Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >
On the morning of April 30th, a shortwave trough was positioned over Eastern Oklahoma and was propagating to the east away from the Norman weather forecast office's (WFO) county warning area (CWA). However, another shortwave trough was taking shape over the Four Corners region. This second shortwave trough provided large scale ascent (rising motion) over the Texas, Oklahoma, and Kansas region by mid-afternoon. At the surface, a north-to-south-orientated dryline was situated from near Dodge City, KS southward through near Lubbock, TX and provided the necessary lift for thunderstorm initiation. In addition to the dryline, an old outflow boundary from the morning thunderstorms associated with the first shortwave trough was draped from near Dodge City east-southeastward across Southern Kansas and Northern Oklahoma. This outflow boundary not only provided lift for thunderstorm development just like the dryline, but it also enhanced the low-level wind shear across Northern Oklahoma by directing the surface wind direction to be more easterly than southerly.
Instability certainly was not lacking on this day with convective available potential energy (CAPE) indices exceeding 3000 J/kg everywhere east of the dryline and south of the outflow boundary. Convective inhibition (opposite of CAPE) was near zero in that same area by mid-afternoon, so no obvious factor was limiting the development and sustenance of thunderstorms. Additionally, vertical wind shear (change of wind direction and speed with height) was favorable for organized convection (for example, supercells and bow echoes) as indicated by deep layer wind shear values around 45 to 50 knots and low-level wind shear values around 30 knots.
Given the above ingredients, three separate clusters of severe thunderstorms developed near Lubbock, TX, Amarillo, TX, and Dodge City, KS. The cluster of storms near Lubbock had no impact on the Norman WFO's CWA. The Amarillo cluster of severe thunderstorms eventually moved into Western Oklahoma during the early evening hours. This cluster of storms continued eastward and produced wind damage in some spots in Central Oklahoma around the Oklahoma City metro. The third cluster of severe thunderstorms near Dodge City propagated east-southeastward along the outflow boundary into Northern Oklahoma. These storms took advantage of the enhanced low-level shear near the boundary and produced several brief tornadoes, along with large hail and strong winds, between Dodge City, KS and Ponca City, OK. Additionally, a supercell developed east-southeast of the propagating cluster of severe storms along the outflow boundary and produced a couple of longer track tornadoes, as documented under the other associated tabs at the top of this webpage.
More weather information (storm reports, weather maps, soundings, etc.) about this day can be found at this link: https://www.spc.noaa.gov/exper/archive/event.php?date=20120430
 Approximate Damage Paths for the April 30, 2012 Tornadoes |
 Storm Total Precipitation Estimates for April 28-May 1, 2012 |
| Tornado Number |
Date | Time (CST) |
Length of Path (miles) |
