Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 190626

Area Forecast Discussion
National Weather Service Northern Indiana
226 AM EDT TUE JUL 19 2016

Issued at 220 AM EDT Tue Jul 19 2016

Under mostly clear skies, temperatures will drop into the lower
and middle 60s by daybreak. Very hot and humid conditions are
expected Thursday through the weekend. High temperatures are
expected to be around 90 to the middle 90s with overnight lows
only in the middle 70s from Thursday to Saturday. Heat indices
during this period could reach from near 100 to 110 degrees.


.SHORT TERM...(This Evening through Tuesday)
Issued at 307 PM EDT Mon Jul 18 2016

Cold front moving through the forecast area and should exit the
southeast early this evening. A few light showers have developed
along boundary but are quickly sliding southeast. Mesoanalysis still
shows about 1-2k J/KG CAPE in the far south so will carry a slight
chance of thunder until front clears...ending by 00z.

High pressure to slide in overnight with sfc winds becoming light or
calm. Some patchy fog could develop overnight...especially south and
west where moderate to heavy rain fell last night and NAM12 wants to
hold onto sfc dewpoints in the mid 60s while drier air infiltrates
from the north across northern and eastern areas. Most other
guidance wants to drop dew points into lower 60s in the southwest.
For now will not add any fog mention to grids but evening shift can
watch dew point trends.

Tuesday should be nice July day as broad high pressure sits over the
region.  Seasonable temperatures in the low to mid 80s expected and
tolerable dew points in the 60s. Could be some cu development
northeast with short wave leading to partly cloudy skies there but
low levels look too dry for any pop mention.


.LONG TERM...(Tuesday Night through Monday)
Issued at 307 PM EDT Mon Jul 18 2016

Increasing heat and humidity remains the story for the long term
period. Still some questions as to how hot it will get given
potential for ridge riding convective systems and our proximity to
active ridge periphery. Strong cold front possible by late Saturday
or Sunday followed by cooler and less humid conditions early next

Temperatures and humidity to slowly rise with heat and humidity
peaking in the Friday and Saturday window. Several uncertainties to
contend with as has been discussed at length for the past several
days. Impressive mid summer expansive ridge will build from the
central plains into the northern plains and Mississippi River valley
region Tuesday. This will keep northwest flow aloft from Minnesota
to the Carolinas with a couple ridge riding short waves progged to
move through the flow. First wave looks to dive into western Great
Lakes Wednesday with potential ongoing MCS making a run for local
area. High pressure will still be in control at the surface and
model forecasts for instability look meager with lack of good return
low level moisture feed. Concern though that potential MCV will
bring its own mesoscale moisture and with expected bulk shear in the
30-40 knot range could see at least non-severe storms or residual
showers make it into local area...similar to what we saw this past
Sunday. Will maintain low chance pops for Wednesday and Wednesday
night with this scenario in mind but expect a lot of changes and
refinement closer to Wednesday. Also kept low pop Thursday with nod
to latest ECMWF and its MCS placement early Thursday.

Large scale ridge looks to expand northeast in wake of
aforementioned short waves with subsidence later Thursday. This
should allow heat and humidity to expand into our area. As this
occurs...ridge expected to flatten upstream with additional short
wave energy moving toward us by Saturday. Westerlies will be
dropping southward and possible strong cold front passage appears
likely on Saturday or Sunday with model differences noted. Given
expected moisture and strong heating in place ahead of this
front...possible severe weather event is not out of question
depending on timing and model evolution.

Heat indices likely to push 100-110F during this short heat wave.
Possible advisories will be needed if expected conditions happen.
Any convective system to our north could easily spread high canopy
of clouds over us and limit temps so remain cautious at this time.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 211 AM EDT Tue Jul 19 2016

Somewhat drier air was trying to spread over northern Indiana
behind a weak front. Ground fog was forming over the south half of
the area. The visibility at Fort Wayne had dipped under 3 miles in
this ground fog. Conditional climatology supports a strong signal
of IFR conditions through 13Z followed by rapid improvement. Have
incorporated these factors into the 06Z TAFs. The visibility at Ft
Wayne could vary greatly early this morning until the fog lifts.


.IWX Watches/Warnings/Advisories...


SHORT TERM...Lashley
LONG TERM...Lashley

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