Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 090536 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 1236 AM EST Tue Mar 9 2021 .SYNOPSIS... Exiting high pressure will give way to southerly flow over the Ohio Valley through at least Thursday. Dry air will gradually be worked in with some moisture through this time, then rain Thursday night and Friday will accompany a cold front as it crosses south of the Ohio River. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Some mid clouds may pass across the northern part of the forecast area overnight. Otherwise just more (mostly thin) cirrus. The center of the high is far enough away that some southerly winds will persist through the night, except in far southeast counties. Winds have gone light there which is also reflected in their temperatures being colder. Given trends, have dropped lows a bit in that area. Elsewhere, lows look reasonable. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Weak ridge aloft moves east fairly quickly during the day, although the tightening of any surface gradient will likely not be enough to create the potential for winds greater than 10 mph, and certainly inhibit any gusts. Thicker cirrus will also inhibit boundary layer warming, but the southwest flow at the surface will naturally bring in warmer air with readings 2-4 degrees warmer than what is seen over the region today. Highs will be more uniform around 64-65. Overnight lows will be even milder as the southwest winds maintain themselves at least somewhat - looking for 40-45 with the warmest readings in the northwest as cloud cover increases from w-e overnight, also aiding the inhibition of temperature drops. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Fairly shallow upper level ridge will slowly sink south as a broad but slowly deepening trough over the western CONUS approaches the region and the ridge sinks toward the SE CONUS. Overall southwest flow and tightening pressure gradient over the area as the trough amplifies will allow for increasing high clouds on Wednesday, as well as winds gusting to near 25-30mph along with much above normal temperatures in the mid to upper 60s. With lingering dry lower levels of the atmosphere in place, as well as a slowing of the overall progression of the trough, onset of precipitation has slowed a bit as deterministic GFS/ECMWF models struggle to resolve the slow down and both GEFS and ECME members are slowing the amplification of the trough as it eventually transitions to a cut off low over the SW CONUS. For Thursday, a boundary from the upper Mississippi Valley into the Great Lakes will slowly sink south above the retreating upper ridge, bringing a chance for showers on Thursday. Still some uncertainty as to how far south the boundary will advance, so have only brought in slight chances in the southeast with drier air to overcome and still closer to the retreating ridge. High temperatures on Thursday someone uncertain but best chance for upper 60s in the far south and southeast where precipitation less likely. The boundary will sink through the area Thursday night into Friday, bringing a likelihood of more widespread rain. Still uncertain as to just how far south the boundary will sink through the southern forecast area on Friday, as it depends on the energy ejecting eastward from the cutoff low over the SW CONUS, and the progression of the more shallow and quickly moving upper low and shortwave advancing through the Great Lakes. Still too much uncertainty to hone in on precipitation chances and timing, so kept with chance for precipitation focused especially in southern Ohio/SE Indiana/Northern Kentucky through the weekend. More seasonable temperatures take over for the weekend and into early next week, with highs in the mid 40s to mid 50s depending on boundary positioning, with lows in the lower to mid 30s. There is some uncertainty with how far south of our area the front will make it on Friday and then where it will lay out to our south heading into the weekend. As the the western upper level low and mid level energy eject eastward across the southern Plains through the weekend, the boundary may begin to lift back north toward our area. Given the uncertainty, will hang on to chance pops through the rest of the long term period, keeping the highest pops across our south. Will range highs on Friday from the upper 50s in the northwest to the low/mid 60s in our south. Cooler temperatures will then settle into the region through the weekend with highs by Sunday back into the the mid 40s to lower 50s. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... We can be certain that VFR will persist under high pressure and a very dry airmass. Winds staying from the southwest may gust close to 20 knots at DAY, with lower velocities at other sites. Sky cover will continue to consist of altocumulus and cirrus clouds arriving on a westerly flow aloft. OUTLOOK...Wind gusts up to 30 kt possible on Wednesday and up to 35 kt on Thursday. MVFR ceilings and visibilities possible from Thursday afternoon into Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Franks NEAR TERM... SHORT TERM...Franks LONG TERM...JDR AVIATION...Coniglio

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