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fxus63 kiwx 200811 
afdiwx

Area forecast discussion
National Weather Service northern Indiana
411 am EDT Sat Jul 20 2019

Synopsis...
issued at 409 am EDT Sat Jul 20 2019

Hot and muggy conditions will persist through Saturday night.
Afternoon highs today are expected to reach into the lower to mid
90s with afternoon heat indices between 105 and 110 degrees.
There is potential for showers and thunderstorms this afternoon,
with better chances arriving Saturday night through Sunday night
as a cold front drops south through the region. Cooler and less
humid conditions will then follow for much of next week.

&&

Short term...(today and tonight)
issued at 409 am EDT Sat Jul 20 2019

A impressive Bow echo that started in WI this evening and dropped
southeast into SW lower Michigan with nearly 70 mph winds at GRR before
rapidly weakening as it approached the Michigan state line. The outflow
boundary from this feature (as well as lots of mid and high
clouds) was screaming south as we speak with the outflow expected
to slow down and wash out somewhere US 30 or south most likely.
Cloud cover should hopefully mix out rapidly this morning, but
given stubborn clouds past few mornings not a lot of confidence on
this.

As heating commences, temps should easily soar through the 80s and
likely into the 90s with dewpoints still in the 70s with heat
indicies similar to yesterday in the 105 to 110 range. Not a
perfect setup with combination of cold front slowly sinking south
across Michigan during the afternoon and evening hours and also the
above noted outflow boundary residing somewhere that could provide
some isolated convection in any weaknesses in the strong capping
across the south. Will let headlines ride though 00z expiration.

Cold front will sink south into the area tonight into the long
term period with increasing chances for showers and storms. Given
performance of cams past 24 hours and major differences in
handling of tonights convection (ranges from storms west of US to
large area of convection over US to more sct in nature) no major
changes tonight with mainly chc pops. If convection can organize
and get expansive enough, later forecasts will need to bump up
pops. Swody1 has northern areas in slight risk with remainder in a
marginal risk, mainly focus on tonight with the front itself.
While shear parameters will approach 20 to 30 kts, main threat
would be damaging winds and heavy rain.

&&

Long term...(sunday through friday)
issued at 409 am EDT Sat Jul 20 2019

Cold front will sink south through the day with best chance for
showers and storms occuring Sunday afternoon and evening. Marginal
risk of severe still in place for the entire area for Sunday and
seems reasonable with plenty of instability around, but better
shear lagging behind the front. Looks like front may be a touch
slower getting out of southeast areas on Monday so some lingering pops
there.

Cooler and less humid air will settle in by Monday and persist the
remainder of the period with little/no chance for precip until
maybe towards the end of the period.

&&

Aviation...(for the 06z tafs through 06z Saturday night)
issued at 206 am EDT Sat Jul 20 2019

VFR to MVFR conditions are expected through the taf period at both
sites. There is potential once again at kfwa later tonight for some
br development thanks to the abundant moisture, but winds should
keep things mixed up enough to limit visibility from dropping too
low. May end up being a lower cloud deck. Otherwise, the main
concern tonight is the approaching thunderstorm complex to our
north, which is moving southeast at around 50 mph. This line of
storms has already produced wind gusts up to 56 kts near Muskegon,
47 knots near Holland, and 60 knots at Grand Rapids, mi(as of 553z).
The question is will the line of storms die out before reaching
ksbn? If so, what is the projected severity? Current observations
suggest the storm is becoming outflow dominant, which suggests a
weakening trend as it moves southeastward. Furthermore, nearly all
of the model guidance suggests that it will die out before it
arrives (though their performance hasn't exactly been stellar with
this system). For now, given low confidence have thunderstorms in the vicinity in at ksbn
from 8-11z. Will make amendments if needed to the ksbn taf as
storm gets closer to add in details on timing/wind gusts/etc. If
it were to make it to FWA (extremely unlikely) it would be around
9-10z but confidence was too low to include a mention at this
point.



&&

Iwx watches/warnings/advisories...
in...excessive heat warning until 8 PM EDT /7 PM CDT/ this evening
for inz003>009-012>018-020-022>027-032>034.

Michigan...excessive heat warning until 8 PM EDT this evening for
miz077>081.

Ohio...excessive heat warning until 8 PM EDT this evening for ohz001-
002-004-005-015-016-024-025.

Lm...none.
&&

$$

Synopsis...mesoscale discussion
short term...Fisher
long term...Fisher
aviation...mesoscale discussion



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