Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 280204

Area Forecast Discussion
National Weather Service Northern Indiana
904 PM EST Mon Feb 27 2017

Issued at 435 AM EST Mon Feb 27 2017

A series of systems will impact the region starting late tonight.
Each one will bring increasing moisture and rain chances.
Isolated thunderstorms are also possible Tuesday night into
Wednesday morning. It will remain mild through midweek. Highs
today will reach the upper 40s to lower 50s and into the upper
50s to lower 60s on Tuesday. Colder air will arrive by later
Wednesday into Thursday with chances for snow showers lingering
through the end of the week.


Issued at 855 PM EST Mon Feb 27 2017

Forecast generally on track into the overnight hours. Dry air mass
remains in place with dewpts in the 30s. Band of radar returns
across Central Illinois not reaching the ground nor is shower
activity in portions of Missouri. Hi res models all seem to match
with this scenario with rapid uptick on precip after 6Z as low
level jet ramps up and surge of higher theta e air moves rapidly
NE. Elevated showers/isolated thunderstorms still appear on track
and no sig changes to timing or coverage.


.SHORT TERM...(Tonight through Tuesday night)
Issued at 300 PM EST Mon Feb 27 2017

Potent upstream sw trough digging through cntrl CA attm will swing
through the srn Rockies tonight and through the central plains
Tue night. Downstream lee side cyclogenesis will consolidate Tue
aftn across KS and then lift northeast through MI on Wed. Until
then warm sector will expand greatly with significant low level
thermal troughing building into the srn lakes. Will bump max temps
higher esp in light of strong mixing Tue aftn. Otherwise lead
buldge of higher theta-e air on nose of newd advancing low level
jet will lead to shra and perhaps embedded thunder after midnight

Initial theta-e surge weakens Tue under modest mid level capping.
Lack of background synoptic forcing suggest little of concern until
late aftn west tied to renewed...rapidly increasing low level
mass flux. Of concern is escalation of deep layer flow Tue night
within destabilizing airmass esp srn half and deep tropospheric
ascent that develops within/ahead of prefrontal trough overnight.
Depth of low level theta-e ridge certainly supportive of potential
severe storms here from late afternoon through early Wed morning
with a damaging wind threat given extreme background low level
flow in place. Nonetheless some significant rainfall may
materialize through the Wabash and Maumee basins and elicit some
minor river flooding given wide open GOMEX feed.


.LONG TERM...(Wednesday through Monday)
Issued at 300 PM EST Mon Feb 27 2017

Progressive system aloft will pass through the lakes Wed as sfc cold
front sweeps east. Mild morning temps will crash esp west as low
level cold advection wraps in with aftn snow showers far north
pending where mid level deformation zone/moisture plume tracks.

Secondary clipper follows Thu with a period of warm advection snow
followed by a period likely lake enhancement Thu night north half
and secondary cold advection surge into Fri. Thereafter zonal flow
aloft develops before amplifying late weekend. Thus cold temps Fri
will quickly moderate back to well above normal by Sun.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 616 PM EST Mon Feb 27 2017

High pressure will lead to southerly flow this evening. VFR
conditions will persist until ceilings begin to drop into MVFR by
12z at KSBN and slightly later at KFWA as rain showers associated
with a warm front pushes eastward. Isolated thunder is possible
but left out of forecast due to low confidence. Rain chances
decrease by early afternoon but ceilings are expected to remain





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