Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 290719
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
319 AM EDT SUN MAY 29 2016

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

&&

.SYNOPSIS...
Issued at 319 AM EDT Sun May 29 2016

Scattered thunderstorms will again be possible this afternoon as a
weak cold front tracks through the area. Dry weather is expected to
begin the week with less humidity. Rain chances will return by
midweek as a storm system tracks through central Indiana. Cooler and
drier air will follow in the wake of this system for next weekend.

&&

.NEAR TERM /Today/...
Issued at 319 AM EDT Sun May 29 2016

Muggy morning in progress as central Indiana remains in a moist
southerly flow. Mid and high level clouds continue to blanket the
region with pockets of stratocu. Isolated showers had briefly snuck
into Warren County early this morning as the remnants of evening
convection across Illinois continue to weaken as they move
northeast. 07Z temps were in the upper 60s and lower 70s.

Upper low centered over Minnesota early this morning will lift N/NE
into Canada and become absorbed into a broader trough through the
course of the day. The remnant wave associated with the upper low
will drift east across the Great Lakes today in tandem with a
weakening cold front. As both features interact with an increasingly
unstable airmass later today...expect renewed convective development
across the region focused on the afternoon hours and primarily over
the southeast half of the forecast area extending east into Ohio.

This morning will be quiet with a modest amount of sunshine as high
level clouds shift off to the northeast. Strong heating will
generate a modestly unstable airmass by 18Z with MLCAPEs in excess
of 2000 J/KG developing as surface temps rise into the 80s. The
arrival of the frontal boundary will help to provide additional lift
to generate isolated to scattered convection primarily after 18Z.
Bulk of the model guidance has come in faster with both the arrival
of the front and departure of the upper wave off to the east...
resulting in the axis of deeper moisture and greater instability
being shifted further east as well. Hi-res guidance has latched on
to this idea with isolated to scattered convection developing
generally along and east of a Washington-Indy-Anderson line in the
18-22Z time period. Have adjusted precip chances accordingly...
focusing highest 30 pops across the southeast half of the forecast
area. Drier air advecting into the region behind the front should
shut off convective chances quickly to the west during the second
half of the afternoon. Any convection should be out of the entire
forecast area by early evening.

The potential for a few strong storms remains with the presence of
the modestly unstable airmass and model soundings showing a
favorable thermodynamic setup with steepening lapse rates as mid
level drying occurs. This would support the potential for gusty
winds in stronger cells...along with hail as wet bulb zero levels
hover around 8kft. Lack of more substantial shear and weak low level
forcing should limit overall storm intensity and coverage however.

Temps...Expectation of more sunshine will support max temps a few
degrees warmer than Saturday in general. Leaned a bit closer to the
warmer METMOS guidance which was supported nicely by the raw temps
off the 4KM NAM. Felt the MAVMOS was too cool while the RAP and HRRR
were both too aggressive with warming. Expect mid 80s for most of
the area.

&&

.SHORT TERM /Tonight through Tuesday Night/...
Issued at 319 AM EDT Sun May 29 2016

Forecast challenges focus primarily on temps as surface ridging
brings dry weather for a good portion of the short term.

Remnant frontal boundary with associated scattered convection will
be east of the forecast area this evening. A high pressure ridge
will expand into the area overnight bringing with it a nice surge of
drier and less humid air into central Indiana. Skies will become
mostly clear tonight...persisting into Memorial Day as the surface
ridge continues as the dominant weather feature.

Both the NAM and GFS attempting to bring isolated precip into the
northern forecast area Monday night as a warm front extends
southeast from low pressure moving into the Upper Midwest. Prefer to
maintain a dry forecast at this time as model sounding and RH progs
show an abundance of dry air and subsidence. Have introduced low
chance pops for areas to the northwest of the Indy metro for Tuesday
afternoon and night...but the drier airmass combined with stagnant
flow and little forcing aloft will serve as hindrances to
convective development as the surface ridging lingers across the
Ohio Valley.

Temps...The warm summer-like temperatures will continue through the
short term albeit it with lower humidity than that experienced the
last several days. MOS guidance in general aligned well with low
level thermals as highs both Monday and Tuesday are expected in the
mid to possibly upper 80s. The combination of light flow and the
drier air should enable a broader range to overnight lows at night
ranging from the upper 50s in the normal cool spots to the mid 60s
in the urban areas.

&&

.LONG TERM /Wednesday Through Saturday/...
Issued at 233 AM EDT Sun May 29 2016

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

An upper trough and a surface frontal system will bring chances for
rain Wednesday and Thursday.

Another upper trough will move in for Friday into Saturday. Looks
like there might be enough forcing/moisture for Superblend`s slight
chance PoPs Friday, but removed any of its PoPs for Saturday as best
forcing/moisture will have moved off just to the south and east of
the area.

Temperatures will start out above average, but cool to below average
by next weekend.

&&

.AVIATION /Discussion for 290600z TAF issuance/...
Issued at 1228 AM EDT Sun May 29 2016

With dewpoint depressions expected to only run a couple degrees at
the outlying sites and winds dropping below 5 kts could see MVFR fog
develop after around 9z. Radar mosaic shows line of storms over
Illinois but hi res models show this weakening and scattering before
dissipating, which keeps any rain away from the sites. Looking at
current track though and proximity to KLAF think a few showers could
sneak close to that site and so included a VCSH there. Will have
some chances for thunderstorms this afternoon ahead of the cold
frontal passage. Looks like the best chances for thunder will be
east of most of the sites but could clip KIND. Given this included a
PROB30 there. Forecast soundings show some potential for wind gusts
around 14-20 kts out of the west generally in the wake of the
frontal passage and these should drop off around sunset.

&&

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

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....50
AVIATION...CP/50



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