Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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390 FXUS63 KLSX 310355 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1055 PM CDT Thu May 30 2024 .KEY MESSAGES... - Another round of showers and scattered thunderstorms will move across the area late Friday into Saturday. - There will be a continued chance for showers and thunderstorms into next week with temperatures climbing above normal. && .SHORT TERM... (Through Late Friday Night) Issued at 221 PM CDT Thu May 30 2024 We are enjoying another dry day with near normal temperatures as a surface high centered over the Great Lakes continues to usher relatively dry air into the area. The HREF is showing the upper ridge currently over western Missouri moving east across the area tonight keeping the area dry. This will change tomorrow as the trough over the Plains will deepen on Friday and then move across Missouri and Illinois on Friday night. The GFS/NAM is in reasonable agreement showing the attendant surface low moving northeast across the CWA late Friday night into Saturday. Latest runs of the CAMS including the HRRR are showing that the chance for showers and thunderstorms will not move into central Missouri until late tomorrow morning, with likely/categorical PoPs spreading from west to east across the CWA tomorrow afternoon and evening as there will be stronger ascent from the upper low and a low level jet. These high chances will not exit the eastern CWA until late Saturday afternoon when upper low moves east of the area. Overall, rainfall amounts look to be on the order of 0.5-1.0"+ with this system, but with PWATS near 1.7", a few of the showers and thunderstorms will be capable of producing some locally heavy rainfall. Temperatures will be close to normal through Saturday as 850mb temperatures remain near 10C with the increased clouds and rain chances with the upper low. Britt && .LONG TERM... (Saturday through Next Thursday) Issued at 221 PM CDT Thu May 30 2024 Global models and the LREF is showing the pattern becoming quasi- zonal early next week before an upper trough enters the north central CONUS by the middle of next week. This still causes a certain amount of uncertainty with regards of the timing and strength of the shortwave troughs that will move across the area Sunday into Tuesday that will bring showers and thunderstorms to the region. At this point, it still appear that Sunday into Sunday evening will have lower chances for rain (10-30%) as a shortwave ridge moves across the area, while there will be higher chances(40- 60%) on Monday into Tuesday as a pair of troughs move across Missouri and Illinois. It should be noted that while some of the raw QPF from the global models looks too high because of convective feedback, there could be some locally heavy rainfall as the LREF has PWATS near 1.6". There will be an additional chance of showers and thunderstorms into Wednesday as the attendant cold front of the upper low moves across Missouri and Illinois. While there is some potential for a few strong storms next week, the CAPE/shear setup is not particularly impressive for organized severe storms. It still looks like we are on track for a warm up next week as the LREF is showing 850 temperatures climbing to near 20C between Monday and Wednesday with low level southwesterly flow before the cold front moves through midweek. The NBM 75th percentile for highs are showing highs AOA 90 degrees early next week, so few spots certainly could reach 90 ahead of the cold front where there is less rain and more sun. Overall confidence in the warmup remains high as the NBM IQR is around 5 degrees or less ahead of the cold front, but then increases to around 10 degrees behind the cold front next Thursday. Britt && .AVIATION... (For the 06z TAFs through 06z Friday Night) Issued at 1051 PM CDT Thu May 30 2024 No major changes to the timing of the onset of precipitation on Friday. Through mid morning Friday expect VFR flight conditions. Showers will begin to move into KCOU and KJEF between 17z and 20z Friday, while they won`t move into KUIN and St. Louis metro TAF sites until between 22z Friday and 00z Saturday. Otherwise by late afternoon through Friday evening, coverage and intensity will increase with MVFR ceilings moving in after 00z-03z Saturday. Also, added vicinity thunderstorms during this period as well. As for winds, they will persist out of the southeast through the entire forecast period, though could see gusts near 20kts at times during the day on Friday. Byrd && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX