953 FXUS63 KEAX 170338 AFDEAXArea Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 1038 PM CDT Tue Sep 16 2025
...Updated 06z Aviation...
.KEY MESSAGES...
* Well needed rainfall chances increase across the region through the weekend with a slow moving upper level low approaching from the intermountain-west.
* Above normal temperatures through the forecast period.
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.DISCUSSION... Issued at 252 PM CDT Tue Sep 16 2025
Rex block across the east coast will keep the pattern fairly stagnant leading to slowly evolving pattern. Upper trough removed from the upper level flow across southern Montana into Wyoming is expected to gradually shift east leading to increased low level warm air advection and isotropic assent ahead of cold front expected to move through the region on Friday.
SPC mesoanalysis shows ~2500 J/kg of weakly capped CAPE across the region. Flow through the atmospheric column is weak, therefore storm motions are generally expected to be 10 knots or less favoring a northerly trajectory. Flash flood guidance remains incredibly elevated (generally 3-4"/1 hr, 3-5+"/3-hr), and with the weak shear, expect storms and locations that receive rainfall to be fairly spotty. With shear remaining very weak, expect airmass thunderstorms only lasting for an hour or two, thus self limiting the potential for flooding despite slow storm motion.
CAMs have been fairly consistent in storms continuing to percolate through the evening hours and kept 20 percent pops in the evening hours largely west of highway 65. Agree with SPC assessment that there is enough dry air in the column that a wind gust or two to 50 knots are possible with the strongest cores. Any moisture from the spotty storms could lead to patchy fog early Wednesday morning with skies gradually clearing and light flow overnight.
Weak shortwave building into the region on Wednesday is expected to lead to a renewed thunderstorm threat especially through the afternoon hours. Once again, shear will be relatively weak leading to slow storm motion. This combined with deep warm cloud depths could lead to locally heavy rainfall in locations that see activity. While the coverage is expected to be greater than today with slightly more organized forcing, expect more widespread activity to hold off till Thursday into Friday when cold front attempts to move through the region (and upper trough approaches). With that said, the upper trough weakens late week into the weekend, and with the uncertainty in where the trough stalls out, there is a bit of spread in the ensemble guidance this weekend. The increased clouds and precipitation will keep temperatures closer to seasonal averages, but temperatures are expected to remain above normal through the forecast period with ridge building to the west of the upper trough late week.
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.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1037 PM CDT Tue Sep 16 2025
Expecting VFR clouds to move through from activity over the High Plains overnight. Will be watching for thunderstorm potential Wednesday afternoon along a weak boundary. High resolution models are showing an increasing trend in coverage starting after 20z in eastern Kansas, moving eastward into west-central Missouri. For now have placed TSRA into PROB30 groups for STJ and the KC Metro TAF sites. Will continue to monitor trends during the overnight hours.
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.EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None.
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DISCUSSION...BT AVIATION...Krull
NWS EAX Office Area Forecast Discussion