SUMMARY: An official, New York State 24 hour precipitation record was set at Islip, NY on August 12-13, 2014 with 13.57" of rain (See Public Information Statement). This breaks the previous record of 11.6" at Tannersville, NY on August 27-28, 2011 during Hurricane/Tropical Storm Irene. 1.76" of rain fell in just 15 minutes from 5:39 am to 5:54 am (See Islip, NY Rainfall Data)! An anomalously deep upper level trough was moving into the northeast the morning of August 13th, transporting deep moisture over Long Island. At the surface, a parent low pressure system was moving across southeast Canada, with secondary low development just south of New York City. Heavy precipitation focused along and just north of the warm front associated with the secondary low pressure system. The mean storm motion was parallel to the orientation of the warm front and was significant in helping maintain heavy rain over Islip, NY for several hours. Click the links below to view different aspects of this historical event.
Radar and Satellite Review | Dual Polarization Data | Moisture | Islip, NY Rainfall Data |
Photos | Rainfall Reports | Local Storm Reports | NWS Products |
KOKX Base Reflectivity Loop 2-9 AM (Images Every 15 Minutes) |
IR Satellite and Weather Prediction Center (WPC) Surface Analysis | Water Vapor and Rapid Update Cycle(RAP) 500 mb Analysis |
KOKX Storm Total Accumulation Full Domain | KOKX Storm Total Accumulation Zoom |
Instantaneous Precip Rate (5:30 am) | Specific Differential Phase (5:30 am) (Higher the value, the more liquid water) |
Deep, tropical moisture was available throughout the atmosphere as the event unfolded. The 00 UTC sounding from Wallops Island, VA (KWAL) observed a precipitable water of 2.38". This high moisture content air would be transported north towards Long Island from the negatively tilted trough. The 12 UTC sounding from Upton, NY (KOKX) contained a precipitable water of 1.81". However, this may be slightly underdone due to failure of the RH sensor around 600 mb. The animation below illustrates the large area of high precipitable water along the Middle Atlantic coast that was being advected northward by the low level wind field. Deep saturation was also present in both of these soundings below the freezing level. The warm cloud layer (between cloud base and freezing level) was 13,809 ft in depth in large part due to a freezing level of 15,162 ft.
0000 UTC August 13, 2014 KWAL Sounding | 1200 UTC August 13, 2014 KOKX Sounding |
RAP 850 mb Height (m), Wind (kt), and Layer Precipitable Water (in) |
Precipitable water climatology data from Wallops Island, VA, courtesy of the Rapid City, SD NWS forecast office, illustrated the anomolous nature of the air mass that was transported towards Long Island. The 2.38" at Wallops Island was in the 99th percentile since 1963. This means 99% of the observed precipitable water values at Wallops Island have been below 2.38." The observed 1.81" precipitable water at Upton, NY was in the 75th percentile, and a little below 2 standard deviations above normal. However, this may be slighly low due to the failure of the RH sensor around 600 mb.
Wallops Island Precipitable Water Climo Star represents 0000 UTC Aug 13, 2014 observed value |
Upton Precipitable Water Climo Star represents 1200 UTC Aug 13, 2014 observed value |
1-Minute Rainfall Data from Islip Automated Surface Observation System (ASOS)
Below is a plot of 1-minute rainfall observations from Islip, NY from the morning of Wednesday, August 13. 1.08" of rain was recorded in just 9 minutes from 5:39 am to 5:47 am! A total of 1.76" was recorded in just 15 minutes from 5:39 am to 5:54 am! The data here is plotted from 1 am EDT to 10 am EDT. The total rainfall shown in the chart is 13.21"
Exceedence Probability Analysis
The Hydrometeorological Design Studies Center (HDSC) analyzed annual exceedance probabilities (AEPs) at Islip, NY. An AEP gives the probability of exceeding a given amount of rainfall at least once in any given year at a given location. The map below illustrates rainfall magnitudes with AEPs ranging from 1/10 (10%) to smaller than 1/1000 (0.1%) for the 3-hour duration of heaviest rainfall. Note the the corridor with AEPs smaller than 1/1000 where the heaviest rain indicates the true rarity of this historic event. For more information, please view the document, Exceedance Probability Analysis for the Islip, NY Rainfall Event, 13 August 2014, by the HDSC.
