####018011967#### FXUS63 KJKL 161621 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1221 PM EDT Fri May 16 2025 .KEY MESSAGES... - There is an enhanced to moderate risk of organized severe thunderstorms with significant severe weather possible from today into tonight. - After Saturday, shower/storm chances continue at times through the middle of next week, mainly during the afternoon and evening hours. - Temperatures will be 5 to 10 degrees above normal today - then nearer to normal from Saturday through Tuesday. && .UPDATE... Issued at 1220 PM EDT FRI MAY 16 2025 As the morning has progressed, multiple rounds of showers and thunderstorms have affected portions of the CWA, with the heavier rainfall form these falling generally south of the Mountain Parkway and near or north of the Cumberland Parkway to Hal Rogers Parkway to KY 80 corridor. Guidance generally has the heaviest additional rainfall, QPF, in the Cumberland Basin while 1 and 3 hour FFG, etc. are generally lowest south of I-64 and east of I-75. Additional rounds of convection should affect the area this afternoon and this evening into the early part of the overnight. The convection has displayed supercellular characteristics at times this morning with hail up to golf ball size reported. Additional discrete convection at least at times this afternoon to early this evening, especially the southern half of the area. Currently MLCAPE is analyzed at 500 J/kg or less near I-64 and nearer to the WV border with a gradient across the middle of the CWA from Pulaski County to the Big Sandy region (where storms have largely been tracking recently) and 2000 J/kg or higher from near LOZ to EKQ east to US 25E with no CIN. MUCAPE near and south of the Mtn Pkwy is analyzed at 2000 J/kg or more. Low level lapse rates have increased to 6 to 6.5 C/km south of the Mtn Pkwy with mid level lapse rates roughly 5.5 to 6.5C/km. Effective shear remains substantial and will well into the evening if not later per guidance. In between rounds of convection and depending on heating, MLCAPE may reach as high as 1500 to in excess of 2000 J/kg in the southwest CWA at points in the afternoon to early evening. The threat for discrete cells continues and with hodographs having more length the directional shear/curvature for the time being large hail and winds remains the main threat, though the potential for tornadoes would increase toward evening with any discrete cells or with a late evening to early overnight QLCS. However, fairly widespread damaging wind gusts of 60 to 75+ mph would be the primary threat with the QLCS. The multiple rounds of convection with heavier amounts haven fallen or expected to fall over the more southern locations and considering the recent FFG, a Flood Watch was issued through 4 AM EDT on Saturday for all counties south of I-64. As for the convective threat this afternoon into this evening, Severe Thunderstorm Watch is in effect through 6 PM EDT. Additional watches may be needed as the evening progresses. UPDATE Issued at 118 AM EDT FRI MAY 16 2025 After a few early evening elevated thunderstorms over the southwest part of the forecast area, the night has turned quiet, with convection well upstream also dying out. Can't rule out some showers or storms yet, mainly toward dawn, but the real action should hold off at least until the day on Friday. UPDATE Issued at 942 PM EDT THU MAY 15 2025 Elevated convection has moved through our southwest counties this evening, leaving very little precip due to a layer of very dry air below the convective base. Below this dry layer there is warm and moist surface layer which has remained capped. The early evening activity likely resulted in dry lightning for some locations-- an extremely rare event for this area. Models suggest the elevated moist layer could result in precip overnight, but with the same dry layer expected to persist between about 850 and 600 mb, it's still questionable how much could get to the ground vs remaining virga. The night time POP is being held generally no higher than 20%. && .SHORT TERM...(This evening through Friday night) Issued at 220 PM EDT THU MAY 15 2025 There is not much change to the ongoing near-term forecast. PoPs have been lowered below 15 for the remainder of this afternoon as convection has remained suppression given rapidly rising mid-level heights. PoPs are gradually increased again into the evening and overnight as subtle height falls occur with a shortwave impinging into the mid-level ridge axis as it crosses far eastern Kentucky. This will be the beginnings of a much more favorable environment for upstream convection to sustain itself into eastern Kentucky, but will also increasingly provide a more favorable environment (i.e., increased shear and moisture/instability advection) for new convective development over the area. The atmospheric environment over eastern Kentucky becomes extremely conducive for multiple rounds of thunderstorms beginning as early as Friday morning and lasting into Friday night, with the potential for scattered to numerous severe thunderstorms as a stout mid-level jet moves over a warm sector characterized by mid-60s dew points. The primary uncertainty late tonight through