Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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946 FXUS63 KJKL 062336 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 736 PM EDT Sat Jul 6 2024 .KEY MESSAGES... - Seasonably hot and rain-free weather follows for tomorrow before a humid and unsettled weather pattern develops for the new work week. - Forecasters will continue to monitor Beryl`s remnants for possible impacts here in eastern Kentucky. && .UPDATE... Issued at 713 PM EDT SAT JUL 6 2024 Increased cloud cover is streaming into eastern Kentucky from central and eastern Tennessee from an area of slightly increased instability and moisture. This may have an impact on the extent and severity of fog coverage overnight if the cloud cover remains persistent enough. Otherwise, changes were minimal with the forecast initialized using the latest hourly observations. && .SHORT TERM...(This evening through Sunday night) Issued at 420 PM EDT SAT JUL 6 2024 Aloft seeing minor height rises across the eastern CONUS through the short term while a broad trough over the Great Plains begins to fill and lift north-northeastward towards the Upper Midwest. At the surface high pressure shifts slowly from the Midwest into New England by the of the period. That makes temperatures and the potential of fog the main forecast challenges for the short term. Sensible weather features a moderation or warming in temperatures through the period. The seasonably pleasant (mid 80s) and relatively comfortable weather experienced today will feel a bit warmer tomorrow as temperatures climb to near 90. However, winds remain out of the north-northeast through the period. Consequently do not expect a surge in moisture across the area and a return to super muggy conditions, though surface dew points will tend to creep up as the high passes to our east and return flow begins to kick in by the end of the short term. Overnight lows will be pleasantly cool through the period, with our cooler valleys dropping to around 60 tonight and lower 60s tomorrow night. Cross over temps are generally in the low to mid 60s. Thus we can expect the formation of some valley fog through the overnight, possibly not quite as dense and widespread as this morning as a result of some of our boundary layer moisture being mixed out during the day today. .LONG TERM...(Monday through Saturday) Issued at 505 PM EDT SAT JUL 6 2024 The 06/12z model suite upper level analysis beginning Monday morning shows mean ridging extending the Western Atlantic into the Southeast US and Greater Antilles. To the northwest, a positively-tilted trough extends from a parent low over the Hudson Bay to the Southern High Plains. Hurricane Beryl should be nearing or making landfall around this timeframe as well, likely over southeast Texas. At the surface, a wavering frontal boundary extends from the New England Coast, southward along the eastern slopes of the Appalachians, and then more westward along the Gulf Coast to the vicinity of Beryl. A cold front extends northward from Central Texas to a weak surface low over Lake Superior. Weak surface ridging, wedged between these frontal boundaries, extends from the Mid-Mississippi Valley up into the Mid-Atlantic/Lower Great Lakes. The surface high over the Ohio Valley will become increasingly squished between the upper level trough/cold front advancing from the west on Monday and Tuesday. Convection is expected to develop over the Central and Southern Appalachians on Monday afternoon and again on Tuesday as moisture tries to seep northwestward into the Ohio Valley. While a majority of this activity should remain south and east of the JKL CWA on Monday, some spotty convection cannot be ruled out closer to the Virginia and Tennessee borders. With the continued rise in moisture, deep convection on Tuesday is expected to be more scattered to numerous. Forecaster confidence is increasing that deeper tropical moisture with Beryl`s remnants will arrive late Tuesday evening or night as the aforementioned cold front half-heartedly pushes into the Lower Ohio Valley. Return flow ahead of the boundary will pull anomalously high 2.0-2.2+ inch PWATs into the Ohio Valley. The strength and track of Beryl`s post-tropical wind field and surface low (still a point of uncertainty in the guidance) will determine the location of any notable axis of heavy rainfall as well as the degree of downslope rain shadowing over the southeastern 2-3 tiers of counties. Modeled instability is very meager with the tropical remnants, limiting the severe weather threat. However, a very moist sounding to near the tropopause including a deep saturated warm layer will be supportive of efficient rainfall processes and torrential rainfall rates. The big question remain how much rain shadowing occurs. As Beryl`s remnant low departs to the northeast, anticipate that its cyclonic circulation will aid the cold front in pressing the remainder of the way through eastern Kentucky by Friday or Saturday. However, lingering cyclonic flow with the trough passing aloft will likely remain supportive of at least some spotty diurnally driven convection heading into next weekend. In sensible terms, mostly sunny skies should generally be the rule on Monday with just a small shower or thunderstorm chance (10-30%) south of the Mountain Parkway, highest near the Virginia and Tennessee border. It will be hot and more humid with highs in the upper 80s to the lower 90s but the increasing humidity values will buoy heat indices close to 100 in the warm spots. A similar story is expected to unfold on Tuesday, except rain chances (40 to 60%) are better by the afternoon. The best rain chances of the period (60-70%) come late Tuesday night through early Thursday morning with the passage of Beryl`s remnants. Rainfall during this time period could be torrential at times, leading to instances of high water. Temperatures will trend cooler, generally lower to middle 80s for highs on Wednesday and Thursday, with all of the clouds and precipitation. Warmer temperatures (middle to upper 80s) and more dry time can be expected for Saturday and Sunday, though a shower or thunderstorms cannot be ruled out on either day, especially during the afternoon and early evening. Nighttime lows in the mid 60s to mid 70s are forecast through the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 733 PM EDT SAT JUL 6 2024 VFR flight conditions are forecast through the period. Overnight valley fog development is not expected to impact any terminals overnight, though there is just enough uncertainty where VCFG was used at KLOZ and KSME between 06z and 12z. Main concern in the immediate short-term is a broken deck of clouds near/around 045 to 050 moving northeast across the area. Winds will average around 5 kts or less through the period, generally from the west. KSYM may tend to flow out of the west- southwest due to local terrain effects. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CMC SHORT TERM...RAY LONG TERM...GEERTSON AVIATION...CMC