Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 192118 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 418 PM EST Mon Feb 19 2018 .SHORT TERM...
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(This evening through Tuesday night) Issued at 405 PM EST MON FEB 19 2018 As of mid to late afternoon, a mid and upper level ridge was centered south of Bermuda with another ridge over parts of the eastern Pacific. A trough was located over the western Conus and Rockies with southwest flow aloft. Meanwhile, a baroclinic zone extended from Quebec into the Great Lakes to mid MS Valley to the southern Plains. Despite some passing mid and high clouds and cumulus having developed, with south to southwest flow warmer air has advected into the region behind a warm front. Temperatures have reached the low to mid 70s in all but the VA border counties where clouds have been more extensive. Record highs have been at least tied so far at both JKL and LOZ. The ridge located south of Bermuda should build west into the southeast and eastern seaboard tonight and into Tuesday as a trough continues to work across the west with a series of shortwaves moving from the Rockies and Plains to the Great Lakes and into Ontario. At the surface, the region will remain in the warm sector during the period, with a sfc wave of low pressure and an initial shortwave moving into the Great Lakes tonight and weakening. Another wave of low pressure should develop in the Lee of the Rockies in advance of the next shortwave tonight and track into the Western Great Lakes on Tuesday. A more potent shortwave will move across the Rockies and into the Plains from Tuesday into Tuesday night, combined with the mid and upper level ridge building north off of the eastern seaboard, should begin to push the baroclinic zone/cold front into the Lower OH Valley by the end of the period. However, with weak forcing at best during the period, a considerable amount of clouds are expected through the period though it should remain rain free. However, there have been breaks in the low clouds today and there may be some breaks at times through the period. Cumulus clouds should dissipate tonight with breaks in clouds expected. Deeper sheltered valleys should decouple this evening with eastern valleys dropping off well into the 50s with ridgetop and more open terrain only dropping to around 60. Continued southerly flow and 850 mb temperatures climbing a coupe of degrees C should bring record highs for the 20th to both JKL and LOZ. Depending on the amount of sunshine, the all time February record high of 79 at JKL from 1996 will likely be broken as the forecast high is currently 80. LOZ will likely set a record daily high for the 20th, but fall short of the all time February record high. Deeper and more sheltered eastern valleys should again fall well into the mid 50s on Tuesday night. .LONG TERM...(Wednesday through Monday) Issued at 254 PM EST MON FEB 19 2018 Model solutions for the extended are in good agreement through Thursday. There is general agreement in the overall mid/upper level pattern thereafter but a few more significant differences show up that will influence any details of sensible weather. The extended will remain under the influence of southwest flow until the end of the period when stronger systems riding out of the southwest CONUS begin to wear down high pressure just off the Atlantic Coast, causing steering winds aloft to veer more westerly. At the surface we find a semi-stationary baroclinic zone has set up across the Ohio Valley. An associated surface frontal boundary will drop down across our area late Wednesday or Wednesday night. This boundary then stalls in the vicinity of our area as dynamics driving the surface system lift northeast into eastern Canada. This boundary quickly shifts back to the north during the day Friday as a wave of surface low pressure passes through the lower Ohio Valley and into the Great Lakes. Several minor waves of low pressure continue to traverse the region along this baroclinic zone until a final more significant wave sweeps everything out to our east by late Sunday or early Monday. Sensible weather features generally unsettled and warmer than normal weather through the extended. There will be some threat of rain just about anytime through the extended. Temperatures will run some 10 to 20 degrees above normal through the period. The main exception will be Thursday when the surface frontal boundary stalls and produces a large temperatures gradient across the area with low to mid 50s in the north and near 70 across the south. Otherwise high temperatures will run in the mid 60s to mid 70s on average. Overnight lows will run generally in the 50s. Temperatures do drop back down much closer to normal by the end of the period. There does appear to be enough surface based instability in place across the area to maintain the mention of thunderstorms on Wednesday with the arrival of the surface front. There is also a short period of elevated instability across the area early Friday north of the surface boundary as it lifts northward. Is it possible meteorological spring arrived a bit early this year?
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&& .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) ISSUED AT 105 PM EST MON FEB 19 2018 The region is in the warm sector with south to southwest flow. Some low clouds are working across the region, but other than for locations south of the TAF sites, these are in the VFR range. With continued heating this afternoon bases in all areas should rise with VFR is expected within the next 2 to 3 hours for all locations. The low levels will remain rather moist so some low clouds in the 3 to 5 kt feet range will be possible. However, with drying at mid levels as ridging builds over the Southeast Conus, mostly high clouds are expected after cumulus dissipate toward 22Z. Overall, VFR should prevail at the TAF sites through the period. Winds will generally be sustained out of the south at 10 to 15kt through 23Z with gusts up to 25KT or so possible, especially at LOZ, SME, and SYM. Winds should slacken to the 5 to 10kt range from 23Z to 14Z, before increasing to around 10kt late in the period out of the south. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...RAY AVIATION...JP

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