284
FXUS63 KOAX 172316
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
616 PM CDT THU SEP 17 2026
KEY MESSAGES
- MIX OF CLOUDS AND SUN TODAY WITH HIGHS IN THE 70S TO LOW 80S.
AREAS ALONG AND SOUTH OF I-80 COULD SEE SOME SPOTTY SHOWERS OR
STORMS THIS AFTERNOON (20% CHANCE).
- STORMS REDEVELOP ACROSS FAR NORTHEAST NEBRASKA LATE TONIGHT
INTO FRIDAY MORNING (60-80%) AND COULD BRING SOME HEAVY RAIN.
- MORE STORMS REDEVELOP FRIDAY AFTERNOON AND EVENING (40-60%
CHANCE). THERE IS A 5% CHANCE THAT SOME COULD BE SEVERE.
ADDITIONAL STORM CHANCES PERSIST FOR MUCH OF THE WEEKEND
THROUGH MONDAY WITH COOLER TEMPERATURES.
DISCUSSION
ISSUED AT 158 PM CDT THU SEP 17 2026
SHORT TERM /TODAY THROUGH FRIDAY NIGHT/
18Z SPC MESOANALYSIS SHOWS H5 RIDGING REMAINING FIRMLY IN PLACE
OVER MUCH OF THE SOUTHERN PLAINS AND SOUTHEAST US. AT THE SFC,
HIGH PRESSURE IS SEEN OVER THE DAKOTAS AND MINNESOTA, EXTENDING
SOUTHWARD INTO THE MISSOURI RIVER VALLEY. SHOULD SEE SOME OF THE
PESKY STRATUS CLOUDS LINGER THIS AFTERNOON AS SUBSIDENCE FROM
THE HIGH PUSHES DOWNWARD AND TRAPS RESIDUAL MOISTURE. SPOTTY
SHOWERS AND A FEW ISOLATED STORMS MAY PERSIST ACROSS OUR FAR
SOUTHERN AREAS THIS AFTERNOON (20% CHANCE) AS LOW LEVEL WARM
ADVECTION REMAINS IN PLACE. HIGHS TODAY REACH THE MID TO UPPER
70S.
WILL SEE THE SFC HIGH PASS TO THE NORTH AND EAST, WHILE A SFC LOW
GETS SPUN UP IN FAR EASTERN COLORADO. THE H8 BAROCLINIC ZONE
LIFTS NORTHEASTWARD ACROSS MOST OF THE STATE, A LLJ WILL
OVERSPREAD TO THE EAST OVER MUCH OF CENTRAL INTO NORTHERN AND
NORTHEAST NEBRASKA. SPEED CONVERGENCE ALONG THE JET NOSE, IN
ADDITION TO AN APPROACHING H5 SHORTWAVE, SHOULD HELP FORCE
PARCELS UPWARD AND TAP INTO A NARROW RIBBON OF MUCAPE OF 500 TO
1,000 J/KG, RESULTING IN SOME SHOWERS AND STORMS. BULK SHEAR OF
AROUND 30 KTS COULD SUPPORT A BRIEF STRONG UPDRAFT CAPABLE OF
SOME GUSTY WINDS OR HAIL, BUT THE MORE LIKELY THREAT WILL BE
HEAVY RAINFALL. PWATS REMAIN HIGH AT 1.75 TO 1.9 INCHES, WHILE
WARM CLOUD DEPTHS REMAIN MARGINAL JUST UNDER 4,000 METERS. MOST
CAMS TEND TO KEEP THE ACTIVITY SOMEWHAT PROGRESSIVE WHICH COULD
LIMIT FLOODING POTENTIAL, BUT STILL CAN'T RULE OUT A FEW AREAS
SEEING LOCALLY HEAVY RAINFALL UNDERNEATH ANY STORMS. POPS OF 60
TO 80% ARE FORECAST FOR PRIMARILY FAR NORTHEAST NEBRASKA ALONG
THE BORDER WITH SOUTH DAKOTA AFTER 03Z, CLEARING BY 11Z. THERE
IS SOME POTENTIAL FOR FOG DEVELOPMENT TONIGHT, PARTICULARLY IN
NORTHEAST NEBRASKA NEAR THE NORFOLK VICINITY (20-30% CHANCE PER
12Z HREF GUIDANCE). HOWEVER, WIND SPEEDS WILL RANGE FROM 5 TO 10
MPH OVERNIGHT WHICH COULD LIMIT THE THREAT.
