Beginning during the early morning hours on Tuesday, August 26 rain began to overspread western North Carolina from the southwest from the remnants of Tropical Storm Fay with only light rain and drizzle across central NC. The reason why the heaviest precipitation was focused in the western part of the state was because of an upslope component to the wind. By this I mean the wind was blowing up the higher terrain as the wind was blowing from the SE to NW. This aids in lifting necessary to get precipitation. Combine this process with abundant tropical moisture and the remnant circulation from Fay, you get very very heavy rainfall.
The heavy rains continued to affect the mountains, foothills, western Piedmont and southwest sandhills of NC. Drizzle and light rain continued across the Triangle. The large area of heavy rains finally began to shift NE through the early morning hours on Wednesday, August 27 with some of this rain getting as far east as Johnston county. By 7am, a trailing squall line of heavy rain and thunderstorms was crawling across eastward across the state. The line had rainfall rates of 2-4 inches an hour in spots. It finally reached the Triangle with 1.57 inches of rain falling in one hour at RDU.
Tornadoes then became a major threat as there were several boundaries draped across the state. Whenever a remnant circulation from a tropical storm exists, isolated tornadoes are a possibility. There was also a good amount of wind shear as well as a parameter called helicity which takes into account the wind shear and the possibility of a storm to ingest horizontal spin into its updraft. Wind shear is the change of wind with height. We had southeasterly winds at the surface and southwesterly winds in the middle and upper levels. There was also a increase in the speed of these winds as you go up. Due to the copius amounts of moisture, getting a quick tornado to spin up and touch down was certainly possible. Tornadoes are much more likely to occur when saturation of the air is occurring very low to the surface of the earth. Even if all the parameters necessary for tornadoes exist, if the low level air is dry a tornado may not be as much of a threat.
Below are the damage survey results from the tornadoes that touched down. If you were listening to the news, radio, or are a weather hobbyist you know the Raleigh National Weather Service had issued many warnings in the afternoon.
RANDOLPH COUNTY TORNADO NEAR RANDLEMAN...
TORNADO: EF-0
PEAK WIND: 60 MPH
PATH LENGTH: 500 YARDS
PATH WIDTH: 50 YARDS
TIME/DATE: 1230 PM WEDNESDAY, AUGUST 27, 2008
INJURIES: NONE NONE
FATALITIES: NONE
CHATHAM COUNTY TORNADO NEAR SILK HOPE...
TORNADO: EF-0
PEAK WIND: 75 MPH
PATH LENGTH: ONE AND A HALF MILE
PATH WIDTH: 100 YARDS
TIME/DATE: 415 PM WEDNESDAY, AUGUST 27, 2008
INJURIES: NONE NONE
FATALITIES: NONE
WAYNE AND WILSON COUNTY TORNADO SURVEY...
FIRST TOUCHDOWN AT AYCOCK CHURCH ROAD
TORNADO: EF-0
PEAK WIND: 75 MPH
PATH LENGTH: ONE HALF MILE
PATH WIDTH: 50 YARDS
TIME/DATE: 1258 AM THURSDAY, AUGUST 28, 2008
INJURIES: NONE NONE
FATALITIES: NONE
SECOND TOUCHDOWN AT BEAVER DAM ROAD
TORNADO: EF-0
PEAK WIND: 65 MPH
PATH LENGTH: 150 YARDS
PATH WIDTH: 25-50
TIME/DATE: 102 AM THURSDAY, AUGUST 28, 2008
INJURIES: NONE NONE
FATALITIES: NONE
Now back to the heavy rainfall..
Heavy rain and thunderstorm bands continued through the night across central and eastern NC. Wake county got in on torrential rains and embedded lightning from around 10 through 2am. Here are some totals from around the region reported by the NWS. Note: I had to change the RDU report as I believe they made an error. I also highlighted some notable amounts including one in Greensboro with 10.99" and added Charlotte to the list also as they were not in the report sent out by the Raleigh office. The report totals go from 8am Tuesday the 26th to 8am Thursday the 28th.
LOCATION 48-HR RAINFALL TOTAL
----------------------------------------------------
...ALAMANCE COUNTY...
HAW RIVER 7.23"
GRAHAM 6.58"
BURLINGTON 0.8SE 4.70"
BURLINGTON AIRPORT 4.69"
...CHATHAM COUNTY...
PITTSBORO 6.5W 8.07"
PITTSBORO 5.4NW 7.81"
CHATHAM WATER TREATMENT PLANT 4.83"
SILER CITY 5.5ENE 4.58"
GOLDSTON 4N 3.91"
...CUMBERLAND COUNTY...
