Area Forecast Discussion
Issued by NWS Indianapolis, IN

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294
FXUS63 KIND 181105
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
605 AM EST Thu Jan 18 2018

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

&&

.SYNOPSIS...
Issued at 322 AM EST Thu Jan 18 2018

Dry weather with moderating temperatures will be the rule over
central Indiana through Friday night as high pressure shifts to the
southeastern states and the Atlantic, ahead of a Rockies system. The
Rockies system will lift northeast to the Great Lakes during the
early part of next week. Increasing moisture and lift from that
frontal system will bring rain chances to central Indiana starting
Saturday night.

Seasonable temperatures will follow the frontal passage with a
lingering chance of rain or snow through next Tuesday.

&&

.NEAR TERM /Today/...
Issued at 322 AM EST Thu Jan 18 2018

Temperatures and winds will be the main focus for today.
Southwesterly low level flow around a southern states high and only
a few high level clouds ahead of an upper trough will allow
temperatures to warm up nicely today. However, with the snow pack,
prefer to play it cooler than 00z MOS, closer to superblend.

Decent low pressure gradient between the southern high and a broad
low over western Canada will allow for sustained winds of 10 to 20
mph and gusts 20 to 30 mph. So despite the warmup, wind chills will
start up slightly below zero at most locales. Look for afternoon
wind chills in the upper teens and lower 20s.

Confidence in temperatures and wind chills are moderate at best
today, mainly due to the snow pack.

&&

.SHORT TERM /Tonight through Saturday night/...
Issued at 320 AM EST Thu Jan 18 2018

The main focus for the short term will be on temperatures and then
whether or not we will see any rate late in the period.

Models in good agreement that the southern high will shift to the
southeastern states and Atlantic this weekend. Meanwhile, the
western upper ridge will flatten and moves over the Ohio Valley
Friday night, and an upper low will move over the South. The result
will be prolonged warm air advection. The flow will have a better
Gulf component by Saturday and Saturday night. Models were also
showing increasing isentropic lift on the 300K level. However, model
time secs were slow to moisten the mid levels and were only showing
saturation up to about 800 millibars by Saturday evening. Forecast
Builder starts to bring in slight chance pops to our far southern
counties by Saturday afternoon and small pops over all of central
Indiana by Saturday night. With the dry mid levels, would not be
surprised to see it dry through Saturday night. However, do not
think leaving the small pops in is that bad an idea at this point.

Prior to Saturday, with a dry southwest flow, good confidence in
little cloud cover with moderating temperatures. Low level thermals
suggest highs 5 plus degrees warmer each day which reflects the
regional blend and translates to near normal highs in the middle and
upper 30s Friday and above normal highs in the lower 40s Saturday.
Confidence in temperatures trends is good. Although, confidence in
highs to within a few degrees is moderate at best, especially
Friday,  due to the dying snow pack battling it out with warm air
advection.

&&

.LONG TERM /Sunday through Wednesday/...
Issued at 332 AM EST Thu Jan 18 2018

Ensembles are in good agreement during this period, albeit a little
slower overall with the system expected to affect the area early
next week. An upper trough is expected to move through the area
around Monday, while an associated low pressure system moves into
the Great Lakes.

Will keep PoPs in the forecast for rain on Sunday and Monday to
cover the passage of this feature, with the highest PoPs on Sunday
night and Monday morning, coinciding with the passage of the cold
front.

Given the slower movement of the system, the potential for some wrap
around light precipitation on the back side of the trough to linger
into early Tuesday is increasing, especially over the northern
zones. As a result, will add some chance PoPs for light rain or snow
to the forecast Monday night and Tuesday morning.

&&

.AVIATION /Discussion for the 181200Z TAFS/...
Issued at 605 AM EST Thu Jan 18 2018

No significant cloud cover and unrestricted visibility expected at
the terminals today.

Surface winds 220-240 degrees at 8-12 kts this morning, with occasional
surface gusts 18-20 kts from midday through the afternoon hours.

&&

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

$$

SYNOPSIS...MK
NEAR TERM...MK
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JAS



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