Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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180 FXUS63 KJKL 141742 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 142 PM EDT Thu May 14 2026 .KEY MESSAGES... - Patchy frost is possible late tonight into early Friday morning in sheltered rural valleys and hollows, away from mainstem rivers. - Additional shower and thunderstorm chances arrive to start the weekend followed by a pattern shift that favors temperatures 10 to 15 degrees above normal. && .UPDATE... Issued at 1215 PM EDT THU MAY 14 2026 Clouds are extensive over most of the area and temperatures are slower to climb than was forecast. Have lowered today`s fcst max temps a little bit based on the morning`s trends. UPDATE Issued at 810 AM EDT THU MAY 14 2026 Hourly grid were freshened up based on recent observations and satellite trends. A general trend to a filling in the low clouds over sections of eastern KY is occurring. Following that trend, opted to to increase in sky cover this morning to early or mid afternoon in the east compared to the previous NBM based forecast. && .SHORT TERM...(Today through Friday) Issued at 535 AM EDT THU MAY 14 2026 Early this morning, an upper level ridge extended from Mexico/Southern Plains across the Central and Northern Plains to Saskatchewan while an upper low was centered in Ontario with the axis of the upper trough south across the mid Atlantic states to the Carolinas to FL. Further north another upper low was located in the vicinity of the Alberta/Saskatchewan/MT border area with troughing south into sections of the Rockies/western Conus. At the surface, an area of low pressure was centered in the Lake Ontario to mid Atlantic coast with a cold front trailing into the Southeastern states and then north in the High Plains. Sfc high pressure extended from Ontario south through the MS Valley/western Great Lakes and was building into the Lower OH and TV Valleys. Winds across eastern KY as the night has progressed and at this point, some low clouds were over Northeastern KY with another area in the Big Sandy region to Black Mtn area. Temperatures in the deeper valleys and low lying areas have fallen to the upper 30s to lower 40s while temperatures elsewhere ranged into the mid to upper 40s. Today and tonight, 500 mb height rises are expected to occur across the Commonwealth as the upper trough with an axis east of eastern KY continues to move to and then off the eastern seaboard. Behind that the upper ridge shifts across the Central Conus and MS Valley and then into the eastern Conus while the upper low near the US/Canadian border is progged to trek into Manitoba and an associated shortwave trough crosses the Plains and Upper MS Valley and nears the western Great Lakes to mid MS Valley. The ridge axis moves across eastern KY Friday morning followed by a shortwave trough moving through the OH Valley and then some height rises by the end of the period. At the surface, the ridge of high pressure shifts across the Great Lakes, OH and TN Valleys and into the Southeast/Southern Appalachians through tonight and then south and east of the area to end the period. An area of low pressure and the interaction of it with shortwaves moving across the central Conus is expected to send the boundary currently south of of the OH back north as a warm front and into the Lower OH Valley and TN Valley by early Friday evening. The northwest flow aloft and high pressure ushering a colder and drier airmass for today will result in high temperatures trending colder compared to Wednesday and about 10 degrees below normal for mid May. A disturbance in the northwest flow and increase in low level moisture should result in more in the way of cloud cover in the eastern half of the area as compared to the west with this cloud cover diminishing toward sunset this evening. Dewpoints today should average in the 30s and with high pressure shifting across the area tonight light winds and mostly clear to clear skies are anticipated. This will set the stage for some patchy frost in the more rural deeper valleys and hollows with fog more favored along the larger creeks, rivers, and near lakes. If afternoon mixed dewpoints end up below the current forecast the areal extent of the frost concern could expand and trends will be monitored. Weak return flow results in temperatures moderating back to near normal for mid May on Friday. .LONG TERM...