Area Forecast Discussion
Issued by NWS Paducah, KY
Issued by NWS Paducah, KY
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936 FXUS63 KPAH 221907 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 207 PM CDT Sun Sep 22 2024 .KEY MESSAGES... - A few waves of increased shower and thunderstorm activity is expected late this afternoon and again Monday night. A few severe storms are possible with damaging winds the primary concern. Locally heavy rainfall will occur with thunderstorms. - A cold front moves through Tuesday leaving behind cooler and less humid conditions are expected for the rest of the week. - Returning rain shower chances are becoming more likely towards the second half of the week into next weekend. Forecast confidence is below average in how a potential tropical system down in the Gulf of Mexico may interact with an upper-level disturbance in the vicinity of the region and anything that would be more impactful. && .DISCUSSION... Issued at 207 PM CDT Sun Sep 22 2024 A steady conveyor belt of mid and upper level moisture has cloudiness spread over the northern half of the quad-state this afternoon. The southern half of the area has received quite a bit more broken sunshine through the last few hours and temperatures are approaching 90 degrees with dewpoints in the low 70s. MLCAPEs are around 1500 J/kg which is less than yesterday, but deeper layer shear is stronger which will give us at least some window for a few severe storms, with wind the main threat. This risk focuses mainly over southeast Missouri and far western Kentucky where instability has built up the strongest and sfc-700mb theta-e differences are around 25-30 K. A few radar returns are starting over south central Missouri that appear to be on the leading edge of an area of diffluence that will likely be the focusing mechanism for activity today. The expectation is activity will start to pick up by 21-22z and persist through 02-03z. Heavy rainfall rates are also likely with PWATs around 2.00" but decent forward motion and dry antecedent soil conditions should limit flooding risk. A decrease in precip is expected through the overnight although the chances never really go to zero anywhere before starting to increase in the late overnight, after about 09z or so. A relative increase in coverage with a return of a few thunderstorms. After another early Monday lull a trough approaches increasing large scale ascent and more widespread showers and storms look likely to refire. Deep and lower level shear looks reasonably favorable for some organized thunderstorm activity but instability looks limited owing to cloud cover and weak mid-level lapse rates. Models show an axis of a little bit heavier rain on the leading edge of low-level moisture advection but that could shift north to south a little bit from current projections. A surface cold front moves through Tuesday morning decreasing humidity. By Tuesday night an upper level low drops into the Missouri Valley and cuts off from the main flow. That will likely result in a very tricky forecast Wednesday and Thursday. GFS/ECMWF also bring a tropical cyclone into the Gulf coast region later this week that may interact with that system. The 12z ECMWF positions the upper low in a way to return quite a bit of moisture from the southeast US and the impinging tropical system where the GFS focuses that rainfall a little south of us. The NBM has a 20-40% all periods forecast which might could be improved upon a little but its difficult to argue with it much given the uncertainty given the fact that a cut-off low and a tropical cyclone might be two of natures most cantankerous systems to model at days 4-7. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1221 PM CDT Sun Sep 22 2024 High MVFR ceilings will slowly rise over parts of southeast Missouri as convective clouds begin forming. Thunderstorm development is expected over the region later this afternoon and through early evening. A decrease in activity is then expected after sunset. After midnight increased influence from an approaching storm system is expected to lead to lower ceilings with rain showers and embedded thunderstorms possible from about 08-15z. The new forecast calls for low MVFR ceilings although IFR ceilings are possible. Below VFR ceilings are expected through midday Monday with areas of rain and a few thunderstorms remaining possible. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ DISCUSSION...JGG AVIATION...JGG