Area Forecast Discussion
Issued by NWS Springfield, MO
Issued by NWS Springfield, MO
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474 FXUS63 KSGF 251726 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 1226 PM CDT Thu Apr 25 2024 .KEY MESSAGES... - Multiple rounds of moderate to heavy rainfall and some storms today and tonight, bringing a slight risk of flooding in southwest Missouri/southeast Kansas, especially along and south of Hwy 160/60. - Risk of severe storms Friday through Sunday night as multiple rounds of storms move through the region. Greatest severe threat appears to be Saturday night. - Heavy rain and the potential for flooding will continue to accompany the active weather period through this weekend. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 141 AM CDT Thu Apr 25 2024 Current water vapor imagery clearly depicts a potent shortwave trough entering the SW CONUS with a plume of cirrus overspreading the southern Plains. A ridge axis is positioned here up through ND. A longwave trough is also situated over the eastern CONUS. This synoptic setup is bringing NW`ly flow aloft over our region. At the surface, lee cyclogenesis across the Colorado front range is underway with a warm front extending from CO southeast through OK and AR. A diffuse cold front has stalled across our CWA and is generally dissipating, leaving lows this morning in the mid-50s along the MO/KS border and in the mid-40s toward central MO. Atop this front in the mid-levels, a ridge axis is displaced eastward from the upper-level ridge axis. The mid-level ridge axis is over the "Chicken Chef States" (aka, LA up through MN). Subtle shortwave energy and SW`ly flow at 700 mb is just to the west of this feature in KS/CO. At the inflection point of this features, strong warm-air advection is progged across the central Plains. In east KS/west MO at the eastward nose of the WAA and associated isentropic upglide, scattered showers have developed and will continue to increase in coverage as nocturnal dynamic forcing upticks. Multiple rounds of moderate to heavy rainfall today and tonight: Bottom line of the forecast for today and tonight is that many, if not all, locations will see rainfall today. Pinpointing the location of the higher amounts has been, quite frankly, a nightmare with model guidance still varying from model-to-model and run-to-run. The latest and greatest thoughts, however, gives two main rounds of more widespread moderate to heavy rainfall. The first round will develop at the nose of mid-level WAA in NE OK between 6-9AM. This area of rain will impact extreme SW MO (generally along and south of Hwy 60) between 9AM and 2PM. After this round exits, a pseudo-MCS riding the surface warm front is forecast to dive SE into west MO around 3-5PM. This second area of heavier rainfall would impact areas mainly along the Hwy 160 to Hwy 60 corridor in the 4-9PM timeframe. In between these rounds, rain will still persist across much of the area, but consist of more scattered, light, and on and off showers. Embedded thunderstorms will be possible with all rounds of rain as the MUCAPE gradient lines up with the precipitation, but no severe weather is expected for this timeframe. Although, there may be some higher wind gusts with the second round of rain with the pseudo-MCS. Rainfall amounts will largely depend on where exactly these embedded thunderstorms within the rounds of heavier rainfall line up. Again, position and timing of these rounds have been shifting, but the 00Z HREF LPMM precipitation amounts are coming in with rather impressive values. The two main corridors associated with the two aforementioned rounds of heavier rainfall are south of I-44 and west of Hwy 65, and along the Hwy 160 corridor. HREF LPMM brings QPF totals up to 1.5-3" in these areas with localized values between 4-7 inches. And that is a 24-hour total through 11 PM Thursday. While the localized values are certainly a low confidence higher-end scenario, it does show a signal for localized areas of heavy rainfall and perhaps some flooding in SW MO. The WPC has also outlined this area in a slight (2/4) risk for excessive rainfall. Outside of these areas, rainfall totals will range from 0.5-1.5" with lower values toward central MO, further from the warm front. With widespread rain and cloud cover, and the warm front staying SW of the area, highs will be around 60 F and lows will be in the mid-50s. Slight risk for severe storms Friday into Friday night: The mid- and upper-level shortwave will become compact and intensify as it lifts NE through the central Plains overnight Friday. N-S oriented remnant convection from storms in the central Plains will move through the area Friday morning before stalling across central MO during the early afternoon. With upper-level divergence/diffluence within the right-entrance region of a jet stalling over MO, and a 40-60 kt LLJ parallel to the forcing axis, the stalled showers and thunderstorms in central MO will likely train. This will bring another slight (2/4) risk for excessive rainfall and flooding across our CWA during the day Friday, although the QPF footprint is lower than for today (Thursday). Rain totals from this training convection look to be in the 0.5-1" range, but HREF suggests a 40-60% chance that some areas will reach 1-1.5" with a 20-30% chance of localized values higher than 1.5". These chances are generally for our entire CWA. The focus then shifts to a severe threat Friday evening. As the compact and energetic shortwave lifts into NE/IA, the associated surface low will do the same, advecting mid-60s dewpoints across our area, especially along the MO/KS border. Highs will also thus be warmer in the lower 70s. A dryline will setup somewhere in extreme east KS. The moisture will bring >1000 J/kg of SBCAPE across our entire forecast area with a narrow corridor of 2000-2500 J/kg just east of the dryline along the MO/KS