Friday afternoon is the timing of storms, and whether these storms will take on a more discrete nature or develop in clusters. Any discrete storms during the morning through late afternoon will be particularly capable of producing large damaging hail, as indicated by long straight hodographs in the 3 to 9 km layer. However, damaging winds and an isolated tornado or two also cannot be ruled out. Any tornado threat would be maximized along any warm front or other mesoscale boundaries over the area. Models show unusually high confidence in one, maybe two, fast- moving mesoscale convective systems moving east across the forecast area Friday evening into the overnight Friday night, with the severe threat increasingly becoming damaging winds, some of which may be significant (gusts greater than 75 mph). Large hail and isolated QLCS tornadoes will also be possible. A flash flood risk will also exist during the evening and overnight, especially where storms repeat over the same area in fairly rapid succession. .LONG TERM...(Saturday through Thursday) Issued at 455 PM EDT THU MAY 15 2025 The models, and their individual ensemble suites, are in pretty good agreement aloft through the weekend and for the start of the new week, but that similarity fades by the middle of the new week. They all depict a strong but weakening closed low trough moving through the Great Lakes, well north of strong ridging over the Gulf of America. This is supporting fast mid level flow through Kentucky to start the weekend with a key impulse passing through to the east as the period kicks off. This flow then takes on more of a northwest tilt with weak energy moving through the area into Sunday morning. However, the next area of troughing upstream will let more energy stream east to the Tennessee Valley by midday Sunday providing upper support for potentially more active weather. This energy from the west will serve to counteract and blunt the rising heights of the ridging building north from the Gulf Coast into Monday morning. That Western trough then deepens and digs through the Four Corners region early Tuesday building the downstream ridging more effectively, but temporarily. It is also at this point that the model differences become more stark with the ECMWF holding its version of the Southern Plains trough as a deeper, slower, and closed one compared to the GFS ensembles. This leads to higher uncertainty for weather conditions from late Tuesday through Thursday. Even the operational ECMWF then pushes 5h height falls into eastern Kentucky on Wednesday with its trough arriving in the western Ohio Valley by evening. The core of this trough then moves into Kentucky on Thursday along with its core mid-level energy - still slow compared to the GFS solutions. The small model spread through Tuesday supported using the NBM as the starting point with minimal adjustments needed - mainly to factor in some radiational cooling based, terrain distinctions, in temperatures at night at the start of the new week. Sensible weather features improving conditions for Saturday in the wake of a storm lined cold front passing southeast of the area around dawn, then after a lull in activity convective chances pick up again later in the weekend and Monday but with much higher chances through mid-week. The rest of Saturday should be dry after the main fropa that morning, though a secondary cold front passes through in the evening with a small potential for a shower or storm as it does so. A drier air mass, but low clouds, and CAA will support uniformly cooler low temperatures into Sunday morning. It is Sunday that will be in doubt, weather-wise, as the NAM12 lifts the boundary northeast toward the Cumberland Valley by midday with another potential cluster of storms working through southwestern parts of the JKL CWA. Meanwhile, the ECMWF (and for the most part GFS) keep any activity to the west and south of the area. Another night of dry weather is expected into Monday morning though there is better agreement for that southern boundary lifting into the area later in the day with showers and storms a better bet with higher confidence in occurrence . Low pressure approaching from the Plains will then support additional storm chances through the night into Tuesday and continuing on Wednesday as the sfc low settles over the area per the ECMWF - perhaps clearing out early with a more easterly low from the GFS at midweek. Likewise, the slowly progressing ECMWF cluster keeps convection around through the day, Thursday, compared to the GFS's high pressure driven drying. Either way cool temperatures are anticipated for Thursday. The changes to the NBM starting point consisted primarily of adding enhanced terrain distinction to the temperatures for Saturday and, especially, Sunday nights. As for PoPs - did not deviate from the NBM solution given the similar model solutions aside from Sunday and late in the period - when uncertainty is highest. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 636 AM EDT Fri May 16 2025 Scattered showers and thunderstorms are currently moving across portions of the area early this morning. Additional showers and thunderstorms will move into the area by the mid morning hours with better coverage expected with this the activity. This activity will move out of the area by early this afternoon. Additional isolated showers and storms will be possible at times this afternoon but coverage will be more limited and not all locations will be impacted. Then another round of showers and storms will move across the area this evening into tonight. Thunderstorms today will bring temporary sub- VFR conditions to. Thunderstorms today and especially this evening into tonight will bring the potential for high winds and hail. The storms will move out of the region tonight with MVFR ceilings expected to develop into early Saturday morning. && .JKL WATCHES/WARNINGS/ADVISORIES... Flood Watch through late tonight for KYZ058>060-068-069-079-080- 083>088-104-106>120. && $$ UPDATE...JP SHORT TERM...CMC LONG TERM...GREIF AVIATION...WFO SGF ####018005112#### FXUS66 KSGX 161624 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 924 AM PDT Fri May 16 2025 .SYNOPSIS... Cooler conditions with increased winds and cloud coverage expected over the weekend. Low clouds are expected to fill in much of the coastal basin each night and morning. There are chances of light rain and drizzle west of the mountains tonight into Saturday and Saturday night into Sunday. Warmer conditions with a shallower marine layer is expected for next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible satellite at 9 AM was showing low clouds had reached well into the Inland Empire, but had not fully filled in the coastal basin. A few areas of drizzle were reported this morning. A closed low is expected to pass through northern Baja this morning, but an overall troughing pattern will remain as a stronger low pressure system digs into the Pacific Northwest. Cross sections of our local WRF are indicating a fairly deep saturated layer for tonight into Saturday morning. Current indications are this layer will be saturated enough to produce areas of drizzle or light rain west of the mountains and on mountain slopes during that time. Minimal accumulations are expected with chances of rainfall totals reaching or exceeding 0.10" at 5 percent or less. As the low pressure system moving into the Pacific Northwest begins to dig south into the Great Basin Saturday afternoon and evening, rain chances increase especially for San Diego County. Any rainfall is expected to be light, but more widespread across the coastal basin compared to what is expected tonight into Saturday morning. It's unlikely rainfall totals will exceed 0.20" for the coast and valleys and 0.40" for the coastal mountain slopes. The most likely places for accumulating rainfall are in the San Diego coast, valleys, and mountains. Stronger, gusty southwest to west winds are expected for the desert slopes of the mountains and deserts for Saturday afternoon into Saturday night. Stronger gusts of 50 to 60 mph with isolated gusts to 70 mph in the northern Coachella Valley below the San Gorgonio Pass are expected. Gusty west winds will continue Sunday afternoon and evening but not quite as strong with gusts to 45 to 55 mph and isolated gusts to 65 mph. High pressure will bring dry weather with warming Monday through Thursday. High temperatures on Thursday will be around 10 degrees above average, ranging from the lower to mid 70s near the coast, the 90s for the Inland Empire, and 104 to 109 for the lower deserts. For Wednesday and Thursday, NBM chances for high temperatures in the warmer portions of the Inland Empire to exceed 100 are around 35 to 45 percent with NBM chances for the warmer portions of the lower deserts to exceed 110 on Thursday at 5 to 10 percent. The marine layer will become shallower with night and morning coastal low clouds not extending inland past the far western valleys for Wednesday and Thursday. && .AVIATION... 161615Z...Coast/Valleys...Low clouds based 1200-1500 ft MSL spread into the western and southern Inland Empire this morning but are beginning to erode on the western edge at this hour. Clouds will continue to scatter out through 18z, but patchy clouds will likely lingering along the coast. Local vis reduced to 3-5SM on higher coastal terrain and inland valleys until scattering. Low clouds with slightly higher bases 1500-2000 feet MSL will push ashore and inland after 00z, filling the entire coastal basin to the foothills by early Saturday. Mountains/Deserts...SCT high clouds late today and tonight. After 22Z, pockets of westerly surface winds increase to 25-30 knots with gusts to 40 knots through mountain passes into adjacent deserts. This could produce intermittent strong up/downdrafts in the lee of mountains such as vcnty KPSP. && .MARINE... No hazardous marine conditions are expected through Saturday morning. Stronger winds late Saturday into early Sunday could lead to choppy seas and hazardous boating conditions in the outer waters near San Clemente Island for Saturday evening. && .BEACHES... Elevated surf will impact beaches Sunday and Monday. Expected surf of 4-6 feet would produce a high rip current risk. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from noon Saturday to 2 AM PDT Sunday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE/BEACHES...Munyan