********************STORM TOTAL RAINFALL******************** LOCATION STORM TOTAL TIME/DATE COMMENTS RAINFALL OF /INCHES/ MEASUREMENT CONNECTICUT ...FAIRFIELD COUNTY... FAIRFIELD 1.63 1035 AM 8/13 TRAINED SPOTTER BRIDGEPORT AIRPORT 1.59 1023 AM 8/13 ASOS DANBURY 1.52 1200 PM 8/13 TRAINED SPOTTER DANBURY AIRPORT 1.02 1024 AM 8/13 ASOS BETHEL 0.70 1114 AM 8/13 TRAINED SPOTTER ...NEW HAVEN COUNTY... MADISON 4.50 909 AM 8/13 PUBLIC NEW HAVEN 2.70 1025 AM 8/13 ASOS HAMDEN 1.62 940 AM 8/13 TRAINED SPOTTER MERIDEN 0.96 1029 AM 8/13 ASOS ...NEW LONDON COUNTY... MONTVILLE 4.45 903 AM 8/13 AMATEUR RADIO LYME STATION 3.90 903 AM 8/13 EAST LYME OLD LYME 3.62 1200 PM 8/13 PUBLIC GROTON AIRPORT 2.40 1025 AM 8/13 ASOS COLCHESTER 2.12 809 AM 8/13 AMATEUR RADIO NEW JERSEY ...BERGEN COUNTY... RIDGEWOOD 0.98 930 AM 8/13 TRAINED SPOTTER TETERBORO 0.56 706 AM 8/13 ASOS WESTWOOD 0.54 645 AM 8/13 TRAINED SPOTTER OAKLAND 0.20 914 AM 8/13 TRAINED SPOTTER ...ESSEX COUNTY... MAPLEWOOD 0.74 1000 AM 8/13 PUBLIC NEWARK AIRPORT 0.58 800 AM 8/13 ASOS CALDWELL AIRPORT 0.41 800 AM 8/13 ASOS ...HUDSON COUNTY... NORTH BERGEN 0.88 1000 AM 8/13 TRAINED SPOTTER NEW YORK ...KINGS COUNTY... MIDWOOD 1.34 706 AM 8/13 TRAINED SPOTTER ...NASSAU COUNTY... MASSAPEQUA 8.20 930 AM 8/13 PUBLIC WANTAGH 7.84 825 AM 8/13 TRAINED SPOTTER MERRICK 6.81 749 AM 8/13 TRAINED SPOTTER LIDO BEACH 5.30 900 AM 8/13 TRAINED SPOTTER OLD BETHPAGE 5.27 1045 AM 8/13 TRAINED SPOTTER BELLMORE 5.20 830 AM 8/13 PUBLIC GARDEN CITY 4.75 800 AM 8/13 TRAINED SPOTTER PLAINVIEW 4.70 840 AM 8/13 TRAINED SPOTTER LONG BEACH 4.64 729 AM 8/13 PUBLIC SYOSSET 4.01 658 AM 8/13 TRAINED SPOTTER MUTTONTOWN 3.41 945 AM 8/13 TRAINED SPOTTER EAST HILLS 3.16 1100 AM 8/13 PUBLIC FLORAL PARK 2.80 745 AM 8/13 TRAINED SPOTTER BAYVILLE 2.63 730 AM 8/13 TRAINED SPOTTER MALVERNE 0.98 700 AM 8/13 TRAINED SPOTTER ...NEW YORK COUNTY... CENTRAL PARK 0.72 1032 AM 8/13 ASOS ...ORANGE COUNTY... MONTGOMERY AIRPORT 0.65 800 AM 8/13 ASOS ...PUTNAM COUNTY... COLD SPRING 1.30 1100 AM 8/13 TRAINED SPOTTER ...QUEENS COUNTY... NYC/JFK AIRPORT 3.26 940 AM 8/13 ASOS NYC/LA GUARDIA 0.77 800 AM 8/13 ASOS ...SUFFOLK COUNTY... ISLIP AIRPORT 13.57 1159 PM 8/13 ASOS HOLBROOK 12.57 119 PM 8/13 NWS EMPLOYEE WEST ISLIP 11.50 958 AM 8/13 TRAINED SPOTTER BAY SHORE 11.35 915 AM 8/13 TRAINED SPOTTER ISLIP 10.20 850 AM 8/13 TRAINED SPOTTER DEER PARK 8.40 1240 PM 8/13 PUBLIC RONKONKOMA 8.20 640 AM 