Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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951 FXUS63 KLMK 141720 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 120 PM EDT Tue May 14 2024 ...Updated Aviation Discussion... .KEY MESSAGES... * Active pattern with 2 storm systems bringing chances of showers and storms through Saturday. * Scattered showers and storms, especially during the afternoon Tuesday and Wednesday. * Main impacts from this activity will be gusty winds, small hail and heavy rain that could result in localized minor flooding. * Another similar system arrives for the end of the week and into the weekend with a chance of showers and a few embedded storms. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 324 AM EDT Tue May 14 2024 A stacked low pressure center will drift from southeast Missouri this morning into western Kentucky tonight, with a weak warm frontal structure developing eastward along the length of Kentucky this afternoon. Though the best moisture will remain well to our south along the Gulf and southeast Atlantic coasts, there will still be plenty enough of a supply this far north to support widespread clouds and showers ahead of the advancing low. Instability this afternoon will be kept in check due to the clouds and rain, but models do suggest moderate lapse rates, 1000-1500 J/kg of SBCAPE with 25-30kt of deep layer shear, and 25-30kt mid level winds supporting loosely organized convection. The lack of strong synoptic scale wind energy and DCAPE progged below 800 J/kg suggest mostly sub-severe wind gusts, with any stronger gusts likely associated with the heaviest downpours. WBZ heights indicate marginally severe hail may be possible in the strongest updrafts. Slightly backed surface winds ahead of the low will contribute to low level shear and may facilitate a non-zero chance of an isolated, brief tornado (STP < 1 all day), especially in the vicinity of the warm front. The best chance of any severe storms will be from mid afternoon into early evening south of Interstate 64. Precipitation amounts will vary from one location to the next due to the convective nature of the rainfall, but half an inch to an inch is a good ballpark number for southern Indiana and central Kentucky today through tonight. Though we`ll have a warm start this morning around 60 degrees, clouds and rain should prevent temperatures from warming much past the lower and middle 70s this afternoon. Lows tonight will again be around 60. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 324 AM EDT Tue May 14 2024 Wednesday morning, the low pressure system bringing showers and storms during the short-term will be directly over the CWA. The pooled moisture with the system will have precipitable water values reaching into the 1.3-1.5" range over southern Indiana and central Kentucky, and even though the system will quickly get pushed east of the Washington D.C. area by 0z Thursday, its moisture over the CWA won`t have the same urgency to leave. Model soundings show deep layer moisture with modest instability, around 500-1,000 J/kg of MLCAPE, during the afternoon and evening hours. Shear will remain low with 0-6km values less than 20 knots, so it will likely be a overall wet drizzly, sprinkly kind of day. There could be some isolated to scattered heavier showers with a few thunderstorms before things taper off in the evening/early Wednesday night. Wednesday night will see the arrival of upper ridging and a sliver of surface high pressure stretching south over the Great Lakes down into the Mississippi Valley. Expect clearing skies over the CWA into Thursday which will help boost temperatures from the mid 70s on Wednesday to the upper 70s to low 80s Thursday afternoon/evening. Thursday night through the weekend is where the forecast has been a little messy the last few days due to model variation. The forecast has carried precipitation chances through this time not because there is really a chance of ongoing rain showers for several days, but it`s the uncertainty during the period. Both the deterministic models and ensembles have had this issue. For the last two nights, there appears to be a better signal to move the precipitation in earlier, beginning Thursday night or Friday. This earlier trend was picked up first by the GFS, last night the Euro jumped on board, and now that the NAM is in focus, it`s even earlier. Thursday night and Friday look to be the best chance for heavier rain showers and thunderstorms. A lower chance of precipitation could remain during the weekend, but believe the trend is drier. Most of the data keeps any showers and/or storms on Friday sub-severe. There could be some instability which would make thunderstorms more likely, but limited shear would limit storm development. If the NAM is correct, it brings more impressive instability and shear Thursday night ahead of the line of convection, but by the time the line would arrive in the CWA, it would be elevated, which again would limit the severe threat. For now, the weekend looks mostly sunny with highs in the 80s. && .AVIATION /18Z TAFS THROUGH 00Z THURSDAY/... Issued at 120 PM EDT Tue May 14 2024 Surface low pressure system moving into western KY will bring showers and scattered thunderstorms through tonight. Periods of MVFR/VFR ceilings are likely, perhaps even brief (low confidence) IFR conditions at times for area terminals. A brief break in precipitation chances overnight will give way to another round of scattered showers and thunderstorms after 12z Wednesday with MVFR ceilings/visibilities. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...13 LONG TERM...KDW AVIATION...MK