Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 190501
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1201 AM EST Sun Feb 19 2017

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

&&

.SYNOPSIS...
Issued at 145 PM EST Sat Feb 18 2017

High pressure to the south and east will control Indiana weather
through Monday. After a weak cold front passes Tuesday, high
pressure should back in charge Wednesday. A large low pressure
system with several associated fronts will affect Hoosierland the
last few days of the week.

&&

.NEAR TERM /Overnight/...
Issued at 944 PM EST Sat Feb 18 2017

Light rain near and south of the Ohio River pulling away to the
southeast rather rapidly this evening as the upper wave shifts
away to the east. Scattered mid level clouds remain over the
southern half of the forecast area with pockets of lower stratus
developing as well. 0230Z temps ranged from the upper 40s to mid
50s.

Not much change made to the overnight forecast as questions still
exist as to how extensive the lower stratus and fog will get over
the region late tonight. Hi-res guidance continues to hit both
rather hard over central Indiana towards daybreak...with simulated
satellite data offering some support as well. The stratus will
likely focus more over the southern half of the forecast area with
the entire area susceptible to patchy fog at a minimum. Trends
this evening have suggested more extensive fog will develop to our
west over southern and central Illinois then spread into the
Wabash Valley after 06Z and further east across the forecast area
closer to daybreak. Considering strength of the inversion set to
develop below 2kft...think potential does exist for locally dense
fog but overall confidence is still a bit too low to include at
this time. Will continue to monitor closely into the overnight and
adjust as needed.

Rest of the forecast looked good. Made subtle changes to lows
overnight. Previous discussion follows.

&&

.SHORT TERM (Sunday through Tuesday)...

Issued at 145 PM EST Sat Feb 18 2017

The forecast problem is how warm we can get tomorrow.

The models agree we should have a lot of sunshine in a continued
southwest flow Sunday.  The consensus forecast has been too cool for
highs recently. Given the situation is basically unchanging, the
SuperBlend will be raised a category.

The models remain consistent with Sunday night mostly clear, clouds
arriving Monday ahead of the next system, then progressively higher
rain chances starting Monday night. Consensus temperatures have been
doing well at night. Clouds and precipitation starting Monday may
end the recent tendency for temperatures to exceed guidance.

All things considered, the forecast for Monday to Tuesday will
mostly reflect SuperBlend.

&&

.LONG TERM.../Tuesday Night through Friday night/
Issued at 238 PM EST Sat Feb 18 2017

Models continue to be in similar agreement with a couple mid-upper
shortwaves moving northeast from the southwest U.S. towards the
Upper Great Lakes. System currently over southern CA will move
northeast into the Plains phasing with one shortwave, while another
develops within active southern stream.

By Thursday, next mid-upper level shortwave will move into the
Rockies with cyclogenesis over the central High Plains region. The
good news here is our mild weather will continue Wednesday and
Thursday, but the bad news is that rain and possibly some
thunderstorms will spread over the region Thursday and Friday. Given
our temperatures have been above normal for this time of year, some
of the rain and storms could be strong Thursday night/Friday
afternoon ahead of an approaching cold front.

Cold front currently projected to move through region late Friday
afternoon dropping temperatures through the 40s into the mid-upper
30s by Saturday morning.

Confidence: moderate through Wednesday.

&&

.AVIATION /Discussion for 190600Z TAF Issuance/...
Issued at 1201 AM EST Sun Feb 19 2017

Deteriorating flying conditions are expected overnight continuing
through mid morning in fog and low stratus before returning to
VFR conditions this afternoon.

Stratus with ceilings near or just below 1000ft have been steadily
expanding northeast all evening from southern Illinois with
pockets of visibility restrictions. Model soundings and RH progs
with most short range guidance continue to show the stratus
overspreading much of the area over the next few hours as a shallow
but sharp inversion develops. Confidence is growing in sub-IFR
ceilings impacting the terminals pre dawn hours through midday
with potential for locally dense fog.

The inversion will slowly weaken through midday with a return to
VFR conditions for this afternoon and evening along with light
winds and just scattered mid level clouds as high pressure passes
to the south. May see another round of low stratus and fog
impacting the terminals early Monday morning as the upper ridge
axis remains just west of the region.

&&

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

&&

$$

SYNOPSIS...JK
NEAR TERM...Ryan
SHORT TERM...JK
LONG TERM....DWM
AVIATION...Ryan



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