8/13 TRAINED SPOTTER FARMINGVILLE 7.73 800 AM 8/13 TRAINED SPOTTER CENTEREACH 6.71 918 AM 8/13 NWS EMPLOYEE ST. JAMES 6.11 935 AM 8/13 PUBLIC SMITHTOWN 5.17 900 AM 8/13 TRAINED SPOTTER PORT JEFFERSON STATI 5.10 900 AM 8/13 PUBLIC EAST FARMINGDALE 4.93 800 AM 8/13 ASOS MEDFORD 4.45 800 AM 8/13 TRAINED SPOTTER MOUNT SINAI 4.40 1007 AM 8/13 CO-OP OBSERVER EAST NORTHPORT 4.40 1153 AM 8/13 TRAINED SPOTTER CENTERPORT 3.18 700 AM 8/13 CO-OP OBSERVER UPTON 1.75 1036 AM 8/13 NWS OFFICE STONY BROOK 1.59 515 AM 8/13 TRAINED SPOTTER SHIRLEY AIRPORT 1.15 800 AM 8/13 ASOS SOUTHAMPTON 0.70 940 AM 8/13 TRAINED SPOTTER WESTHAMPTON AIRPORT 0.68 800 AM 8/13 ASOS ORIENT 0.62 1102 AM 8/13 TRAINED SPOTTER 1 NNE MONTAUK 0.14 800 AM 8/13 ASOS ...WESTCHESTER COUNTY... SCARSDALE 1.40 1115 AM 8/13 TRAINED SPOTTER WHITE PLAINS AIRPORT 0.85 800 AM 8/13 ASOS **********************24 HOUR RAINFALL********************** LOCATION 24 HOUR TIME/DATE COMMENTS RAINFALL OF /INCHES/ MEASUREMENT CONNECTICUT ...FAIRFIELD COUNTY... 3 ENE WESTPORT 1.50 800 AM 8/13 COCORAHS 3 SSE BROOKFIELD 0.67 700 AM 8/13 COCORAHS ...MIDDLESEX COUNTY... 1 N WESTBROOK CENTER 2.31 725 AM 8/13 COCORAHS 3 WSW EAST HAMPTON 0.93 700 AM 8/13 COCORAHS 1 S PORTLAND 0.87 800 AM 8/13 COCORAHS ...NEW HAVEN COUNTY... 2 E MILFORD 1.51 900 AM 8/13 COCORAHS 2 NW NEW HAVEN 1.21 800 AM 8/13 COCORAHS NEW JERSEY ...BERGEN COUNTY... 2 S RIVER VALE TWP 0.99 1044 AM 8/13 COCORAHS WNW GLEN ROCK 0.81 800 AM 8/13 COCORAHS 1 E SADDLE BROOK TWP 0.75 730 AM 8/13 COCORAHS 1 W TENAFLY 0.71 700 AM 8/13 COCORAHS 1 SSE OAKLAND 0.22 725 AM 8/13 COCORAHS WNW OAKLAND 0.16 720 AM 8/13 COCORAHS 1 ESE OAKLAND 0.08 700 AM 8/13 COCORAHS ...ESSEX COUNTY... 1 WSW VERONA TWP 0.82 900 AM 8/13 COCORAHS 1 SE MAPLEWOOD TWP 0.72 700 AM 8/13 COCORAHS 1 NE CEDAR GROVE TWP 0.62 600 AM 8/13 COCORAHS 1 NE WEST CALDWELL T 0.58 900 AM 8/13 COCORAHS ...HUDSON COUNTY... N HARRISON 0.58 700 AM 8/13 COCORAHS ...PASSAIC COUNTY... 1 WNW LITTLE FALLS T 0.79 800 AM 8/13 COCORAHS S HAWTHORNE 0.66 530 AM 8/13 COCORAHS 3 SSE RINGWOOD 0.24 820 AM 8/13 COCORAHS ...UNION COUNTY... 1 ESE NEW PROVIDENCE 0.78 800 AM 8/13 COCORAHS 1 NNW SUMMIT 0.75 700 AM 8/13 COCORAHS 1 NW UNION TWP 0.73 800 AM 8/13 COCORAHS 1 NE WESTFIELD 0.73 645 AM 8/13 COCORAHS 1 SSE KENILWORTH 0.71 1000 AM 8/13 COCORAHS NEW YORK ...KINGS COUNTY... 3 NW BROOKLYN 0.95 700 AM 8/13 COCORAHS ...NASSAU COUNTY... E LEVITTOWN 5.66 800 AM 8/13 COCORAHS W FLORAL PARK 2.53 700 AM 8/13 COCORAHS ...PUTNAM COUNTY... 