Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 181141
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
641 AM EST Wed Jan 18 2017

.SYNOPSIS...
High pressure and drier air will move in from the southwest
today. Low pressure traveling to the Great Lakes will bring
showers back into the forecast late Thursday into Friday. Mild and
mainly dry weather is expected Saturday in the southerly flow
behind the low.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Cold front is to the east, pushed by a closed 5520 meter 500 mb
low. Drizzle occurring in persistent low level moisture will diminish
by mid morning as the upper low and associated forcing depart
east. This will leave cloudy skies through early afternoon, with
some breaks possibly showing up later as high pressure moves to
near Evansville.

Temperatures rising to the lower 40s will be limited by the weak
insolation and cold advection on a west wind.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
High pressure moving across Kentucky to West Virginia should keep
dry weather over the ILN area tonight through early Thursday.
Skies will probably remain partly to mostly cloudy with low level
moisture persisting under an inversion around the periphery of
the high.

Low pressure developing to the west on Thursday will move up the
flank of an upper ridge to the vicinity of Chicago by Friday
morning. A stream of moisture carried by a 35 knot low level jet
will be lifted on the warm conveyor belt ahead of the low,
producing widespread rain. Models indicate around a half an inch
of rainfall with this event.

The rain will end Friday morning as the low weakens and redevelops
over the northern plains. A relatively dry southerly flow in the
wake of the low, coupled with above normal geopotential heights
and weak forcing aloft, should result in dry weather conditions
Friday afternoon.

Temperatures will exhibit an upward trend in this warm advection
regime, with highs mainly in the lower 50s Thursday, increasing to
the mid and upper 50s Friday. These anomalously high temperatures
will be occurring when normal highs are in the mid and upper 30s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
In the wake of Fridays closed low there will be a brief period of
subsidence on the backside of the PV, but the main question is how
quickly will the precipitation return. Overall ridging begins to
setup across eastern Canada and the northeastern United States
with an upper level trough over the western United States. The
pattern will be messy though as multiple waves of mid-level energy
can be found in the flow. The GFS is slightly further east with an
upper level low pushing north on the western side of the mid-level
ridge. As this occurs the ridge will slowly start to move east.
The GFS is slightly stronger with this low Saturday and tries to
bring in precip to the area Saturday afternoon across the western
zones. The CMC looks similar to the GFS while the ECMWF is
slightly weaker with the energy Saturday. Looking at forecast
soundings on the GFS for Saturday shows dry air between 850 and
700 mb which would favor a later onset of precipitation. Given the
above have trended the forecast towards the ECMWF solution and
kept Saturday drier.

Sunday, another stronger piece of energy will push east across the
southern United States and wrap up into an upper level low. As this
happens a wedge of PV will push northeast ahead of the low and move
across the ILN forecast area. PWATs at this time again rise to
around 1.00". Forecast soundings on the GFS show some dry air trying
to remain in various levels of the sounding at this time so have
kept PoPs at chance. Seeing how strong the upper level lift
currently looks on the ECMWF and GFS Sunday, PoPs will probably have
to be raised. Sunday into Monday the upper level low will drift
overhead keeping the clouds and a chance of rain in the forecast. It
should be noted that the low looks to be vertically stacked with dry
air entrained. This means that a break in the precip will probably
occur sometime on Monday (possibly in the morning) but given this is
day 7 have just broad brushed the PoPs at this time. On Tuesday the
upper level low will slowly drift east taking the rain and
precipitation with it.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Mid level shortwave evident on water vapor imagery, rotating
through the eastern Great Lakes. Shallow low level moisture
led to areas of drizzle along with some rain showers overnight.
As this s/w shifts east precipitation will come to an end early
this morning. Low clouds will persist though late morning when
IFR CIGS are expected to improve to MVFR.

MVFR cigs will persist through much of the day with some gradual
improvement possible from the southwest this evening as the low
level flow begins to back. Expect an increase in high level clouds
late tonight ahead of the next weather system.

West winds around 10 kts will persist through the day and then
back southwest at less than 10 kts tonight.

OUTLOOK...MVFR/IFR ceilings possible into Thursday. MVFR/ IFR
ceilings are again possible Thursday night into Sunday.

&&

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

&&

$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio
SHORT TERM...Coniglio
LONG TERM...Haines
AVIATION...AR


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