Area Forecast Discussion
Issued by NWS Wilmington, OH

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384 FXUS61 KILN 211725 AFDILN Area Forecast Discussion National Weather Service Wilmington OH Issued by National Weather Service Jackson KY 1225 PM EST Sat Jan 21 2017 .SYNOPSIS... Temperatures will remain well above normal today into Sunday as warm southerly flow persists across the region. A developing upper level low pressure system will move across the southeastern United States Sunday into Monday, bringing an increasing chance of rain to the area. This will also be accompanied by somewhat cooler temperatures for the start of the work week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Mid and high level clouds continue to overspread the area, with a bit more thickening in the south-southeast. Temperatures are responding nicely to southerly flow, particularly in the south. Radar mosaic does show some very light echos moving northeast across our southeastern zones, but expectations are that nothing is reaching the ground. HRRR has consistently suggested the potential for some isold shower activity across our southeast later this afternoon and based on current trends this seems reasonable as there is an occasional uptick in intensity with those radar echoes. Did expand our forecasted slight pop just a bit further northwest based on recent runs and trends in the HRRR. Inherited temperatures from previous shift looked very good. Thus afternoon highs in the low to mid 60s appear on target. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... Quite a bit of uncertainty arises in the forecast tonight into Sunday as the models continue to struggle with exactly how to handle the developing upper level low that will move from the Southern Plains to the East Coast through the rest of the weekend. There are then additional uncertainties with the timing and placement of mid level energy rotating around the upper low. The 00Z NAM seems to be somewhat of an outlier with an elongated upper low extending up toward the southern Great Lakes by Sunday night. Meanwhile the 00Z ECMWF and CMC are farther south than the 00Z GFS with the track of the upper low across the southeastern United States through the day on Sunday. The ECMWF is pretty much keeping our area dry through the day on Sunday while the remaining models are spreading a pretty good slug of moisture up across our area. This seems to be backed up by the NCAR ensemble forecast with most of its members spreading precipitation up into our area through the day on Sunday. Will therefore go ahead and trend that way and have high chance to likely pops developing across our area. Some instabilities will also spread up into our area through the day on Sunday so will go ahead and allow for at least a chance of thunder across our southern areas for mainly Sunday afternoon. Temperatures on Sunday will again be mild with highs in the upper 50s to around 60 degrees. Additional uncertainties arise for Sunday night into Monday as the upper low pivots up across the mid Atlantic States. All of the models are in pretty good agreement that there will be a pretty heavy swath of precipitation somewhere along the pivot point with the general consensus that this will primarily be southeast of our FA. That being said, a few of the GEFS members are showing 1.5 to 2 inches of rain across parts of our southeast Sunday night into Monday and the parallel run of the GFS is actually cranking out over three inches of rain at PMH. Based on all of the timing and placement issues, there is quite of bit of uncertainty here, but will go ahead and include a mention of some heavy rain in our HWO product for our southeast. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Cooler conditions will continue into Tuesday as clouds remain in place, with low-level winds beginning to shift to the west, and eventually the southwest. A narrow ridge will move east through the area on Tuesday night into Wednesday, shifting the pattern firmly to warm advection for a relatively short period of time. It is at this point in the forecast that confidence in specifics becomes poorer, with increasing spread between the timing and magnitude of features between GEFS members and between the 12Z GFS / 12Z ECMWF. However, there is high confidence in the general pattern, with a surface low and upper trough moving through the Great Lakes. This will allow a cold front to move east through the Ohio Valley at some point on Wednesday, though limited moisture will limit the chances for precipitation. Ahead of the front, the pressure gradient will increase, and some slightly gusty conditions may occur -- along with temperatures well above normal. Max temps were increased for Wednesday, slightly above the model consensus. Behind the front, cooler conditions through the end of the week. There is a very large amount of spread in the timing of additional precipitation chances on Thursday and Friday, as a general pattern of broad troughing moves over the Great Lakes and Ohio Valley through the end of the week. Temperatures during the low end of the diurnal cycle may be cool enough to support some snow, depending on when precipitation occurs. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Expecting generally VFR conditions for area terminals through the bulk of the first 18 to 24 hours of the TAF period. However, light rain and lower CIGS will overspread much of the area from the south through the day Sunday. Initial disturbance moving across the deep south is responsible for the mid and high level cloudiness over the area. There are some very light echoes showing up on the radar mosaic and models do suggest the potential for some isold shower activity generally southeast of a line from CVG to CMH this afternoon and across our north later tonight. Consequently there should be some areas of virga across our southeast at a minimum along with the possibility of some isold shower activity. Fairly confident that CVG, LUK, DAY will remain precipitation free this afternoon. However, will include mention of some showers in the vicinity of ILN, CMH, and LCK. Shower activity may continue to affect portions of the forecast area tonight, but generally across the north. A more significant storm system and surface low pressure center will ride up into the lower Ohio Valley and Tennessee Valley region Sunday. With decent model agreement in details of sensible weather, confidence is increasing that rain will rotate northward across the area through the day Sunday, affecting CVG/LUK by mid morning and our more northern terminals by early afternoon. Aforementioned storm system moving through the area Sunday night and Monday will keep our weather unsettled. There appears to be a lull in the weather Tuesday and Tuesday night. Then a cold frontal boundary will bring showers back into the area by Wednesday. OUTLOOK...MVFR/IFR ceilings and visibilities possible Sunday through Monday, then again Wednesday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...Ray SHORT TERM...JGL LONG TERM...Hatzos AVIATION...Ray

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