Scattered multicellular convection was expected ahead of a cold front on the night of February 10th. Late in the evening, disorganized cells developed into a loosely organized line of storms that briefly produced severe hail just after crossing the Mississippi River into Randolph County.
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The episode as NWS LSX wrote it up.
Scattered multicellular convection was expected ahead of a cold front on the night of February 10th. Late in the evening, disorganized cells developed into a loosely organized line of storms that briefly produced severe hail just after crossing the Mississippi River into Randolph County.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS St. Louis, MO wrote its last area forecast discussion before the first event at Feb 10, 11:15 AM CST, 1 hour 5 minutes earlier. Its key messages:
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1115 AM CST Sat Feb 10 2024 .KEY MESSAGES... - Cooler weather is in store through the weekend behind last night's cold front. Highs each day are forecast to range from the mid 40s to low 50s with overnight temperatures dropping into the upper 20s to mid 30s. - Rain is expected to change over to snow early Monday across parts of the area. The most likely area for accumulating snowfall is in parts of southeast Missouri based on the track of the storm. Widespread 2-3" amounts are expected at this time with locally higher amounts possible in the higher terrain of the eastern Ozarks. && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 313 AM CST Sat Feb 10 2024 A cold front has just cleared the far southeastern portion of the CWA as of 0900 UTC. Behind the front, temperatures drop through the 40s into the mid to upper 30s. Continued low-level cold air advection along with variable cloudiness will help lead to much cooler high temperatures this afternoon compared to yesterday. Highs are forecast to range from the mid 40s to low 50s from northwest to southeast. While these readings are significantly cooler (~20 degrees) than yesterday, they would still be some 5-7 degrees above normal for the date. Mostly dry weather along with seasonably warm temperatures are forecast to continue through the end of the weekend. After some sunshine to start off Sunday, increasing mid/high level cloudiness is forecast ahead of the next storm system. Gosselin && .LONG TERM... (Sunday Night through Friday) Issued at 313 AM CST Sat Feb 10 2024 (Sunday Night - Monday Night) A closed mid/upper level low will move out of the south-central Plains Sunday evening through the mid south on Monday. Widespread precipitation is forecast to move into southern sections of the area Monday morning due to enhanced divergence aloft beneath the left- exit region of a jet streak, increasing low-level moisture convergence, and positive vorticity advection downstream of the midlevel cyclone. Model soundings show the precipitation starting as rain, but show a transition to snow due to dynamic cooling within the heaviest precipitation rates. These high precipitation rates are supported by strong low/mid level frontogenesis along with reduced stability (negative EPV) in the layer above the frontogenetical forcing. In fact, some deterministic guidance depicts highly negative EPV values (<-0.25), which supports the possibility of upright convection. NWP soundings also show very steep midlevel lapse rates (6.5-7.0 C/km), further buttressing at least a low probability of some thunder. Regardless of any thunder/lightning, there is a fairly strong signature on the mesoscale for enhanced banded precipitation. This leads to higher confidence in this changeover from rain to snow. However, exactly when/where and how widespread is uncertain. Given some of the instability parameters alluded to above, this suggests a narrow band of heavy precipitation. Given the very marginal setup, areas that have lighter precipitation rates very well may stay as a cold rain with snow centered within the heart of the enhanced banding. The consensus track of the 850-hPa low has wobbled about 25 miles back to the northwest, generally passing ENE through the bootheel of Missouri toward the Ohio River. Using the 90 nm (100 mile) rule from Browne and Younkin (1970), this would put the heaviest axis of precipitation (snowfall) most likely from KFAM>>KSAR. The higher elevations of southeast Missouri should also aid in yielding higher snowfall totals. This is where widespread 2-3" totals are expected with some of the highest terrain potentially seeing 4+". If the rain can changeover to snow a couple hours earlier, cannot completely rule out isolated areas nearing warning criteria (5"). This higher-end potential is supported by the 90th percentile of the NBM and the LREF. However, there are still scenarios where little/no snow falls within the CWA. A 75 mile shift to the southeast would leave basically the entire CWA high and dry. Weaker forcing for ascent could yield more modest precipitation rates with less in the way of dynamic cooling. If this were to occur the precipitation may stay rain a lot longer or only mix with snow. That is why the 10th percentile of the NBM/LREF has little/no snow accumulation. While I don't think either of these two latter scenarios is particularly likely, it is a low possibility and worth mentioning. Of course, a 50-75 mile shift of the track the other direction (further northwest) is also on the table. There have been several instances this winter season where there were similar shifts within 2-3 days of the event. What should limit too much of a pull to the northwest is the mid/upper level confluence overhead due to a northern stream shortwave moving through the Great Lakes late Sunday. However, if this feature is faster and/or further northeast, this would allow some more room for the main system to pull more poleward. A continued slower trend of the Sunday night-Monday storm could also allow for a slightly further north track. While time of day (falling mainly during daylight hours on Monday) and the antecedent warm/wet ground are not exactly conducive to accumulating snowfall, the expectation is for heavy enough snowfall rates to overcome these concerns. While a majority of the snow will accumulate on grassy/elevated surfaces, I do think that highest rates may approach 1"/hr, which would allow for accumulation of snowfall on roadways. Precipitation should exit the CWA from west to east late Monday afternoon through the evening. One consistent trend has been for a slower storm system (both to arrive and exit). Therefore, boosted PoPs significantly Sunday afternoon/evening from the previous forecast, but these may be too low and may warrant further increases with future forecast packages. (Tuesday - Friday) No significant forecast changes were made for the remainder of the next work week. Both the GEFS/EPS suggest quasi-zonal flow aloft with a series of weak shortwaves moving across the country. Uncertainty remains fairly high with the details though of the weather pattern, with WPC 500-hPa height clusters showing the most substantial variability with the location/strength of a longwave trough in southern Canada. This feature will be key as there are increasing signs of the bitterly cold air from Alaska/northern Canada to push southward. The lack of ridging along/near the west coast should keep most of it bottled up in Canada, but some may spill close enough to shift the storm track gradually southward through the period. At this time however, generally at or slightly above normal temperatures are expected through much of next week with low chances of rain Wednesday night and beyond associated with multiple midlevel shortwave troughs. Gosselin && .AVIATION... (For the 18z TAFs through 18z Sunday Afternoon) Issued at 1103 AM CST Sat Feb 10 2024 Dry, VFR conditions with northwesterly winds of generally 5-10 kts will prevail through the TAF period. Jaja && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service St Louis MO 334 AM CST Sat Feb 10 2024 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-110945- Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL- Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL- Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO- Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO- Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO- Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO- Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO- Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO- Madison MO-Reynolds MO- 334 AM CST Sat Feb 10 2024 This Hazardous Weather Outlook is for portions of eastern and central Missouri as well as west central and southwest Illinois. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Accumulating snow is likely on Monday across parts of the area, mainly in southeast Missouri. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. Gosselin
The St Louis radar (KLSX), 120 km away, was scanning. The volume nearest the first event began at 18:17 UTC.
1 hail. Local standard time, as filed.
A Facebook user posted a photo of a hail stone laying next to a ruler. The stone's long edge measured 1 inch.
After NWS Directive 10-1605, the rules offices file Storm Data by.
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NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1152784.