THE SFC LOW IS PROGGED TO LIFT NORTHEAST, DRAGGING THE SFC WARM FRONT
THROUGH MOST OF THE FORECAST AREA BY THE DAYTIME HOURS. THIS
SHOULD LEAD TO ANOTHER PLUME OF INSTABILITY OVERSPREADING THE
WARM SECTOR, RANGING FROM 2,000 TO 3,500 J/KG BY THE LATE
AFTERNOON. 0-6 KM BULK SHEAR REMAINS RATHER WEAK AT TIMES,
AROUND 20 TO 25 KTS SEEN FROM SOME HIRES CAMS AND THE VARIOUS
PARAMETERIZED MODELS WHICH COULD LIMIT STORM ORGANIZATION. LARGE
SCALE FORCING FOR ASCENT STILL APPEARS TO LACK AROUND THIS
TIMEFRAME TOO AS THE H5 IMPULSE WON'T ARRIVE UNTIL LATE FRIDAY
NIGHT, BUT ANY REMNANT MCV FROM OVERNIGHT CONVECTION COULD
PROVIDE SOME LIFT FOR STORM DEVELOPMENT. BUFKIT SOUNDINGS WOULD
ALSO SUGGEST SOME ELEMENT OF LOW LEVEL CAPPING AROUND H8 THAT
COULD LIMIT STORM DEVELOPMENT IN THE LATE AFTERNOON HOURS. IF
STORMS CAN MANAGE TO FORM NEAR AND ALONG THE APPROACHING SFC
FRONT, THE MAIN SEVERE THREAT WOULD BE DAMAGING WIND GUSTS OR
EVEN A BRIEF TORNADO, BUT THAT WILL LARGELY BE DEPENDENT ON IF
WE CAN BE SFC BASED. BY THE EVENING HOURS, A 30-40 KT H8 LLJ
WILL RAMP UP ACROSS OUR SOUTHEASTERN AREAS WHICH COULD FIRE OFF
ADDITIONAL ELEVATED CONVECTION, SOME OF WHICH COULD HAVE SOME
GUSTY WINDS OR HAIL. POPS AT THIS TIME REMAIN AT 40 TO 60%
FRIDAY EVENING, PARTICULARLY OVER FAR EASTERN NEBRASKA INTO
WESTERN IOWA.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
THE SFC FRONT WILL HAVE MOVED OFF AWAY FROM THE AREA SATURDAY,
RESULTING IN HIGHS REACHING THE 70S TO LOW 80S. MORE CHANCES
FOR STORMS CONTINUE SATURDAY INTO SUNDAY AS ANOTHER MID LEVEL
IMPULSE AND REMNANT H8 ADVECTION PERSIST. EXPECT POPS OF 50 TO
70%, PARTICULARLY ALONG AND SOUTH OF INTERSTATE 80 LATE SATURDAY
INTO SUNDAY MORNING. RAINY CONDITIONS CONTINUE INTO SUNDAY AS
THE CLOSED H5 LOW NOW OVER THE NORTHERN CALIFORNIA COASTAL AREA
FINALLY TREKS EAST INTO THE NORTHERN PLAINS, PROVIDING SOME LIFT
WHILE LOW TO MID LEVEL MOISTURE TRANSPORT REMAINS POINTED IN
THE AREA. RAIN GRADUALLY ENDS BY MONDAY AFTERNOON AS THE MID
LEVEL WAVE MOVES AWAY FROM THE AREA AND SFC HIGH PRESSURE BUILDS
BACK IN. MOSTLY DRY CONDITIONS ARE PROGGED FOR TUESDAY, WHILE
OUR NEXT DISTURBANCE APPROACHES FOR WEDNESDAY AND THURSDAY WITH
MORE POPS OF 20 TO 40% AREAWIDE. TEMPERATURES SUNDAY THROUGH AT
LEAST WEDNESDAY WILL REMAIN ON THE COOLER SIDE, WITH HIGHS IN
THE 60S TO NEAR 70F. THERE IS SOME SIGNAL FOR A WARM UP TO THE
UPPER 70S AND LOW 80S LATE NEXT WEEK AS H5 RIDGING MAKES ITS WAY
BACK TOWARD THE AREA.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 608 PM CDT THU SEP 17 2026
SCATTERED SHOWERS WILL BE POSSIBLE AT KOMA AND KLNK FOR THE NEXT
FEW HOURS. OTHERWISE OVERNIGHT RAIN CHANCES WILL PRIMARILY
TARGET FAR NORTHEAST NEBRASKA, OCCASIONALLY GIVING KOFK A
GLANCING BLOW BETWEEN 04-06Z AND 11-13Z. CEILINGS WILL ALSO
LOWER WITH THE PASSING SHOWERS, BECOMING MVFR BY MIDNIGHT, AND
FALLING TO IFR/LIFR THROUGH THE OVERNIGHT HOURS. WHILE SOME
PATCHY FOG IS POSSIBLE, SOUTHERLY WINDS REACHING SPEEDS OF
5-12KTS WILL KEEP WIDESPREAD DENSE FOG FROM DEVELOPING. CEILINGS
WILL IMPROVE AS SHOWERS MOVE EAST OF THE AREA FRIDAY MORNING.
EXPECT VFR CONDITIONS TO PREVAIL BY AROUND 15Z AT ALL 3 TAF
SITES.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...CASTILLO
AVIATION...KG
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