Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 281138
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
638 AM EST Mon Nov 28 2016

.SYNOPSIS...
Issued at 346 AM EST Mon Nov 28 2016

Widespread rain is expected today and tonight. Up to an inch is
possible in some areas. This may lead to minor rises on area rivers
and ponding in low lying areas but impacts are expected to remain
minimal. Wind gusts up to 35 mph will also be possible today and
tonight. Dry and mild weather anticipated on Tuesday with a return
to cool and cloudy conditions later this week. Some light lake
effect rain and snow may be possible Thursday into Friday.

&&

.SHORT TERM...(Today and Tonight)
Issued at 346 AM EST Mon Nov 28 2016

Lead WAA wing of impressive 976mb cyclone over the Northern Plains
is currently moving overhead and generating some light rain.
Coverage and intensity expected to dwindle through the morning as
precip intersects drier air aloft (ref 00Z KDTX sounding) and
becomes increasingly orphaned from nearly stationary/gradually
occluding cyclone well to our NW. Brief break in rain expected
during the late morning and early afternoon. However, latest water
vapor loop clearly shows a strong, secondary vort max rounding the
base of large negative height anomaly upstream. NE ejection of
this wave and the corresponding jet streak will bring another
batch of heavier and more widespread rain late this afternoon and
into the overnight. Mid/upper dynamics are excellent with our CWA
in left exit region of 150+ kt upper jet and pronounced mid/upper
diffluence downstream. 1.5 PVU surface extends to almost 600mb and
moves directly over our CWA. Equally impressive is the degree of
moisture transport as further tightening of low level gradient
supports a LLJ near 60 kts. 850-700mb specific humidities climb to
around 6 g/kg with PW values near an inch (close to climatological
max for this time of year). Despite favorable dynamics and strong
LLJ, still holding firm on no thunder mention due to poor midlevel
lapse rates and surface temps/dewpoints only in upper 40s. Suppose
an isolated clap of thunder may be possible with an
embedded/elevated storm but sub-850mb stable layer will prevent
any impact and not worth a blanket mention. Still, even without a
convective component, total QPF remains largely unchanged from
previous forecasts with up to an inch possible, especially west of
I- 69. Minor rises anticipated on area rivers but system is fairly
progressive and rivers should be able to handle this QPF with
minimal impact. Latest river forecasts for our CWA are all below
flood stage and only minor/nuisance ponding expected in typical
low- lying areas. Another item to note is potential for a few wind
gusts around 30-35 mph tonight due to tight gradient. Temps will
hover in the mid to upper 40s for the bulk of the short term
period.

&&

.LONG TERM...(Tuesday through Sunday)
Issued at 346 AM EST Mon Nov 28 2016

Pronounced dry slot will envelope the region on Tuesday and lead to
a relatively pleasant day (by late Nov standards). Should see at
least some sun during the day, between exiting high clouds in the
morning and returning low clouds late in the day. 925mb temps
approach 10C by the afternoon and could see highs around 60F if
clouds behave. Leaned toward warmer MOS guidance during this period.

Quick low level theta-e surge Tuesday night could bring some light
rain and could also be some light rain in our east during the day
Wed as final piece of Pacific jet lifts through the region.
Maintained just low chance PoPs during this time with weak/nebulous
forcing. Colder air begins to filter in by Wed but should still be
warm enough for just rain if anything does occur.

Barotropic low then slowly moves across the Great Lakes on Thur and
Fri with increasing NW/cyclonic flow bringing chances for some lake
effect/enhanced precip through the end of the week. Best chances
will depend on exact timing/track of subtle, embedded shortwaves but
overall not a great signal for any significant precip. Likely just a
nuisance rain/snow mix at times with thermal profiles appearing too
warm at this point to support any meaningful snow accumulation. Do
however expect another extended period of cloudy conditions with
limited diurnal ranges generally in the 30s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 630 AM EST Mon Nov 28 2016

Deteriorating aviation weather conditions for today with trends to
IFR expected by later this afternoon at KSBN, and this evening at
KFWA. Initial band of rain showers associated with lead vort max
will continue to progress across northeast Indiana over the next
few hours. It still appears as though a sizable lull in greater
rain coverage will unfold later this morning into early this
afternoon. A strong vort max approaching west Texas this morning
will rapidly lift east-northeast into the Ohio Valley tonight. An
impressive column of moisture will advect northward in advance of
this feature late afternoon with widespread rain this evening.
Rain should exit overnight as occluded front tracks across the
area with improvement in cigs expected overnight to MVFR and
eventually VFR toward end of the period. The other story for today
will be strong south winds gusting to around 25 knots, with a few
gusts to 30 knots possible late afternoon/early evening. Despite
strong surface winds, a very strong low level jet developing this
evening may necessitate another LLWS mention for the 00-06Z
period this evening.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Gale Warning until 4 AM EST Tuesday for LMZ043-046.

&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Marsili


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