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Area forecast discussion 
National Weather Service northern Indiana
353 PM EDT sun Apr 19 2015

issued at 130 PM EDT sun Apr 19 2015

Low pressure will move north from the Ohio River to the Great
Lakes this afternoon and tonight. Rain will spread north across
the area during the afternoon. Temperatures will fall into the 50s
after the rain begins. Overnight lows will remain in the 50s as
well. The rain should diminish this evening but more rain is
expected Monday.


Short term...(this evening through monday)
issued at 351 PM EDT sun Apr 19 2015

Regional radar mosaic shows large area of rain associated with
negatively tilted short wave and deepening surface low moving
through the region. Surface low expected to continue strengthening into
the evening as it moves north near the in/Illinois border. Impressive
moisture advection and negative tilt to system providing strong lift
and deep moisture profiles. Convection over southern Continental U.S. May have
robbed some moisture but as system strengthens further think this
will be overcome through early evening with precipitation amounts of half to
three quarters inch possible.

Dry slot seen on satellite and in radar mosaic will move into the
area during the middle to late evening with precipitation diminishing. May see
some drizzle or very light showers at times overnight but precipitation
chances increase again toward daybreak as secondary wave over OK
this afternoon works northeast. Expect showers to develop early
Monday with likely to categorical probability of precipitation warranted through at least
middle afternoon until this wave passes.

Temperatures were falling into the 50s with onset of rain and latest
guidance suggest they will remain there through the night. May see a
small rise in temperatures Monday...especially east prior to deeper cold
air advection.


Long term...(monday night through sunday)
issued at 351 PM EDT sun Apr 19 2015

The second upper level trough in as many days will be moving across
the forecast area at the start of this period Monday night. Left a
chance for lingering showers over eastern areas including mainly
Northwest Ohio as this system moves east. For the rest of the
period...very chilly air will spread over the upper Great Lakes
region as a negative height anomaly remains over southeast Canada.
Thermal profiles support a mix of precipitation at times...with a
mix of sleet possible late Tuesday given extremely cold temperatures
aloft for this time of year with the wet bulb zero remaining below
3k feet. The GFS has trended the low level more unstable Tuesday
afternoon during the past few runs with lapse rates from about 8.5c
to 10c per km from the surface to 600 mb with limited cape now
showing up. Kept a chance for showers northeast areas Tuesday
afternoon given these conditions. Left sleet out for now given
lingering uncertainties about precipitation type with afternoon
temperatures climbing into the low to middle 50s.

Given some recent advancement concerning Spring grow in sensitive
plants and fruit trees due to warm temperatures...have updated the
hazardous weather outlook earlier today to highlight frost and
freeze concerns during this week. Have trended down most high and
low temperatures in accordance with the latest superblend given GFS and
European model (ecmwf) 850 mb temperatures staying below zero after Tuesday. Highs should be
mainly in the low to middle 50s and lows in the low to middle 30s...with
some middle to upper 20s possible Wednesday night through Friday night.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 130 PM EDT sun Apr 19 2015

Radar shows large area of rain gradually moving north and should
begin to reach terminal sites early this afternoon. Dry lower
levels initially keeping ceilings in the VFR range but expect these to
lower as rain persists and area of low pressure moves closer and
intensifies. MVFR conditions followed by IFR expected toward late
afternoon or early evening. Dry slot works in middle to late evening.
Could see brief improvement depending on strength of drying but
for now stayed with solid IFR ceilings overnight. Second wave moves in
Monday morning with next batch of rain showers expected during the


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