Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 261526
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1026 AM EST Sun Feb 26 2017

.SYNOPSIS...
High pressure will push quickly east across the region today
resulting in dry conditions and seasonable temperatures. A fast
moving upper level disturbance will bring the chance for some
rain showers late tonight and into the day on Monday. A warm
front will lift north across the area on Tuesday, leading to
warmer temperatures and a continued chance for showers. More
widespread rain showers will overspread the Ohio Valley region
Tuesday night into Wednesday as a cold front sags slowly
southeast through mid week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Lower clouds pulling east of forecast area with plenty of sun
for today along with beginning warm air advection with surface
high passing across the southern forecast area, surface winds
have already pulled around to southerly at this time for all but
the eastern forecast area. With southerly flow already
beginning, have slightly adjusted temperatures to moderate a
little more further into the forecast area into the mid 40s to
upper 40s far south.


&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
High pressure will push off to the east tonight and this will
allow for increasing southwesterly flow overnight and into
Monday morning. A weak mid level short wave will push quickly
east across the area Monday morning but there is quite a bit of
model differences in pcpn coverage among the 00Z models. The
00Z ECMWF is the most aggressive and will lean a bit more this
way as there is a 30-40 knot 850 jet nosing up into the mid Ohio
Valley by mid Monday morning. As the short wave moves off to
the east and the low level jet begins to weaken and also shift
east, will taper off pops heading through the afternoon. Lows
tonight will be in the mid 30s so suppose there could be a
chance for a brief mix with snow depending on just how fast any
pcpn develops later tonight. However, thermal fields on both the
NAM and GFS soundings support primarily liquid pcpn later
tonight and into Monday morning, so have kept pcpn all rain.
Highs on Monday will range from the upper 40s north to the mid
50s south.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Monday night will start off dry as a shortwave exits the region and
surface high pressure moves east out into the Atlantic ocean. At the
same an upper level trough axis will be located over the western
United States with a series of upper level disturbances ejecting
east out ahead of the trough axis. One of these disturbances will
then move over the area early Tuesday morning pulling a warm front
through the CWA. As this happens widespread overrunning will
commence. Looking at GFS potential temperature surfaces the lowest
condensation pressure deficits are forecasted to occur near the OH/
MI border. Due to this think the FA will likely see rain but higher
totals will be north. GFS forecast soundings for Tuesday morning
also don`t completely saturate which also helps to undermine
confidence.

Tuesday afternoon through Wednesday the pattern will turn more
active as an upper level disturbance will eject east Tuesday morning
allowing surface cyclogenesis to occur over the plains. The surface
low will then track northeast Tuesday afternoon towards southern WI.
As this occurs forecast soundings begin to destabilize across our
southwest. Into Tuesday evening forecast soundings destabilize
across the entire region. Looking more closely at GFS/ NAM/ ECMWF
forecast soundings does show a weak CAP in place but this looks
questionable given weak shortwaves traversing the area. Also on the
forecast soundings is a great deal of shear. SFC - 1 km shear is
averaging around 30 kts with SFC - 3 km SRH around 450 m2/s2. MU
CAPE values also are mostly around 700 J/kg. Better upper level
support does appear to be down south towards Arkansas though (at
least for Tuesday afternoon). Given the above SPC has the OH valley
in a slight risk for day 3.

Tuesday night into Wednesday morning a potent jet streak that was
over Arkansas/ Missouri will push northeast bringing ILN into a RRQ.
Also Tuesday evening another upper level disturbance will rotate
around the upper level trough axis that was centered over the
Mountain West and head northeast. As this occurs another surface low
will form along a stalled front that will run from Texas into Iowa.
As the second surface low pressure forms Tuesday afternoon it will
ride northeast along the baroclinic zone with the upper level
disturbance helping to progress the upper level trough axis east. By
Wednesday morning the second surface low will be in Illinois/
Indiana along with the surface cold front. At the same time
Wednesday morning the upper level jet will begin to split over
Kentucky. PWATs across the CWA are forecasted to be around 1.30" (or
97th percentile according to the NAEFS). It should be noted that at
this time a subtropical ridge will be anchored east of Bermuda with
strong low level southwesterly flow through the region. This flow
will originate from the Gulf of Mexico with the NAEFS indicating WV
transport approaching the 99th percentile. Further evidence of
strong moisture transport can be found in 850 mb winds averaging
around 50 kts (97th percentile for this time of year). Given the
strong upper level lift, stalled boundary, surface low, anomalously
high PWATS and moisture transport have kept categorical PoPs from
Wednesday morning through the day. WPC has also included the area in
a day 3 marginal for excessive rainfall. Wednesday evening the cold
front will finally start to move east and clear the CWA Wednesday
night. Drier air will work into the area Thursday morning but with
lapse rates steepening across the region can`t completely rule out
the chance of some light snow (esp across the north).

Thursday night the upper level disturbance that brought showers and
thunderstorms to the area on Wednesday will wrap up over
southeastern Canada with another upper level disturbance heading
southeast from Alberta. The track of this clipper is in general
agreement but minor differences between the ECMWF/ GFS/ CMC equate
to differences in QPF. The ECMWF and GFS have snow forming across
our northern zones and more towards northern Ohio while the CMC is
further south. Any precipitation that does form will likely be snow.
Friday into Saturday the upper level trough axis will head east
allowing high pressure to spill southwards across the eastern United
States. Sunday, surface high pressure will be centered across the
southeast United States as an upper level disturbance heads east
across Michigan.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
An area of MVFR to low VFR cigs is lingering across northeast
portions of our fa this morning. It does look like it is
beginning to erode away from the west and expect this to
continue over the next few hours as the low level flow starts to
back. Will go ahead and hang on to an hour or so of MVFR cigs
at KCMH and KLCK to start off the tafs. Otherwise, expect VFR
conditions today into this evening as high pressure pushes east
across the Tennessee Valley. Increasing southwesterly flow and
developing isentropic lift will lead to some mid and eventually
lower VFR clouds later tonight and into Monday morning. This
will also likely lead to some light shower development from the
southwest toward the end of the taf period.

OUTLOOK...MVFR ceilings and visibilities possible Tuesday into
Wednesday along with a chance of thunderstorms. MVFR ceilings
and visibilities along with wind gusts to 30 kts will be
possible on Thursday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...JGL
NEAR TERM...JDR
SHORT TERM...JGL
LONG TERM...Haines
AVIATION...JGL



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