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
741 FXUS63 KJKL 111100 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 700 AM EDT Thu Jul 11 2024 .KEY MESSAGES... - Seasonable temperatures, but relatively less humid weather will continue today. - Hotter conditions make a comeback as we move into the weekend and for next week. - The next significant chance of rain will hold off until the middle of next week. && .UPDATE... Issued at 645 AM EDT THU JUL 11 2024 No big changes to the forecast with just the inclusion of the latest obs and trends for the T/Td/Sky grids. These adjustments have been sent to the NDFD and web servers. In additional, an SPS is in effect for locally dense valley fog around through 9 am EDT. && .SHORT TERM...(Today through Friday) Issued at 440 AM EDT THU JUL 11 2024 08Z sfc analysis shows a pleasant area of high pressure over eastern Kentucky early this morning. This is keeping skies mostly clear and the winds light. This allowed for some radiational cooling through the night making for a small ridge to valley temperature split. Accordingly, temperatures currently vary from near 60 in the sheltered low spots while the hills, and more open areas, are running in the mid 60s. These conditions have also led to the formation of fog in the valleys with some locally dense patches around. The fog will start to clear out by 13Z. The models, and their individual ensemble suites, are in excellent agreement aloft through the bulk of the short term portion of the forecast. They all depict general troughing through the Great Lakes and Ohio Valley to close out the work week. This pattern is fairly stable as it is downstream from a persistent large ridge over the Desert Southwest. Within this eastern trough several impulse will strafe northern parts of the state through the short term portion of the forecast. There is some model spread, including in the CAMS, with a wave that passes by north of the JKL CWA on Friday afternoon. Overall, the consensus is that this will not impact the area south of the Ohio River, but trends with this feature will need to be watched with future model runs. Given the overall limited model spread have gone with the NBM as the starting point for the forecast grids. Sensible weather features a more seasonable day of weather today than yesterday as the summertime temperatures and some humidity return to the area. High pressure will keep conditions dry into tonight with another small ridge to valley temperature split and development of valley fog into Friday morning. For Friday proper, the heat builds further with highs on the warm side of normal along with increased humidity. Currently, the forecast is for dry conditions on Friday, but we will need to watch for potential incursions from more active weather to the northwest of eastern Kentucky. For now, though, have kept the forecast dry but confidence is not as high as it is for dry conditions today. As it stands, most would welcome such incursions bringing needed rain and some cooling. The main changes to the NBM starting point consisted of adjusting the temperatures to better account for more terrain details tonight into Friday morning. PoPs were kept in the single digits from the NBM through the period, though with the caveats outlined above. .LONG TERM...(Friday night through Wednesday) Issued at 357 AM EDT THU JUL 11 2024 Pattern aloft suggests a relatively quiet (uneventful) forecast for our area. We start the extended with mean ridging across the western CONUS and a mean trough over the east. Core of westerlies generally remains along the Northern Tier, or just south, with wind fields that are seasonably weak, particularly at the start of the extended. Shortwave energy eventually slides southward from northern Canada and strengthen winds fields along the Northern Tier, resulting in a general weakening of the western ridge, along with a flattening of the ridge eastward as the mean trough in the east fills and lifts northward. The end result is predominant zonal flow pattern aloft with the Commonwealth just south of the track of most shortwave energy. Pattern does amplify just a bit at the end of the forecast window, as shortwave energy carves out a trough over the Upper Midwest, which begins to impact the Ohio Valley at the very end of the forecast window, or just beyond. At the surface, high pressure remains over the Ohio Valley until the end of the period, when it succumbs to a surface cold front dropping southeastward into the Midwest by Wednesday. Sensible weather features seasonably warm and humid weather through the extended...or very typical summertime conditions. The less amplified pattern aloft, a mean westerly (versus southerly) synoptic wind or flow, and weaker ridging across the region, will tend to keep afternoon surface dew points in the 60s (versus mid to upper 70s) through much of the extended. While this will still result in muggy weather, but it should not feel quite as oppressive as we have occasionally experienced over the past several weeks. Wednesday could be the exception as moisture is drawn northward into the Ohio Valley ahead of an approaching cold front. Heat indices will still climb to around the 100 degree mark each afternoon from Monday through Wednesday, though suspect the NBM afternoon maximum temperature guidance is a bit too high. This has been the case in the majority of cases over the past several weeks. The potential for rain (showers and thunderstorms) will be limited to those times where northern stream energy manages to dig far enough south to impact eastern Kentucky. That would be mainly our northern zones for Sunday and late Monday, and then all of eastern Kentucky Tuesday and Wednesday afternoon and evening. PoPs will be low (20%) across the north Sunday and Monday evening, and 20- 30% for most of the area Tuesday afternoon into Tuesday evening. Our highest PoPs (up to 50%) during the period will be realized by Wednesday afternoon as the aforementioned trough drops southeastward into the Upper Midwest and its associated cold front moves into the Midwest proper. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 700 AM EDT THU JUL 11 2024 Look for the, mainly valley, fog and low clouds to disperse as we mix out through 14Z. This will leave us with VFR CIGs and visibility for the remainder of the period along with light and variable winds. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...RAY AVIATION...GREIF