Moderately unstable conditions developed over eastern Nebraska during the afternoon and evening of May 18th as temperatures warmed into the 80s and dew point temperatures reached the mid to upper 60s. As an upper level trough approached from the Rockies, thunderstorms developed in western Nebraska and western Kansas.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS OAX wrote it up.
Moderately unstable conditions developed over eastern Nebraska during the afternoon and evening of May 18th as temperatures warmed into the 80s and dew point temperatures reached the mid to upper 60s. As an upper level trough approached from the Rockies, thunderstorms developed in western Nebraska and western Kansas. These storms moved east across eastern Nebraska and western Iowa and produced isolated areas of wind damage.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Omaha, NE wrote its last area forecast discussion before the first event at May 18, 11:32 PM CST, 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1232 AM CDT SUN MAY 19 2013 .AVIATION... 06Z TAFS FOR KFOK...KOMA AND KLNK. ALTHOUGH THUNDERSTORM CHANCES LINGER OVER THE REGION THROUGH SUNDAY AFTERNOON/EVENING...19/06Z FORECAST JUST CARRIED MENTION THROUGH 10Z WITH INITIAL ROUND. AFTER THAT RESIDUAL MOISTURE COULD ALLOW LOW CLOUDS WITH IFR/LOWER RANGE MVFR CONDITIONS POSSIBLE UNTIL DAYTIME HEATING CAN IMPROVE CONDITIONS. HOWERVER...MIXING FROM CONTINUED SHOWERS/ISOLD TSTMS WOULD IMPACT THAT. ANOTHER ROUND OF CONVECTION EXPECTED SUNDAY AFTN AND EVENING. CHERMOK && PREV DISCUSSION... /ISSUED 338 PM CDT SAT MAY 18 2013/ DISCUSSION... SEVERE THUNDERSTORM CHANCES THROUGH SUNDAY EVENING ARE THE PRIMARY FORECAST CONCERNS. WESTERN UPPER WAVE WAS DRIFTING TOWARD THE ROCKIES THIS AFTERNOON. STRONG SOUTHWEST FLOW AHEAD OF THIS SYSTEM WAS OVERSPREADING HIGH PLAINS REGION...INDUCING CYCLOGENESIS IN SOUTHWEST NEBRASKA AND WESTERN KANSAS WHERE SKIES HAD CLEARED. STRONG INSTABILITY HAS DEVELOPED AHEAD OF THIS LOW WITH MOST UNSTABLE CAPES RUNNING OVER 4000 J/KG FROM SOUTHWEST NEBRASKA THROUGH CENTRAL KANSAS...JUST AHEAD OF DRY LINE. SPC HAS JUST ISSUED A TORNADO WATCH FOR THESE AREAS COVERING WESTERN NEBRASKA THROUGH MUCH OF WESTERN INTO CENTRAL KANSAS. FOR OUR AREA...BROKEN MID LEVEL CLOUD COVER HAS DAMPENED INSOLATION THIS AFTERNOON...HOLDING TEMPERATURES IN THE LOWER 80S. OVERNIGHT EXPECT CONVECTION FROM WESTERN AREAS TO ROLL EAST AND NORTHEAST ACROSS CENTRAL INTO EASTERN NEBRASKA...AND EVENTUALLY SOUTHWEST IOWA...AS LOW LEVEL JET PUSHING 40KT CONTINUES TO PUMP HIGHER THETA-E AIR INTO OUR REGION. HOWEVER...EXACT EVOLUTION OF WESTERN CONVECTION WILL HAVE TO BE WATCHED AS SEVERAL SHORT RANGE MODELS SUGGEST A SPLIT IN ACTIVITY WITH ONE AREA LIFTING INTO