totals during the event.
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