FXUS63 KIWX 271041

Area Forecast Discussion
National Weather Service Northern Indiana
640 AM EDT Sat May 27 2017

Issued at 331 AM EDT Sat May 27 2017

A weak high pressure system will move across the area today
providing fair weather. A low pressure system will move northeast
across our area Sunday, likely causing a period of showers and
thunderstorms. This low is expected to intensify and become nearly
stationary over Ontario and the upper Great Lakes early next week
causing cool temperatures and a chance of showers in our area.


.SHORT TERM...(Today and Tonight)
Issued at 331 AM EDT Sat May 27 2017

Scattered showers contg across se portion of cwa along trailing
edge of MCV movg across nrn OH. This convection expected to
move out of the area by 12z. With threat of heavy rainfall
diminishing, have canceled Flash Flood Watch a few hours before
12z expiration.

Upr trof from ND-NV expected to deepen as it moves east to
a MN-KS line by Sunday morning. Fair wx expected today as
upr ridging in advance of this system moves across the cwa.
Diurnal heating should cause low cloudiness this morning
to mix out to a sct-bkn cu deck this aftn allowing for
highs mainly in the m70s.

As upr trof moves east, lee sfc low over se CO/ne NM expected to lift
ne into central IL. Forcing and moisture/instability return
along/ahead of this system's warm front may cause showers/tstms to
spread into the cwa late tonight. Maintained likely pops across the
sw portion of the cwa for late tonight tapering to slight chc ne,
though some concern pops may be overdone as bulk of high res models
suggest a QLCS will race e-se across the mid MS/lower OH valley's
overnight disrupting moisture/instability return into our area.


.LONG TERM...(Sunday through Friday)
Issued at 331 AM EDT Sat May 27 2017

Sfc low expected to lift ne across the cwa Sunday with
showers/tstms likely developing/continuing as the warm front
moves through in the morning and a second round psbl in the aftn
along the system's trailing cdfnt. Aftn pre-frontal CAPE fcst
1500-2500j/kg with 30kt unidirectional deep layer shear and
steep lapse rates suggesting an isolated damaging wind/large hail
threat but wk frontal convergence and capping are sgfnt limiting
factors. Brief heavy rain psbl with any storms Sunday but attm
appears convection will be fairly short-lived at any given
location, so not expecting it to have sgfnt hydro impacts.

Sunday's sfc low expected to lift n-nw into Ontario with a deep
vertically stacked low forming in this region Monday. This
will result in a cool Memorial Day with a chc of showers/tstms as
a wk shrtwv rotates around the upr low across the wrn Grtlks.
Similar conditions Tue as cyclonic flow and CAA conts, though
prbly cool enough by that time to keep convection sufficiently
shallow to prevent thunder.

Upr low will grdly fill and move east across se Canada Wed-Fri
with sfc high movg through our area. This should provide generally
fair wx through this timeframe, though an isolated shower psbl
with trailing wk shrtwv's movg across the area. Slow departing
upr trof should allow for a slow moderating trend for temps to close
to normal by late week.


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 640 AM EDT Sat May 27 2017

Mcv over wrn lake Erie beginning to advect some drier air swd into
srn MI and suspect given deepening subsidence will aide in mixing
cigs hgts into vfr n-s through this morning. Otherwise winds remain
blo 10kts through the pd.






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