Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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412 FXUS63 KJKL 182025 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 425 PM EDT Wed Sep 18 2024 .KEY MESSAGES... - Additional shower (and possible thunderstorm) chances will occur through Thursday. - A warming trend will lead to temperatures around 10 degrees above normal over the upcoming weekend. - Active weather returns for the 1st half of next week, with showers and thunderstorms possible. && .UPDATE... Issued at 1110 AM EDT WED SEP 18 2024 Updated the grids just before 10am to make sure the near term grids were on track with the current conditions. This only resulted in some minor changes to the ongoing forecast so far. There was also some pops included in the far northeast of the CWA which weren`t materializing on radar, so went ahead and removed them. Also made some minor changes to the pops over the next few hours based on the latest CAMS, blending back into the forecast for later this afternoon and evening as scattered pops cover a large portion of the eastern and central CWA. This also resulted in updates to the weather grids. All updates have been published and sent to NDFD/web. A new set of zones and SAFs were also sent out to remove any morning fog wording, and also update the changes to the pop/weather in the forecast. && .SHORT TERM...(Today through Thursday) Issued at 411 AM EDT WED SEP 18 2024 Current surface analysis has the forecast area being impacted by a weak surface low that`s been slowly riding up the eastern seaboard. Low-level moisture, attributed to this system, has caused a stratus deck to develop along and south of the Hal Rogers Parkway. Areas north are seeing mostly clear skies. Temperatures overnight have fallen into the low to mid-60s. The aforementioned surface low and upper-level shortwave will continue to impact the area today through the remainder of the forecast period as it very slowly lifts northeastward out of the area. Isolated to scattered showers and storms are forecast to develop this afternoon. Forecast soundings for this afternoon indicate that decent instability will be in place with pretty solid PWs. However, not expecting anything in the way of severe weather as shear is largely lacking across the area. High temperatures are expected to climb into the upper-70s to low 80s. Showers and storms will taper off toward sunset with mostly clear skies anticipated overnight Wednesday into Thursday. Thursday brings another chance albeit small chance of showers and thunderstorms; mainly for areas along and east of the Mountain Parkway as the system, that`s been impacting the region, finally begins to eject out of the region. Forecast soundings continue to favor thunderstorm development but once again, the lack of shear will prevent any storm from really gaining strength. Highs for Thursday will climb into the low to mid-80s as surface high pressure nudges in from the southwest. Overall, the period will be highlighted by afternoon showers and thunderstorms with increasing temperatures. Daytime highs will begin to climb toward the mid-80s by Thursday with overnight lows holding steady in the upper-50s to lower-60s. .LONG TERM...(Friday through Wednesday) Issued at 425 PM EDT WED SEP 18 2024 The 18/12z model suite analysis beginning Friday morning depicts a positively-tilted ridge axis extending from an ~592 dam high over/near Del Rio, TX northeastward across the Lower Ohio Valley and then northward across western Quebec. At the surface, high pressure ridging is situated just east of the upper level ridge and extends from Labrador southward along the spine of the Appalachians. Upstream, a mean trough dips south from Canada across the Northern Plains/Northern Rockies. Another closed low is crossing Southern CA as it rounds the base of the upper level trough. Ahead of that upper- level trough, a cold front is draped from an ~992 mb surface low over northeast Manitoba down through Duluth, MN and Kansas City, MO and westward to near/over the OK Panhandle. Ahead of the cold front, west to southwesterly low-level flow will advect unseasonably warm temperatures (17-19C @ 850 mb) across eastern KY by Saturday and Sunday. While portions of the area, primarily near the VA border, have received a wetting rainfall this week, many locations further north and west remain very dry (soil moistures remain lower than 10 to 20 percentile in many spots as per NASA SPoRT-LIS). Given the low soil moisture values, decreasing evapotranspiration, and fair skies, stronger sensible heating warranted nudging daily maximum temperatures upward on Friday through Sunday toward or slightly in excess of the NBM 75th percentile while also nudging afternoon dew points toward the NBM 10th percentile. This yields high temperatures mainly in the mid 80s on Saturday and then a few degrees warmer for both Saturday and Sunday when warmer locales could eclipse the 90 degree mark. This drying pattern will also support moderate ridge-valley temperature splits developing each night--expect lows in the mid 50s coolest valleys to mid 60s in the thermal belts. Looking ahead to new work week, the closed low initially over CA will eject out onto the Plains Sunday and become an open wave riding northeastward toward the Great Lakes. This system will be accompanied by a surface wave riding the aforementioned frontal boundary across the Plains, Great Lakes, and on into Eastern Canada. Ensemble clustering shows significant spread developing during this time as members struggle to resolve additional energy of North Pacific origin diving into the trough, which could encourage slowing/amplification of the parent trough, while, at the same time, another tropical system potentially forms over the Gulf of Mexico. These factors will have significant bearing upon whether the surface low is able to push the cold front through eastern KY by the end of the forecast period. That, of course, will have significant sensible implications in terms of temperatures and rain chances during the second half of the long-term period. Given the uncertainties, the portions of the forecast from Monday onward remain very close to the NBM with only some minor adjustments for topography. Forecast highs cool from the mid 80s on Monday to near normal, in the upper 70s to near 80, on Wednesday. However, temperatures could be substantially warmer or cooler depending upon the how the pattern evolves. Precipitation probability, timing, and intensity are also uncertain. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 200 PM EDT WED SEP 18 2024 A strong low pressure system located east of the state will continue to impact the region through the next 24 hours. A scattered to broken low CU deck is in place across all the TAF sites, generally MVFR to low end VFR (1500 - 3500 ft). These will persist through the rest of the day, and could also lead to some isolated to scattered showers and a possible thunderstorm during the rest of the afternoon hours, mainly across KJKL and KSJS. Didn`t include any reductions to VIS or CIGs with this VCTS as the exact set up and impacts are still unknown. Will continue to monitor through the afternoon in case updates need to be made based on SH and TS materializing. Then as we head into tonight, what little wind there was today will quickly dissipate, along with the clouds and precip potential. Models are all continuing to suggest enough moisture and cooling across the region to lead to fog across eastern KY, including the TAF sites. Still expecting most sites to beginning dropping in VIS after 6Z, reaching IFR or even LIFR status by the wee hours of the morning. These values may need to be adjusted a bit as the fog begins to form and we see the whites of it`s eyes, but do plan on some widespread impacts. This fog will begin lifting by daybreak, giving way to mostly clear skies and another round of (this time VFR) diurnal CU during the daytime hours tomorrow/Thursday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...VORST LONG TERM...GEERTSON AVIATION...JMW