Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 271729
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
129 PM EDT Fri May 27 2022

.SYNOPSIS...
Issued at 808 AM EDT Fri May 27 2022

Scattered showers and isolated thunderstorms are expected today
into this evening. Warm and mainly dry conditions will follow
this weekend into early next week.

&&

.SHORT TERM...(Today and Tonight)
Issued at 355 AM EDT Fri May 27 2022

Shower coverage today and timing of PoPs will continue to be the
main forecast challenge for the near term.

A lull in the showers has developed early this morning across most
of the forecast area with dominant regional area of rain showers
taking shape from southeast Wisconsin into west central Illinois in
association with deformation forcing to the north of the mid level
height minimum across southern Illinois. Water vapor imagery early
this morning depicts a stronger vort lobe rotating through the base
of the upper low which appears to be enhancing some renewed shower
development across southern Indiana over past hour or two. Through
mid morning, expecting deformation forcing area across northern
Illinois to slowly shift eastward into NW Indiana/SW Lower Michigan,
with a secondary area of higher PoPs across southern/southeast
portions of the area as the stronger vort lobe works northeast.
Overall have not made drastic changes from inherited PoPs with the
most widespread rain shower activity in association with the
deformation forcing across the northwest portions of the forecast
area.

Instability magnitudes will be even more marginal today due to
low level/near sfc cooling in comparison to past few days. These
cooler low level temps coupled with weak mid level lapse rates
should only yield surface based CAPEs on the order of 500 J/kg
this afternoon. Deep layer shear profiles also become more
marginal with 0-6km shear magnitudes only on the order of 20 knots
east of the sfc trough axis. Thus given environment today, severe
weather is not expected. Some low end concern for minor ponding
could accompany the deformation axis as it shifts across northeast
Indiana/south central Lower Michigan given heavier rainfall
amounts over the past few days. However, with upper low becoming
slightly more progressive this afternoon would expect any ponding
issues to be confined to any potential smaller convective cores
embedded in the deformation forcing area which is of very low
confidence.

Otherwise for today, some patchy morning fog is possible over
southern Lake Michigan and immediate lakeshore areas for a time
through early to mid morning as sfc reflection tracks across
northwest Indiana. Hourly temps today should exhibit a non-diurnal
steady/slowly falling trend across the west/northwest given track of
sfc reflection.

Lingering rain showers east of I-69 corridor this evening should
shift off to the east with decreasing cloud trend from west to
east tonight.

&&

.LONG TERM...(Saturday through Thursday)
Issued at 355 AM EDT Fri May 27 2022

Mainly dry conditions will characterize most of the long term with
just a few periods of rain chances.  The big story for the long term
will be the sharp warming trend that will begin on Saturday, and
culminate for Tue-Wed.

A low amplitude, long wave ridge will build across central CONUS
on Saturday as pesky upper low of past few days departs to the
east and a longwave trough begins to deepen across western CONUS.
West-southwest mid-upper level flow trajectories late Saturday
will allow elevated mixed layer to advect across the southern
Great Lakes region Saturday night as a weak short wave trough
tracks across the western Great Lakes. This elevated mixed layer
will effectively cap more shallow rooted instability Saturday
night, but there could be just enough elevated moisture to realize
some of the steeper mid level lapse rates aloft for an isolated
shower/storm chance across far northern Indiana/southern lower
Michigan. Given high based nature of parcel origination in this
setup, confidence is low in PoPs and will keep mention at slight
chance.

Mid/upper level ridge from the upper Great Lakes to the Mid Atlantic
states will amplify into Sunday allowing for a sharper warming trend
which will continue into Monday and Tuesday. It still appears
highs could be well into the 85 to 90 degree range by Tuesday and
Wednesday. Expansive low level ridging across southeast CONUS
should limit extent of near sfc moisture for early next week that
should keep dew points in check in the mid 60s. This should
prevent any significant heat index concerns for Tue-Wed.

By Wednesday, medium range guidance continues to hint at another
cold front passage possible, but local area may only be grazed by
stronger upper height falls as stronger forcing lifts across south
central Ontario. A few stronger storms could be possible midweek
with the cold front passage but much of this will depend on timing
of the front. This setup may be one where stronger shear is
limited to post-frontal environment which could also tend to
discourage better convective organization. Will maintain highest
PoPs Wednesday, but broadbrush chances were maintained into
Thursday with some guidance indicating potential fast moving
eastern Pacific waves holding up the front a bit during this
period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 129 PM EDT Fri May 27 2022

The upper low is shifting across Indiana this aftn will be east
of the terminal sites tonight. As the low pulls away showers will
come to an end this evening. Cigs have been IFR at KSBN most of
the day and will slowly improve to MVFR around 22Z and VFR
tonight around 06Z. KFWA should be mainly MVFR cigs through the
fcst period. Winds will be NW at KSBN for the duration while
turning from SW to NW this evening at KFWA.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement through late tonight for INZ003.

MI...Beach Hazards Statement through late tonight for MIZ077.

OH...NONE.
LM...Small Craft Advisory until 5 AM EDT Saturday for LMZ043-046.

&&

$$

SYNOPSIS...Steinwedel
SHORT TERM...Marsili
LONG TERM...Marsili
AVIATION...MF


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