Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, 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
623 FXUS63 KJKL 221935 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 335 PM EDT Sun Sep 22 2024 .KEY MESSAGES... - A potential for showers and thunderstorms will persist through much of this week. - After high temperatures well into the 80s to near 90 today, readings will trend downward through the week. && .SHORT TERM...(This evening through Monday night) Issued at 302 PM EDT SUN SEP 22 2024 The frontal boundary that had been draped across far northern Kentucky has begun to move north into Ohio and West Virginia as warm advection increases across central and eastern Kentucky. Upstream over the mid-Mississippi River Valley, a disturbance continues to move east toward eastern Kentucky, and will be the primary trigger for shower and thunderstorm development later this afternoon into the early evening. The greatest instability will be over the southwestern quadrant of the forecast area, but there will be sufficient instability for thunderstorms anywhere across the forecast area into this evening. Additional rounds of showers and thunderstorms are possible into the overnight tonight, with the greatest instability over the southern half of the forecast area, as an active jet stream continues to usher disturbances across Kentucky. With at least broken cloud cover and continued warm advection, expect little in the way of any ridge- valley temperature differences. Fog will be dependent on the amount of cloud cover. A stronger southwesterly jet stream develops over Kentucky Monday, and this combined with stronger moisture advection into the area will result in MLCAPE values approaching 1500-2000 J/kg by early to mid-afternoon. The increasing shear and sufficient instability will mean a Marginal Risk for severe thunderstorms, with gusty winds and large hail the primary severe threats. A mitigating factor may be that the better shear does not arrive until after sunset, when instability becomes more limited, especially if earlier convective overturning has resulted in stabilization of the atmosphere. With the strong upper trough still approaching from the west, showers and thunderstorms are likely to continue through the overnight Monday night. Despite the recent dry conditions, isolated/localized instances of high water are possible where storms train across particular area. .LONG TERM...(Tuesday through Sunday) Issued at 335 PM EDT SUN SEP 22 2024 The latest run of the GFS has an active flow pattern aloft across the CONUS. A trough of low pressure is currently forecast to be coming onshore in central California on Tuesday, with another well developed trough positioned over the northern Plains. Another persistent trough is still in the picture off the eastern seaboard to begin the period on Tuesday, but looks like it will be a bit further offshore. Another feature of great interest in the extended will be the development of a tropical cyclone in the southern Gulf of Mexico toward the middle of the week. Based on the latest model runs, it is looking more and more likely that a tropical cyclone will form somewhere over the Gulf of Mexico, and perhaps rapidly intensify over those extremely warm waters as it moves northward toward the central or eastern Gulf Coast. There is quite a bit of uncertainty regarding how this system will evolve and progress once it moves inland, should it indeed form, and how it might affect the weather of eastern Kentucky, so we`ll be watching this particular feature quite closely over the coming days. Our first weather maker, however, will be the northern Plains trough and frontal systems that will be extending from it. The latest models suggest that a weak shortwave may also form along the leading edge of the approaching trough on Tuesday. This, along with the passage of a surface cold front, will act as sources of lift to support shower and storm formation across our area. Showers and storms will move in from the north and west, as the cold front moves through. With a potential tropical cyclone moving in from the south, the front could slow up greatly, or even stall, over our area. If this scenario occurs, it would mean an extended period of light to perhaps moderate rainfall across our area Tuesday through Thursday. As much one to three inches could fall over the area during that three day period. With extensive cloud cover and persistent precipitation expected across our area for at least a few days, temperatures should be near normal during the extended, and perhaps even a few degrees below normal at times. Daily highs will range from the low to mid 70s on the coolest days, to the mid to upper 70s or even lower 80s on the warmest day. As far as hazards go, we`ll be watching closely for the potential for locally heavy rainfall during the Tuesday through Thursday time frame, when the most widespread and persistent rain is expected to occur. There is also a marginal risk, or 10% probability, that severe storms will occur on Monday, as the cold front makes its initial push through the region. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) ISSUED AT 124 PM EDT SUN SEP 22 2024 Mainly VFR conditions are expected to last into tonight. However, isolated thunderstorms are forecast to this afternoon and last into the evening before dissipating. Additional scattered showers and thunderstorms may occur overnight, but this is lower confidence. Any thunderstorm or heavy shower has the potential to bring sub-VFR conditions. Valley fog and low status are also forecast once again tonight, but its extent is questionable. If significant precip occurs first, it would favor fog. However, the presence of clouds would also inhibit fog development. Additional more widespread showers and thunderstorms are expected to develop at the very end of the TAF period, which will be reflected in future TAF packages. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CMC LONG TERM...AR AVIATION...CMC