Area Forecast Discussion
Issued by NWS Springfield, MO
Issued by NWS Springfield, MO
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570 FXUS63 KSGF 211752 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 1252 PM CDT Tue May 21 2024 ...AVIATION UPDATE... .KEY MESSAGES... - Severe storms possible late this afternoon into the evening...with an Enhanced (3 of 5 level) risk over west central and central MO and a Slight Risk for much of the region southward to the Arkansas border. Damaging wind gusts are the primary concern followed by large hail up to two inches in size. The tornado threat is limited. - Another round of severe weather is possible again Wednesday toward south-central Missouri with Slight (2 of 5 level) to Enhanced (3 of 5 level) risk. Damaging winds, large hail, an Isolated tornado and localized flooding will all be a concern. - Unsettled weather may persist through the end of this week and into Memorial Day weekend (daily 30-50% chances for showers and thunderstorms). && .UPDATE... Issued at 1210 PM CDT Tue May 21 2024 Surface low near KCNK this morning will deepen as it moves into western IA this afternoon. The resultant surface pressure gradient has led to 30-40 wind gusts over the western CWA this morning. As for thunderstorm development...the 12z SGF RAOB depicts a significant cap/EML of ML CINH over 250 J/KG and perhaps more significant SB CINH over 500 J. With the convective temperature well over the forecast highs in the mid to upper 80s it is very questionable that surface based storms will be achieved. A band of 2000-3000 ft clouds depicts a cold front aloft with decreasing temperatures from h8-h7 MB extending westward, combined with a slight increase in surface dew points and general synoptic scale lift caused by diffluence ahead of the short wave will allow updrafts to overcome the cap this afternoon. The 15z HREF convective allowing models (CAMS) suggests that storms will develop east of Interstate 35 reaching west central MO into southeast Kansas by mid afternoon...and developing southeastward into this evening. As for storm mode, the HREF 15z ensemble forecasts ML CAPES of 3500 J/KG with other ensemble data highlighting 0-6 KM shear reaching 50 knots. Surface winds have temporarily backed to the SSE though some veering to the SW is expected with 0-1 KM helicity approaching around 150 and 0-3KM helicity of 250 thus anticipate rotating updrafts to enhance hail size as supercells initially form ahead of the southeastward moving front and eastward moving dry line. The front will likely overtake the dry line from reaching the CWA but the potential for discrete supercells is expected based upon the environment and CAMs. The question the becomes storm mode farther southeast as the supercells congeal and or the frontal boundary becomes the main forcing. As for impacts...the combination of rotating updrafts and significant instability will yield hails to at least baseballs though much of the forecast area west of Highway 63, becoming more of a damaging wind threat over the eastern Ozarks. The threat of tornadoes is limited due to the cap and the ENE storm movement. Any southeast deviant storms though will need to be monitored closely. && .SHORT TERM /THROUGH TONIGHT/... Issued at 235 AM CDT Tue May 21 2024 Another day of above average temperatures can be expected today as strong warm air advection continues. Highs this afternoon will again climb into the middle to upper 80s, which is a good 10 degrees above average for this time of year. Along with the warm air, moisture will continue to feed into the region. The primary concern for the forecast for today focuses on a storm system in the plains and a cold front that will make its way east through the day. In advance of the front, surface winds will increase and become gusty (20-30mph) as the surface pressure gradient tightens. The ingredients for severe weather will be in place across the Ozarks as a result of the aforementioned conditions. There will be a CAP (50-100 J/KG) in place ahead of the front, though the cap will weaken with afternoon heating. Convective is expected to develop late in the afternoon as the front makes its way into the area. GEFS is still showing mean SBCAPEs by 00z around 3500J/kg along the Missouri/Kansas border and 0-6km bulk shear approaching 35-45 knots. Organized severe convection is expected with initial storms developing as discrete supercells thanks to the ample instability, however expectations are for the storms to become linear quickly as the storms progress east along and ahead of the cold front. Models do indicate a dry layer initially around 700mb, but mid level lapse rates will be strong (7-8 C/k). This would allow for very large hail as a prime threat. If super cells develop a limited tornado threat will exist, but storms should transition into a line rather quickly which should limit this. As the storms develop into a squall line, damaging winds will become a concern with 60-70mph gusts likely. The front, or effecting boundary, and line of storms will progress through the Ozarks overnight, into Wednesday morning with the severe threat continuing the overnight hours. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 235 AM CDT Tue May 21 2024 Wednesday into Thursday: Models, including synoptic and some of the CAMS, push the front just south of the Ozarks Wednesday morning, which should give the region a short reprieve. However, the front/boundary is expected to move back north as far as the I-44 corridor by Wednesday afternoon where the 850mb front will have remained. With heating, the front and better upper level support another round of severe weather is expected Wednesday afternoon into the evening. Hail will once again be a prime concern with two inch hail a possibility. Damaging winds will also be a concern. The southwest to northeast orientation of the front coincident with the upper flow parallel with the stalling/slow movement of the front will also potentially set the stage for training storms and excessive rainfall into Thursday morning. Precipital water values are forecast in the 1.5-1.75" range which is 1-2 standard deviations higher than normal for late May. The NBM does indicate at least a 25% probability of 1-2 inches generally along and south of I-44, with isolated chances for 3" of rain. This rain, on top of earlier rains this week, would set the stage for potential flooding. The front will have made some progress south by Thursday morning, but additional shortwave energy will move through the southwesterly flow pattern and bring the chance for additional severe weather. As another upper level trough moves across the northern plains, a surface low develops in the plains and will lift energy into the plains and the Ozarks. This combination will allow for storms to develop again late Thursday afternoon into the evening. Friday into the Holiday Weekend - Southwest to westerly upper flow will continue as shortwave energy shifts toward the Canadian. Though weaker upper flow is forecast, several slow moving frontal boundaries will move through the pattern serving as the focus for convection each day. This will provide for daily rain chances (20-50%), though not all areas will see rain each day. The pattern will see a shift finally by early next week, becoming more northwesterly by Tuesday as an upper level low moves south out of Canada and upper level ridging develops over the Rockies. This would finally place the region under northwesterly flow aloft or under the eastern edge of an upper ridge. This process would allow for additional rain chances Monday and Tuesday, but would finally bring drier weather to the region for the middle to end of next week. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1246 PM CDT Tue May 21 2024 An active period of strong to severe thunderstorms will impact the region this evening into the overnight. Storms will develop over east central KS by mid afternoon and propagate southeastward producing severe winds and large hail. Questions exist on post event TSRA activity which could continue to impact aviation operations overnight. Additional thunderstorms...with again some possible strong to severe will be possible from late morning Thursday into the early afternoon. && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ UPDATE...Runnels SHORT TERM...Hatch LONG TERM...Hatch AVIATION...Runnels