8 NE COLD SPRINGS 0.14 700 AM 8/13 COCORAHS 4 ESE BEACON 0.08 620 AM 8/13 COCORAHS ...QUEENS COUNTY... 1 SW MIDDLE VILLAGE 1.43 700 AM 8/13 COCORAHS ...RICHMOND COUNTY... 1 SE STATEN ISLAND 0.73 730 AM 8/13 COCORAHS ...ROCKLAND COUNTY... 1 WSW WEST NYACK 0.88 730 AM 8/13 COCORAHS ...SUFFOLK COUNTY... 1 SSW JAMESPORT 0.73 900 AM 8/13 COCORAHS 1 S SOUTHOLD 0.69 832 AM 8/13 COCORAHS 1 WNW EAST MORICHES 0.15 800 AM 8/13 COCORAHS ...WESTCHESTER COUNTY... N PEEKSKILL 0.85 830 AM 8/13 COCORAHS 1 SW YORKTOWN HEIGHT 0.73 800 AM 8/13 COCORAHS 2 NW SOUTH SALEM 0.72 700 AM 8/13 COCORAHS $$ JP |
PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE NEW YORK NY 845 PM EDT WED AUG 13 2014 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0113 AM MARINE TSTM WIND NYC/JFK AIRPORT 40.64N 73.76W 08/13/2014 M41 MPH QUEENS NY ASOS 0140 AM MARINE TSTM WIND 8 WNW BUOY 44065 40.42N 73.84W 08/13/2014 M43 MPH ANZ355 NY MESONET 0245 AM MARINE TSTM WIND 1 SW BREEZY POINT 40.55N 73.93W 08/13/2014 M42 MPH QUEENS NY MESONET 0358 AM FLASH FLOOD FARMINGDALE 40.73N 73.45W 08/13/2014 NASSAU NY BROADCAST MEDIA ROAD CLOSED DUE TO FLOODING. ROUTE 110 BETWEEN ROUTE 109/FARMINGDALE ROAD AND RULAND ROAD. 0403 AM FLASH FLOOD MASSAPEQUA 40.67N 73.47W 08/13/2014 NASSAU NY BROADCAST MEDIA SUNRISE HIGHWAY/ROUTE 27 CLOSED DUE TO FLOODING BETWEEN CARMANS ROAD AND UNQUA ROAD 0410 AM FLASH FLOOD FARMINGDALE 40.73N 73.45W 08/13/2014 NASSAU NY FIRE DEPT/RESCUE ROUTE 110 CLOSED BOTH WAYS DUE TO FLOODING FROM CONKLIN STREET TO SHERWOOD AVE. 0425 AM FLASH FLOOD JERICHO 40.79N 73.54W 08/13/2014 NASSAU NY FIRE DEPT/RESCUE ALL LANES CLOSED ON THE NORTHERN STATE PARKWAY AT EXIT 35 0438 AM MARINE TSTM WIND 1 E POINT LOOKOUT 40.59N 73.56W 08/13/2014 M39 MPH NASSAU NY MESONET 0501 AM FLASH FLOOD DIX HILLS 40.80N 73.34W 08/13/2014 SUFFOLK NY BROADCAST MEDIA LONG ISLAND EXPRESSWAY CLOSED AT EXIT 51 DUE TO FLOODING. 0501 AM FLASH FLOOD BRENTWOOD 40.78N 73.25W 08/13/2014 SUFFOLK NY BROADCAST MEDIA SAGTIKOS PARKWAY IS CLOSED SOUTHBOUND AT EXIT S2 DUE TO FLOODING. 0509 AM FLASH FLOOD BELLMORE 40.66N 73.53W 08/13/2014 NASSAU NY BROADCAST MEDIA 8 INCHES OF WATER IN THE FIRST FLOOR OF A HOUSE 0515 AM MARINE TSTM WIND POINT LOOKOUT 40.59N 73.58W 08/13/2014 M41 MPH NASSAU NY MESONET 0525 AM FLASH FLOOD 1 SE BETHPAGE 40.74N 73.47W 08/13/2014 NASSAU NY BROADCAST MEDIA NY 135 CLOSED DUE TO FLOODING AT POWELL AVENUE. 