Width of Path (yards) |
F-Scale | Killed | Injured | County | Location |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 04/29/2012 | 1957-1959 | 1.3 | 220 | EF1 | 0 | 0 | Osage | 7 E Fairfax - 13.5 SW Pawhuska |
| 2 | 04/30/2012 | 1834 | 0.1 | 20 | EF0 | 0 | 0 | Alfalfa | 2.5 W Jet |
| 3 | 04/30/2012 | 1840-1857 | 3 | 30 | EF0 | 0 | 0 | Alfalfa | 3 NW - 6 NNW Jet |
| 4 | 04/30/2012 | 1910 | 0.1 | 50 | EF0 | 0 | 0 | Nowata | 4 W Nowata |
| 5 | 04/30/2012 | 1912 | 0.2 | 75 | EF1 | 0 | 0 | Nowata | 4 W Nowata |
| 6 | 04/30/2012 | 1913-2005 | 16 | 300 | EF1 | 0 | 0 | Grant | 5 N Nash - 2 SSE Wakita |
| 7 | 04/30/2012 | 1925 | 0.1 | 50 | EF0 | 0 | 0 | Nowata | 4 NW Nowata |
| 8 | 04/30/2012 | 1933 | 0.2 | 75 | EF0 | 0 | 0 | Nowata | 3 N Nowata |
| 9 | 04/30/2012 | 1959-2003 | 1.5 | 200 | EF1 | 0 | 0 | Nowata | 2.5 NE - 4 NE Childers |
| 10 | 04/30/2012 | 2006-2010 | 1 | 50 | EF1 | 0 | 0 | Grant | 1.5 SW - 1 S Medford |
| 11 | 04/30/2012 | 2010-2100 | 14 | 400 | EF1 | 0 | 0 | Grant | 1 SE Medford - 2 E Deer Creek |
| 12 | 04/30/2012 | 2029-2050 | 12 | 200 | EF1 | 0 | 0 | Grant | 3.5 NE Nash - 1 N Pond Creek |
| 13 | 04/30/2012 | 2105-2106 | 1 | 75 | EF0 | 0 | 0 | Craig | 10 N - 10.5 N Cenralia |
| 14 | 04/30/2012 | 2107-2113 | 2 | 50 | EF1 | 0 | 0 | Kay | 0.5 W - 2 S Nardin |
| 15 | 04/30/2012 | 2125-2138 | 7 | 100 | EF1 | 0 | 0 | Kay | 2.5 SSE Nardin - 6 W Tonkawa |
| 16 | 04/30/2012 | 2342-2348 | 7 | 300 | EF1 | 0 | 0 | Nowata | 8 WSW - 6.5 NW Nowata |
| 17 | 05/01/2012 | 0030-0032 | 1 | 150 | EF2 | 0 | 1 | Craig | 1 N - 2 NE Welch |
NWUS54 KOUN 301755
LSROUN
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NORMAN OK
1255 PM CDT MON APR 30 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0848 PM HAIL 2 NW ENID 36.42N 97.90W
04/29/2012 E1.00 INCH GARFIELD OK PUBLIC
0924 PM HAIL HUNTER 36.56N 97.66W
04/29/2012 E1.00 INCH GARFIELD OK PUBLIC
1022 PM HAIL MAY 36.62N 99.75W
04/29/2012 M1.25 INCH HARPER OK TRAINED SPOTTER
1110 PM HAIL 12 ESE WAYNOKA 36.52N 98.68W
04/29/2012 E1.00 INCH WOODS OK PUBLIC
1125 PM FLASH FLOOD 3 NNW PONCA CITY 36.75N 97.11W
04/29/2012 KAY OK LAW ENFORCEMENT
HUBBARD ROAD CLOSED JUST WEST OF WAVERLY STREET DUE TO
HIGH WATER CROSSING THE ROAD.
1130 PM FLASH FLOOD PONCA CITY 36.71N 97.09W
04/29/2012 KAY OK EMERGENCY MNGR
WIDESPREAD STREET FLOODING. SEVERAL CARS STALLED. PONCA
CITY PD ASSISTING DRIVERS.
0122 AM FLASH FLOOD 1 W PONCA CITY 36.71N 97.10W
04/30/2012 KAY OK PUBLIC
WATER REPORTED TO BE NEARLY THREE FEET DEEP. WATER
BEGINNING TO ENTER HOMES ON WEST SIDE OF PONCA CITY.
0142 AM FLASH FLOOD 4 NNW TONKAWA 36.73N 97.34W
04/30/2012 KAY OK LAW ENFORCEMENT
6 TO 8 INCHES OF WATER COVERING INTERSTATE 35. REPORTED
BY OHP
&&
MORE REPORTS WILL BE ADDED AS THEY BECOME AVAILABLE.
$$
NWS NORMAN
|
NWUS54 KOUN 012012
LSROUN
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NORMAN OK
312 PM CDT TUE MAY 01 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 PM HAIL 12 W ALVA 36.80N 98.88W
04/30/2012 E1.75 INCH WOODS OK PUBLIC
0730 PM TORNADO 2 W JET 36.67N 98.22W
04/30/2012 ALFALFA OK BROADCAST MEDIA
KFOR-TV STORM CHASER REPORTED A BRIEF TORNADO 2 MILES
WEST OF NASH. NO DAMAGE WAS REPORTED WITH THE TORNADO.
