Area Forecast Discussion
Issued by NWS Springfield, MO
Issued by NWS Springfield, MO
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679 FXUS63 KSGF 221040 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 540 AM CDT Sun Sep 22 2024 .KEY MESSAGES... - Marginal (1 of 5) Risk for severe thunderstorms today and Monday afternoon and evening. Main hazards will be damaging wind gusts up to 60 mph, small hail, and brief heavy downpours. - Multiple rounds of widespread showers and thunderstorms are expected today through Monday night (40-85% chance). Most locations will see an additional 0.50 to 2 inches of rainfall through Monday, with a flooding threat across the eastern Ozarks from localized higher amounts of 3 to 6 inches. - A cold front will bring cooler temperatures next week with highs in the 70s with limited rain chances. - Early Heads-Up: There is a 20-30% chance for a scenario late next week where a system sits over the south-central Plains bringing prolonged and widespread rain to the region. Trends will continue to be monitored. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 345 AM CDT Sun Sep 22 2024 Current water vapor imagery depicts a robust mid- and upper- level low over the Four Corners region. Paired with radar imagery and mesoanalysis, mid-level positive vorticity advection and coupled upper-level jet streaks are forcing widespread rain showers and thunderstorms across east KS and north MO. This area of rain is out ahead of a surface cold front that stretches from east IA, down through east KS and central OK, with a weak surface low in NE KS. These features will be the focus for multiple rounds of widespread showers and thunderstorms through Monday night (some possibly severe and conducive for localized flooding). Marginal (1 of 5) Risk for severe thunderstorms today: The cold front will push southeast through the region over the course of today. This will bring a gradient of high temperatures with values in the mid to upper 70s north of I-44, and in the lower to mid-80s south of I-44. As the cold front pushes SE, the widespread showers and thunderstorms just north of our CWA will follow suit, pushing into our northern counties early this morning (60-80 % chance along and north of the Hwy 54 corridor). As the morning goes on, the mid- and upper-level wave will actually deamplify some, and coverage should decrease into the afternoon (becoming 30-50% chances). Meanwhile, along and south of I-44 will be mostly dry, with any showers/storms being isolated. Despite mostly widespread cloud cover, a few breaks in clouds leading to temperatures in the 80s, along with deeper low-level moisture, will lead to 500-1500 J/kg of MLCAPE. A 25-35 kt mid-level jet downstream of the shortwave trough will produce 25-35 kt of unidirectional 0-6 km bulk shear overtop of the unstable sector. With a surface cold front pushing through and sufficient support aloft, scattered showers and thunderstorms should develop along and ahead of the boundary after 2 PM (30-50%). Given the marginal thermodynamics and kinematics described above, some of these storms could produce wind gusts up to 60 mph and small hail. HREF mean forecast soundings show relatively deep moisture in the low levels with moderate dry air aloft. Much like what was observed yesterday, this could lead to some very localized wet microbursts with brief wind gusts up to 70 mph. There is still question as to the best corridor for these storms to develop. It will be somewhere along and south of I-44, but recent model trends have the cold front pushing further south, keeping the storms confined closer to the MO/AR border. Trends will continue to be monitored. Nevertheless, these storms should clear/dissipate by 9-11 PM. Marginal (1 of 5) Risk for severe thunderstorms Monday: After a brief lull, additional widespread shower and thunderstorm development looks likely late Sunday night into Monday morning (60-85% chance). This comes as a result to the shortwave slightly amplifying thanks to a small energy boost from a digging shortwave in the northern CONUS. This round of convection is not expected to be severe and even creates uncertainty in the degree of destabilization for severe thunderstorm development Monday afternoon. Despite this uncertainty, models suggest that a surface low progressing eastward through extreme south MO will lead to some renewed moisture and warm-air advection, bringing 500-1000 J/kg MLCAPE in our counties along the MO/AR border. With the shortwave slightly