477
FXUS63 KOAX 171809
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
109 PM CDT SUN MAY 17 2026
KEY MESSAGES
- THE ONGOING ROUND OF SEVERE STORMS ENDING EARLY SUNDAY
MORNING. THE REST OF THE MORNING HOURS WILL BE COOL AND
BREEZY, BUT BECOME WARM AND MUGGY LATER SUNDAY
- SEVERE STORMS WILL DEVELOP AGAIN ON SUNDAY AFTERNOON. VERY
LARGE HAIL, DAMAGING DOWNBURST WINDS, AND TORNADOES WILL BE
POSSIBLE. THE GREATEST SEVERE POTENTIAL WILL BE NORTHWEST OF A
LINCOLN TO HARLAN LINE.
- A FINAL ROUND OF SEVERE STORMS DEVELOPS ON MONDAY AFTERNOON.
VERY LARGE HAIL, DAMAGING DOWNBURST WINDS, AND TORNADOES ARE
ONCE AGAIN POSSIBLE, PARTICULARLY SOUTHEAST OF A SEWARD TO
ONAWA LINE.
- MUCH COOLER CONDITIONS ARE EXPECTED FOR THE REST OF THE WORK
WEEK.
DISCUSSION
ISSUED AT 1141 PM CDT SAT MAY 16 2026
OVERVIEW:
A VOLATILE SEVERE WEATHER SETUP WILL AFFECT THE LOCAL FORECAST AREA
THROUGH MONDAY, WITH MULTIPLE ROUNDS OF SEVERE STORMS LIKELY EACH
DAY, AND SIGNIFICANT SEVERE WEATHER AT TIMES, INCLUDING VERY LARGE
HAIL AND TORNADOES.
EARLY SUNDAY:
WIDESPREAD THUNDERSTORMS HAVE BEEN VERY EFFICIENT IN EATING UP
INSTABILITY LATE SATURDAY EVENING INTO EARLY SUNDAY MORNING. THIS
WILL BE CAPPED OFF BY A BROAD ARC OF SURGING SEVERE THUNDERSTORMS
WORKING ALONG THE NEBRASKA/KANSAS STATE LINE. THIS BOW ECHO WILL
PUSH OFF TO THE EAST OF THE FORECAST AREA BY AROUND 3 AM, GIVE
OR TAKE WITH A BROAD STABLE REGION OVERSPREADING THE AREA AND
PUSHING SOUTH INTO KS. CURRENTLY BELIEVE THAT THE STABLE AIRMASS
WILL SPREAD 40 TO 70 MILES SOUTH OF THE KS/NE BORDER. NORMALLY
WOULD SUSPECT IT WOULD DIVE FARTHER SOUTH, BUT THE 0-3 KM SHEAR
VECTORS ARE FAVORING ENE GUSTING SEGMENTS WITH THIS MAIN BOW,
AND THE OVERALL FLOW PATTERN WITH AN INCOMING STRONG SHORT WAVE
WITH NEGATIVE TILT AND DEVELOPING SURFACE LOW WILL QUICKLY DRAW
THE UNSTABLE AIRMASS BACK NORTH. ALL THIS TO SAY THAT THE AREA
IS SET UP FOR A PRETTY PLEASANT MORNING ON SUNDAY AFTER A RAINY
SATURDAY NIGHT. BUT THAT WILL CHANGE OVER THE COURSE OF THE DAY.
SUNDAY AFTERNOON INTO SUNDAY NIGHT:
THE CENTER OF THE UPPER TROUGH AXIS WILL REMAIN WELL TO THE WEST ON
SUNDAY BUT AN EMBEDDED LEAD SHORT WAVE TROUGH AND ATTENDANT JET
STREAK WILL EJECT FROM EASTERN CO INTO EASTERN NE DURING THE DAY. AN
ELONGATED TROUGH OF SURFACE LOW PRESSURE WILL EXTEND FROM THE MAIN
SURFACE LOW IN SOUTHEAST CO UP THROUGH SOUTH CENTRAL NE AND INTO
SOUTHEAST SD. EXPECT THIS TO BE A ZONE OF PERSISTENT STRONG DEEP
MOIST CONVERGENCE THROUGH THE AFTERNOON. ADDITIONALLY, THERE IS A
STRONG MODEL SIGNAL FOR A NARROW DRYLINE SURGE INTO CENTRAL NE AND
CENTRAL KS DURING THE AFTERNOON. EAST OF THIS, IN THE WARM SECTOR,
MIDDLE TO UPPER 60S DEWPOINTS WILL SURGE BACK NORTH DURING THE DAY.
