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000
FXUS61 KILN 072059
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
359 PM EST Sun Mar 7 2021

.SYNOPSIS...
Surface high pressure will track southeast of the region
tonight. Winds will then become southerly and mark a warming
trend for the week, culminating in breezy conditions with
increased clouds that spread across the area Wed and Thurs.
This is in advance of a frontal system that will pass through
and bring a good shot of rain late Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Generally clear skies with a few passing cirrus clouds this
evening will be found as high pressure settles over the region.
This high will move southeast overnight and a return to
southerly flow will begin to bring in warmer air versus the past
few days of cold advection on northerly flow.

Lows will dip into the mid 20s for one more night in the east,
but western portions of the CWA will only drop to around 30.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Generally sunny skies will be found again, as high temperatures
rise to the 60-65 degree range, warmest in the northwest where
slightly stronger winds will bring in warmer air.

Winds will lighten overnight, but remain southerly and help keep
temperatures from dropping below freezing for the first time
this month. Lows will range from the lower 40s in the northwest
to the mid and upper 30s in the southeast.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY NIGHT/...
The long term period will feature somewhat of a dichotomy of a
forecast across the region, with the first several days
featuring tranquil weather, warm temperatures and not much (if
any) in the way of pcpn while the end of the workweek into this
weekend will be much more unsettled and cooler.

Broad surface high pressure centered to the southeast of the Ohio
Valley will position the region in broad southwesterly flow at the
surface, and to a lesser extent, aloft as well. A quick-moving
mid/upper level S/W will bring some cloud cover to the area on
Tuesday, but no rain is expected. However, it may end up being more
partly sunny than mostly sunny as this disturbance moves east
through the region during the daytime period. And despite the
increased cloud cover Tuesday, still expect highs to reach into the
60s just about everywhere. Recent NBM guidance has been going much
too cool on daytime highs, likely influenced at least somewhat by
the cooler-than-normal conditions over the past 60-day BC training
period. Either way, decided to trend more toward the 75th percentile
NBM maxT for both Tuesday and Wednesday, despite the anticipation
for some cloud cover on both days.

The warmer temps on Wednesday will be aided at least somewhat by the
fact that a slightly tighter pressure gradient will be positioned in
the Ohio Valley by midweek, with indications for favorable diurnal
mixing Wednesday and even again on Thursday. This will be in spite
of some moisture advection NE into the region, courtesy of the
stiffer southwesterly LL flow that will become established. Will see
SW winds of 15-20 MPH with gusts to 30 MPH Wednesday with highs
generally in the mid/upper 60s. If the pcpn can hold off through the
daytime on Thursday, the tightened pressure gradient and favorable
mixing in the open pre-frontal warm sector would suggest gusts to 35-
40 MPH are possible Thursday late morning/afternoon/early evening.
Will begin to highlight this wind potential in the HWO.

By Thursday, with expansive mid/upper level ridging centered over
the Gulf and a digging mid/upper level low west of the Four Corners
region, broad southwesterly flow aloft will become established
near/east of the mid-Mississippi River Valley, with the general trof
axis stretching from the upper Midwest to California. At the
surface, an area of low pressure will race from the upper midwest to
north of the Great Lakes, leaving in its wake a trailing cold front
which will slowly progress southeast through the region Thursday
into Thursday night. High confidence remains in widespread rain
impacting the ILN FA Thursday night into Friday morning. Past this
juncture, the solutions begin to diverge and the uncertainty in the
evolution of the pattern increases rather substantially as we
progress into next weekend.

The divergence in longer-range model solutions stems from , in part,
the difference in the handling of how fast to eject the mid/upper
level low over the Four Corners region east into the plains and
eventually MS/OH Rvr Valleys. The ECWMF and CMC continue to show
solutions suggesting the mid/upper level low cutting off from the
main flow, allowing it to meander about the Four Corners region
through the weekend. Meanwhile, the GFS brings this feature east
much quicker, which would enable the attendant lee-side low to
develop faster and would stunt the southward progression of the
front through the OH/TN Valleys to a much greater extent. The faster
ejection of the mid/upper level low into the central plains would
certainly spell a wetter scenario for the Ohio Valley as it would
not allow the front to clear the OH Vly for the entire stretch of
Thursday night through Sunday night. Meanwhile, the CMC and ECMWF
continue to show the ILN FA getting in the post-frontal environment
Saturday/Sunday (due to the digging nature of the S/W energy into
the interior NE US Saturday) before ultimately rain chances increase
again on Monday with the delayed arrival of the "Four Corners"
system.

With all of this being said, it does seem like there is a subtle
trend by the CMC/ECMWF to show a solution slightly more in-line with
what the GFS has been showing, which also would indicate a shorter
"dry" stretch between the sagging front on Thursday/Friday/Friday
night and the system due to arrive Sunday/Sunday night/Monday. Still
quite a bit to be ironed out with the evolution of the pattern late
week. However, confidence remains high in widespread rain Thursday
night into Friday, potentially lingering Friday night closer to the
Ohio River as a weak surface impulse translates along the
stalling/increasingly zonal-oriented baroclinic zone. Cooler temps
will evolve Friday into Saturday with ample clouds, some
precipitation, and the potential to be in a post-frontal
environment.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
VFR conditions will persist with some cirrus spilling into the
region from the west on Monday. Northerly winds under 10kt this
afternoon will quickly die down or go calm as they change
direction to southerly for Monday. South-southwest winds will
see speeds increase in the late morning to over 10kt.

OUTLOOK...Wind gusts up to 30 kt possible on Wednesday. MVFR
ceilings and visibilities possible on Thursday and Friday.

&&

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

&&

$$
SYNOPSIS...Franks
NEAR TERM...Franks
SHORT TERM...Franks
LONG TERM...KC
AVIATION...Franks
FIRE WEATHER...