FAYETTEVILLE AIRPORT 3.36"
FORT BRAGG 3.26"
FAYETTEVILLE 3.00"
...DAVIDSON COUNTY...
LEXINGTON 4.70"
WINSTON SALEM 7.7S 3.47"
...DURHAM COUNTY...
DURHAM 9.5N 6.32"
DURHAM 7.4 NNW 5.20"
DURHAM 5.15"
DURHAM 1.2NW 3.42"
DURHAM 6.2S 2.96"
...EDGECOMBE COUNTY...
TARBORO 0.50"
...FRANKLIN COUNTY...
YOUNGSVILLE 1.2E 2.62"
YOUNGSVILLE 4.1SE 1.80"
LOUISBURG 8.2ESE 1.53"
LOUISBURG 1.05"
...FORSYTH COUNTY...
LEWISVILLE 4.2N 6.73
RURAL HALL 4.22"
PFAFFTOWN 3.24"
WINSTON-SALEM 0.6S 3.22
SMITH-REYNOLDS AIRPORT 3.15"
...GUILFORD COUNTY...
GREENSBORO 6.5SSE 10.99"
GREENSBORO 1SE 6.74"
PTI AIRPORT 5.79"
BROWNS SUMMIT 3NW 5.29"
GREENSBORO 5.07"
OAK RIDGE 2.3SSW 4.30"
...HALIFAX COUNTY...
ROANOKE RAPIDS 0.73"
HALIFAX CO AIRPORT 0.57"
SCOTLAND NECK 0.26"
...HARNETT COUNTY...
ERWIN-DUNN 3.12"
COATS 0.7W 1.69"
...HOKE COUNTY...
RAEFORD 2.59"
...JOHNSTON COUNTY...
SMITHFIELD 2.8SE 2.09"
CLAYTON 2.1W 2.07"
SMITHFIELD 1.98"
KENLY 6.6NW 1.27"
CLAYTON 5.8S 1.23"
CLAYTON 0.71"
...MECKLENBURG COUNTY...
CHARLOTTE INTERNATIONAL AIRPORT 8.54"
...MONTGOMERY COUNTY...
JACKSON SPRINGS 2.65"
TILLERY DAM 2.48"
...NASH COUNTY...
NASHVILLE 3.2W 1.19"
ROCKY MOUNT-WILSON AIRPORT 0.63"
...ORANGE COUNTY...
CHAPEL HILL 5.32"
CHAPEL HILL AIRPORT 5.02"
HILLSBOROUGH 7.4NW 4.88"
HILLSBOROUGH 4.9SW 4.02"
MEBANE 7.4SSE 2.99"
...RANDOLPH COUNTY...
RANDLEMAN 7.24"
ASHEBORO 1.2SW 4.91"
ASHEBORO 2.2SSE 4.58"
ARCHDALE 1.3SE 6.72"
...RICHMOND COUNTY...
BLEWETT 1.25"
...SAMPSON COUNTY...
CLINTON 1.16"
...SCOTLAND COUNTY...
LAURINBURG-MAXTON AIRPORT 1.58"
LAURINBURG 0.99"
...STANLY COUNTY...
STANFIELD 4.42"
ALBEMARLE 3.60"
...VANCE COUNTY...
HENDERSON NNE 3.09"
...WAKE COUNTY...
WAKE FOREST 4.6SW 4.45"
WILLOW SPRINGS 4.5SE 3.94"
RALEIGH 10.3N 3.90"
HOLLY SPRINGS 3.76"
APEX 6.1ESE 3.72"
RALEIGH-DURHAM AIRPORT 3.65"
RALEIGH 8.4N 3.43"
HOLLY SPRINGS 1.8ESE 3.35"
HOLLY SPRINGS 2ESE 3.33"
HOLLY SPRINGS 3.6SSE 3.24"
HOLLY SPRINGS 1.1ESE 3.16"
RALEIGH 1.5WNW 2.75"
GARNER 3W 2.65"
CARY 0.4NNW 2.53"
CARY 2.48"
CARY 2.6ESE 2.47"
APEX 2.47"
APEX 3.5W 2.29"
KNIGHTDALE 1.9WSW 2.19"
...WARREN COUNTY...
ARCOLA 1.44"
...WILSON COUNTY...
WILSON 1.95"
WILSON 2.1NNW 1.31"
...WAYNE COUNTY...
GOLDSBORO 1.5NE 3.35"
GOLDSBORO 4.4E 2.36"
GOLDSBORO 2.12"
GOLDSBORO AIRPORT 1.01"
Finally, The map below is showing the event total from the Raleigh NWS radar. This really puts in perspective just how much rainfall fell.
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