Area Forecast Discussion
Issued by NWS Jackson, KY

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128 FXUS63 KJKL 272336 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 736 PM EDT Sun May 27 2018 .UPDATE...
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Issued at 736 PM EDT SUN MAY 27 2018 Scattered showers and storms will linger across portions of the area along and south of the Hal Rogers Parkway this evening. This activity should dissipate quickly once the sun goes down. Overnight we can expect partly to mostly cloudy skies and light winds. For now have only used the latest surface obs to establish new trends in the hourly forecast data. Will update the forecast again between 0 and 1Z to remove the pre-first period that the day shift put in. Also want to wait a bit longer to see how much the ongoing showers and storms die off.
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&& .SHORT TERM...(This evening through Monday night) Issued at 414 PM EDT SUN MAY 27 2018 The afternoon surface analysis shows a weak high pressure nearby and generally little influence form synoptic boundaries. We are seeing more influence from mesoscale features and boundaries this afternoon, and this is further complicating the behavior of convection this afternoon. The better coverage has of stronger showers and thunderstorms has been across NW parts of the CWA. This is where there could be a left over outflow boundary and some upper level vorticity advection. The biggest issue with thunderstorms this afternoon will be frequent lightning, heavy rainfall (PWATs greater than 1.5 inches) and even some higher gusts of around 35 to 40 mph. Given this did up POPs slightly across that region based on the latest radar trends. Otherwise, we will see a eventual decrease in coverage through the evening, as we loose the better instability from daytime heating. The biggest issue tonight will be when do we see a eventual end to the convection and then what happens with cloud cover for better fog production. The broken record of river valley fog will continue, but the coverage could be more particularly in areas where rain has already or will fall this afternoon and evening. Again, opted to not go too crazy on temperatures splits given the potential for leftover cloud cover. By Monday, we begin to get some influence from Tropical Storm Alberto, and this will once again lead to more showers and thunderstorms mainly in the afternoon. Given the additional moisture feed from the tropical system, we will continue to experience heavy rainfall in some of the showers and thunderstorms on Monday. Overall these should have a little more steering flow to the northwest, and help some with the slow moving nature of these thunderstorms we have seen over the past few days. Did keep some mention of showers into the night given this extra support in the mid and upper levels from Alberto. However, we should see a general downward trend in the thunderstorms through the evening and overnight Monday. .LONG TERM...(Tuesday through Sunday) Issued at 501 PM EDT SUN MAY 27 2018 Models continue in agreement on the handling of Alberto`s weakening remains during the period, and are fairly consistent since yesterday. They track the center from Al on Tuesday, to the lower Ohio valley by Wednesday, with the remains picked up by the westerlies and moving northeast over the Great Lakes on Thursday. Although this path takes the heaviest precip with the core to our west, the general pattern still favors precip in a deep moisture environment over our area through much of the period, especially during afternoon and evening hours during peak instability. The best shot at precip with Alberto passing by still looks to be on Wednesday. A modest increase in winds is also expected as its center passes by to our west and northwest on Wednesday and Thursday. Alberto`s mid/upper level remains are expected to merge with a shortwave trough over southeast Canada Thursday night and Friday, and then drop back south during the weekend. The track of this wave after the merger is still uncertain. The GFS scenario, also favored by its ensemble mean, has a closed low which drops south to the vicinity of WV, western VA, and East TN by Sunday. Meanwhile, the ECMWF is maintains more of an open wave and is more progressive, taking the mid/upper level system off the mid Atlantic coast by Sunday. Both scenarios allow a cold front to pass through our area and result in cooler temperatures to some extent during the weekend. The differences involve the potential for precip and the extent of cooling. The GFS generates precip under the upper low over our area during the weekend and is cooler, while the ECMWF is mainly dry during the weekend and is not as cool. The model blend which was used results in low POPs being carried in the forecast during the weekend, and temperatures still slightly above normal. && .AVIATION...
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(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 736 PM EDT SUN MAY 27 2018 Isolated to scattered showers and storms will linger near LOZ and SME this evening before quickly dissipating after sunset. Some MVFR fog is expected overnight, especially at locations that received rain today. May even see isolated instances of IFR fog depending on much clearing occurs tonight. Winds should remain light and variable through out the period. More showers and storms can be expected on Monday, especially during the afternoon, as Alberto approaches from the south and moisture streams into the area. At this time only scattered showers and storms are expected.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...DJ LONG TERM...HAL AVIATION...AR

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