Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
260 FXUS63 KLMK 260535 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 135 AM EDT Wed Jun 26 2024 ...Updated Aviation Discussion... .KEY MESSAGES... * Isolated to scattered showers and storms will be possible into the evening. A few storms may be strong to severe with locally damaging wind the main threat. * Better shower and storm chances arrive Wednesday, bringing much needed rain to the region. A few storms may produce locally enhanced gusty winds and hail. * Above-normal temperatures into next week with chances of shower and storms returning this Saturday. && .SHORT TERM /THROUGH TONIGHT/... Issued at 308 PM EDT Tue Jun 25 2024 Latest forecast update focuses on the convective chances later this evening into the overnight. As of the early afternoon, convection ongoing across IN/IL will be the focus as storms continue to progress along the cold frontal boundary and pushing southward toward the forecast area. While environmental shear parameters are weak, plenty of CAPE and steep low level lapse rates are present across the area according to the latest high resolution model soundings. Latest HRRR run has convection moving into the region between 6 PM and 9 PM EDT this evening, with a break and then another chance for rain through Wednesday. Wednesday is the best chance for accumulating rainfall from 0.25 to 1.25 of rain through Wednesday evening. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 308 PM EDT Tue Jun 25 2024 Synopsis...The medium range forecast will feature well above-normal temperatures and at least two waves of rainfall/storms: this weekend and again by the middle of next week. Initially, mid-level pattern will showcase shortwave trough with broad cyclonic circulation over the Eastern CONUS, large blocking high centered over the Southwest with ridge extending northward across the Rockies and finally a strong upper low entering through the Pacific Northwest. During the next coming days leading into the weekend, the mid-level high will progress to the east and build across the South and Mid Atlantic as the Eastern shortwave trough ejects to the Atlantic. Meanwhile, the upper-low will continue moving eastward along the northern third of the Lower 48 with as it experiences gradual weakening and evolves into an open shortwave. Nonetheless, this wave will be responsible for increasing rain/storm chances over the weekend as the accompanying front rushes through the region. For next week, mid- level high will remain stationary along the southern half of the CONUS while the northern-stream branch of the jet stays active with continuous shortwave energy pulses. Model Evaluation/Confidence...There is fairly good confidence in the synoptic pattern evolution going into the weekend as the 25/0Z deterministic guidance show a very similar evolution of this weekend shortwave trough and the timing of the frontal wave. On the other hand, uncertainties exist on the severe weather probabilities this Saturday afternoon/evening as pre-frontal/frontal convection could overlap with best daytime instability and slightly enhanced low- to mid-level flow to yield a low chance of damaging winds and hail. There is some support behind that reasoning from the latest two runs of the CSU ML algorithm. Overall, forecast confidence decreases next week, especially regarding the timing of precipitation from Wednesday and onwards. So far, there has been consistency between the ECWMF and GFS in representing the mid-level stationary high retrograding to the west and allowing vorticity energy under NW flow aloft to move across the OH Valley. Conversely, the CMC is slower and less amplify, so it keeps the high/ridge extended a longer period over the forecast area. Thursday - Friday...Most of the convective activity from Wednesday should be moving out of the area Wednesday night with quick drying of the column and mid-level strong subsidence accompanying the building mid-level high and a surface high pressure transitioning along the Great Lakes. Therefore, expect mostly sunny conditions on Thursday with north to northeast surface winds. Although highs on Thursday afternoon will still be in the mid to upper 80s, dewpoints will decrease a few degrees providing a slight relief from the heat. Quick moisture recovery will occur on Friday as winds shift to the south and temperatures surge back up to the low 90s. Friday is still being advertised as a dry day but mid to upper clouds will overspread the Lower Ohio Valley. Weekend...Above-normal temperatures and increasing rain chances will be the headlines this weekend as the region falls on Saturday in the warm sector of the next storm system. First, muggy conditions are anticipated on Saturday with highs around the mid 90s and dewpoints in the lower 70s. If the precipitation forecast verifies in the late afternoon and early evening, then there is a chance for heat indexes to stay in the low triple-digits for several hours. Showers and storm will most likely arrive late in the afternoon and early evening with a non-zero chance of marginally severe weather (as explained above). Besides chances of strong to severe storms, it would very beneficial to have scattered rainfall totals of a quarter to half an inch across the region to mitigate some the long-term precipitation deficits and drought concerns. Next Week...Above-normal temperatures and mostly dry weather will be found at the beginning of the week with a wetter outlook by the second half of the week (including the 4th of July). Nonetheless, forecast confidence remains relatively low on any potential scenario. && .AVIATION /06Z TAFS THROUGH 12Z THURSDAY/... Issued at 134 AM EDT Wed Jun 26 2024 Weakening convection over western Kentucky continues to slowly move southeastward. Will likely lead to VCSH over HNB and BWG through the early morning. Through the day, a cold front will approach and move through the region. Along and ahead of this front, showers and storms will be scattered to widespread at times. Some storms could become strong and lead to gusty winds and heavy rain. Main time frame will be in the afternoon through midnight. As the front moves through winds will veer to a northerly direction, showers will cease, and skies will begin to thin. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...EBW SHORT TERM...MCK LONG TERM...ALL AVIATION...SRM