Sunrise 6:23 AM   Sunset 8:10 PM Moonrise 11:29 PM   Moonset 7:24 AM

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FXUS63 KEAX 270511 AFDEAX

Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 1211 AM CDT Sat Apr 27 2024

KEY MESSAGES

- Enhanced risk for severe storms across western and NW MO. Confidence is higher in severe storm potential north of I-70; however, some severe storms are possible south of I-70.

- All hazards are possible with damaging winds, large hail (2+ inches), and tornadoes (some strong). Flooding (both flash and river flooding) is also likely with repeated rounds of rainfall expected over the next several days.

- Further rounds of showers and thunderstorms are expected Saturday night into Sunday and again Sunday afternoon. These storms also have the potential to be strong to severe. Severe storms are expected primarily overnight Saturday into Sunday.
It is imperative to have ways to get weather warnings/information during the overnight.

MESOSCALE
Issued at 604 PM CDT Fri Apr 26 2024

Two regions of convection continue in the region. The first is multiple supercells arcing just east of the Missouri River in western Iowa and northwestern Missouri. The second is near our southern CWA border, where a long-lived supercell is approaching southern Bates County at 6 pm. In between, convection has failed to initiate or sustain itself, in a region of relatively weak large-scale ascent (and even some indication of subsidence upstream of the main shortwave farther to the north). As a result, think the severe-weather threat is relatively low for the KC metro, with higher probabilities at the northern and southern CWA borders early this evening. The environment with both areas of convection remains strongly support of severe storms capable of all hazards, with effective SRH exceeding 300 J/kg (and locally higher where boundary enhancement exists) and MLCAPE > 1000 J/kg. The threat should diminish during the late evening, both from a geographic perspective (storms moving into southern Iowa and central Missouri) and from a diurnal perspective (nocturnal near-surface stabilization).

DISCUSSION
Issued at 1249 PM CDT Fri Apr 26 2024

An early publication of the discussion today as the outlook for strong to severe storms later this afternoon and evening looks more confident as the morning goes on. All hazards types remain possible including large hail (2+ inches), damaging winds, and tornadoes (some strong). There are still several factors that add uncertainty and may result in storms forming or not forming, but the potential continues. Any discrete storms that form have the potential to quickly become severe.

Today/Tonight: Isentropic ascent across the warm sector assisted by the low level jet kept showers and storms around through the morning hours. These storms are moving eastward out of the region bringing locally heavy rainfall and gusty winds in excess of 35-40 MPH. The question that remains is will the cloud cover associated with these storms move out of the area allowing the environment to destabilized once more this afternoon and evening. Looking at satellite imagery the edge of the cloud cover stretches across eastern KS and is swiftly moving into the area. There is already some wave clouds over Hutchinson, KS showing some turbulence/instability already building in that region. High-res model guidance still favors portions of far NW MO for an enhanced risk of severe weather. Vertical profiles show a favorable environment for severe storm development with substantial lift, instability (CAPE > 2200 J/kg), and bulk shear suggesting discrete storms including supercells. Lapse rates above 7C/km project the potential for large hail (2+ inches); however, confidence in that could be increased if upper level drier air intrudes into the area steepening lapse rates. Speed and directional shear are more than adequate for tornadoes (some strong possible); however, like with lapse rate, a slight bit more rotation in vertical winds would increase confidence in tornadic development.

While far NW MO remains the most favorable area, CAMs continue to show the potential for discrete storms across areas south of and including the KC metro. Any discrete storm that forms has the chance to become severe and produce damaging winds and large hail. An isolated tornado cannot be ruled out even though the environment looks slightly less favorable south of I-70. Storms are expected to occur between 4PM and 9PM tonight. Unfortunately, this is shaping into one of those environments where it will go from nothing to something rather quickly and not much in between. This is mainly due to the multitude of factors including, but not limited to cloud cover clear, ample forcing, and frontogenetic processes (including occlusion) near the triple point of the low.

Meanwhile ahead of these discrete storms, a more disorganized complex of showers and thunderstorms is expected to lift out of SW MO traversing central and NE MO. These storms are not expected to be severe; however, long duration rainfall increases flooding potential as more rain accumulates. Widespread 4-6" event total rainfall accumulations are possible. Flash flooding along roadways as well as area creeks and streams are possible becoming more likely during subsequent rounds of heavy rainfall. River flooding is also possible in the coming days as runoff slowly makes its way into larger rivers.

Saturday into Sunday: Most of the daytime Saturday will likely remain dry. The modified dry line that will help initiate Friday's storms retreats back westward. This eventually sparks convection across central and eastern KS. These storms are expected to form into a line that progress into the area overnight. Instability and continued advection of warm and moist air maintains the line as it heads eastward following the associated low and LLJ. This line is anticipated to reach the region during the overnight hours. Model vertical profiles once again show the potential for this line to be strong to severe exhibiting QLCS characteristics. Once again, all severe hazards remain possible including damaging winds, hail, and isolated quick forming/short duration tornadoes along the line. Due to the primarily overnight timing of storms, it is imperative to have ways to receive weather warning and information during the overnight hours.

Sunday through the rest of the week: The low and associated fronts slow Sunday morning keeping linger showers and thunderstorms around.
These are not expected severe; however, a strong wind gust is possible given the antecedent environment. As Sunday afternoon and evening approaches, storms are expected to strengthen across central and eastern MO Sunday evening. Strong to severe storms are possible with the most likely hazards being damaging winds and hail.
Looking forward to next week, we get a brief break in the weather before chances for precipitation return mid week. Several uncertainties remain this far out, but the synoptic pattern suggested shows further possibilities of strong to severe storms this season.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1211 AM CDT Sat Apr 27 2024

A cold front is nearly stationary between STJ and MCI with low-level moisture being pumped into the region south of the front. This is leading to MVFR ceilings from MCI southward. With the front nearly stalled, and likely to lift north in the morning hours, the low clouds will likely linger through a good chunk of the morning. Conditions become VFR this afternoon as deeper mixing allows for the lower cloud bases to lift. It also looks like more widespread showers and storms move in to the region after 00Z. Winds will be southerly through the forecast with gusts 20 near 25kts.

EAX WATCHES/WARNINGS/ADVISORIES
MO...Flood Watch from noon CDT today through Sunday afternoon for MOZ020>023-028>033-037>040-043>046-053-054.
KS...Flood Watch from noon CDT today through Sunday afternoon for KSZ025-057-060-102>105.

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