Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 270222
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1022 PM EDT Sun Mar 26 2017

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 338 PM EDT Sun Mar 26 2017

A rather active period will continue as several systems move
across Central Indiana through the forecast period. After a bit of
a lull tonight, the first is progged to enter the area tomorrow.
This system does have the potential to produce some severe weather
across the southernmost portions of the forecast area. After that,
weak ridging will result in dry conditions around mid-week, but
another system will approach from the southwest on Wednesday
night. This will keep high rain chances in the forecast through
the end of the week. At that point, the pattern will almost repeat
again with a dry period early in the weekend followed by another
system late in the extended period.

&&

.NEAR TERM /Rest of Tonight/...

Issued at 938 PM EDT Sun Mar 26 2017

Most of the rain showers have moved out of the forecast area as of
930 pm EDT. Could see a light shower yet in the northeast counties
over the next hour or two so maintained a slight chance there, but
went with low pops elsewhere. North of I-70 though have seen some
very light echoes develop and could see some light drizzle out of
these with the moisture there so added patchy drizzle to the
forecast through around midnight.

Did not add any fog to the forecast at this time, as current
expectation is low level moisture will produce some stratus rather
than fog with some mixing in the lower levels, but confidence on
this is only moderate and cannot completely rule out fog
development during the overnight. This will continue to be
monitored.

Low temperatures in the mid to upper 40s still look on track and
no adjustments made there.

&&

.SHORT TERM /Tomorrow through Wednesday/...

Issued at 338 PM EDT Sun Mar 26 2017

The main focus of the short term period will be thunderstorm
chances with the next system approaching from the southwest.

Models have been fairly consistent over the last few days with
the track of tomorrow`s system, bringing it from the Central
Plains and across the Missouri Valley. As a result, there is high
confidence in the best potential for severe activity across the
southern portions of the forecast area. This matches well with the
Day 2 Slight Risk by SPC across those counties.

Best dynamics will be late afternoon Monday through the early part
of the night. As a result, trended slightly above latest
Superblend initialization and increased pops to definite at times
during the evening/early night.

The thunderstorm threat should taper off by Tue 06Z with just
lingering rain showers at that point, becoming confined to just
the eastern counties by Tuesday morning. At that point, ridging
will strengthen aloft, and dry conditions will then prevail
through the remainder of the short term period.

Temps through the period will generally be above normal with highs
in the 60s and lows in the 40s and 50s. Models seem to have a good
handle on this system, so stuck close to a blend.

&&

.LONG TERM /Wednesday night through Sunday/...

Issued at 234 PM EDT Sun Mar 26 2017

A pair of systems will bring the threat for showers to central
Indiana late next week and early next weekend as well as late next
weekend.

Models in general agreement that a pacific system will strengthen
over Rockies and move into the southern Plains and northeast across
the Ohio Valley and lower Great Lakes next Friday. Then after brief
ridging on Saturday, another Pacific system will move into the
Plains on Monday. A moist and unstable flow off the Gulf and ahead
of advancing cold front, combined with the synoptic scale forcing,
favor high pops Thursday into Friday morning. Left in lingering
chance pops through Friday night as a buffer. Then, chance pops look
reasonable by Sunday afternoon as the second system gets closer and
more Gulf moisture advects northward ahead of it.

Instability progs suggest thunder is a possibility with the first
system but probably not with the start of the second.

Low level thermal progs and expected cloud cover support the
slightly above normal temperature blend output from Forecast Builder
with highs in the upper 50s to mid 60s.

&&

.AVIATION /Discussion for the 27/0300 TAF Issuance/...

Issued at 1018 PM EDT Sun Mar 26 2017

Updated ceilings to adjust to current observations and brought LAF
into MVFR earlier than initially forecasted. Previous discussion
follows.

VFR conditions across TAF sites will drop into MVFR as ceilings
drop around sunrise. Winds will weaken and shift from the
southwest to the southeast overnight. Some isolated lowered
visibilities will be possible with weak winds and a moist surface.
Ceilings should raise back to VFR by mid morning before dropping
again as showers move into Central Indiana. Thunder will be
possible during the afternoon but with low confidence on timing it
will be left out for this issuance.


&&

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

$$

SYNOPSIS...TDUD
NEAR TERM...CP
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...White


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