NORTHEAST NEBRASKA AND ANOTHER SETTING UP OVER NORTHERN KANSAS. BUT OTHERS SUGGEST A MCS WILL ROLL RIGHT INTO EASTERN NEBRASKA LATE THIS EVENING. AT ANY RATE...PRECIP CHANCES WILL BE ON THE INCREASE FROM LATE EVENING ON...WITH THE THREAT OF SEVERE WEATHER STILL THERE. MODELS SUGGEST ELEVATED CAPE VALUES WILL STILL BE TOPPING 2000 J/KG AS STORMS MOVE IN...SO HAIL IS CERTAINLY A THREAT. IF STORMS DO NOT BECOME ELEVATED WITH TIME AS EXPECTED...THEN WINDS COULD ALSO BE A PROBLEM...ESPECIALLY DURING THE LATE EVENING. MOST LIKELY AREAS FOR SEVERE WOULD BE NEAR THE KANSAS BORDER WHERE A PLURALITY OF SHORT RANGE ENSEMBLE MEMBERS PAINT A SWATH OF STRONG STORMS...OR OVER NORTHEAST NEBRASKA WHERE SEVERAL MODELS POINT TO MCS TRACK. ACTIVITY SHOULD CONTINUE WELL PAST MIDNIGHT BEFORE MOVING EAST OF OUR AREA SUNDAY MORNING. LOOKS LIKE WE COULD HAVE A SUBSTANTIAL LULL IN ACTIVITY DURING THE MORNING BEFORE ROUND TWO BEGINS SUNDAY AFTERNOON. UPPER TROUGH WILL PUSH FARTHER INTO THE PLAINS...PUSHING SURFACE TROUGH/LOW INTO EASTERN NEBRASKA AND EASTERN KANSAS. SUBSTANTIAL INSTABILITY WILL EXIST AHEAD OF THIS BOUNDARY DURING THE AFTERNOON...BUT SHEAR PROFILES WILL BE DECREASING WITH TIME AS WE HEAD LATER IN THE AFTERNOON OWING TO SLACKENING GRADIENT CLOSER TO SURFACE/UPPER TROUGHS. VERY STEEP LOW AND MID LEVEL LAPSE RATES ON THE ORDER OF 8 C/KM WILL EXIST OVER MUCH OF OUR AREA...AND FORECAST SOUNDINGS SHOW INHIBITION GOING AWAY BY MID TO LATE AFTERNOON. MIXED LAYER CAPE VALUES OVER 2500 J/KG ARE PROGGED OVER MUCH OF OUR AREA...WITH 0-6KM SHEAR AROUND 40KT. SO SUPERCELLS LOOK LIKELY WITH LARGE HAIL AND DAMAGING WINDS CERTAINLY...BUT TORNADO POTENTIAL IS STILL IN QUESTION. LOW LEVEL SHEAR IS MOST PRONOUNCED IN OUR FAR SOUTHEAST CWA...BUT ANY WARM FRONTAL BOUNDARY THAT ROTATES NORTH AROUND SURFACE LOW WILL BE A CANDIDATE TO FOCUS TORNADO THREAT AS WELL. SEVERE THREAT WILL LAST THROUGH THE EVENING BEFORE SURFACE BOUNDARY SHIFTS EAST AND FOCUSES STORMS MORE IN IOWA AND MISSOURI. HOWEVER UPPER LOW CUTTING OFF JUST NORTH OF NEBRASKA AND LINGERING MID LEVEL INSTABILITY WILL BRING CONTINUED THUNDER CHANCE INTO MONDAY. THAT LOW WILL REMAIN IN OUR AREA THROUGH AT LEAST MID WEEK...BRINGING OFF AND ON SHOWERS AND ISOLATED THUNDERSTORMS ALONG WITH COOLER TEMPERATURES. IT LOOKS LIKE A WARMING TREND IS IN STORE FOR LATE IN THE WEEK AS UPPER LOW FINALLY MOVES EAST AND HEIGHTS BEGIN TO RISE. DERGAN && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 553 PM CDT SAT MAY 18 2013 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-191300- MONONA-HARRISON-SHELBY-POTTAWATTAMIE-MILLS-MONTGOMERY-FREMONT- PAGE-KNOX-CEDAR-THURSTON-ANTELOPE-PIERCE-WAYNE-BOONE-MADISON- STANTON-CUMING-BURT-PLATTE-COLFAX-DODGE-WASHINGTON-BUTLER- SAUNDERS-DOUGLAS-SARPY-SEWARD-LANCASTER-CASS-OTOE-SALINE- JEFFERSON-GAGE-JOHNSON-NEMAHA-PAWNEE-RICHARDSON- 