Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 301215 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 815 AM EDT Tue May 30 2017 .UPDATE...
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Issued at 755 AM EDT TUE MAY 30 2017 Hourly grids were freshened up based on recent observations and trends. Some of the 6Z guidance and some of the convective allowing models suggest greater coverage late this afternoon and evening in the Cumberland Valley and less coverage of convection in the southeast. With that in min, opted to increase pops to 30 in the Cumberland Valley, but did not decrease pops in the southeast just yet.
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&& .SHORT TERM...(Today through Wednesday) Issued at 358 AM EDT TUE MAY 30 2017 Early this morning the region was under the influence of trough extending south into the MS valley region from a closed low over Ontario. Several weak shortwaves were rotating around this low and through the trough. One is currently moving into the Eastern Great Lakes and middle and upper Oh Valley regions. Another is upstream over IA south into MO with one or more additional shortwaves upstream entering the Dakotas and MN area. In advance of the first upstream shortwave was an associated surface cold front with yet another upstream of that associated with the shortwave entering the northern Plains. The center of the upper low should meander north through the period with the shortwaves and cold fronts working across the OH Valley and Great Lakes region. The first will move through the area today with the second one approaching the area on Wednesday. With the trough in place, a considerable amount of cloud cover is expected through the period along with chances for showers and perhaps a few mainly diurnally driven thunderstorms. Moisture and instability will be higher across the south and southeastern counties this afternoon and evening and thus slight chance to chance pops were carried across these locations. The model consensus keeps locations in the far north, especially form I 64 north dry today. Models generally bring another shortwave into the MS Valley and Lower OH Valley and TN Valley tonight. The NAM guidance is likely overdone with moisture and lift with this feature, but at least some convection will be possible mainly late tonight across the southwest part of the area near Lake Cumberland. This shortwave should move through early with another rotating into the Great lakes sending the cold front into East KY in the afternoon. Moisture and instability will be somewhat limited, but isolated to scattered convection is anticipated. With more convection expected earlier in the day than 24 hours ago the risk of any strong to severe thunderstorms is diminished. However, one or two stronger storms with gusty winds cannot be completely ruled out nearer to the TN and VA borders in the afternoon. .LONG TERM...(Wednesday night through Monday) Issued at 245 AM EDT TUE MAY 30 2017 High pressure will progress southward across the area Wednesday night through Thursday evening, providing a dry period of weather. As the high shifts south and east, return flow will start to bring better moisture into the area by Friday. We could see a few pop up showers or storms on Friday, but the lack of any forcing will keep things fairly isolated. A nice connection to the gulf develops Friday night and Saturday with ample moisture streaming north into the region. This occurs as a back door cold front pushes in from the north and east. Some weak ascent will spread over the area on Saturday with a vort max passing across the area. This should allow for better coverage of showers and storms. PW`s will increase to near 1.70 from Saturday through Sunday. With the front stalling to our north and the flow lining up nearly parallel to the front, the threat for training storms and more flash flooding will return. Overall details remain uncertain, but will continue to highlight the potential for flash flooding in the HWO. 00z GFS has trended slower with moving things out Sunday night/Monday, so have kept pops going into Monday, before drying things out Monday night. The added length of the moisture air over the region, will likely aid in the threat for flash flooding. && .AVIATION...
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(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 805 AM EDT TUE MAY 30 2017 VFR conditions will generally be the rule throughout the period. One exception will be initial fog, especially in the valleys. This will affect LOZ and SME Winchell with MVFR reductions. However, the fog should dissipate areawide by 13Z. The other would be any direct hits from isolated to scattered showers or thunderstorms will accompany the passage of a weak front/surface trough mainly between 18Z and 00Z. For now have used VCTS at LOZ, SME, JKL, and LOZ. The activity should remain south of the northern counties and SYM is not expected to be affected. Winds should remain 10KT or less through the period outside of any thunderstorm gusts.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...JP LONG TERM...KAS AVIATION...JP

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