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Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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625 FXUS63 KJKL 030655 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 255 AM EDT Wed Jul 3 2024 .KEY MESSAGES... - Warm and humid weather continues for Wednesday to Friday and afternoon heat indices may reach near 100 in some locations Wednesday through Friday. - Dry weather lasts into early Wednesday afternoon, then the potential for showers and thunderstorms returns and lingers into the weekend. - The highest probability of rain is on Thursday and Friday and a few thunderstorms could produce strong to damaging wind gusts. && .UPDATE... Issued at 1140 PM EDT TUE JUL 2 2024 No significant changes to the forecast other than the inclusion of the latest obs and trends for the T/Td/Sky grids. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the zones and SAFs. UPDATE Issued at 745 PM EDT TUE JUL 2 2024 23Z sfc analysis shows our cool and comfortable Canadian high pressure area from yesterday now well off to the east of the area. This made for a warmer and much more humid day across eastern Kentucky. Southerly winds of 5 to 10 mph, with occasional higher gusts, contributed to the rise in temperatures and higher dewpoints this afternoon under mostly sunny skies. After peaking in the mid to upper 80s earlier, temperatures are starting to fall back to the upper 70s and lower 80s currently. Meanwhile, dewpoints are staying up across the board - in the upper 60s to lower 70s most places. The current forecast is on track for a small to moderate ridge and valley temperature split along with patchy valley fog developing after midnight. Accordingly, have mainly just added in the latest obs and trends for the T/Td/Sky grids. These minor adjustments have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Wednesday night) Issued at 450 PM EDT TUE JUL 2 2024 Late this afternoon, an upper level ridge of high pressure was centered over the lower MS Valley into the Southeast and extended across much of the eastern Conus as well. The axis of this upper ridge is currently west of eastern KY, but return flow in the lower levels as ushered warmer and more moist air back into the region. PW is currently analyzed in the 1.2 the 1.6 inch range with the lower values in the north and east and the higher values near Lake Cumberland. Dewpoints have risen about 10 to 20 degrees compared to 24 hours ago while temperatures are on average about 10 degrees warmer as well. With the increase in moisture rather extensive, but shallow cumulus has developed across the region with some cirrus passing overhead at times as well. Meanwhile an upper level low was centered near the Manitoba and Ontario border with an associated upper level trough south across the Northern Plains and into parts of the southwest Conus. Tonight and Wednesday, the axis of the upper level ridge will shift east across the OH valley region including eastern KY this evening and then east of the area overnight. Upper level ridging will remain anchored over the southeastern Conus to the eastern seaboard. At the same time, the upper level low is expected to move toward Hudson and James Bay and begin to merge with a deeper upper low and trough over Southern Canada. A shortwave trough should move across the upper MS Valley to western Great Lakes tonight and then across the eastern Great Lakes and into Quebec. Another shortwave trough moving around ridging in the eastern Pacific should emerge from the Rockies and into the Plains through Wednesday afternoon and evening. This shortwave trough should advance east and reach the mid MS to Lower OH Valley through the end of the period. Meanwhile, at the surface, a frontal zone preceding the shortwave trough should reach the Great Lakes tonight reaching western Quebec to the eastern Great Lakes to the mid MS Valley to the Southern Plains becoming stationary or nearly stationary on the southern end. As the upper trough approaches the boundary should sag to near the OH Valley to end the period. Dry weather should persist through tonight to midday on Wednesday as the dominance of ridging begins to dwindle. Further warming along with an increase in moisture should continue in southwest flow between departing sfc high pressure and a front beginning to approach. PW is forecast to climb to to the 1.4 inch southeast to 1.8 inch range west and northwest by Wednesday evening and then to about 1.8 to 2.2 inch range from southeast to northwest to end the period. Afternoon dewpoints outside of the highest elevations near the VA border should be in the upper 60s to low 70s. This will allow heat indices to peak in the mid 90s to near 100 degree range. The increase in moisture, daytime heating as well as weak height falls could lead to some convection developing in or moving into the northwest and perhaps portions of the west by late afternoon and evening. If convection does not move into that regions some CAM runs have an outflow moving in that could be a focus for some convection. Limited instability and shear should limit storm strength, some storms could produce brief heavy downpours. Continued increasing moisture, the approach of a cold front and the approach of a shortwave trough and perhaps a weaker lead one should lead to coverage of convection increasing into Wednesday night. Some locally heavy rain is not out of the question in the more northern areas if convection were to train, but the probability is rather low. .LONG TERM...(Thursday night through Tuesday) Issued at 255 AM EDT WED JUL 3 2024 The forecast period will begin with mean upper-level zonal flow but a digging shortwave moving through upper-Mississippi valley will eject into the Great Lakes. At the surface, a stationary boundary is draped across the CWA keeping chances of PoP across the area to start the period but to the west, the aforementioned shortwave will bring a renewed chance of PoP as a surface cold front approaches the area. Along and ahead of the front, showers and thunderstorms are likely through the day Friday into Saturday before the front exits Saturday evening. Severe chances look to be largely limited with FROPA as widespread cloud cover will inhibit instability and shear is fairly weak ahead of the boundary. However, can`t rule out an isolated severe thunderstorm with FROPA during the day Friday. Also, there`s forecast 90-99th percentile above climatological precipitable water values, 2.10" to 2.30", through FROPA is expected. Which, if these showers and storms are efficient, heavy rainfall leading to possible hydro issues could be possible before the front exits on Saturday. High pressure builds in for Sunday into Monday before another double- barreled surface low sets up for next week. The first is another shortwave developing in the upper-Mississippi Valley and ejecting into the Great Lakes with a cold front crossing through the Commonwealth. The second feature is a weak surface low riding along a low-level jet streak. The second feature will bring increasing showers and thunderstorms to the region Monday afternoon before the first system drags a cold front through the region on Tuesday. Showers and thunderstorms are forecast to persist through the day Tuesday and linger through the remainder of the forecast period. Overall, the period will highlighted with periods of showers and thunderstorms that`ll bring much needed rain to the area. Also, temperatures will return to more seasonal ranges as daytime highs in the mid-80s to low-90s and overnight lows ranging from the upper-50s to upper-60s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 830 PM EDT TUE JUL 2 2024 VFR will persist through the period though there will be a bit of valley fog between about 06 and 13Z. This should not affect any TAF sites. Winds should generally be less than 10 kts through 12Z from the southeast to south. Winds then become increasingly southwest at around 10 kts for more western and northwest locations such as KSME, KLOZ, and KSYM through the end of the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...VORST AVIATION...JP/GREIF