THIS WILL SET UP VERY STRONG INSTABILITY WITH MLCAPE LIKELY IN THE
3000-4000 J/KG RANGE. IT IS WORTH NOTING THAT EVEN AMIDST THIS
HIGHLY UNSTABLE ENVIRONMENT, THERE IS A SLIGHT WEAKNESS IN THE MID-
LEVEL WINDS, SO FORECAST PARAMETERS SUCH AS THE 0-6 KM SHEAR VECTOR
ARE NOT PARTICULARLY IMPRESSIVE. HOWEVER, ONE LOOK AT HODOGRAPHS
TELLS A STORY OF AMPLE CYCLONIC CURVATURE IN THE LOWEST PORTIONS OF
THE HODOGRAPH WITH WHAT IS LIKELY ENOUGH OF A WIND DIFFERENCE TO
KEEP THE UPDRAFTS RELATIVELY CLEAN OF DOWNDRAFTS. MODEL GUIDANCE IS
CONSISTENT IN DESTABILIZING SUFFICIENTLY FOR INITIATION BY 4 PM, AND
WOULD NOT BE SURPRISED IF IT'S SLIGHTLY EARLIER. THAT INITIAL
CONVECTIVE INITIATION WILL LIKELY EXTEND ON A NORTH-SOUTH LINE
FROM KNOX COUNTY DOWN THROUGH BOONE COUNTY, AND DUE SOUTH FROM
THERE. THIS IS WHERE THINGS GET ESPECIALLY INTERESTING. THE
STRENGTH OF THE FORCING WILL PLAY A SIGNIFICANT ROLE IN WHETHER
STORM MODE BECOMES LINEAR OR REMAINS LARGELY CELLULAR. THE DEEP
SHEAR VECTORS, WHILE NOT LARGE IN MAGNITUDE, ARE LARGELY
PERPENDICULAR TO THE LINE, SO AS LONG AS THE FORCING ISN'T
OVERWHELMING, CONVECTION IS LIKELY TO REMAIN CELLULAR. THE
SIGNIFICANT SPEED AND DIRECTIONAL SHEAR IN THE LOWEST LEVELS,
IMPRESSIVE AT INITIATION AND INCREASING NOTABLY INTO THE EARLY
EVENING HOURS, POINT TO THE POTENTIAL OF QUICK ORGANIZATION INTO
A LINE OF SUPERCELLS WITH TORNADO, HAIL, AND DOWNBURST
POTENTIAL. ANY LONGER-LIVED SUPERCELL FEATURES THAT CAN PERSIST
INTO THE INTENSIFYING ENVIRONMENTAL SHEAR CONDITIONS WILL HAVE A
CHANCE TO PRODUCE STRONG TORNADOES. WITH THAT SAID, THE STORM
MODE IS NOT A SIMPLE FORECAST WITH THIS EVENT, AND WILL HAVE
SOME DEPENDENCY UPON THOSE MID-LEVEL WINDS, TIMING OF CONVECTIVE
ONSET, AND INTENSITY OF LINEAR FORCING.