amplifying and the axis slowly progressing into our region, 0-6 km bulk shear will also increase to 35-40 kts. In this environment, any storms that move through the MO/AR border corridor will be capable of producing wind gusts up to 60 mph (localized 70 mph in wet microburst storms) and hail up to the size of quarters. With CAPE profiles being rather meager and skinny, the greater threat is wind gusts, with the potential for some line segments thanks to bulk shear pushing 40 kts. During this time, the cold front will be somewhere along the MO/AR border, leading to highs Monday in the upper 60s to lower 70s. Localized flooding threat across the eastern Ozarks: In addition to the severe threat, any storm will have the potential for heavy downpours and localized flooding as deep moisture in the low-levels will lead to PWATs in the 1.75-2.00" range. This alone can create a localized flooding threat under the individual stronger storms, however, with the shortwave axis sitting in one spot for much of the time through Monday night, the belt of stronger flow/ascent aloft looks to force multiple rounds of widespread showers and thunderstorms over the eastern Ozarks. The HREF mean has widespread areas of 1.25-2 inches east of Hwy 65, with 48-hour LPMMs pinpointing localized areas of 3-6 inches within Howell, Oregon, Shannon, and Texas counties. With no drought conditions across the eastern Ozarks, and multiple rounds of storms moving through, a localized flooding threat may materialize across this area through Monday night. Adding confidence to this threat, the Extreme Forecast Index is at a 0.8 for QPF across the eastern Ozarks with 2 shifts of the statistical tail, highlighting a potentially abnormal rainfall event over the area for late September. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 345 AM CDT Sun Sep 22 2024 Cooler temperatures next week with highs in the 60s/70s: Precipitation should finally clear out by sunrise Tuesday morning with only 10-20% chances of lingering light rain showers in the eastern Ozarks. The cold front and mid- and upper-level trough will also finally fully settle into the region, bringing cooler temperatures and dry conditions. Highs Tuesday through Sunday will be consistently in the lower to middle 70s with lows in the middle 50s. Potential next system arrives late week (20-30% chance): Ensemble cluster analysis reveals a large divergence in model agreement late next week. The Euro and Canadian ensembles favor a shortwave breaking off as a cut-off low and sitting right over the south-central CONUS Wednesday through the weekend. Interestingly, both those deterministic models also show a tropical system wrapping into the upper-level low for some good ol` fashion Fujiwhara action. This scenario would bring widespread and prolonged rainfall somewhere in the south-central CONUS (including potentially our CWA) Thursday through Sunday. Currently, there is a 20-30% chance for this scenario as other models like the GFS/GEFS depict no upper-level low at all and keep us warmer and drier. Once again, model trends will need to continue to be monitored, but this scenario warrants a heads- up since if it does pan out, it could potentially be a higher impact event. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 540 AM CDT Sun Sep 22 2024 A lot going on weather-wise for this TAF period. Scattered showers and thunderstorms are currently ongoing in the vicinity of SGF and JLN. These are expected to slowly shift east and dissipate by 18Z. A frontal boundary is also hanging around the area, bringing variable winds as it oscillates in and out of TAF sites. The front should clear the sites by 19Z, bringing N`ly 8-12 kt winds afterwards. Additionally, chances for scattered showers and thunderstorms will occur through the entire TAF period, despite limited PROB30 mentions. For now, it looks mostly dry after 18Z. However, guidance has been inconsistent on the best timing and placement of rounds of storms. At the moment, the best chance for showers and thunderstorms is at BBG around 19-00Z (30-50% chance). Otherwise, ceilings will gradually lower through the period. After the fropa after 00Z, ceilings will reach MVFR with a 30-50% chance for IFR conditions. && .CLIMATE... Issued at 345 AM CDT Sun Sep 22 2024 Record Highest Minimum Temperatures (Springfield): September 22: 70 (2017) Forecast: 70 && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ SHORT TERM...Price LONG TERM...Price AVIATION...Price CLIMATE...Price