478
FXUS63 KOAX 211851
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
151 PM CDT FRI AUG 21 2026
KEY MESSAGES
- THERE IS A CONDITIONAL THREAT FOR SEVERE STORMS THIS AFTERNOON
AND EVENING. STORMS COULD HAVE VERY LARGE HAIL (2+ INCH) AND
DAMAGING WINDS (60-80 MPH).
- AFTER A BRIEF LULL IN ACTIVITY LATE TONIGHT, MORE STORMS
DEVELOP WEST OF A NELIGH TO WAHOO TO NEMAHA LINE (20-40%
CHANCE) AFTER MIDNIGHT.
- STORMS CLEAR LATE SATURDAY MORNING LEAVING A PLEASANT DAY.
PERIODIC STORM CHANCES CONTINUE INTO NEXT WEEK.
DISCUSSION
ISSUED AT 151 PM CDT FRI AUG 21 2026
SHORT TERM /TODAY THROUGH SATURDAY NIGHT/
18Z METARS SHOW A SFC FRONT DRAPED FROM NEAR HEBRON NORTHEAST TOWARD
WEST-CENTRAL IOWA. ELEVATED CONVECTION HAS CONTINUED TO FESTER
OVER PARTS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE
EARLY AFTERNOON, LARGELY DRIVEN BY SOME H7 WARM ADVECTION AND
WEAK CONVERGENCE ALONG THE H8/H9 FRONT THAT'S DISPLACED FARTHER
NORTH INTO NORTHEAST NEBRASKA.
THE SFC FRONT WILL CONTINUE PUSHING SOUTHWARD THIS AFTERNOON AND
EVENING, WHILE ALOFT, A SUBTLE H5 DISTURBANCE APPROACHES FROM THE
NORTHWEST. NEAR AND AHEAD OF THE FRONT, EXPECT A WARM AND HUMID
AIRMASS IN PLACE WITH CAPE OF 1,000 TO 2,000 J/KG. LIFT PROVIDED BY
THE WAVE, LOW LEVEL FORCING FROM THE FRONTAL FEATURES, AND ANY
OUTFLOW BOUNDARIES SHOULD HELP TRIGGER MORE SCATTERED SHOWERS
AND STORMS ACROSS THE FORECAST AREA THIS AFTERNOON AND EVENING.
HOWEVER, THERE IS STILL A LOT OF UNCERTAINTY ON HOW AFTERNOON
AND EVENING CONVECTION WILL EVOLVE WHICH IS LARGELY EVIDENT IN
THE LATEST HIRES CAM OUTPUTS MAKING THIS SEVERE THREAT LARGELY
CONDITIONAL.
12Z GUIDANCE FROM THE NSSL WRF AND HIRES FV3 TAKE THE CURRENT
CLUSTER OF STORMS OVER CENTRAL NEBRASKA TO THE SOUTHEAST, CLIPPING
OUR FAR SOUTHERN COUNTIES LATER THIS AFTERNOON WITH ADDITIONAL
STORMS FIRING OFF ALONG THE FRONTAL ZONE. MEANWHILE, OTHER SOLUTIONS
FROM BOTH THE HRRR AND NAMNEST WOULD SUGGEST THE CLUSTER ACROSS
CENTRAL NEBRASKA WEAKENING WITH SOUTHEASTWARD EXTENT, AND LITTLE TO
NO LATE AFTERNOON/EARLY EVENING STORM ACTIVITY. GIVEN THE GOOD
AMOUNT OF INSTABILITY PRESENT AND 0-6 KM SHEAR OF 45-50 KTS PROVIDED
BY AN H5 JET, STORMS WOULD LIKELY BECOME SEVERE. THEIR MAIN HAZARDS
WOULD BE VERY LARGE HAIL OF UP TO 2+ INCHES GIVEN THE FAVORABLE,
ELONGATED HODOGRAPHS AND STEEP H7-H5 LAPSE RATES OF 7 TO 8 C/KM, AND
ALSO DAMAGING WIND GUSTS OF 60-80 MPH AS BUFKIT SOUNDINGS SHOW
A RATHER DEEP LOW LEVEL POCKET OF DRY AIR CONTRIBUTING TO LARGE
DOWNDRAFT CAPE OF 1,100 TO 1,400 J/KG.
WITH THIS FORECAST UPDATE, HAVE KEPT POPS OF 15 TO 30% FOR MOST OF
EASTERN NEBRASKA THROUGH 00Z TONIGHT. HIGHS TODAY WARM TO THE MID TO
UPPER 80S.