0740 PM TORNADO 2 NW JET 36.69N 98.21W
04/30/2012 ALFALFA OK STORM CHASER
KFOR-TV AND ALFALFA COUNTY EMERGENCY MANAGER REPORTED A
TORNADO THAT FORMED ON THE SOUTH SIDE OF THE GREAT SALT
PLAINS LAKE. THE TORNADO DAMAGED AN OUTBUILDING ON THE
SOUTH SIDE OF THE LAKE BEFORE MOVING NORTH. THE TORNADO
LIKELY LIFTED SIX MILES NORTH-NORTHWEST OF JET AROUND
1955 CDT.
0755 PM HAIL GREAT SALT PLAINS LAKE 36.74N 98.20W
04/30/2012 E1.75 INCH ALFALFA OK PARK/FOREST SRVC
0810 PM TORNADO 4 NNW NASH 36.72N 98.08W
04/30/2012 GRANT OK STORM CHASER
LOCAL BROADCAST MEDIA AND A STORM CHASER OBSERVED A
TORNADO THAT BEGAN ABOUT 4 MILES NORTH-NORTHWEST OF NASH.
IT IS SOMEWHAT UNCERTAIN AT THIS TIME WHETHER THIS WAS A
SINGLE TORNADO OR IF MORE THAN ONE TORNADO OCCURRED. THE
TORNADIC CIRCULATION BEGAN TO OCCLUDE 8 MILES
WEST-SOUTHWEST OF MEDFORD, AND BEGAN MOVING MORE NORTH.
THE TORNADO APPEARED TO HAVE LIFTED A MILE OR SO
SOUTH-SOUTHWEST OF WAKITA.
0835 PM HAIL 7 NW CAPRON 36.97N 98.67W
04/30/2012 E1.75 INCH WOODS OK EMERGENCY MNGR
0901 PM TORNADO 3 SW MEDFORD 36.77N 97.78W
04/30/2012 GRANT OK BROADCAST MEDIA
THIS TORNADO DEVELOPED SOUTHWEST OF MEDFORD AND MOVED
NORTHEAST. THE MESONET SITE 1 MILE SOUTHWEST OF MEDFORD
REPORTED A WIND GUST OF 84 MPH AT 2110 CDT. THE TORNADO
LIKELY MOVED JUST SOUTH OF THE SITE, AS WELL AS SOUTH OF
THE TOWN OF MEDFORD. THE TORNADO CONTINUED NORTHEAST, OR
EAST-NORTHEAST, MISSING THE TOWN OF DEER CREEK TO THE
NORTH. DAMAGE WAS REPORTED TO HUNDREDS OF POWER POLES AND
THE HOHMANN SUBSTATION WEST OF DEER CREEK. THE TORNADO
LIKLEY LIFTED A COUPLE OF MILES EAST OF DEER CREEK.
0910 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M84.00 MPH GRANT OK MESONET
THE WIND GUST OCCURRED AS A LIKELY TORNADO MOVED SOUTH OF
THE SITE.
0915 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M58.00 MPH GRANT OK MESONET
0929 PM TORNADO 3 NE NASH 36.70N 98.01W
04/30/2012 GRANT OK STORM CHASER
THIS TORNADO DEVELOPED BETWEEN 3 AND 4 MILES NORTHEAST OF
NASH. THE TORNADO MOVED EAST-SOUTHEAST TOWARD POND CREEK,
LIFTING JUST TO THE NORTH OF TOWN AROUND 2150 CDT. MINOR
DAMAGE WAS REPORTED NEAR POND CREEK, WITH SEVERAL LARGE
TREES UPROOTED.
0930 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M65.00 MPH GRANT OK MESONET
0935 PM HAIL 5 SSW VINSON 34.83N 99.90W
04/30/2012 E1.75 INCH HARMON OK AMATEUR RADIO
0945 PM HAIL 5 SSW VINSON 34.83N 99.90W
04/30/2012 E1.75 INCH HARMON OK AMATEUR RADIO
0950 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M68.00 MPH GRANT OK MESONET
0955 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M67.00 MPH GRANT OK MESONET
0958 PM HAIL HOLLIS 34.69N 99.92W
04/30/2012 E1.00 INCH HARMON OK AMATEUR RADIO
1000 PM TSTM WND GST 1 SW MEDFORD 36.79N 97.75W
04/30/2012 M65.00 MPH GRANT OK MESONET
1000 PM TSTM WND GST 2 NW KNOX CITY 33.44N 99.84W
04/30/2012 M74.00 MPH KNOX TX MESONET
ROOF DAMAGE AT KNOX CITY HOSPITAL. TRAMPOLINES HANGING
FROM POWER LINES. NUMEROUS POWER OUTAGES. REPORTED BY
KNOX COUNTY 911.
