Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 210233 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1033 PM EDT Mon Mar 20 2017 .UPDATE...
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Issued at 1033 PM EDT MON MAR 20 2017 Last of the thunderstorm activity just about to depart Pike county. Instability will be greatly diminished through the remainder of the night, so will leave out any mention through the remainder of the night. The cold front will slip south overnight and will bring a continued threat for a few showers as it pushes southward. Most of the shower activity should be fairly light and sporadic. In fact, still some pretty good dry air in the low levels over the area, so it may take a little time to saturate up to see showers in some places. Activity will depart by daybreak with a mainly dry Tuesday on tap. Models continue to shift everything southward towards the frontal boundary on Tuesday, so have continued moving the rain chances southward. We may not see anything reach far southern Kentucky until closer to 00z tomorrow evening. Updated grids to reflect these latest changes. UPDATE Issued at 754 PM EDT MON MAR 20 2017 Showers and storms are feeding on some elevated instability (above 10kft). Latest satellite imagery shows stable low level clouds in place across central Kentucky. This would indicate a surface layer very stable despite the elevated instability. Thus, no real concern of winds mixing down to the ground. Thunderstorms are now bearing down on areas just north of I-64 in northeast Kentucky. Still looks like this activity will stay on our fringe counties in northeast Kentucky. Rest of the area looks to stay dry through the evening. Still watching the cold front approaching from the northwest and will still be the focus for a few showers or storms as it sinks southward later tonight. Updated grids to increase rain chances in northeast Kentucky. UPDATE Issued at 620 PM EDT MON MAR 20 2017 Complex of showers and storms continues to skirt into far northern Kentucky this evening. A few isolated/scattered showers have popped up ahead of this activity and drifting across Fleming, Rowan and Bath counties. On the current trajectory, the complex of showers/storms will just skirt our northeast counties as it drops southeast. Should see a weakening trend as instability is much less to the southeast of this system. However, a period of rain will be possible in northeast Kentucky. Elsewhere, looks like a dry evening for the rest of the area as dewpoints remain quite low in the wake of the earlier day activity. As the front pushes on through overnight, we may see moisture push back across the area ahead of the front and could trigger some showers/storms as it passes through the area overnight. Enough moisture may linger behind the front to yield a bit of drizzle late tonight/Tuesday morning. Tuesday is looking drier and drier as models continue to back off on precipitation chances. Thus, removed most of the pops through mid afternoon. May go further with this pending the 00z hi-res model runs.
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&& .SHORT TERM...(This evening through Tuesday night) Issued at 359 PM EDT MON MAR 20 2017 The latest surface map features broad low pressure sprawled from the southern Plains into Ohio Valley, with high pressure having retreated to the Gulf Coast. Aloft, fairly zonal flow exists across the heart of the CONUS, with several embedded weaker short wave troughs. A more vigorous short wave trough is rotating through south central Canada. Convection has been dominating the synoptics thus far over the past 24 hours, with a decaying MCS exiting eastern Kentucky. This left an impressive differential heating boundary across the Commonwealth, with a nearly 40 degree gradient in place at one point earlier this afternoon. Temperatures are now rebounding in our area, as clouds have thinned, and better low level warm air advection has engaged. Meanwhile, upstream convection is growing across Indiana and into western Ohio, closer to the surface low and surface boundary, along with a secondary line of activity forming along a leftover outflow boundary. There is general model agreement with modest short wave energy helping to bring the surface front southeast into our area overnight, with convection likely recycling or sustaining itself. Have maintained categorical POPs to the northeast, and chance POPs west of I-75. Lows tonight will be much milder compared to previous nights, with readings generally ranging from the upper 40s to lower 50s. Convection will be exiting to our east Tuesday morning, before refiring along the surface cold front during the afternoon and early evening. Highs will range from around 60 north, to the upper 60s south. The models have trended further south with the boundary position, and the best POPs for the afternoon will be along the Cumberland Valley. Convection will gradually wind down through Tuesday night, as high pressure builds in from the north. Lows Tuesday night will range from the lower 30s north of I-64, to the lower 40s bordering Tennessee and Virginia. .LONG TERM...(Wednesday through Monday) Issued at 330 PM EDT MON MAR 20 2017 Rain will push south of eastern Kentucky Wednesday morning as an upper low across the Northwestern Passages and Hudson Bay dislodges east, sending a trailing trough axis through the Great Lakes and upper Ohio Valley. Surface ridging will follow a similar trajectory along the southeastern Great Lakes, ushering a cooler airmass into the Commonwealth in wake of a cold front. High temperatures look to largely drop into the mid 40s to low 50s, prior to lows Wednesday night dipping into the upper 20s to low 30s. Valley locales across far eastern Kentucky may even drop into the mid 20s, promoting frost formation by daybreak Thursday. Will have to monitor exactly how far aforementioned surface ridging pushes south, as the possibility may exist for a stray shower or two to develop into south central Kentucky through Wednesday evening as energy moves through in a northwest flow regime aloft. Not currently expecting anything measurable out of this given overall subsidence in place, but again will have to see if a clean frontal passage can occur earlier in the day to completely scour out available moisture. A warming trend will take place Thursday into the weekend as upper ridging slides in aloft with winds veering southerly at the surface. This will be in response to surface high pressure moving into the Atlantic while lee cyclogenesis materializes in the southern to central Great Plains downstream of a digging upper low east of the Four Corners Region. Dry conditions look to remain in place through the end of the week, as precipitation stays shunted off farther north across the Ohio Valley and upper Midwest into the Great Lakes nearer greater forcing from another Hudson Bay upper low. Greater moisture will also reside at farther north latitudes along a cold front extending south off of this feature, as well as along a warm front passing north of eastern Kentucky Thursday into Friday. Rain chances will increase into the weekend as the stacked low pressure system plows east, bringing both an increase in forcing and moisture out of the Gulf of Mexico. Thunderstorms will also be possible by Saturday afternoon as temperatures warm to near 70 degrees. Will have to continue monitoring synoptic/mesoscale details later in the week regarding strong to severe thunderstorm potential for the weekend. A brief dry period looks to ensue by late weekend into early next week, before cyclonic flow loads up once again off to the southwest. This should preclude much in the way of any significant cooldown in wake of the weekend system. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 754 PM EDT MON MAR 20 2017 VFR conditions will last through the evening hours. A cold front will push on through overnight with ceilings lowering through the second half of the night. Latest model guidance is struggling with the low clouds early tomorrow morning. Its possible we stay in the MVFR category tomorrow morning, although GFS LAMP guidance continues to support some IFR. For now, going to stay with the MVFR as it matches model soundings better. MVFR may linger through much of tomorrow as we stay just north of the cold front as it stalls to our south. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...GEOGERIAN LONG TERM...GUSEMAN AVIATION...KAS

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