Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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401 FXUS63 KLSX 211732 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1232 PM CDT Sat Sep 21 2024 .KEY MESSAGES... -Several rounds of showers and thunderstorms are expected through Monday night will bring some beneficial rainfall to some areas. The best chance (70-90%) will be late tonight into Sunday morning. -There is the potential for some locally heavy rainfall late tonight into Monday. Isolated strong to severe storms are also possible over parts of central and southeast Missouri on Sunday afternoon and evening. && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 405 AM CDT Sat Sep 21 2024 Latest radar mosaic was showing a complex of showers and thunderstorms over western Missouri on the nose of the low level jet early this morning. The latest runs of the CAMS continue to show that this complex will weaken as it moves east into the CWA early this morning as the LLJ veers and weakens. Have lowered PoPs to 40- 60% over southeast and central MO early this morning based on the recent trends. Chances for showers and thunderstorms the rest of the day into the evening will be dependent on developing along a warm front moving over the area or any residual outflow boundaries underneath an upper level ridge. Will keep chances in the 20-40% range for now. Better chance is still late tonight into Sunday as the axis of the aforementioned upper ridge will begin to shift to the east and an upper low currently over the southwestern CONUS will lift out and move into the Plains. Lift associated with an initial shortwave trough will move into the area late tonight at the same time that a cold front will move southeast out of Iowa. The increase in the low level jet will bring added moisture with PWATS around 2". Will continue with high PoPs (70-90%) late tonight into Sunday morning as the front will move slowly southeast as it will be aligned with southwesterly flow aloft. There may be an isolated strong to severe storms capable of producing damaging wind gusts on Sunday afternoon and evening ahead of the slow moving front. MLCAPES will be in the 1000-2000 J/kg range with deep layer shear range ahead of the front before it moves south of the area early on Sunday evening. Highs will be in the 80s to near 90 where the clouds can clear out. There will be a contrast in temperatures from north to south based on the front moving through with 70s in the north and 80s in the south. Britt && .LONG TERM... (Sunday Night through Friday) Issued at 405 AM CDT Sat Sep 21 2024 Will continue with the high PoPs Sunday night into Monday night (50- 80%) as all of the available guidance is showing one or two additional troughs moving through the area along with an attendant cold front, though with different timing and strength. The LREF does match these high PoPs, with some lower chances on Tuesday before going dry Tuesday night into Wednesday night as a surface high moves through the Midwest. Will continue with slight chances for showers at the end of the week as some of the guidance is showing an upper low over the central CONUS. Temperatures will be below normal to start next week, with Monday having highs in the 60s over northwest half of the CWA where there will clouds, rain, and CAA. Temperatures will gradually climb back to near normal Wednesday into Friday. Britt && .AVIATION... (For the 18z TAFs through 18z Sunday Afternoon) Issued at 1231 PM CDT Sat Sep 21 2024 This morning`s showers extending from northeast through central Missouri continue to very slowly diminish in coverage. For this reason, took VCSH out of the St. Louis metropolitan terminals this afternoon. There is a slight chance of showers and thunderstorms through this evening, but coverage and chances are too small to include mention in the TAFs. Widespread rain with some thunder is forecast to begin late tonight and continue into tomorrow morning ahead of a cold front. Winds will shift dramatically during this time period, making it difficult to choose a direction at any given terminal. This is exacerbated given the outflow boundaries in the area and the exiting warm front. Winds during the period are not expected to be especially gusty, with prevailing winds generally at 10 kts or less. Jaja && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX