Headlines
– Warmer temperatures this weekend into next week
– Rain will move in late Saturday and Saturday night
– A second round of rain and possibly embedded thunderstorms arrives early on Monday. Locally heavy amounts between 1 and 2 inches.
Discussion via the National Weather Service:
Much of today will be quiet across central Indiana with exiting
upper ridging. Warm advection aloft will continue to bring in
moisture, leading to thickening and lowering cloud cover during the
day.
Later this afternoon, 850mb winds ramp up and bring in lower level
moisture to the area. An approaching upper level low will
bring in broad forcing to western portions of the area by 00Z.
Isentropic lift will increase. Thus, expect the forcing and moisture
to produce rain across the western quarter to third of the area by
00Z. Will go with likely or higher PoPs there late this afternoon
with lower PoPs to the east.
Surface winds will remain southeast, so warm advection won`t be
strong. However, there will still be enough to bring temperatures
into the 40s most areas.
Tonight, the upper level low will move into central Indiana. Ahead
of it, the 50-60kt low level jet will continue to pump moisture into
the area. Good forcing will continue across the entire area as the
system moves in. Will go high PoPs all locations.
While the warm conveyor belt will get pushed east overnight tonight,
forcing from the upper low moving in will keep some rain across much
of the area through the end of the period.
Instability will be nil or very low, so odds of any elevated thunder
are too low to mention.
With the plentiful moisture with this system, rainfall amounts
between a third and three quarters of an inch will be common, with
amounts closer to an inch possible for some areas.
Clouds and rain will keep temperatures warmer, with lows in the
upper 30s into the 40s.
The long term will begin well above normal, with central Indiana
situated between two passing waves. Within this regime, low level
moisture is expected to remain elevated. Model soundings continue to
show a brief period of subsidence above the rich moisture layer,
leading to the likely occurrence of near zero QPF drizzle at times
Sunday into Sunday night. Given the lack of dry air advection,
clearing of this stratus is also likely to by mitigated, leading to
a bump in expected cloud cover and corresponding temperatures Sunday
night. Calming of winds beneath this stratus could lead to patchy
fog Sunday night, but with temperatures remaining stable, saturation
may be confined to the 950-850mb layer.
The second wave will push into the Ohio Valley early Monday morning.
This second wave shares similar characteristics vertically with the
first, but with greater surface cyclogenesis expected over the
Northern Plains, resulting in a more westerly oriented LLJ. The
greater low level warmth with this second system also is likely to
result in greater lapse rates, especially through the 850-500mb
layer. Ensemble members are still spread on the placement of the
near surface warm sector, leading to uncertainty on if this
instability will be surface based. Nonetheless, pockets of 300-600
J/kg of MUCAPE will be likely leading to scattered convective
updrafts and lightning development.
QPF with this second system is a bit more uncertain. Highest totals
in the system have been well modeled, but the location of the precip
axis has a spread from northern central Indiana to the southern Ohio
Valley. This is due to the aforementioned more westerly orientation of
the LLJ and its location, of which will be more dictated by the
developing low level cyclone. Model progs should become more aligned
later this weekend, but for now specific location of precip totals
should be taken with caution as these could shift over the next few
days. Regardless of location, highest totals are still expected to
be rather anomalous. Convective development co-located with deep
saturation to the tropopause on Monday will likely lead to narrow
24hr totals between 2 to 3 inches.
As we head towards the middle of next week, another wave is expected
to develop on the remnant baroclinicity of the Monday system. This
wave is expected have greater availability of cold air, leading to
higher amounts of uncertainty on p-type/intensity. Latest trends are
rooting the wave further into the warmer air mass, keeping p-type
liquid, but this will still need to be monitored to see if these
trends continue.
INDY SEVEN DAY FORECAST

Never miss me! Subscribe for free. My Huge Radar has real-time weather tracking, current temperatures, and severe weather watches and warnings. Get detailed Indiana conditions by clicking here. Click here to see my central Indiana 7-Day Forecast. Follow these links to get my forecasts for Lafayette, Muncie, Hendricks County, and Hamilton County. Need a second opinion? Click here for central Indiana National Weather Service forecasts. (Some charts via WeatherBELL.)