Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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832 FXUS63 KJKL 010710 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 310 AM EDT Wed May 1 2024 .KEY MESSAGES... - Fog this morning mixes out after sunrise. - Very warm Wednesday, followed by near-record highs on Thursday. - Showers and thunderstorms return to the forecast Friday through Sunday. && .SHORT TERM...(Today through Thursday) Issued at 308 AM EDT WED MAY 1 2024 A very foggy start this morning for most of the forecast area; areas along the escarpment are the exception as of this writing. However, satellite trends show some subtle westward expansion of fog. Therefore, there is still time for the likes of Somerset and Morehead to experience fog. Conditions were ripe for fog given rainfall that occurred during the day followed by clearing skies and calm wind. While we will mix out nicely this afternoon (temperatures soaring well into the 80s with dew points in the 50s), ensemble forecast soundings indicate the low-level inversion will come roaring back overnight. Due to the anticipated daytime mixing, we think the fog will be less widespread. Therefore, we`ve introduced fog to the river valleys tonight to start. This can be finessed further by day shift. An upper-level ridge in place over the Southeast US amplifies on Thursday, resulting in a hot afternoon. High temperatures will be close to records. Jackson`s record is 87 set in 2012 while London`s is 88 set in 1959. Relative humidities will plummet in the afternoon which raises a non-zero fire weather concern (similar conditions today, though RH value will be slightly higher). Of course, recent rain will squelch the concern overall, as will light wind. One last item to consider on Thursday is a non-zero chance of an isolated pop-up thunderstorm. The forecast remains dry at this time, but this possibility was noted in the CAMs. Dew points in the 50s will result in significant dew point depressions which will be challenging to overcome. Ensemble soundings indicate marginal instability of about 500j/kg and virtually no shear. However, convective temperatures will likely be met which could afford at least some cumulus clouds attempting to bubble up. Forcing may come in the form of a weak perturbation rippling atop the ridge, ahead of an incoming trough digging in over the lower Mississippi River Valley. .LONG TERM...(Thursday through Tuesday) Issued at 327 PM EDT TUE APR 30 2024 The period begins with good agreement in the deterministic and ensembles on the mid-level ridging the Southeast US and high pressure off toward the Atlantic Coast line. This will keep the weather quiet, with very dry low levels and capping inversion aloft. This could lead to some flat cumulus in the afternoon, but very warm afternoon high temperatures in the mid-80s to near 90 degrees. This could eclipse record high temperatures, with JKL 87 degrees set in 2012 and LOZ 88 degrees set in 1959. The ridging does push east as a mid-level wave rides toward the Ohio Valley Thursday night into Friday. This will aid in giving way to showers and thunderstorms Friday afternoon, as moisture surges northward and small amount of instability comes with it. This as multi-model ensembles show 40-50 percent chance of greater than 250 J/kg of CAPE. Overall guidance, including ensembles are in good agreement with best chance of rain (around 60-70 percent) Friday night into early Saturday. There seems to be a little uncertainty on Saturday in terms of timing, with first wave and next shortwave pushing into the Midwest, Saturday night into Sunday. The deterministic and ensemble data are disagreeing on the amplitude of this wave too and leads more uncertainty by late weekend into early next week. Particularly as there could be some shortwave ridging in between these features. Therefore, the PoPs drop back into the 40-50 percent range mainly in the afternoon hours Sunday into Tuesday. It will remain 10 to 15 degrees above normal through this time range. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 118 AM EDT WED MAY 1 2024 Highly variable conditions are noted at the TAF sites as of this writing. Fog has developed through the valleys per RGB satellite imagery. An expansion westward is noted beyond JKL and LOZ. Therefore, I do think all sites will see some BR or FG through the early morning hours. Confidence in time of arrival (for those VFR or MVFR) is low. Conditions improve after sunrise, but fog is probable again early Thursday morning and will need to be wrestled into the next TAF issuance. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BROWN LONG TERM...DJ AVIATION...BROWN