Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 260330
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1130 PM EDT Tue Jul 25 2017

.UPDATE...

The Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 122 PM EDT Tue Jul 25 2017

High pressure spreads thoughout the Great Lakes and Upper Ohio
Valley. This high will gradually move eastward over the northeast
U.S. tomorrow bringing southeast to southerly flow and a gradual
return of moisture Wednesday afternoon into the evening. Looks
like the next chance for rain and thunderstorms will be late
Wednesday and Thursday.

&&

.NEAR TERM /Tonight/...
Issued at 947 PM EDT Tue Jul 25 2017

Quiet night on tap for central Indiana. Made minor adjustments to
min temps and dewpoints, but otherwise grids are ok. Previous
discussion follows.

Issued at 933 AM EDT Tue Jul 25 2017

High pressure over lower MI dominates the weather for today. This
high will keep skies mostly sunny with some clouds this afternoon,
much like yesterday. Easterly winds will also keep temperatures
comfortable around the area.

&&

.SHORT TERM /Wednesday through Friday afternoon/...
Issued at 249 PM EDT Tue Jul 25 2017

Models are varied in their solutions this morning on what will happen
late Wednesday into Thursday. All are in agreement in rain and
thunderstorms, just vary in their solution on how much and timing.

The NAM seems to be the odd one as it brings a mid/upper level short
wave trough over the southwest U.S./southern Plains ridge from
the northern Rockies eastward across the Plains then into the
upper MS Valley the Ohio Valley late Wednesday and Thursday.
Discussions from WPC and model discussions look at this as
convective feedback which is enhancing a MCS-like feature that
results in copius amounts of rain over the northern half of IN.
Compare this to the GFS/ECMWF which do not generate as much rain,
but still focuses the precipitation north and northeast of central
IN. Both these models bring the mid/upper level trough
southeastward from Lake Winnepeg southeast into the upper Great
Lakes which is resulting in the difference in the solutions.

Will lean towards the Super Blend at this time which seems the only
reasonable solution. Am concerned that the models are persistent
in giving precipitable water values 2.00 give or take 0.10. So,
tried to portray QPF values a little higher as the Blend gave 1.02
inches total between 27/06Z and 28/06Z in central IN. Sense that
some areas or later runs of the model will give us some higher
amounts in the northern and central parts of our CWA. It is hard
to ignore PWats of 2.00" right now.

Temperatures will be up in the mid 80s for Wednesday, then dew
points begin their climb with moisture return starting Wednesday
from the low 60s before 26/12Z to 70 degrees by evening. Thus,
lows will be in the low/mid 70s before the rain and thunderstorms
move into western section of central IN Wednesday night.

Confidence: High on rain and thunderstorms, low-medium on timing
and amounts.

&&

.LONG TERM /Friday night through Tuesday/...
Issued at 238 PM EDT Tue Jul 25 2017

Dry weather is likely for much of the extended period as the upper
level system that will bring the rain on Wednesday night and
Thursday exits region.  High pressure, along with northerly flow,
will bring seasonably cool and dry conditions for Central Indiana
through Monday.  Highs through the period are forecast to be in the
upper 70s and lower 80s and lows will range from the upper 50s Friday
night up to the mid 60s by Tuesday night as moisture slowly rebounds.

By Monday the chances for rain and thunderstorms increase as a series
of weak upper level disturbances move into the region.  Timing is
still quite uncertain with significant inconsistencies between models
and model runs, so will be keeping POPs broad-brushed at this time.
At this time, the best chance for rain and thunderstorms looks to be
Tuesday afternoon and evening.

&&

.AVIATION /Discussion for the 26/06Z TAFs/...
Issued at 1130 PM EDT Tue Jul 25 2017

VFR through the period.

Surface high pressure over the area will keep conditions quiet,
winds variable below 10KT, and skies mostly clear.

A bit of an increase in high cloud can be expected later in the
period ahead of the next system, impacts of which remain largely
beyond the current TAF period.

Cannot completely rule out brief patches of high end MVFR fog near
daybreak, but this is quite uncertain and likely to be minimal in
impact if it does occur. Will leave out.

&&

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

&&

$$

SYNOPSIS...DWM
NEAR TERM...DWM/NIELD
SHORT TERM...DWM
LONG TERM...White/Tucek
AVIATION...NIELD


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