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
708 FXUS63 KJKL 070925 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 525 AM EDT Fri Jun 7 2024 .KEY MESSAGES... - Cooler and noticeably less humid air is expected to reside over the area today into Saturday. - The next passing cold front will bring increasing rain chances to eastern Kentucky Saturday night into Sunday. - Cooler air will be reinforced across the region early next week, before temperatures modify back to above normal by the end of the period. && .SHORT TERM...(Today through Saturday) Issued at 450 AM EDT FRI JUN 7 2024 08Z sfc analysis shows high pressure building into Kentucky from the west in the wake of a cold front that passed through on Thursday. This has now cleared out most of the clouds and brought light and variable winds overnight. Drier and cooler air is also noted this night from advection along with a decent bout of radiational cooling underway. Accordingly, temperatures currently vary from the mid 50s in the sheltered valleys to the low to mid 60s on the ridges and more open terrain. Meanwhile, dewpoints are generally in the middle to upper 50s. The clearing skies and still damp ground also allowed for fog to form in the river valleys and become locally dense. This should start to clear out after 9 am. The models, and their individual ensemble suites, are in good agreement aloft through the short term portion of the forecast. They all depict Kentucky between a cluster of 5h troughs to the north and ridging along the Gulf Coast. This keeps the area in northwest mid level flow through the start of the weekend. This pattern will support a few impulses passing overhead into Saturday. The early Saturday one appears to have the best chance to be impactful and crosses the JKL CWA around midday. Despite some model difference with that latter wave, the spread is small enough that the NBM was used as the starting point for the short term grids along with the incorporation of the CAMs` details for PoPs on Saturday. Sensible weather features a pleasant end to the week and start of the weekend thanks to an area of high pressure working through the area and keeping humidity lower than the past few days. Dry weather will hold through Saturday morning with a small chance for showers around into the afternoon, but limited instability for thunder - as modeled at this point. It still looks like a storm cluster develops to the northwest of eastern Kentucky later tonight and propagates toward the area with the expectation that it will basically die out before it reaches the JKL CWA by midday Saturday. However, there is a small potential for it to hold together or get a second wind so while thunder has been left out for now the potential is non zero. Do also expect more in the way of valley fog and a ridge to valley temperature split tonight - again potentially mitigated should that anticipated storm cluster hold together better and results in clouds pushed into the area towards dawn. The main adjustments to the NBM starting point consisted of adjusting the NBM PoPs to include CAMs details for the shower chances on Saturday. The temperatures from the NBM were adjusted early this morning and again tonight to allow for more terrain details. .LONG TERM...(Saturday night through Thursday) Issued at 525 AM EDT FRI JUN 7 2024 The 07/00z model suite begins the long-term in good synoptic agreement. An ~592 dam subtropical high will be found along the central Gulf Coast while multiple upper lows are found within a trough extending from Maine/Atlantic Canada to the southern Canadian prairies. Multiple disturbances will be passing through the flow aloft between the troughing to our north and the ridging to our south. Ahead of a more substantial disturbance, a weak surface low is found over southern Illinois with a warm front extending southeast into Middle Tennessee and a cold front trailing back to the southwest into the Southern Plains. Model agreement undergoes rapid degradation in the first 48 hours of the long-term period. While there is good agreement that the surface low and upper level disturbance to our west will pass through the Ohio Valley on Sunday, there is uncertainty as to how the upper level troughing to our north evolves as it tries to pivot cyclonically and potentially shears apart leaving a closed low to drift across the Ohio Valley during the early and mid-portions of the week. If this low does form, as depicted in recent runs of the 00z GFS, several days of wet weather can be anticipated for many locations through mid-week. (Note: The GFS solution does appear to be a minority solution based off of a cluster analysis.) On the other hand, if the trough remains more open and progressive, such as the 00z ECWMF/Canadian solutions, then a much drier and warmer scenario is likely to unfold once the trough axis crosses our area early in the week. Accordingly, chance to likely PoPs (40 to 80% chance) are in the forecast for Sunday with the initial low/frontal passage. Lower PoPs follow for Monday (30 to 40% chance) to account for the approach and/or passage of the upper level trough axis/low. Thereafter, the NBM solution was favored as it offers a compromise solution with just slight to low chance PoPs to account for the potentially wetter but currently less favored scenario. Daily forecast highs are only in the 70s through Tuesday before trending back above normal late in the week. Nighttime lows start in the lower to middle 60s on Saturday night before retreating into the 50s for the remainder of the forecast period. A few upper 40s cannot be ruled out in the most sheltered valleys on Monday and Tuesday nights if skies clear. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) ISSUED AT 145 AM EDT FRI JUN 7 2024 VFR conditions will hold through the TAF period, while fog will be confined to the river valleys. Winds will average west to northwest at 10 kts or less during the day and light and variable at night. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...GEERTSON AVIATION...CMC/GREIF