MONDAY:
THE PRIMARY TROUGH AND STRONGEST JET STREAK EJECT ACROSS NEBRASKA ON
MONDAY. SUNDAY'S CONVECTION LOOKS TO CLEAR THE AREA VERY EARLY
MONDAY MORNING, AND ONCE AGAIN EXPECT A ROBUST EARLY-DAY RECHARGE OF
MOISTURE AND INSTABILITY NORTH INTO NEBRASKA AND IOWA. THERE ARE
QUESTION MARKS REGARDING JUST HOW FAR NORTH AND EAST THIS WILL
EXTEND, BUT A MAJORITY OF 00Z MODEL GUIDANCE BRINGS IT WELL NORTH,
PERHAPS EXTENDING AS FAR AS A HEBRON TO WAHOO TO ONAWA LINE BY
EARLY TO MID AFTERNOON. WARM SECTOR INSTABILITY WILL ONCE AGAIN
BE QUITE STRONG. DEEP LAYER WIND SHEAR WILL BE SUFFICIENT FOR
SUPERCELLS STORM MODE TO BE DOMINANT. STORM MOTION MAY TAKE
THESE STORMS SLIGHTLY MORE PARALLEL TO THE INITIATING BOUNDARY
WHICH MAY COMPLICATE STORM MODE, BUT MOST ALL SIGNS POINT TO A
BROKEN LINE OF SUPERCELLS, POTENTIALLY TRAINING OVER SOME AREAS,
WITH FAVORABLE HODOGRAPHS FOR SUSTAINED SUPERCELLS, VERY LARGE
HAIL, DOWNDRAFTS, AND TORNADOES. ALSO SEE POTENTIAL FOR STRONG
TORNADOES PARTICULARLY IN LONG-LIVED, MORE ISOLATED SUPERCELLS.
THE QUESTION IS NOT NECESSARILY THE AVAILABLE INGREDIENTS FOR
SEVERE WEATHER ON MONDAY, BUT THE LOCATIONS IN WHICH THEY WILL
BE PRESENT...HOW FAR NORTH AND WEST. AND WE MAY NOT KNOW THAT
WITH GREAT CONFIDENCE UNTIL MONDAY MORNING.
AFTER MONDAY:
TEMPERATURES COOL SHARPLY WITH HIGHS IN THE 50S AND 60S AT MID WEEK
AND EVEN SOME POTENTIAL FOR FROST ON A COUPLE OF MORNINGS. THEN
ANOTHER SLOW WARMUP EXPECTED BY THE WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1256 PM CDT SUN MAY 17 2026
KOFK: MVFR CONDITIONS PERSIST AT THE TERMINAL AT THE EARLY ONSET OF
THE FORECAST PERIOD. EXPECT A CHANCE FOR STRONG TO SEVERE
THUNDERSTORMS BY 23Z. ANY STORMS THAT DO DEVELOP WILL HAVE THE
POTENTIAL OF PRODUCING STRONG WIND GUSTS, LARGE HAIL, AND HEAVY
RAINFALL RESULTING IN REDUCTIONS TO VISIBILITY. AN ISOLATED TORNADO
CANNOT BE ENTIRELY RULED OUT. WINDS SHIFT FROM SOUTHEASTERLY
THIS AFTERNOON TO NORTHWESTERLY BY 23Z. CEILINGS MAY FALL TO IFR
LEVELS TOWARD THE END OF THE TAF PERIOD, AFTER 11Z.
KOMA: VFR CEILINGS WILL DETERIORATE TO MVFR AS STORMS DEVELOP
THIS EVENING. STRONG TO SEVERE THUNDERSTORMS WITH ALL HAZARDS
ARE TO BE EXPECTED AFTER 00Z WITH BETTER CHANCES CLOSER TO 02Z
AT THE TERMINAL. SOUTH WINDS SHIFT TO THE NORTH TOMORROW MORNING
BY 13Z WITH CEILINGS EXPECTED TO LOWER TO IFR LEVELS.
KLNK: VFR CEILINGS WILL LOWER TO MVFR BY 23Z AS A STORM SYSTEM
MOVES INTO THE REGION. EXPECT STRONG TO SEVERE THUNDERSTORMS AS
EARLY AS 00Z WITH BETTER POTENTIAL AFTER 02Z. ALL SEVERE TYPES
(HAIL, WIND, ISOLATE TORNADO) WILL BE POSSIBLE. SOUTH WINDS
PERSIST THROUGH THE AFTERNOON, BECOMING NORTHERLY AFTER 05Z.
CEILINGS ARE EXPECTED TO FALL TO IFR LEVELS BY 14Z.
OAX WATCHES/WARNINGS/ADVISORIES
NE...FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH TUESDAY MORNING
FOR NEZ065-066-068-078-088>093.
IA...NONE.
DISCUSSION...BARJENBRUCH
AVIATION...ANW
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