Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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789 FXUS63 KLSX 071746 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1246 PM CDT Sun Jul 7 2024 .KEY MESSAGES... - Above normal temperatures will return today along with a chance of afternoon thunderstorms across portions of central and northeast Missouri and west-central Illinois. - Shower and thunderstorm chances (40-70%) will increase and expand across the entire CWA tonight through Monday. - Depending on the track, the remnants of tropical cyclone Beryl could bring heavy rain to parts of southeast/east central Missouri and southern Illinois Tuesday through Tuesday night. && .SHORT TERM... (Through Late Monday Afternoon) Issued at 348 AM CDT Sun Jul 7 2024 MCS sliding east along the MO/IA border will continue to weaken early this morning, so expect little to no rain over portions of northeast MO. With the surface ridge sliding off to the east, southerly flow returns to the region once again today. So the combination of increasing moisture/instability and any residual outflow boundary, as well as a possible MCV, will be the trigger for additional showers and thunderstorms by this afternoon, especially over portions of central/northeast Missouri as well as west central Illinois. Otherwise, today will be the warmest day for the upcoming week due to the southerly flow and warmer temps aloft (850mb temps 16-19C). In the meantime, the majority of the latest deterministic as well as ensembles still have an upper level trough deepen over the northern/central Plains. Then the trough will slowly slide eastward into the mid to upper MS Valley by Monday night. Ahead of the trough, a southwesterly low level jet will develop and usher in a series of shortwaves in addition to the increasing low level moisture/instability. This combined with a cold front over the central Plains will generate another round of showers and storms late tonight through Monday, as the front moves into the region. Byrd && .LONG TERM... (Monday Night through Saturday) Issued at 348 AM CDT Sun Jul 7 2024 The latest NHC forecast has TC Beryl come on shore over the middle portions of the Texas gulf coast Monday morning. In the meantime with the very slow movement of the upper level trough, a number of the latest deterministic as well as ensembles have the remnants of TC Beryl recurve across the mid MS Valley and become absorbed by the trough by Tuesday. There are still quite a few differences among the models as far as the track of the associated surface low. GFS is further north tracking near STL while the NAM tracks it across the MO bootheel and the ECMWF is slower, but has similar placement to the NAM. For now with some uncertainty, stuck with the latest NBM solution, though did increase POPs to likely/categorical across portions of southeast/east central MO, as well as southern IL for Tuesday into Tuesday night. Latest WPC qpf has increased rainfall amounts over the region with an axis of 2 to 4 inches, mainly along the I-44 corridor in MO and I-70 corridor in IL. Beyond Tuesday night, the trough continues to weaken with the rain tapering off by Wednesday afternoon. Expect mainly dry conditions for the remainder of the work week and into early next weekend. Otherwise, temperatures will remain near normal this week, though Tuesday will be 5 to 15 degrees below normal due to the widespread showers and storms. Byrd && .AVIATION... (For the 18z TAFs through 18z Monday Afternoon) Issued at 1237 PM CDT Sun Jul 7 2024 For KCOU, KJEF, and KUIN: Scattered showers and thunderstorms will continue to develop across western MO this afternoon, and eventually develop or move into central and northeast MO by late afternoon and into the evening. This has prompted VCTS at KJEF, KCOU, and KUIN generally within the 00-03/04z time frame, and if there is a direct terminal impact then flight conditions will be reduced and gusty winds will be possible as well. After around 04z, there will be potential for showers into the overnight hours impacting these same terminals, and then some MVFR stratus on Monday morning. For KSTL, KSUS, and KCPS: At this time, the St. Louis region terminals are expected to be VFR and remain east of the shower and thunderstorm activity through tonight. Showers and maybe evening a thunderstorm will be possible after 14-15z Monday however confidence is low, hence at this time only VCSH has been mentioned. Glass && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX