Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 201735 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY Issued by National Weather Service WILMINGTON OH 135 PM EDT Tue Mar 20 2018 .UPDATE... Issued at 825 AM EDT TUE MAR 20 2018 The mid-level short wave continues to cruise eastward, with a quickly diminishing precipitation shield across southern Ohio. Meanwhile, some showers have developed along the remnant cold front still aligned across far southeastern Kentucky. Have adjusted the POPs through the day, which keep at least some scattered activity along the boundary. Elsewhere, the lull looks to be more pronounced through much of the day, as we will be in short wave ridging, so kept lower in POPs a bit longer. Temperatures have also cooled quite a bit in the northwest, with some mid 30s noted. While a little recovery will take place today, adjusted some of the high temperatures down to account for this cooler trend. Updates have been sent. && .SHORT TERM...(Today through Wednesday) Issued at 359 AM EDT TUE MAR 20 2018 The latest surface map features broad surface low pressure situated from eastern Kentucky down to South Carolina. Aloft, a short wave trough is moving nearly along the Ohio River, with a secondary trough moving across the Plains. Widespread showers have lifted north out of our area, with dry slotting working in from the southwest, keeping showers limited in areal coverage. Expect a general lull in the action through early this afternoon, as the short wave trough continues to move off to our northeast and east, leaving us in temporary short wave ridging. The next wave will move in from the west. This wave will cutoff and help to deepen surface low pressure that will be developing just off to our east and southeast. Wrap around moisture will fill in across the area late today and especially tonight into Wednesday. Winds will become northwesterly, with the column gradually cooling off enough to allow for snow. Will be leaving much unchanged from the previous forecast, although, given the generally lighter precipitation rates, have allowed for a bit more disparity between the valley accumulations and ridgetop amounts in some areas. Most of the valleys will range in the 1 to 2 inch range, while ridges will be in the 2 to 3 inch range. The exception to this will be our southeast terrain, with the higher elevations along the Pine and Black Mountain chains seeing 3 to 5 inches by Wednesday evening. Temperatures will be averaging well below normal through the short term, and have favored the cooler NAM MOS numbers, especially for tonight and Wednesday. Highs today will range from the lower 40s in the northwest to the mid 50s in the far southeast. Readings will drop down into the lower 30s tonight, with readings likely not moving much on Wednesday, given the ongoing precipitation and cold air advection. Highs will be in the upper 30s for most locations, some 20 degrees below the normal highs for the latter half of March. .LONG TERM...(Wednesday night through Monday) Issued at 407 AM EDT TUE MAR 20 2018 The extended period begins with the remnants of a system moving to the east. Lingering snow showers will be possible with the exiting system early Thursday. The main feature of interest is forecast to occur this weekend, with another potential system to begin the next work week. Before the main system makes its way through Saturday afternoon, an upper level jet streak coming from the northwest will set up over the western part of the Commonwealth. The GFS shows a small band of precipitation Friday morning into the afternoon associated with this source of lift. However, the ECMWF does not show as much QPF. This could be because the lift is coming from an area of ridging to the northwest. Therefore, whether or not there will be sufficient moisture to go along with the lift generated from the jet streak before the main system moves in Saturday afternoon is still uncertain. To account for this, it looks like the Blend gave slight PoPs in the south Friday morning into the afternoon. The models are coming into better agreement in terms of timing with the weekend system, but the GFS is still slightly quicker than the ECMWF. The GFS also shows higher QPF whereas the ECMWF shows the precipitation tracking a bit more to the north with lesser QPF. Most of the precipitation from this will be rain, but there are chances of a rain/snow mix in the mornings due to the lower morning temperatures. However, with temperatures gradually on the increase over the course of the extended period, the better chance for rain/snow is on Friday as opposed to Monday morning. Furthermore, where the ECMWF shows showers tapering off early Monday morning, the GFS shows lingering showers for Monday with a stout system moving in later Monday into Tuesday. With the model uncertainty towards the end of the extended period, have opted to go with the Blend at this time. && .AVIATION...
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(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 135 PM EDT TUE MAR 20 2018 Low pressure at the surface and aloft will adversely affect aviation through the forecast period. Ceilings starting IFR and as low as LIFR will stay down in the nearly saturated circulation surrounding the low. Precip redevelops later this afternoon and evening as the strengthening system moves overhead. Rain will change to snow tonight as colder air arrives around the low. The snow will reduce visibilities down to 2SM/IFR. Snow is then forecast to continue through the end of the TAF period in lingering moisture and forcing behind the departing system. North winds will become northwest to west as the low progresses across Kentucky.
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&& $$ UPDATE...GEOGERIAN SHORT TERM...GEOGERIAN LONG TERM...CGAL AVIATION...BC is the U.S. government's official web portal to all federal, state and local government web resources and services.