553 PM CDT SAT MAY 18 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF EASTERN NEBRASKA AND WESTERN IOWA. .DAY ONE...TONIGHT AND SUNDAY SCATTERED THUNDERSTORMS ARE EXPECTED TONIGHT...AND SEVERE STORMS ARE POSSIBLE. LARGE HAIL AND DAMAGING WINDS ALONG WITH LOCALLY HEAVY RAIN WILL BE THE PRIMARY HAZARDS. A LARGE UPPER LEVEL SYSTEM HAS COMBINED WITH STRONG SHEAR AND INSTABILITY TO CREATE SCATTERED THUNDERSTORMS...A FEW SEVERE...FROM WESTERN NEBRASKA INTO NORTHWEST KANSAS SATURDAY AFTERNOON. THIS ACTIVITY WILL SPREAD NORTHEAST TONIGHT AS THE UPPER SYSTEM MOVES SLOWLY EAST AND A LOW LEVEL JET STRENGTHENS OVER THE REGION. ALTHOUGH WIND SHEAR IS FORECAST TO BE LESS OVER EASTERN NEBRASKA AND SOUTHWEST IOWA THAN LOCATIONS TO THE WEST...AND SURFACE BASED INSTABILITY SHOULD WEAKEN...CONDITIONS REMAIN FAVORABLE ENOUGH SO THAT STORMS THAT MOVE OR DEVELOP INTO THE REGION COULD BE SEVERE. AFTER A POSSIBLE LULL IN THE ACTIVITY SUNDAY MORNING...ADDITIONAL THUNDERSTORMS SHOULD DEVELOP SUNDAY AFTERNOON AS THE UPPER SYSTEM CONTINUES MOVING EAST. THE HIGHEST INSTABILITY AND WIND SHEAR SUNDAY AFTERNOON AND EVENING IS EXPECTED TO EXTEND FROM SOUTHEAST NEBRASKA AND SOUTHWEST IOWA TO POINTS SOUTH. ALTHOUGH THE GREATEST CONCENTRATION OF SEVERE WEATHER SUNDAY COULD BE ACROSS THAT AREA...SEVERE STORMS ARE POSSIBLE OVER ALL OF EASTERN NEBRASKA AND WESTERN IOWA DUE TO THE STRENGTH OF THE UPPER SYSTEM AND AT LEAST MODEST INSTABILITY EXPECTED OVER MUCH OF THE AREA. VERY LARGE HAIL AND DAMAGING WINDS ARE AMONG THE HAZARDS ON SUNDAY. WITH A POSSIBLE DRY-LINE OR WARM FRONT IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA...ISOLATED TORNADOES ARE POSSIBLE AS WELL. .DAYS TWO THROUGH SEVEN...SUNDAY NIGHT THROUGH SATURDAY THE SEVERE WEATHER THREAT OVER THE AREA SHOULD SHIFT TO FAR SOUTHEAST NEBRASKA AND SOUTHWEST IOWA SUNDAY EVENING BEFORE MOVING OUT OF THE REGION SUNDAY NIGHT. WITH THE UPPER LEVEL SYSTEM CLOSING OFF AND STALLING OVER THE PLAINS...ISOLATED THUNDERSTORMS REMAIN POSSIBLE THEN MONDAY AND TUESDAY...MAINLY WITH AFTERNOON HEATING. ISOLATED STORMS COULD BE SEVERE MONDAY AFTERNOON IF ENOUGH LOW LEVEL MOISTURE AND INSTABILITY CAN LAG BENEATH THE COOLING UPPER LEVEL SYSTEM. .SPOTTER INFORMATION STATEMENT... ALTHOUGH STORM SPOTTER ACTIVITY MAY BE REQUIRED LATE THIS EVENING...SPOTTERS WILL MORE LIKELY BE NEEDED SUNDAY AFTERNOON AND EVENING. CHERMOK
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1040 PM CDT SAT MAY 18 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1031 PM TSTM WND DMG COLUMBUS 41.43N 97.36W
05/18/2013 PLATTE NE EMERGENCY MNGR
SPOTTY TREE DAMAGE REPORTED ALONG WITH SOME POWER
OUTAGES.
