Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 211118 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 618 AM 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/... We have seen some patchy dense fog develop this morning, mainly in areas that were able to clear off for a period overnight. With the combination of some occasional stratocumulus and some additional high level cloudiness moving in overhead, the fog has been somewhat transient so think this will help limit more widespread dense fog development through daybreak. Broad southwesterly flow will continue across the region through this afternoon. This will lead to some continued weak isentropic lift through the day. Moisture is fairly limited through much of the day but does begin to increase a bit later this afternoon, primarily across our southeast. Will try to keep the majority of our FA dry today and just introduce some slight chance pops late in the day across our far southeast. Another mild day is in store for us with highs mainly in the low to mid 60s. && .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 /11Z SATURDAY THROUGH WEDNESDAY/... Most TAF sites VFR this morning besides KLUK. There was some initial fog/ visibility restrictions this morning but widespread mid and upper level clouds has helped to bring the visibilities back up. This afternoon an upper level low over Iowa will rotate northeast keeping southerly winds across the TAF sites. At the same time an upper level disturbance will eject northeast out of Tennessee. Models have struggled on where exactly this upper level disturbance will eject and therefore exactly where the precipitation will setup. Latest set of model runs support the upper level energy ejecting southeast of the terminals. High res models also in general show precipitation remaining southeast of the terminals. NAM forecasts soundings continue to advertise instability this afternoon with the HRRR also showing precipitation making it into the terminals. Taking a closer look at the NAM forecast soundings shows not much moisture in the low levels though. Overall, confidence has grown that the terminals will likely remain precipitation free this afternoon and have kept TAFs dry. Saturday night into Sunday morning an upper level low across Texas/ Oklahoma will push east allowing cigs to slowly lower Sunday morning towards MVFR. OUTLOOK...MVFR/IFR ceilings possible Sunday into Wednesday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...JGL SHORT TERM...JGL LONG TERM...Hatzos AVIATION...Haines

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