ANOTHER ROUND OF STORMS IS FORECAST AFTER 06Z TONIGHT (20-40%
CHANCE) ACROSS OUR FAR WESTERN AND SOUTHWESTERN AREAS AS LIFT
REMAINS IN PLACE FROM CONTINUED LOW LEVEL WARM ADVECTION AND SOME
LINGERING FGEN. SOME OF THESE STORMS COULD HAVE SOME GUSTY WINDS
OR HAIL, BUT THE BETTER POTENTIAL APPEARS TO BE IN CENTRAL
NEBRASKA. POPS TAPER OFF AFTER 15Z AS SFC HIGH PRESSURE
GRADUALLY BUILDS BACK INTO THE NORTHERN PLAINS. THIS SHOULD GIVE
US A PLEASANT DAY WITH HIGHS IN THE LOW TO MID 80S UNDER PARTLY
TO MOSTLY SUNNY SKIES. LOWS SATURDAY NIGHT COOL TO THE 60S FOR
MOST LOCATIONS.
LONG TERM /SUNDAY THROUGH THURSDAY/
ANOTHER MID-LEVEL IMPULSE WILL ARRIVE BY EARLY SUNDAY MORNING, AND
COMBINED WITH CONTINUE LOW LEVEL THERMAL ADVECTION, WILL SEE
ANOTHER ROUND OF STORMS ACROSS OUR WESTERN COUNTIES (20-50%
CHANCE). AT THIS TIME, SEVERE WEATHER APPEARS UNFAVORABLE. THE
SOUTHWEST US H5 RIDGE WILL REMAIN IN PLACE FOR MUCH OF THE LONG
TERM FORECAST PERIOD, PLACING US IN NORTHWESTERLY FLOW WITH
SEVERAL MID-LEVEL IMPULSES RIDING IT. THIS WILL LEAD TO
CONTINUED CHANCES FOR STORMS FOR MUCH OF THE PERIOD, BUT THE
BEST CHANCES APPEAR TO BE LATE SUNDAY INTO MONDAY (50 TO 70%
CHANCE, ESPECIALLY ACROSS NORTHEAST NEBRASKA), TUESDAY (20 TO
40% CHANCE AREAWIDE), AND LATE THURSDAY. THE VARIOUS MACHINE
LEARNING SEVERE WEATHER ALGORITHMS WOULD SUGGEST AT LEAST A
SMALL SEVERE THREAT IS POSSIBLE DURING THOSE DAYS WITH ANY
ACTIVITY, BUT AT THIS TIME IT'S STILL TOO EARLY TO DIG INTO
SPECIFICS.
TEMPERATURES SUNDAY REMAIN COOL IN THE UPPER 70S AND LOW 80S, WHILE
HIGHS IN THE 80S ARE EXPECTED THROUGH THURSDAY.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1232 PM CDT FRI AUG 21 2026
VFR CONDITIONS ARE OBSERVED ACROSS TERMINALS THIS AFTERNOON.
1731Z RADAR IMAGERY SHOWS AN AREA OF WIDELY SCATTERED SHOWERS
AND STORMS ACROSS EASTERN NEBRASKA. A MORE ORGANIZED CLUSTER OF
STORMS IS SEEN JUST WEST OF THE KOFK TERMINAL, AND SHOULD ARRIVE
THERE WITHIN THE NEXT TWO HOURS. ANOTHER DECAYING CLUSTER IS
SEEN JUST SOUTHWEST OF KOMA AND NORTHEAST OF KLNK. AT THIS
TIME, CONFIDENCE IS LOW FOR THESE STORMS TO AFFECT TERMINALS,
BUT WILL MAKE AMENDMENTS IF NEEDED. MORE REDEVELOPMENT OF
STORMS COULD OCCUR AFTER 07Z AND CLIP KOFK AND KLNK, BUT CHANCES
REMAIN LESS THAN 30%. WINDS REMAIN UNDER 12 KTS FOR THE
DURATION OF THE TAF CYCLE, BECOMING NORTH NORTHEAST BY THE
MORNING HOURS. COULD SEE SOME FOG DEVELOP AT KOMA BY 11Z, BUT
CHANCES REMAIN TOO LOW (10%) FOR INCLUSION IN TAF.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...CASTILLO
AVIATION...CASTILLO
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