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
931 FXUS63 KJKL 251026 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 626 AM EDT Wed Sep 25 2024 .KEY MESSAGES... - Showers and thunderstorms could result in heavy rain and isolated flooding through tonight. - The remnants of tropical system Helene are forecast to bring a widespread, soaking rain event later in the week. - Flash flooding could result from the remnants of Helene, but the potential may be limited by the quick movement of the system. - High temperatures will average near normal the rest of the week. && .SHORT TERM...(Today through Thursday) Issued at 608 AM EDT WED SEP 25 2024 A large upper low will drop slowly south from the mid Mississippi Valley during the period, becoming more closed with time. Our flow aloft will initially be from the southwest, still pulling deep moisture over our area, and continuing showers/thunderstorms at times for most places today and tonight. Clouds and precip will limit destabilization today and keep the severe weather threat much lower than on Tuesday. As we move into the day Thursday, tropical system Helene moving north through the eastern gulf will interact more strongly with the mid latitude upper low to our west. Our flow aloft will turn toward the southeast while low level flow sets in from the east. Even though precipitable water is expected to increase to near 2" by evening, the downslope wind components will probably work to limit precip amounts until Helene gets closer in the long term period. .LONG TERM...(Thursday night through Tuesday) Issued at 419 AM EDT WED SEP 25 2024 A very interesting synoptic set up for the extended! Two systems will come together to impact our weather for the duration of the period. First, a strong closed upper level low will be in place across the Mid-Mississippi Valley, allowing for a deep pull of moisture into the state. Meanwhile, Hurricane Helene will have made landfall late Thursday, and will continue to push inland and northward. By the start of the period Thursday night, the two systems will begin to mesh, starting to rotate counter-clockwise around each other while sitting over Kentucky and surrounding states. This will continue until late Friday, at which point they will finally merge together, again remaining nearly stationary across western KY. The low center will finally start to shift eastward Saturday night into Sunday. Models start to diverge in solutions at this point, with the GFS being more progressive in pulling the system to the east, being well out of the state by the end of the forecast period, and the ECMWF keeping it more centered across the Central Appalachians for a bit longer. As for sensible weather, with two systems merging right across the state, it`s no surprise that the amount of lift and moisture, we can expect lousy weather. Friday will be the best day for pops and heavy precip as the remnants of Helene rotate through eastern Kentucky. By the weekend, when the two systems merge, the center of activity will be more across western Kentucky, so this may be the first break that we get in eastern KY through the week. That being said, pops may still be scattered and could lead to precip in some locations. More widespread pops will move back into the CWA by Sunday as the consolidated low moves back eastward across eastern KY. By Monday, kept with the NBM which is a mix of the different model runs. This will keep pops across the CWA for the remainder of the forecast period and scattered sky cover, but depending on which model the forecast starts to trend towards, this could either increase or decrease. Given cloud cover through most of the period, this will limit daytime heating, but also the overnight cooling. It also limits the amount of ridge/valley temperature differences, along with the fog potential. Did go ahead and keep some fog mention in for Friday night, after the heavier rain shifts west of the CWA. Models are suggesting some potential clearing in the cloud cover from the west, which could aid in some fog development. Otherwise, did not make too many changes to the temps or winds from the NBM. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 615 AM EDT WED SEP 25 2024 Scattered showers and thunderstorms were ongoing at the start of the period, bringing localized sub-VFR conditions. Outside of the precipitation, conditions were mainly VFR. This scenario is expected to continue through the forecast. That being said, TAF sites may very well have restrictions at times, but nailing down timing is too difficult to explicitly state when, and including sub-VFR conditions would likely result in greatly over-forecasting poorer conditions. Hence, prevailing VFR is forecast, with the realization that there will likely be times of sub-VFR conditions. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HAL LONG TERM...JMW AVIATION...HAL