Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 170756

Area Forecast Discussion
National Weather Service Northern Indiana
356 AM EDT Mon Apr 17 2017

Issued at 350 AM EDT Mon Apr 17 2017

A ridge of high pressure will bring quiet weather to the area
today under sunny to partly cloudy skies. High temperatures today
will remain above normal ranging from the mid 60s to lower 70s.
The combination of mainly clear skies tonight and light winds will
allow temperatures to drop into the 40s. This high pressure will
shift east for Tuesday allowing for some moderation in
temperatures. A pair of upper level disturbances will bring
chances of showers and thunderstorms late Tuesday night and
Wednesday, and then a greater chance for Wednesday night and early
Thursday. A transition back to cooler temperatures is expected by
the end of the work week.


.SHORT TERM...(Today through Tuesday night)
Issued at 350 AM EDT Mon Apr 17 2017

A quiet weather pattern will continue for today through Tuesday with
above normal temps continuing.

Much drier post-frontal air continues to advect across the area this
morning as sfc dew points have dropped into the mid and upper 30s
across northern Indiana/southern lower Michigan. The majority of
short waves of note will remain either north or south of the area
today. A pair of more distinct upper level short waves will continue
to track across Upper Midwest/Great Lakes region this morning while
a weaker mid level short wave shifts across lower/mid MS Valley
region. Some weak echoes noted across central Illinois this morning
in vicinity of lagging weak mid level baroclinicty/convergence axis,
but any sprinkles will likely remain well southwest of the area
this morning with dry low levels too much to overcome. Expecting
mid clouds to decrease later this morning across the south with a
secondary patch of mid level clouds possibly moving across
northern locations later this morning/early afternoon. Despite low
level cold advection and weak flow today, dry nature to air mass
and good deal of insolation most locations should be sufficient
for well above normal highs again from mid 60s to lower 70s.
Slightly cooler temps are expected near immediate lakeshore areas
with low level anticyclone and cold lake temps promoting
weak onshore flow. Quiet weather in store tonight with mainly
clear skies, and chilly conditions back into the 40s. Low level
anticyclone should remain progressive to the eastern Great Lakes
by Tuesday morning and currently not expecting any frost issues at
this time.

For Tuesday and Tuesday night, attention will turn to a progressive
eastern Pacific wave which is working across Pacific northwest this
morning. This wave will take a northerly track from Northern Plains
to the northern Great Lakes Tuesday. Increasing and slowly veering
southerly flow downstream of this feature will provide a mild day
Tuesday. More notable low level moisture transport will be on the
upswing late Tuesday afternoon into Tuesday evening as low level jet
axis begins to approach the region. Bulk of precip chances later
Tuesday night should be tied to broad pre-frontal confluence zone
to the south of the upper Great Lakes short wave and have kept
ramp up in Pops to high chance low likely from northwest to
southeast for the late Tuesday night-Wednesday morning period with
some potential of embedded thunder increasing overnight.


.LONG TERM...(Wednesday through Sunday)
Issued at 350 AM EDT Mon Apr 17 2017

On Wednesday, cold frontal boundary will likely be sagging across
the southern Great Lakes as stronger mid level wave tracks across
the northern Great Lakes. A band of showers and isolated
thunderstorms should accompany the front Wednesday morning, but
frontal boundary is not likely to make significant progress
southward and stall somewhere across central or southern portions
of the forecast area. This setup should be conducive for a classic
sharp April temperature gradient from south to north across the
forecast area Wednesday afternoon. Tried to sharpen this gradient
up in this mornings forecast, but will obviously need refinement
in future forecasts. Cyclogenesis in lee of Rockies to commence
early Wednesday as next stronger eastern Pacific wave tracks
across central CONUS. A broad region of warm/moist advection over
stalled frontal boundary will result in continued
shower/thunderstorm chances Wednesday afternoon, with
showers/storms becoming likely Wednesday night as low level warm
front lifts north/sharpens and upper speed max becomes to impinge
on the western Great Lakes. This setup should tend to favor
northern portions of the forecast area for heavier precip
Wednesday night/Thursday morning but still good deal of
uncertainty where heaviest precip axis will set up. In terms of
thunder potential, this pattern could favor a forward propagating
thunderstorm cluster to move across northern Indiana/southern
lower Michigan some time later Wednesday night with possibly some
hail/wind threat. Showers/storms continue into Thursday morning,
diminishing in coverage in the afternoon as dry slot/cold front
overspread the area.

Temps to return back to slightly below normal by Friday behind
Thursday system with medium range models at least in general
agreement in splitish flow pattern setting up across western
CONUS with upper trough amplifying across the southern Plains.
Northward migration of strong frontal forcing looks to increase
chances of rain (possibly some thunder) for next weekend.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 120 AM EDT Mon Apr 17 2017

High pressure and very dry air will ensure VFR conditions through
the period. NW winds may approach 5-10 kts at times but will
generally be light and variable.




SHORT TERM...Marsili
LONG TERM...Marsili

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