172
FXUS63 KOAX 200519
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1219 AM CDT SUN SEP 20 2026
KEY MESSAGES
- STORMS EXIT THE AREA EARLY THIS MORNING. MORE SHOWERS AND A
FEW RUMBLES OF THUNDER REDEVELOP IN THE LATE MORNING AND
PERSIST FOR MOST OF THE DAY (40-70% CHANCE). ENJOY THE COOLER
TEMPERATURES AS MOST SEE HIGHS IN THE MID 60S.
- RAIN CONTINUES INTO MONDAY (60-80% CHANCE), ESPECIALLY ACROSS
NORTHEAST NEBRASKA INTO WESTERN IOWA.
- COOLER TEMPERATURES CONTINUE THROUGH AT LEAST FRIDAY WITH
HIGHS IN THE 60S. DRY AND PLEASANT WEATHER EXPECTED TUESDAY
AND WEDNESDAY, WHILE RAIN CHANCES RETURN FOR THURSDAY INTO
NEXT WEEKEND.
DISCUSSION
ISSUED AT 1210 AM CDT SUN SEP 20 2026
SHORT TERM /TODAY THROUGH MONDAY NIGHT/
0508Z KOAX RADAR IMAGERY DEPICTS SHOWERS AND SOME THUNDERSTORMS
OVER SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA. THE BULK OF THIS
ACTIVITY APPEARS TO BE FORCED FROM A WEAK H5 IMPULSE AND ITS
ASSOCIATED VORT MAX TRACKING ACROSS THIS AREA, AND ANY REMNANT
FORCING FROM THE H8 FRONT DRAPED NEAR AND TO THE SOUTHEAST.
THIS ACTIVITY WILL GRADUALLY PUSH OFF TO THE EAST OVER THE NEXT FEW
HOURS. A STRONGER H5 SHORTWAVE AND ITS ASSOCIATED VORT MAX CURRENTLY
OVER WYOMING/UTAH WILL GRADUALLY APPROACH THE AREA BY MIDDAY TODAY.
THE LARGE SCALE FORCING FOR ASCENT FROM THIS FEATURE COMBINED WITH
ANOTHER SUBTLE DISTURBANCE AHEAD OF THE FEATURE SHOULD PROMOTE MORE
WIDESPREAD SHOWERS AND PERHAPS A FEW RUMBLES OF THUNDER BY LATE
SUNDAY MORNING THROUGH THE EVENING. INSTABILITY DOES APPEAR FAIRLY
LOW AT 100 J/KG OR LESS PER FORECAST SOUNDINGS, SO THE THUNDER
THREAT SHOULD BE SOMEWHAT LIMITED. THERE IS SOME SIGNAL TOO PER
FORECAST SOUNDINGS AND RAP CROSS-SECTIONS FOR SOME LIGHT
DRIZZLE TO DEVELOP GIVEN THE WEAK LOW LEVEL LIFT AND SATURATED
PROFILE SEEN JUST BELOW H7. POPS OF 40 TO 70% ARE FORECAST FOR
MOST OF THE AREA, WITH THE HIGHEST CHANCES FORECAST FOR FAR
NORTHEAST NEBRASKA. EXPECT A COOL DAY WITH HIGHS IN THE LOW TO
MID 60S.
LATE TONIGHT INTO MONDAY MORNING WILL SEE THE H5 SHORTWAVE AND VORT
MAX PIVOT THROUGH THE AREA, RESULTING IN CONTINUED RAIN SHOWERS.
POPS PEAK AT 60 TO 80% IN NORTHEAST NEBRASKA INTO WESTERN IOWA BY
MONDAY MORNING. POPS GRADUALLY TAPER OFF BY THE AFTERNOON AND
EVENING HOURS. SLIGHTLY COOLER HIGHS ARE ALSO FORECAST WITH MOST
AREAS REACHING THE MID 50S TO LOW 60S. BY THE END OF THE PERIOD,
EXPECT AREAS TO PICK UP AROUND A QUARTER TO HALF INCH OF
ADDITIONAL RAINFALL.
LONG TERM /TUESDAY THROUGH SATURDAY/
AS THE H5 WAVE EJECTS EAST, SHOULD SEE SFC HIGH PRESSURE CENTERED
OVER MOST OF ONTARIO EXTEND WESTWARD TOWARD THE NORTHERN PLAINS. AS
A RESULT, EXPECT PRIMARILY DRY CONDITIONS TUESDAY AND MOST OF
WEDNESDAY. BY LATE WEDNESDAY INTO THURSDAY, SHOULD SEE WARM
ADVECTION RETURN ALONG WITH A MID-LEVEL IMPULSE. THIS WILL
RESULT IN OUR NEXT BEST CHANCE AT SOME RAIN, WITH POPS OF 50 TO
70% ACROSS OUR WESTERN AREAS. WE'LL RETURN INTO A SOUTHWESTERLY
FLOW REGIME FOR THE REST OF THE EXTENDED PERIOD RESULTING IN
CONTINUED 20-30% CHANCES FOR RAIN. TEMPERATURES REMAIN COOL IN
THE 60S FOR TUESDAY THROUGH FRIDAY BEFORE WARMING TO THE 70S BY
NEXT SATURDAY.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1216 AM CDT SUN SEP 20 2026
MVFR CEILINGS CONTINUE TO SLOWLY TURN IFR OVER THE COURSE OF THE
OVERNIGHT HOURS, WITH NORTH-NORTHEASTERLY WINDS EXPECTED TO
CONTINUE THROUGH THE NEXT 24 HOURS WITH ONLY BRIEF IMPROVEMENTS
THIS AFTERNOON TO MVFR CONDITIONS BEFORE RETURNING TO IFR
TERRITORY AFTER 00Z. RAIN SHOWERS ARE ALSO LOOKING LESS LIKELY,
WITH MIST/DRIZZLE TAKING THEIR PLACE IN THE EXTENDED PORTION OF
THE TAFS, WITH VISIBILITY RESTRICTIONS INCREASING IN PROBABILITY
TOMORROW NIGHT (40% CHANCE). BEYOND THAT, SPEEDS SHOULD REMAIN
RATHER DOCILE AT LESS THAN 15 KTS AND RATHER STEADY DIRECTION-WISE.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...CASTILLO
AVIATION...PETERSEN
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