Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 190720
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
220 AM EST Thu Jan 19 2017

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated below.

&&

.SYNOPSIS...
Issued at 220 AM EST Thu Jan 19 2017

High pressure over Kentucky and Ohio will quickly depart to the
east today. Meanwhile...a strong upper level weather disturbance
over the southern plains will push toward the Ohio valley this
afternoon and tonight this along with an approaching warm front
will bring rain to central Indiana late this afternoon and
Tonight.

A few showers may linger on Friday morning as the front surges
farther north and warm and moist air arrives across Central
Indiana for Friday night through Saturday. This could result in
some scattered showers as the weekend starts...but wide spread
rain is not expected.

By Sunday...another strong Low pressure system will push toward
Indiana within the Warm and moist Southwest flow. This will bring
yet another rain event to Central Indiana as the weekend.
concludes.

More active weather is in store next week with more above normal
temperatures.

&&

.NEAR TERM /Today/...

Issued at 220 AM EST Thu Jan 19 2017

Surface analysis early this morning shows High pressure in place
over Indiana and Ohio. Light southerly surface flow was in place
across Indiana...and Radar Mosaics shows some scattered showers
arriving over southern and Western Illinois. Water vapor imagery
shows the real story though...showing a plume of tropical moisture
streaming Northeast into Indiana from eastern TX and the lower
Mississippi valley. Skies were cloudy across across Central
Indiana...AGAIN! There will be little hope for sunshine over the
coming days.

Main forecast challenge today will be pops.

Forecast soundings show deep moisture arriving by late afternoon
and Time height sections show a deeply saturated column with
excellent lift. GFS and NAM both depict a strong negatively tiled
short wave pushing into Indiana ahead of a deep upper low over the
Central Plains. Within the lower levels a surge of warm air and an
associated warm front arrives this afternoon and passes to the
north Tonight. Finally...the GFS 295K isentropic surface shows
excellent upglide this afternoon with very moist specific
humidities over 8 g/kg. Thus given all of these favorable
dynamics...will trend toward 100 pops this afternoon. Given the
expected clouds and rain but warm air advection...will trend
highs at or slightly below a blend.

&&

.SHORT TERM /Tonight through Saturday night/...

Issued at 220 AM EST Thu Jan 19 2017

Much of the dynamics that will be in place late this afternoon
will still be ongoing this evening. Again the upper
wave...saturated column and strong isentropic lift will continue
past 00Z Fri. Thus will trend toward 100 pops again as rain will
be expected to be ongoing near and after 00z. Given the strong
warm air advection will trend lows closer to the warmer 3 hourly
values of the MAVMOS.

By 12Z friday...models suggest upper support and isentropic lift
will be exiting to the north...reaching NRN Indiana and Lower
Michigan. Time heights show strong mid level drying and
subsidence within the column as the wall of moisture associated
with the forcing departs. Still time heights and forecast
soundings keep lowest levels saturated beneath a trapping
inversion amid the warm air advection and southerly flow in place.
Thus will mean more clouds for Friday. Thus will trend pops
highest across the north to lowest across the south on Friday
morning as the forcing departs...overall trending toward a dry
but cloudy afternoon. Again will trend highs at or above a blend
given the expected warm air advection.

More of the Friday`s weather pattern looks to be in store for
Friday Night through Saturday night. GFS and NAM continue to
suggest strong SW flow in place aloft...allowing a warm and moist
flow of air into the Ohio valley. At this time models suggest
weaker short waves embedded within the SW flow aloft through
saturday night...however...confidence remains low in and given
wave due to the lack of organization and agreement. However
Forecast soundings do show good moisture available and even
reachable convective temperatures on Saturday. Thus will continue
to carry at least a low chc pops on Friday Night through Saturday
night...with best pops mostly likely on Saturday afternoon as
forecast soundings show convection possible amid strong warm air
advection and again on Saturday night when models hint at a
better organized wave pushing toward Indiana being ejected from
the upper low over Texas. Again with the strong warm air advection
pattern will trend temps at or warmer a model blend.

&&

.LONG TERM (Saturday night through Wednesday)...
Issued at 1257 PM EST Wed Jan 18 2017

There is high confidence the weather will be unusually warm. There
is also high confidence there will be lots of rain, but little or no
chance for snow.

The models all predict Indiana is going to be affected by air from
the Gulf Coast. Besides being warm and humid, this air should have
storm systems embedded in it.

It is too early to be precise about rain timing. POPS for any one
period may need adjusting by 20 percent. Given uncertainty about
precipitation, there is some uncertainty about temperatures.
Possible errors are about 4 degrees. It is very likely readings
will be at least 10 degrees above average most of the time.

&&

.AVIATION /Discussion for the 19/06Z TAFs/...
Issued at 1142 PM EST Wed Jan 18 2017

Borderline MVFR/IFR conditions may linger at IND and especially LAF.
HUF/BMG will improve but may experience some MVFR visibilities near
daybreak.

Severe reductions in visibility as previously forecast by short term
consensus blend and HRRR have thus far failed to materialize, and
where low cloud has managed to break up (just now reaching HUF/BMG
after slow northward progression this evening), mid and high cloud
is streaming in to replace. Thus, will back off significantly on fog
and only forecast MVFR visibilities overnight.

Winds will be less than 10kt through the period.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM...JK
AVIATION...NIELD



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