(Friday night through Wednesday) Issued at 450 AM EDT THU MAY 14 2026 A strong area of high pressure and its parent ridging features aloft look to strengthen over the SE CONUS this weekend, leaving much of Kentucky in return flow. A series of shortwave disturbances ejecting around the northwestern periphery of this ridge and into the Greater Ohio River Valley will progressively pull a warm front through our forecast area from Friday night into Saturday. Chance PoPs spread northeast across the forecast area as overrunning moisture arrives after midnight early on Saturday morning. The persistence and continued strengthening of southwesterly low level flow behind Friday night`s boundary will pump a warm, moist airmass into the area on Saturday morning. The front is likely to stall out by midday, but a second, reinforcing disturbances arrives later that afternoon and triggers additional storms. Saturday does not look look like a total washout though, as this second round of convection will likely be isolated to scattered in nature. Showers and storms will have more instability to work with on Saturday than they did on Friday night, but there are several limiting factors present. The LREF depicts a south-north gradient of 500-1000 J/kg of CAPE, but with increasing CIN the closer one gets to the strengthening southeastern ridge. Shower/storm coverage will be greater closer to the boundary, which is progged to be somewhere to the north of the Mountain Parkway corridor on Saturday afternoon. This overlaps with the greatest instability, but the rather weak nature of the dynamics aloft does not favor sufficient bulk shear, 25KT per 00Z LREF mean for widespread organized updrafts. Thus, Saturday`s convection appears pulsy, with a chance for small hail, gusty winds, and frequent lightning in the strongest cells. Some recent GEFS and ENS based AI severe convective hazard probability guidance has somewhat higher probabilities into the OH Valley in the vicinity of the anticipated boundary. SPC has the northern portion of the CWA on the eastern extent of a Day 3 Marginal Risk. Trends will be monitored closely. Once the boundary lifts well to the north of the forecast on Saturday night, the area`s sensible weather will be driven primarily by the further-strengthening ridge. The flow aloft will back further and further towards the southwest as troughing digs deeper into the Great Plains early next week. Such a synoptic pattern favors a noticeable warming trend, and subsidence under the ridge favors mostly clear skies and efficient diurnal warming processes on both Sunday and Monday. The deterministic baseline NBM data has been running too hot in this time frame, bringing temperatures into the 90s on Sunday. Taking a look at the broader probabilistic forecast envelope, temperatures are more likely to reach the 90s on Monday than on Sunday. Midlevel heights reach their maxima on Monday, and there is greater probabilistic support for highs in the lower half of the 90s by then. Following continued coordination with neighboring WFOs and WPC, highs were capped in the upper 80s to around 90 on Sunday and below 95 on Monday. Ridge-valley splits and river valley fog will be possible both nights with the ridging dominating. While the flow aloft favors efficient warm air advection around the ridge on Sunday and Monday, the more robust moisture return will likely hold off late Monday night or Tuesday. This will limit the magnitude of any associated heat risk concerns for Sunday to Monday. However, record highs at the KJKL and KLOZ climate sites could be threatened. The timing of this early-season heat coincidentally aligns with the 2026 National Integrated Heat Health Information System`s Heat Safety Week campaign. Interests are accordingly encouraged to monitor official NWS social media channels to learn more about heat-related impacts and heat safety tips next week. Deeper troughing emerges in the Plains on Tuesday and orients the flow in manner that gives our area better access to Gulf moisture. As the trough and its attending surface low eject into the Upper Midwest on Tuesday, a cold front approaches Kentucky. That boundary is likely to stall out to the west of our CWA, but the return flow out ahead of it will yield widespread dewpoints around or in excess of 60. The greater humidity in the atmospheric column will correspond with increased cloud cover, so temperatures readings on the thermometer will likely be a couple of degrees cooler than what occurs on Monday. Highs in the upper 80s will combine with the aforementioned dewpoints to produce plenty of instability for isolated to scattered open warm sector storms on Tuesday afternoon and evening. PoPs increase overnight into Wednesday as the front sags southeast, and that frontal passage should facilitate a return to more seasonably appropriate temperatures by mid to late week. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 141 PM EDT THU MAY 14 2026 VFR conditions were present at TAF issuance, but there were ceilings mainly in the 3.5-5K ft AGL range generally near/east of I-75. The ceilings will break up from west to east during the late afternoon and early evening, leaving mostly clear skies to finish the TAF period. && .JKL WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...HAL/JP SHORT TERM...JP LONG TERM...MARCUS/JMW/JP AVIATION...HAL