0527 AM MARINE TSTM WIND 1 WSW ROBERT MOSES STAT 40.62N 73.26W 08/13/2014 M41 MPH SUFFOLK NY MESONET 0530 AM FLASH FLOOD NESCONSET 40.85N 73.15W 08/13/2014 SUFFOLK NY FIRE DEPT/RESCUE FIRE DEPARTMENT IS DEPLOYING BOATS TO RESCUE TRAPPED VEHICLE OCCUPANTS AT NICHOLS ROAD AND ROY DRIVE. 0541 AM FLASH FLOOD COMMACK 40.84N 73.28W 08/13/2014 SUFFOLK NY BROADCAST MEDIA JERICHO TPK CLOSED IN BOTH DIRECTIONS IN COMMACK 0542 AM FLASH FLOOD MANORVILLE 40.86N 72.79W 08/13/2014 SUFFOLK NY BROADCAST MEDIA NY 27 AT RAILROAD AVENUE IS CLOSED DUE TO FLOODING. 0610 AM FLASH FLOOD SMITHTOWN 40.86N 73.21W 08/13/2014 SUFFOLK NY BROADCAST MEDIA NY 25 CLOSED DUE TO FLOODING AT MAPLE AVENUE 0625 AM FLASH FLOOD DIX HILLS 40.80N 73.34W 08/13/2014 SUFFOLK NY BROADCAST MEDIA I-495 WESTBOUND CLOSED DUE TO FLOODING BETWEEN EXITS 51 AND 50 0630 AM FLASH FLOOD WEST BABYLON 40.72N 73.35W 08/13/2014 SUFFOLK NY BROADCAST MEDIA SOUTHER STATE PARKWAY AT EXIT 37 CLOSED DUE TO FLOODING. CARS STRANDED. 0635 AM FLASH FLOOD BRANFORD 41.28N 72.81W 08/13/2014 NEW HAVEN CT BROADCAST MEDIA CAR SUBMERGED IN WATER OFF I-95 0645 AM FLASH FLOOD RONKONKOMA 40.80N 73.12W 08/13/2014 SUFFOLK NY TRAINED SPOTTER ESTIMATED 6-12 INCHES OF FLOWING WATER OVER RONKONKOMA AVE AND THE INTERSECTION OF WALTESS ROAD 0653 AM FLASH FLOOD BAY SHORE 40.73N 73.25W 08/13/2014 SUFFOLK NY BROADCAST MEDIA SUNRISE HWY COMPLETELY FLOODED WITH CARS STRANDED IN FRONT OF BAY SHORE MALL 0659 AM FLASH FLOOD HOLTSVILLE 40.81N 73.05W 08/13/2014 SUFFOLK NY PUBLIC NORTH AND SOUTHBOUND RAMPS GOING TO NICOLLS FROM EASTBOUND LIE HAVE CARS STUCK 0714 AM MARINE TSTM WIND 4 ENE PLUM ISLAND 41.20N 72.12W 08/13/2014 M39 MPH SUFFOLK NY MESONET GREAT GULL ISLAND MESONET 34 KT 0716 AM FLASH FLOOD BABYLON 40.70N 73.33W 08/13/2014 SUFFOLK NY PUBLIC ABOUT 3 FEET OF WATER ON LIVINGSTON AVE 0717 AM MARINE TSTM WIND 1 WSW ROBERT MOSES STAT 40.62N 73.26W 08/13/2014 M57 MPH SUFFOLK NY MESONET 0720 AM FLASH FLOOD ROCKY POINT 40.95N 72.93W 08/13/2014 SUFFOLK NY PUBLIC PICTURES OF MULTIPLE CARS STUCK BY HALLOCK LANDING ROAD AND CULROSS DRIVE 0723 AM FLASH FLOOD AMITYVILLE 40.67N 73.42W 08/13/2014 SUFFOLK NY PUBLIC 6-10 INCHES OF WATER ON ROAD AND HALFWAY UP GARGAE DOORS ON UNION AVE 0724 AM FLASH FLOOD ISLIP TERRACE 40.75N 73.19W 08/13/2014 SUFFOLK NY PUBLIC RAINFALL UP TO MAILBOXES ON ARGOSY ST 0724 AM FLASH FLOOD EAST