Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 192334

Area Forecast Discussion
National Weather Service Indianapolis IN
734 PM EDT Wed Oct 19 2016

The AVIATION Section has been updated below.


Issued at 150 PM EDT Wed Oct 19 2016

Low pressure and an associated cold front will remain near Indiana
into Thursday, then be pushed away by high pressure coming from the
west. The high pressure in turn should move off to the east Sunday,
being followed by a relatively weak cold front. A second high
pressure system from the west will control Hoosier weather Monday
into midweek.


.NEAR TERM (Tonight)...

Issued at 150 PM EDT Wed Oct 19 2016

There is excellent model agreement. We can be very confident
precipitation will spread across area. The strong agreement also
supports the consensus temperature forecast.

Cross sections show very unstable equivalent potential vorticity
aligned with moderate frontogenesis and Q-vector convergence. With
these working in tandem, upward motion could be quite strong.
Showers and thunderstorms are the best forecast even though the
location of the surface front to the south suggests stratiform rain.

Given the likelihood of convection and very high precipitable


.SHORT TERM (Thursday and Thursday night)...

Issued at 150 PM EDT Wed Oct 19 2016

Previous solutions varied, but the models are now in agreement
precipitation will mostly end by late tomorrow, with a slight chance
in the east in the evening. Clouds will probably persist most of
Thursday night in cold flow over the lakes.

With colder air moving in and most unstable CAPE rapidly being
lost, tomorrow`s precipitation should be predominately stratiform.
Equivalent potential vorticity continues to show enough
instability aloft that a chance of thunder will be included. Given
precipitable water will stay very high into the afternoon, heavy
rain is going to be a threat from any storms.

The temperature guidance is close. There is no basis for changing
the consensus. Confidence is limited because forecasting how fast
cold air arrives behind a front, as in this case, is always
difficult. Potential errors are about 3 degrees.


.LONG TERM (Friday through Wednesday)...

Issued at 300 PM EDT Wed Oct 19 2016

Progressive...yet amplified flow pattern aloft persists through
the extended across much of the continental U S with generally
quiet weather expected for central Indiana through the middle of
next week. A cool start to the weekend as the Ohio Valley remains
within a cyclonic flow regime on the back side of the deepening
upper low over New England but heights aloft will modify into
early next week as broad ridging focused over the western part of
the country transitions east and centers over the Ohio Valley by
the end of the period.

Large area of high pressure will serve as the primary influence
throughout the period as it drifts into the southeast States. A
fast moving low pressure will track through the Great Lakes with a
trailing frontal boundary late Sunday but no rain is expected to
accompany the front with little moisture available. The main
impact the passage of the front will have will be to slow the
warmup for a day or two early next week before southerly low level
flow can resume over the Ohio Valley by midweek.

Saturday will be the coolest day of the extended with highs
primarily in the 50s. Temps should warm into the 60s thereafter
with further warming into the 70s possible by next Wednesday
ahead of the next storm system set to impact the region late in
the week.


.AVIATION /Discussion for the 20/0000Z TAF Issuance/...

Issued at 722 PM EDT Wed Oct 19 2016

MVFR/VFR conditions will prevail for duration of TAF period as
scattered showers and thunderstorms impact TAF sites at times. Low
pressure and an associated cold front in the area will trigger
the activity through tomorrow. Did, however, move mention of
thunderstorms for tonight though as best forcing moves south of
TAF sites. Winds will generally be northerly at 5 to 10 kts.





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