border. Additionally, 60-70 kt mid-level flow associated with the compact shortwave will create 0-6 km bulk shear of 50-60 kts. Needless to say, these parameters depict a primed sector for severe storms...if they can develop. The ongoing training convection mentioned earlier brings into question the amount of surface destabilization for storms to successfully initiate. Additionally, the most favorable synoptic ascent will be in NW MO/SW IA. With the surface cold front lagging behind in NW KS by Friday evening, the main forcing mechanism for storms will be the dryline in east KS. Dryline forcing will be subtle, making it difficult for storms to initiate, especially with CAMs suggesting some sort of capping inversion just east of the dryline. Nevertheless, subtle forcing along the dryline could be enough for isolated storm development along the MO/KS border. Any storm that does initiate will be in a potent environment for them to become severe with all hazards possible. Forecast soundings along the dryline depict enlarged, curved hodographs boasting 200-300 m2/s2 0-1 km SRH owing to a cranking 40-60 kt LLJ increasing low- level shear to 30-40 kts. Additionally, a saturated profile is noted up to 700 mb with 6-7 C/km lapse rates overtop. This will support a tornado and hail threat, perhaps significant, with any storm that can form and stay surface-based before sunset. Wind gusts up to 60 mph will also be possible. Once again, the uncertainty is in initiation of storms. Early CAMs only have around half initiating any storms in our area, so trends will need to be monitored. Storms should generally diminish after sunset with lows in the mid-60s (near record high minimum). && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 141 AM CDT Thu Apr 25 2024 Slight to Enhanced risk for severe weather Saturday night: Ensemble clusters are actually in impressive agreement for the synoptic setup in the medium range forecast. Another potent impulse of shortwave energy will lift through the central Plains Saturday, once again interacting with a slightly more muggy warm/moist sector characterized by highs of near 80 and dewpoints in the upper 60s. A surface low and sharp dryline will develop in central KS/OK, focusing storm development in that area. While this will keep the main severe threat west of our area, LREF probs give our area along the MO/KS border a 30% chance for 0-6 km bulk shear >40 kts and SBCAPE values >1000 J/kg. Chances increase to 40-50% for values of >500 J/kg. This would be sufficient for severe weather if the storms in OK/KS persisted as they traveled eastward overnight. Some medium range guidance indeed suggests storms persisting to along the MO/KS border. The SPC accordingly has our KS counties in an Enhanced (3/5) risk for severe weather with the western half of our CWA in a Slight (2/5) risk. With medium range guidance suggesting sufficient CAPE and very curved hodographs from another intense LLJ and mid-level jet max, all hazards would be possible with these storms. It is important to mention, with the current timing, this would be an overnight severe threat, generally after midnight. Heavy rain and the potential for flooding Saturday night: Additionally, the upper-level wave is expected to undergo rapid strengthening Saturday and overlap a meridional jet streak over our area with right-entrance dynamics forcing synoptic ascent. With mean flow largely north-south, parallel to the surface boundaries, training of storms will again be likely. With moisture also reaching the 99th percentile according to PWATs, excessive rainfall and flooding will again be a threat Saturday night, especially in our western CWA where the WPC has a slight risk for excessive rainfall coinciding with the main severe threat. Slight risk for severe weather and excessive rainfall Sunday: The system will continue its slow trek northeastward, and the upper-level and surface features will be in a position for severe weather to once again be possible Sunday. The SPC has a 15% out for our entire CWA this day. Once again, even though synoptic setup is in agreement, this far out there is great uncertainty in the location and longevity in convection from Saturday`s severe threat which would determine the location and magnitude of Sunday`s threat. So details will need to be ironed out, but the environment will be supportive for severe weather across our CWA Sunday. And again, the synoptic setup will favor training storms, making excessive rainfall and flooding a threat. The WPC mentions that with the multi-day threat for excessive rainfall, a moderate risk may be needed for our area depending on the level of saturation from the previous rounds of storms, but for now, our eastern half of the CWA is in a slight risk for excessive rainfall and flooding. After some cooler temps with highs in the mid-70s and lows in the mid-50s Sunday and Monday, temperatures will warm into the lower 80s for the rest of the work week with lows also in the lower 60s. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1225 PM CDT Thu Apr 25 2024 Showers and storms continue to track east across the area early this afternoon and will continue to track east through the rest of the afternoons. Coverage should start to decrease late this afternoon into this evening. Some isolated convection will remain possible this evening but not all locations will be affected. Additional more widespread showers and storms will move into the area late tonight into Friday morning. Ceilings will continue to lower into the MVFR and IFR levels this afternoon and continue through tonight. Gusty south to southeasterly winds will develop this afternoon and continue into Friday. && .CLIMATE... Issued at 1225 PM CDT Thu Apr 25 2024 Record High Minimum Temperatures: April 27: KSGF: 67/1899 April 28: KSGF: 68/1896 && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ SHORT TERM...Price LONG TERM...Price AVIATION...Wise CLIMATE...Wise