Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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690 FXUS63 KJKL 150526 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 126 AM EDT Sat Jun 15 2024 .KEY MESSAGES... - A weak cold front will bring a low (20%) for a shower or thunderstorm, primarily north of the KY highway 80/Hal Rogers Pkwy/Cumberland Parkway corridor. - Hot and somewhat humid weather arrives on Sunday and persists into the upcoming week. Afternoon heat indices may peak around 100 at some locations Sunday through Wednesday. - There is a slight chance of afternoon and evening thunderstorms on Monday, Thursday, and Friday. && .UPDATE... Issued at 1156 PM EDT FRI JUN 14 2024 Pesky showers continue as a convective outflow boundary is just entering the CWA from the north. These very isolated showers have been quite resilient so far this evening. For simplicity, went ahead and broad brushed an area of minor PoPs for a good portion of the overnight period. Kept mention of thunder for good measure in case a cell or two over performs. Otherwise, the rest of the forecast appears on track for the most part. Updated suite of products have been issued, including grids. UPDATE Issued at 955 PM EDT FRI JUN 14 2024 No significant changes to the forecast package at this time. Tweaked temps to bring them in line with latest hourly surface obs. Also made some minor adjustments to PoPs for ongoing activity and trends. There is a definite trend downward in activity post sunset. Convective outflow boundary continues to drop southward, just about to reach the Ohio River proper. Can not rule out an isolated shower or thunderstorm over the next 2-3 hours as it continues to move southward. But expect coverage would be isolated at best based on trends. Latest CAM solutions support this line of thinking as well. Updated grids and zones have been issued. UPDATE Issued at 610 PM EDT FRI JUN 14 2024 Convective initiation has been surprisingly robust along the I-64 corridor between Morehead and Louisville this evening ahead of the cold front, in spite of little support from most of the CAMs. Increased PoPs with thunder to slight chance/low chance over southwestern portions of the forecast area down to the Hal Rogers Parkway/Kentucky 80 corridor through 00z as this activity drops southeast. Still anticipate that widely scattered convection will impact locations northeast of KY-15 late this evening and early overnight as the front passes. The latest SPC mesoanalysis continues to show high DCAPE values of 1100 to 1400 J/kg, indicative of abundant dry air in the mid-levels supportive of damaging thunderstorm downburst winds if a particular storm becomes strong. && .SHORT TERM...(This evening through Saturday night) Issued at 442 PM EDT FRI JUN 14 2024 Another seasonably warm afternoon has unfolded over eastern Kentucky this afternoon with high temperatures as of 4 PM ranging from from 85F in the northern foothills to 90F in the cities of Monticello and Somerset. The heat was tempered at higher elevations with the Pike County mesonet reporting a high temperature of 81F atop Flatwoods and the Harlan County mesonet measuring 74F atop Big Black Mountain. Very isolated sprinkles/light showers have bubbled up today and impacted a few locations. Regional satellite shows a band of towering cumulus attending a cold front draped across southern Ohio, through northern Kentucky and southwest through southern Indiana/Illinois. Regional radar shows most of the shower and thunderstorm activity with this front north and northeast of the JKL CWA at 4 PM. The front is associated with a trough passing from the Great Lakes toward the Mid-Atlantic/New England. Most of the system`s forcing remains well to our north. As that trough translates eastward, the associated cold front will sag southward across eastern Kentucky this evening and overnight. Sporadic convection is still expected to fire along the cold front as it passes later this evening and early overnight, especially over northeast Kentucky where low-level forcing may be enhanced by weak outflow boundaries from other convection. Otherwise, look for drier air to gradually work in overnight while patchy fog tries to develop in some of the more sheltered river valleys and in those areas affected by rainfall later this evening. By Saturday morning, the front will be well to our south. Strong upper level high pressure will then begin building over the Southeast US and Ohio Valley for the remainder of the short- term period. Cooler, drier, northerly low-level flow will knock down temperatures a few degrees on Saturday before winds shift back southerly late Saturday night and begin ushering in the warmest air mass of the summer season thus far. In sensible terms, look for spotty showers and thunderstorms this evening and early overnight primarily northeast of KY-15, though a stray shower cannot be ruled out further to the southwest. Otherwise, partly cloudy skies and some patchy river valley fog will be the theme. Overnight temperatures are forecast to be seasonable with lows ranging from the mid 50s in northern valleys where the cooler, drier air arrives first to the lower and middle 60s near the Tennessee border where the front arrives latest. Saturday will be mostly sunny, less humid and slightly cooler with highs ranging from the lower 80s in the northern foothills to the upper 80s in the Middlesboro basin. With the drier air in place and the commencement of low-level warm air advection, expect a sharper ridge-valley temperature split to form on Saturday night under mostly clear skies. Look for lows ranging from the lower 50s in the coolest sheltered northeastern hollows to the mid 60s on the mildest thermal belt ridgetops/slopes. .LONG TERM...(Sunday through Friday) Issued at 400 PM EDT FRI JUN 14 2024 Models are in general agreement for the overall pattern that will affect our area during the long term period. Upper level high pressure will start out centered in the vicinity of the southern Appalachians on Sunday. It is expected to shift north to near NYC at mid week, and then back south to the vicinity of VA on Friday. The ridge is now expected to keep convection capped much of the time for our area. However, one exception is Monday, when the GFS and ECMWF both allow for a bit of mainly diurnal activity in the afternoon and evening as an area of somewhat higher moisture rotates around the western side of the high center. In terms of model differences, the main issue is in the strength of the high/ridge, with the ECMWF being stronger than the GFS, especially later in the week. The weaker GFS allows for deep convection to boil up on Thursday and Friday, whereas the ECMWF is dry. This results in hotter temps in the ECMWF. Will allow for a model blend to smooth out these differences for now, with only a slight chance of precip to be mentioned. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 126 AM EDT SAT JUN 15 2024 VFR conditions will generally prevail through the TAF period. Of immediate concern in the next couple of hours is an outflow boundary moving south across the forecast area, poised to cross KJKL around 06z and then KLOZ and KSME toward 08z. This feature will generate a few isolated showers that will most likely miss the TAF sites, but will also bring a brief period of north to north-northeasterly winds gusting up to 15 kts. Of note, a few models bring a brief MVFR stratus deck that develops over the area to KJKL, KLOZ, and KSME between 08z and around 13z. Will keep any mention of this out of the TAFs given the low confidence. Otherwise, the remainder of the TAF period will be quiet with only passing high clouds and very light winds generally out of the northeast. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...RAY SHORT TERM...GEERTSON LONG TERM...HAL AVIATION...CMC