1005 PM TSTM WND DMG 6 SW LAMONT 36.63N 97.63W
04/30/2012 GRANT OK PUBLIC
LARGE TREES UPROOTED
1010 PM TSTM WND GST 3 W GOULD 34.67N 99.83W
04/30/2012 M76.00 MPH HARMON OK MESONET
1010 PM HAIL 3 E HOLLIS 34.69N 99.86W
04/30/2012 E1.50 INCH HARMON OK AMATEUR RADIO
1025 PM TSTM WND GST 4 NNW FORT COBB 35.15N 98.47W
04/30/2012 M64.00 MPH CADDO OK MESONET
1030 PM TSTM WND GST 4 NNW FORT COBB 35.15N 98.47W
04/30/2012 M60.00 MPH CADDO OK MESONET
1030 PM TSTM WND DMG 1 NW TONKAWA 36.69N 97.32W
04/30/2012 KAY OK EMERGENCY MNGR
SEVERAL POWER POLES BLOWN DOWN
1030 PM HAIL HOLLIS 34.69N 99.92W
04/30/2012 E1.00 INCH HARMON OK LAW ENFORCEMENT
1035 PM TSTM WND GST 5 WNW EL RENO 35.56N 98.04W
04/30/2012 M60.00 MPH CANADIAN OK MESONET
1045 PM TSTM WND DMG 3 S BLACKWELL 36.76N 97.28W
04/30/2012 KAY OK EMERGENCY MNGR
ROOF AND OUTBUILDING DAMAGE 4SE OF HWY11/I35. TIME
ESTIMATED.
1105 PM TSTM WND GST 3 NW SEYMOUR 33.63N 99.30W
04/30/2012 M70.00 MPH BAYLOR TX MESONET
1112 PM FLASH FLOOD BRAMAN 36.92N 97.33W
04/30/2012 KAY OK EMERGENCY MNGR
WATER FIVE TO SEVEN INCHES DEEP ACROSS MAIN STREET AND
RESIDENTIAL STREETS IN BRAMAN.
1125 PM TSTM WND GST 2 SSW MINCO 35.29N 97.96W
04/30/2012 M78.00 MPH GRADY OK MESONET
1130 PM TSTM WND GST 2 SSW MINCO 35.29N 97.96W
04/30/2012 M65.00 MPH GRADY OK MESONET
1133 PM TSTM WND GST WILL ROGERS AIRPORT 35.39N 97.60W
04/30/2012 M62.00 MPH OKLAHOMA OK ASOS
1152 PM HAIL CHOCTAW 35.48N 97.27W
04/30/2012 E1.00 INCH OKLAHOMA OK PUBLIC
1200 AM TSTM WND DMG HARRAH 35.49N 97.16W
05/01/2012 OKLAHOMA OK FIRE DEPT/RESCUE
3FT DIAMTER TREE BLOWN OVER
1200 AM HAIL HARRAH 35.49N 97.16W
05/01/2012 E1.00 INCH OKLAHOMA OK FIRE DEPT/RESCUE
1233 AM TSTM WND DMG 6 SSW CHOCTAW 35.40N 97.31W
05/01/2012 OKLAHOMA OK FIRE DEPT/RESCUE
POWER LINES DOWN NEAR THE INTERSTATE 40 AND 240
INTERCHANGE. REPORTED BY OKC FIRE DISPATCH.
1258 AM TSTM WND GST EARLSBORO 35.26N 96.80W
05/01/2012 E70.00 MPH POTTAWATOMIE OK TRAINED SPOTTER
OUT BUILDING DAMAGED...MOVED 10-15 FEET OFF FOUNDATION. 6
TO 8 INCH DIAMETER TREE BLOWN OVER. REPORT RELAYED VIA
EMERGENCY MGT.
