Area Forecast Discussion
Issued by NWS Springfield, MO
Issued by NWS Springfield, MO
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521 FXUS63 KSGF 300521 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 1221 AM CDT Thu May 30 2024 .KEY MESSAGES... - Some low end rain chances this afternoon and evening(20-50%) over the southwest portion of the forecast area. - Much better chance for widespread rain(60-80%) arrives Friday into Saturday. - Additional rain chances (15-30%) linger through the remainder of the weekend with better chances of rain(30-50%) picking back up early next week. && .SHORT TERM /THROUGH FRIDAY/... Issued at 1259 PM CDT Wed May 29 2024 Weak summertime upper-level flow is for the most part taking hold of the CONUS save for troughing across the Great Lakes and Pacific NW as noted by current water vapor imagery. In between these troughs, large-scale ridging is present across the northern Plains. Water vapor imagery and the latest RAP analysis indicate a very subtle shortwave impulse moving through NW OK overtop the tail-end of a cold front/stationary boundary currently progged across E KS, NE OK, and into N AR. A few light showers are associated with this impulse just ahead of the surface front, which will be the focus for 20-50% chances of showers and thunderstorms in far SW MO today. Highs today are still on track to reach into the lower 80s. Low-end rain chances (20-50%) this afternoon over SW MO: The subtle shortwave impulse will continue to overspread the surface boundary in the extreme SW corner of MO this afternoon. Additionally, the right entrance region of the 700 mb jet will be situated over this region. Lift associated with these features--along with HREF bringing this region to 250-750 J/kg of mean MLCAPE by peak heating--will support the development of isolated to scattered showers and thunderstorms in extreme SE KS and SW MO. SPC (RAP) Mesoanalysis are aggressive with 500-1500 J/kg of SBCAPE which is more supportive for thunderstorms. Nevertheless, mean flow will be near 0, so these showers/thunderstorms will be ordinary cells that are short- lived and slow-moving with outflow possibly triggering other cells in the area. These showers/thunderstorms will likely be focused along the surface cold front, which is currently progged right along the SW corner of MO. Therefore, the greatest chance (30-50%) for showers and thunderstorms would be within Cherokee, Newton, Barry, and McDonald counties. These chances will last until peak heating ceases after sunset. After the rain chances, partly cloudy skies overnight will take hold with lows in the upper 50s to low 60s with lower temperatures toward central MO, closer to the upper-level trough. The mid- and upper-level ridge axis will slowly make its way over MO during the day Thursday. With weak mean flow but sufficient instability across the Plains, at least a few MCSs will develop in OK/KS and move eastward through Thursday morning. There is a low-end chance (15-30%) that remnants of these MCSs could reach into our western CWA during the day Thursday, producing mainly scattered showers and thunderstorms (not expected to be severe). Otherwise, highs will reach into the upper 70s and lower 80s again. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 1259 PM CDT Wed May 29 2024 Widespread rain chances (60-80%) Friday into Saturday: Multiple rounds of MCSs will move through the Plains due to broad westerly flow over the mountains promoting lee cyclogenesis within a modestly unstable airmass. One particular round will be riding ahead of another subtle shortwave impulse that will move along the KS/OK border. Medium-range CAMs suggest that any MCS associated with this impulse will create an MCV that will enhance the mid-level shortwave. In turn, the feedback loop will produce a weak surface low and 850 mb low-level cyclone. Surface fronts and a modest LLJ will be associated with these features. As such, increased rain chances arise for Friday (60-80%) through Saturday morning (30-50%). Current model guidance has the warm front staying south of the MO/AR border, which will keep any severe weather chances out of our area. It will also keep our area rather cool with highs Friday and Saturday in the mid to upper 70s and lows in the lower 60s. However, strong meridional 850 mb flow will ride over the warm front, pumping moisture up into our region. Based on that synoptic setup, widespread rainfall and embedded thunderstorms will be likely for much of our area through the day. With the shortwave displaced from the longwave, and the MCV orienting positive vorticity advection in a way that represents an cut-off low, the wave will progress rather slowly. This will keep rainfall over our area for an extended period of time through Saturday morning making flooding a low- end threat. The WPC does have portions of our CWA in a Slight (2 of 4) Risk for excessive rainfall. However, with 75th percentile NBM QPFs only at 1-1.5" in 48 hours, flooding is still a low-end threat at this time. This is especially true with model spread still quite high. The 25th-75th percentile spread is around 1-1.5", meaning a low-end scenario has most of our CWA at 0.25-0.5" and a higher-end scenario at 1.25-2.5". To further the uncertainty, the NBM has the greatest axis of precipitation west of Highway 65, while the WPC guidance has widespread 1-1.5" across our whole CWA. Greater confidence will come with a better handle on the evolution of the wave and MCV, but the bottom line is that most of our CWA will see at least 0.25-0.5" of rain through Saturday morning. Isolated rain chances (15-30%) for the rest of the weekend: After the shortwave exits, there will be a brief dry period Saturday night through early afternoon Sunday. At this point, ensembles point to a summer-like pattern with the jet stream over the northern states. Low-level flow will still be southerly with a high pressure setting up off the Atlantic coast. This will allow deep summertime moisture to start advecting into the region. With temperatures increasing to the lower 80s and dewpoints in the mid-60s, instability will be present with NBM giving an 80-95% chance for >1000 J/kg SBCAPE. With weak upper- level flow/forcing, pulse-like showers and thunderstorms during peak heating Sunday afternoon appears likely, giving a 15-30% chance for isolated to scattered short-lived showers and thunderstorms. Additional rain chances (30-50%) through midweek next week: The aforementioned synoptic pattern will persist through midweek next week, allowing moisture to continue to advect through the region. The NAEFS and EPS ESATs have >99.5th percentile for mean low-level specific humidity through Wednesday. This should allow for daily isolated to scattered pulse thunderstorms, especially if an MCV or subtle shortwave moves through. This is creating 30-50% chances for rain through midweek next week. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1211 AM CDT Thu May 30 2024 VFR conditions are expected through much if not all of the TAF period. High clouds (with a few low clouds mixed in) will move over the terminal sites this morning. Thunderstorms across the central US will gradually shift east today, and there is some chance (30% confidence) that they will survive long enough to impact the JLN site late this afternoon and evening, so a lightning mention was thrown into a PROB30 group for that location. Winds will be out of the southeast through the forecast period, with gusts of 15-20 kt. && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ SHORT TERM...Price LONG TERM...Price AVIATION...Didio