NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS63 KEAX 231123 AFDEAX

AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 623 AM CDT Sat Sep 23 2023

Discussion
Issued at 311 AM CDT SAT SEP 23 2023

Key Messages:

- Strong to severe storms are likely this afternoon and this evening. Large hail and damaging winds are the most likely hazards. A few tornadoes are possible as well.

- Drier weather with above normal temperatures are expected next week.

Water vapor imagery with 500mb heights overlaid shows a robust shortwave trough moving into southeastern WY and western SD and NE.
This system will be the main player for storms this afternoon and this evening. Further east, a strong low-level jet has developed over the eastern Plains in response to the strengthening upper-level flow associated with the WY shortwave trough and upper-level ridging over Mexico. VWP plots to our west and southwest show this low- level jet to be in the 40-50 kt range at 500m AGL. An area of convergence is noted over eastern KS and this is leading to some AC development as of 07Z. Models are all in decent agreement with strong isentropic ascent developing in this area of convergence and then lifting that to the northeast. This isentropic ascent, which shows up well at 310K may lead to isolated to possibly scattered showers and storms in the predawn hours over eastern KS and western MO. Have maintained the low PoPs from the previous forecast, with some small adjustments, to account for this potential.

This afternoon, the main area of thunderstorms will affect the area.
Upper-level flow will steadily increase as the upper shortwave trough moves east. While we'll see broadly diffluent upper-level flow over the area, the strongest diffluence will be across IA as the shortwave is moving into central and eastern NE and SD. Surface and low-level flow will be more backed to our north, closer to the surface low. This will keep the best chances for tornadoes to our north. Further south the combination of strong moisture transport bringing upper 60 and lower 70 degree dewpoints into eastern KS and western MO, along with steeper lapse rates aloft, will lead to a very unstable airmass for late September. SREF MLCAPE probability of exceeding 3000 J/kg is 10-20% across our southwestern zones. But greater than 90% for 2000 J/kg. This strongly suggest we'll see MLCAPE values in the 2000-2500 J/kg range with a small potential for even greater values. This instability, coupled with deep-layer shear in the 30-40 kt range, oriented westerly across the north-south oriented boundary, favor supercells initially before storms congeal into an MCS. That MCS then dives to the south to southeast away from the area and into the instability axis. Instability in our area weakens with time in the evening and eastward extent. Thus, it looks like the most likely areas for severe storms will be eastern KS and western MO, where all hazards are possible, with diminishing severe weather potential as the storms move eastward into the evening hours.
These storms will also be very efficient rainfall producers thanks to very anomalous precipitable water values 2-3 standard deviations above normal. Precipitable water values greater than 1.75" have a return interval of once every 2 to 5 years for this time of year. Given this, as well as the recent heavy rainfall, flash flooding will also be a concern with this system.

Low-level moisture will be slow to move out of our eastern zones as the upper-low closes off over the northern Plains and Upper Midwest.
This will keep the potential for additional showers and storms going into Sunday. For next week, upper-level ridging builds into the middle of the country. This will lead to drier weather conditions with temperatures in the low to mid 80s for afternoon highs, with is about 5 to potentially 10 degrees above normal for the time of year.

Aviation
(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 619 AM CDT SAT SEP 23 2023

VFR conditions expected through this morning. A few scattered showers cannot be ruled out near terminal space by 15-18Z, but the greater concern is after 22Z when thunderstorms, some strong, will develop near terminals. Gusty southerly winds are expected between 15-00Z. Frontal boundary will slow forward progress by late evening, with stratus development along the boundary an increasing possibility.

EAX WATCHES/WARNINGS/ADVISORIES
KS...NONE.
MO...NONE.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Kansas City/Pleasant Hill, MO,