Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 300709 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 309 AM EDT Thu Mar 30 2017 .SHORT TERM...
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(Today through Friday) Issued at 309 AM EDT THU MAR 30 2017 An area of low pressure resides over eastern Kansas this morning with a warm front extending east across central Missouri and into western Kentucky. A cold front is advancing eastward across the Ozarks region. Isentropic ascent associated with the warm front advancing towards eastern Kentucky has led to a increase in mid/high clouds this morning. Still some support in the hi-res short term models to support some light showers/sprinkles early this morning as the isentropic ascent in the mid levels continues to increase. In fact, a few showers are already trying to get going out across central Kentucky and this should continue to expand in coverage as it moves northeastward. The threat for showers will be short lived as downsloping south-southeast flow takes hold through the day. This leads us to our first threat of the day, an enhanced fire danger. Temperatures will soar to around 80 this afternoon. Dewpoints should mix out into the mid to upper 40s, putting relative humidities between 25 and 35 percent areawide. While this is not in the critical range, it is close. In addition, winds will crank up this afternoon with deep mixing taking place. Sustained winds of 10 to 20 mph are likely along with wind gusts up to 35 mph. The dry air combined with these strong winds could will create an enhanced fire danger today, especially for areas that have managed to dry out over the past 24 to 36 hours. Will highlight the fire danger in the HWO and fire weather forecast this morning. As we head into the evening hours, the low over Kansas this morning will push east across central Illinois and Indiana. The trailing cold front will lead to shower and thunderstorm developing across southern Illinois/Indiana, southward into western Kentucky and western Tennessee. This activity will push east/northeast through the evening hours. This activity will be aided by a potent shortwave it it tracks into eastern Kentucky tonight. This leads to our second threat, severe storm potential tonight. Shear will be tremendous with this system, but instability may be a bit more of a question. With dewpoints slow to come up through the day, the question is, can we generate enough instability to allow for a more robust severe threat. Certainty a questionable setup for eastern Kentucky given the lack of surface instability. However, in this case, we have lots of forcing spreading east across the area and this could compensate for the lack of instability. The storm prediction center has expanded the slight risk of severe storms over all of eastern Kentucky and this seems very reasonable considering the trends. The enhanced risk is sitting just to our west, and would not be surprised to see it expanded west today depending on how things unfold upstream. Best threat would be in our western counties as these areas are less likely be be downsloped and thus dewpoints more likely to come up in these areas. Things become more questionable to the east. Main threats appear to be damaging winds and large hail, although a brief tornado spin up cannot be ruled out. Heavy rainfall will be possible with strong lift associated with the shortwave and PW`s near 1.25 inches. This could produce some rainfall totals in excess of 1 inch tonight. Forcing will depart to the east early Friday morning, but the upper level trough will become anchored over the region keeping some moisture and cloud cover over the region. This may lead to scattered to numerous rain showers Friday afternoon. Mid level lapse rates not quite steep enough to support thunder, but are very close. Should be a much cooler day with highs in the 60s. .LONG TERM...(Friday through Wednesday) Issued at 400 PM EDT WED MAR 29 2017 Models appear to be in good agreement with mid/upper level features until the very end of the extended window. Overall pattern is quite progressive as well. Cutoff low will be pulling off to the east at a rapid pace Friday. Shortwave ridging rides across the region through the weekend. A second cutoff low then transits the Tennessee Valley for the start of the new week before sliding out into the Atlantic by late Tuesday. Final wave of low pressure pushes into the Mississipi Valley and lower Ohio Valley region by the end of the forecast period. At the surface, a frontal boundary will be all but through eastern Kentucky by Friday morning. Wrap around moisture from the exiting system will allow for some lingering instability showers Friday which will taper off to very light rain and/or drizzle by Friday night. We do lose dendritic support which would suggest drizzle through this time frame. But boundary layer moisture is so deep that any lingering precipitation may effectively seem more like very light rain. Thus left any mention of drizzle out for this cycle. The remainder of the weekend looks dry with seasonably warm temperatures. Rain overspreads the area again from the west-southwest late Sunday night and Monday as the second storm system of the extended period pushes through the Commonwealth. Some marginal, mainly elevated instability will keep the threat of thunder in the forecast Monday into Monday night. Decent southeast winds associated with this second system may eat away at potential rainfall totals given downsloping effects. Consequently model QPF may be a bit overdone across our southeast. Once again wrap around moisture from this system may keep a chance of showers going into mid week, at least until another system manages to work its way into the Ohio Valley at the very end of the period, or possibly just beyond bringing another round of rain showers and thunderstorms to the area.
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&& .AVIATION...(For the 06Z TAFS through 06Z Thursday night) ISSUED AT 145 AM EDT THU MAR 30 2017 VFR conditions will prevail through the TAF forecast period. Some mid/high level clouds will be drifting across the area through Thursday evening. Showers and storm chances will increase Thursday evening, but the bulk of the activity will likely hold off until the very tail end of the forecast period, closer to 06z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KAS LONG TERM...KAS/RAY AVIATION...KAS

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