&&
PEARSONPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1131 PM CDT SAT MAY 18 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1131 PM HAIL FAIRBURY 40.14N 97.18W
05/18/2013 E1.00 INCH JEFFERSON NE EMERGENCY MNGR
&&
PEARSONPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1136 PM CDT SAT MAY 18 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1133 PM HAIL JANSEN 40.19N 97.08W
05/18/2013 E1.00 INCH JEFFERSON NE EMERGENCY MNGR
&&
PEARSONSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1142 PM CDT SAT MAY 18 2013
NEZ089>093-190515-
RICHARDSON NE-JOHNSON NE-GAGE NE-NEMAHA NE-PAWNEE NE-
1142 PM CDT SAT MAY 18 2013
...SIGNIFICANT WEATHER ADVISORY FOR RICHARDSON...JOHNSON...CENTRAL
GAGE...NEMAHA AND PAWNEE COUNTIES UNTIL 1215 AM CDT...
AT 1138 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A LINE OF STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM BEATRICE
TO BERN...OR ALONG A LINE EXTENDING FROM 29 MILES NORTH OF MARYSVILLE
TO 21 MILES WEST OF FALLS CITY...AND MOVING NORTHEAST AT 60 MPH.
WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THESE STORMS.
LOCATIONS IMPACTED INCLUDE...
FALLS CITY...AUBURN...TECUMSEH...WYMORE...PAWNEE CITY...HUMBOLDT...
PERU...STERLING...ADAMS...BLUE SPRINGS...COOK...JOHNSON...TABLE
ROCK...SHUBERT...VERDON...STELLA...RULO...DAWSON...NEMAHA AND FILLEY.
LAT...LON 4017 9680 4052 9655 4052 9567 4051 9569
4047 9569 4046 9564 4042 9566 4034 9562
4031 9565 4030 9557 4026 9555 4023 9547
4018 9548 4012 9540 4004 9542 4000 9531
4000 9636
TIME...MOT...LOC 0438Z 234DEG 51KT 4026 9671 3997 9598
MAYESPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1200 AM CDT SUN MAY 19 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1140 PM TSTM WND DMG 6 S BEATRICE 40.18N 96.75W
05/18/2013 GAGE NE LAW ENFORCEMENT
ROOF TAKEN OFF OF A SHED ALONG HWY 77.
&&
J-E.KLISHSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1224 AM CDT SUN MAY 19 2013
IAZ055-069-NEZ034-045-052-190600-
POTTAWATTAMIE IA-HARRISON IA-DOUGLAS NE-WASHINGTON NE-BURT NE-
1224 AM CDT SUN MAY 19 2013
...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN POTTAWATTAMIE...
WESTERN HARRISON...DOUGLAS...WASHINGTON AND SOUTHEASTERN BURT
COUNTIES UNTIL 100 AM CDT...
AT 1221 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM NEAR ELKHORN...OR 12 MILES NORTHWEST OF
OMAHA...MOVING NORTHEAST AT 50 MPH.
HAIL UP TO THE SIZE OF DIMES WILL BE POSSIBLE WITH THIS STORM.
LOCATIONS IMPACTED INCLUDE...
OMAHA...BLAIR...ELKHORN...MISSOURI VALLEY...LOGAN...ARLINGTON...FORT
CALHOUN...MONDAMIN...KENNARD...MODALE...BENNINGTON...BOYS TOWN...
LITTLE SIOUX...MAGNOLIA AND WASHINGTON.
LAT...LON 4120 9604 4134 9641 4137 9642 4139 9640
4140 9633 4143 9633 4144 9636 4145 9637
4182 9610 4181 9583 4164 9564
TIME...MOT...LOC 0521Z 208DEG 43KT 4137 9621
MAYESThe Omaha radar (KOAX), 90 km away, was scanning. The volume nearest the first event began at 05:39 UTC.
1 thunderstorm wind. Local standard time, as filed.
A department of roads sensor along I29 measured a thunderstorm wind gust of 61 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2013Every state in 2013This day in weather historyWarnings in Iowa, May 2013
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 440830.