Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 280820

Area Forecast Discussion
National Weather Service Indianapolis IN
420 AM EDT SAT MAY 28 2016

The AVIATION section has been updated below.


Issued at 330 AM EDT Sat May 28 2016

A warm and humid airmass will persist across the region through the
weekend with chances for showers and thunderstorms as a series of
upper waves pass through the Ohio Valley. Rain chances will end once
a weakening cold front passes through on Sunday...with less humid
weather for Monday and Tuesday. Scattered thunderstorms will return
to central Indiana by mid week as a storm system tracks through the
region. Cooler and drier conditions are expected by next weekend.


.NEAR TERM /Today/...
Issued at 330 AM EDT Sat May 28 2016

Moist southerly flow continues across the region early this
morning with clouds increasing. Isolated brief downpours lifting
north across southern counties on the leading edge of an area of
higher precipitable water. Warm and humid conditions persist with
07Z temps ranging from the upper 60s to the mid 70s.

The Ohio Valley will remain entrenched within a moist southwest flow
aloft as a stubborn upper low over the central plains this morning
lifts northeast through the course of the day. Weak and poorly
defined perturbations aloft continue to eject out from the upper low
and lift into the area and will once again serve to offer forcing
for convective development today...especially this afternoon during
peak heating.

Deeper moisture advecting into the region courtesy of stronger low
level flow helping to generate the isolated activity early this
morning. A few lightning strikes cannot be ruled out with
mesoanalysis indicating subtle instability present...but overall
primarily anticipating showers through mid morning. Slightly
stronger wave aloft poised to lift into the Ohio Valley this
afternoon and with the airmass becoming more unstable with
heating...expect more of a convective component over the forecast
area with scattered thunderstorms developing. Primary focus for
greatest convective coverage likely to align over the eastern half
of the forecast area where axis of deeper moisture will reside...but
chance pops are warranted over all of central Indiana this
afternoon. With boundary layer shear lacking...expect convection to
remain largely disorganized later today with brief heavy downpours
as the main impact.

Temps...Expect less sunshine than Friday for most as model soundings
and RH progs showing a lot of potential for clouds through the
course of the day.  This will serve to keep max temps cooler than
Friday...with low level thermals supporting highs generally in the
lower 80s.


.SHORT TERM /Tonight through Monday Night/...
Issued at 330 AM EDT Sat May 28 2016

Forecast challenges focus on convective chances through Sunday
followed by drier weather for Memorial Day as weak high pressure

The aforementioned upper low will become slowly absorbed into the
mean flow aloft on Sunday as it tracks east across the Great Lakes.
The remnant wave aloft will enhance lift across the region and
combine with a weakening cold front to provide another round for
scattered convection during the afternoon and evening Sunday. Strong
surface heating will produce a modestly unstable airmass with
steepening lapse rates as cooler and drier air in the mid levels
arrives Despite weak low level flow and boundary layer shear...the
frontal boundary and wave aloft should support potential for more
organized and stronger convection in a multicellular mode.
Thermodynamic profiles suggestive of gusty wind and hail potential
with stronger cells. Timing differences still exist between various
models...but chance pops remain warranted and focused during the
second half of the afternoon into the evening as the front tracks
across the area.

Drier air will overspread the region Sunday night as weak surface
ridging reestablishes and the weakening wave aloft departs off to
the east. A dry and slightly less humid airmass will settle into the
Ohio Valley for Memorial Day and Monday night with the surface ridge
in control over the area and slowly rising heights aloft.

Temps...Warm weather will continue across the region through the
short term. Low level thermals remain supportive of highs rising
into the mid 80s both Sunday and Monday for most areas.


.LONG TERM /Tuesday Through Friday/...
Issued at 231 AM EDT SAT MAY 28 2016

Models are close enough that the SuperBlend initialization was
accepted for most items.

During the long term, an upper trough will move into the area. A
surface frontal system will also move through. The result will be
rain chances through most of the period.

The GFS appears to be well overdoing rain chances early in the
period given expected forcing at that time. Its influence on
SuperBlend requires cutting back on SuperBlend`s PoPs on Tuesday.

Above normal temperatures early in the period will give way to near
to slightly below normal values by Friday.


.AVIATION /Discussion for 280900z TAF update/...
Issued at 420 AM EDT Sat May 28 2016

Only minor tweak made to KIND TAF. Isolated showers continue to
develop so kept VCSH mention. Showers would likely not cause any
category reduction.

Previous discussion follows...

Starting to see a few weak echoes in central Indiana and hi res
output suggest this will increase for the next few hours. Included a
VCSH for this, but with the weaker looking echoes and unimpressive
moisture in the time heights will not include any category
reductions. After around 14-16z forecast soundings show wind gusts
of 20-25 kts developing out of 180-210 and continuing through around
sunset. Could see some scattered thunderstorm development during the
afternoon as well. Confidence on timing/placement is still fairly
low, but parameters look a little better than they have the past
couple of days so will bring in a prob30 after 19z.


.IND Watches/Warnings/Advisories...NONE.



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