ISLIP 40.73N 73.19W 08/13/2014 SUFFOLK NY PUBLIC ABOUT 2 FEET OF WATER OVER LAGOON PLACE IN EAST ISLIP 0726 AM FLASH FLOOD NESCONSET 40.85N 73.15W 08/13/2014 SUFFOLK NY PUBLIC BROWNS ROAD CLOSED DUE TO TWO CARS STUCK 0751 AM FLASH FLOOD BAY SHORE 40.73N 73.25W 08/13/2014 SUFFOLK NY PUBLIC SIGNIFICANT FLOODING IN BAY SHORE TRAIN STATION PARKING LOT. AT LEAST 2 FEET OF WATER. 0811 AM FLASH FLOOD SELDEN 40.87N 73.05W 08/13/2014 SUFFOLK NY PUBLIC CAR SUBMERGED FULLY IN FLOOD WATERS AT BLUE POINT ROAD AND MIDDLE COUNTRY ROAD 0825 AM FLASH FLOOD BAY SHORE 40.73N 73.25W 08/13/2014 SUFFOLK NY PUBLIC SUNRISE HIGHWAY AND SERVICE ROAD AT 5TH AVENUE EXIT 43 CLOSED DUE TO FLOODING 0825 AM FLASH FLOOD HOLBROOK 40.79N 73.07W 08/13/2014 SUFFOLK NY PUBLIC TWO CARS STUCK AT INTERSECTION OF UNION AVE AND MILL ROAD DUE TO FLOODING 0830 AM FLASH FLOOD WADING RIVER 40.95N 72.82W 08/13/2014 SUFFOLK NY BROADCAST MEDIA PARTIAL COLLAPSE OF WEST BOUND LANE ON HULSE LANDING ROAD BETWEEN 25A AND SOUND AVENUE 0849 AM FLASH FLOOD ISLANDIA 40.81N 73.17W 08/13/2014 SUFFOLK NY NWS EMPLOYEE LIE WESTBOUND AT EXIT 57 CLOSED DUE TO FLOODING 0919 AM FLASH FLOOD MADISON 41.28N 72.59W 08/13/2014 NEW HAVEN CT BROADCAST MEDIA ROUTE 1 CLOSED UNDER RAILROAD BRIDGE 0922 AM MARINE TSTM WIND MECOX 40.91N 72.30W 08/13/2014 M42 MPH SUFFOLK NY MESONET MECOX BAY MESONET 37 KNOTS 0926 AM MARINE TSTM WIND EAST MORICHES 40.81N 72.76W 08/13/2014 M39 MPH SUFFOLK NY MESONET MESONET WIND GUST 34 KT 0940 AM MARINE TSTM WIND 1 S BLUE POINT 40.73N 73.03W 08/13/2014 M48 MPH SUFFOLK NY MESONET BLUE POINT MESONET 41.5 KNOTS 0628 PM MARINE TSTM WIND 1 S MAMARONECK 40.92N 73.73W 08/13/2014 M42 MPH ANZ335 NY MESONET LARCHMONT HARBOR MESONET 36.7 KNOTS 0636 PM MARINE TSTM WIND 2 WNW LATTINGTOWN 40.90N 73.63W 08/13/2014 M48 MPH NASSAU NY MESONET BAYVILLE MESONET 41.9 KNOTS 0700 PM MARINE TSTM WIND EATONS NECK 40.95N 73.40W 08/13/2014 M40 MPH SUFFOLK NY MESONET EATONS NECK MESONET 34.9 KNOTS && $$ LN |
National Weather Service WFO New York, NY Watches, Warnings, and Advisories
The following links show each Flash Flood Watch, Flash Flood Warning, and Urban Flood Advisory we issued for this historic event. The Flash Flood Watch was issued at 4:04 pm Monday, August 11, 2014. The first flash flood warning was issued at 2:54 am Wednesday, August 13, 2014 for Suffolk and Nassau counties. The first report of flash flooding occurred at 3:58 am.