NWS Wilmington, OH Office (ILN)


Area Forecast Discussion/SKEW-T

          FXUS61 KILN 221745
          AFDILN
          
          AREA FORECAST DISCUSSION
          National Weather Service Wilmington OH
          1245 PM EST Sat Feb 22 2020
          
          .SYNOPSIS...
          High pressure will keep dry conditions across the area through
          the weekend with warmer temperatures. Rain will spread into the
          area late Sunday night and continue into Tuesday as low
          pressure approaches and then move across the region.
          
          &&
          
          .NEAR TERM /UNTIL 6 PM THIS EVENING/...
          A very dry airmass remains in place with just a bit of thin
          cirrus floating across the area. In fact, 12Z KILN sounding
          indicated a 0.05 PWAT value, which is close to the lowest PWAT
          values ever measured during the month of February between the
          Dayton and Wilmington upper air sites (since 1958).
          
          Southwest winds, occasionally gusty across the northern zones,
          will allow for temperatures to warm back above normal. All
          locations are expected to warm into the 40s with an isolated 50
          degree temperature possible across the southern zones.
          
          &&
          
          .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
          Surface high centered southeast of the area will move further
          away, but dry air will still remain in place. Some high clouds
          will start spreading into the area by Sunday well in advance of
          the next system. Lows tonight will be near normal while highs on
          Sunday will be about 5 degrees warmer than today.
          
          &&
          
          .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
          On Sunday night, an expansive area of surface high pressure will
          finally be moving off the southeastern coast, as the weather pattern
          begins to get more active across the CONUS heading into the new
          week. Attention will turn well upstream, where surface low pressure
          and a mid-level trough will be moving east across Oklahoma. As the
          trough continues moving east on Monday, it is expected to weaken /
          dampen as it speeds east-northeast into the Ohio Valley. The surface
          low is also expected to remain somewhat weak as it moves through the
          region. Nonetheless, in association with moisture advecting into the
          area on southerly flow, this system will spread precipitation across
          the Ohio Valley -- beginning late Sunday evening and continuing into
          Monday. Overall model agreement (and thus forecast confidence) is
          good with regard to the system overall, but specifics on the surface
          low track/intensity and speed of the trough are of slightly lower
          confidence. This primarily manifests itself in some timing
          differences, but it is a near certainty that everywhere in the ILN
          CWA will get a decent period of rain from this system. Precipitation
          will primarily be rain, though a brief mix with snow may be possible
          in the northern sections of the forecast area early Monday morning.
          Although warm advection will be occurring on Monday, the rainy
          conditions will keep temperatures in the 40s -- cooler than on
          Sunday.
          
          After the low moves through, precipitation is generally expected to
          lessen considerably by Tuesday morning, with a dry period expected
          for at least the southern half of the CWA on Tuesday. That will also
          allow Tuesday to be the warmest day of the extended forecast, with
          warmer/drier conditions briefly moving into the area on the south
          side of the low. After some non-diurnal conditions Monday night
          (steady or rising temperatures) conditions on Tuesday will range
          from the upper 40s to upper 50s.
          
          As the low moves further away late Tuesday into Tuesday night, a
          cold front will move through the region, and cold advection will
          begin -- and persist through essentially the remainder of the
          extended forecast period. Behind the initial trough -- which
          essentially disappears into the flow -- another amplifying trough
          will develop over the central CONUS and rotate east / southeast into
          the Great Lakes and Ohio Valley on Wednesday. Model agreement is
          actually fairly strong with this system, though ultimately this
          large trough will be moving slowly, so shortwave details may end up
          determining where and when precipitation is heaviest. With the
          continued cold advection, temperatures will eventually get cold
          enough to support some snow mixing in, though there are no signs
          pointing to much in the way of accumulation at this point. Finally,
          depending on the strength of an expected surface low moving
          northeast through the region in this part of the forecast, some
          strong winds could occur -- especially on Thursday. This may be a
          factor to monitor as this part of the forecast gets closer to the
          present.
          
          To end the week, models are not in particularly strong agreement
          with regards to how quickly the upper trough will move out of the
          area, which will obviously have a role in both PoPs and temperatures
          on Friday. This part of the forecast remains low confidence.
          
          &&
          
          .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
          Surface high pressure over the southern States will move to a
          position near or off the southeast U.S. coast by the end of the
          TAF period.
          
          Skies will remain clear through most of tonight with only FEW-
          SCT mid clouds moving into the region toward 12Z. FEW-SCT mid
          clouds and gradually increasing high clouds will occur on
          Sunday.
          
          Southerly winds, locally gusty, will settle down this evening.
          Southerly flow will increase again on Sunday due to diurnal
          heating with gusts of 18 to 22 knots possible.
          
          OUTLOOK...MVFR ceilings may develop late Sunday night. MVFR to
          IFR ceilings and visibilities likely Monday into Tuesday. MVFR
          ceilings and visibilities may then persist into Wednesday.
          
          &&
          
          .ILN WATCHES/WARNINGS/ADVISORIES...
          OH...None.
          KY...None.
          IN...None.
          
          &&
          
          $$
          SYNOPSIS...
          NEAR TERM...Hickman
          SHORT TERM...
          LONG TERM...Hatzos
          AVIATION...Hickman
          
          
Skew-T

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