0155 AM NON-TSTM WND GST CUSHING 35.98N 96.77W
05/01/2012 M58.00 MPH PAYNE OK AWOS
&&
WE WILL UPDATE THIS LIST AS MORE REPORTS BECOME AVAILABLE.
$$
NWS NORMAN
|
 24-hour Precipitation Ending at 7:00 AM CDT on April 29, 2012 |
 24-hour Precipitation Ending at 7:00 AM CDT on April 30, 2012 |
 24-hour Precipitation Ending at 7:00 AM CDT on May 1, 2012 |
Storm Total Precipitation Estimates for April 28-May 1, 2012 |
An extensive thunderstorm complex evolved across northern Oklahoma during the evening of April 29, 2012. These storms trained over the same zone for several hours, stretching roughly from Shattuck to Cherokee to Blackwell. Several reports were received of marginally severe hail up to 1.25" in diameter, and flash flooding was reported in Ponca City.
Widespread street flooding occurred from near Tonkawa to Ponca City. Several inches of water forced the closure of several city streets and county roads, and also caused some automobiles to stall. U.S. Interstate Highway I-35 also had about 6 to 8 inches of water running over it north-northwest of Tonkawa. Some of the water entered residences on the west side of Ponca City.
On April 30, 2012, a cluster of supercells that initiated near a warm front across southwest Kansas and northwest Oklahoma moved across parts of northern Oklahoma. The storms produced up to golf ball size hail, several weak tornadoes, high winds, and heavy rainfall. Heavy rainfall in Kay County resulted in water five to seven inches deep across Main Street in Braman from about 10:15 PM CST to near 12:00 AM CST on April 30-May 1, 2012. Other city and rural streets were also under water.
NWUS54 KOUN 301755
LSROUN
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NORMAN OK
1255 PM CDT MON APR 30 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1125 PM FLASH FLOOD 3 NNW PONCA CITY 36.75N 97.11W
04/29/2012 KAY OK LAW ENFORCEMENT
HUBBARD ROAD CLOSED JUST WEST OF WAVERLY STREET DUE TO
HIGH WATER CROSSING THE ROAD.
1130 PM FLASH FLOOD PONCA CITY 36.71N 97.09W
04/29/2012 KAY OK EMERGENCY MNGR
WIDESPREAD STREET FLOODING. SEVERAL CARS STALLED. PONCA
CITY PD ASSISTING DRIVERS.
0122 AM FLASH FLOOD 1 W PONCA CITY 36.71N 97.10W
04/30/2012 KAY OK PUBLIC
WATER REPORTED TO BE NEARLY THREE FEET DEEP. WATER
BEGINNING TO ENTER HOMES ON WEST SIDE OF PONCA CITY.
0142 AM FLASH FLOOD 4 NNW TONKAWA 36.73N 97.34W
04/30/2012 KAY OK LAW ENFORCEMENT
6 TO 8 INCHES OF WATER COVERING INTERSTATE 35. REPORTED
BY OHP
$$
NWS NORMAN
NWUS54 KOUN 012012 LSROUN PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE NORMAN OK 312 PM CDT TUE MAY 01 2012 1112 PM FLASH FLOOD BRAMAN 36.92N 97.33W 04/30/2012 KAY OK EMERGENCY MNGR WATER FIVE TO SEVEN INCHES DEEP ACROSS MAIN STREET AND RESIDENTIAL STREETS IN BRAMAN. $$ NWS NORMAN |
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Radar Reflectivity Loop for the Vance AFB, OK (KVNX) Radar from 7:00-8:05 pm CDT on April 30, 2012
Radar Velocity Loop for the Vance AFB, OK (KVNX) Radar from 7:00-8:05 pm CDT on April 30, 2012
Radar Reflectivity Loop for the Vance AFB, OK (KVNX) Radar from 8:00-10:41 pm CDT on April 30, 2012
Radar Velocity Loop for the Vance AFB, OK (KVNX) Radar from 8:00-10:41 pm CDT on April 30, 2012
Radar Reflectivity Loop for the Vance AFB, OK (KVNX) Radar from 9:55-11:38 pm CDT on April 30, 2012
Radar Velocity Loop for the Vance AFB, OK (KVNX) Radar from 9:55-11:38 pm CDT on April 30, 2012
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