Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 201655

Area Forecast Discussion
National Weather Service Northern Indiana
100 PM EDT FRI MAY 20 2016

Issued at 445 AM EDT Fri May 20 2016

High pressure will continue to provide fair weather today.
Highs today will be near 70 degrees. A weak upper level
disturbance lifting through the Ohio Valley will bring an increase
in cloud cover to the region. There is a low chance for light rain
along and southeast of the Route 24 corridor tonight. High
pressure will then build back into the region over the weekend
into early next week. This will result in dry conditions and
warming temperatures that could reach near 80 by Tuesday.


Issued at 100 PM EDT Fri May 20 2016

Forecast update sent to increase shower chances across at least the
southeast half of the area as radar and model trends suggest
measurable rainfall may make it further NW than previously thought.

Area of showers was working north and east across southern
Indiana...lining up fairly well with hrrr and rap. MET/MAV guidance
all going categorical for pops in far se areas (Lima, oh) which may
cone to fruition but a lot of dry air for the rain to work on yet
with 15 to 20 degree t/td depressions at the surface. Have therefore
nudged pops up into low end likely in far s/se tonight with
expansion of slight chance or chance pops further nw. More changes
may be needed with afternoon package in a few hours but wanted to at
least start the trend.

.SHORT TERM...(Today and Tonight)
Issued at 438 AM EDT Fri May 20 2016

Multi-lobed mid level circulation over west central Missouri to lift
gradually newd into sern Michigan by daybreak saturday. Initial
northward push of moisture/rain shield thwarted by antecedent dry
air and swrn periphery of mid level height rise centroid/surface
ridge with deep layer dvm. eventually as surface cyclogenesis
unfolds midday over TN to southern OH overnight a more concerted
push of richer 1000-850mb moisture on order of 8-9g/kg reaching
inflection into sern cwa late tonight...before pulling eastward
early Saturday. Given 30-40m/12 hr falls associated with system to
enter cwa and favorable moisture profiles over sern cwa have raised
pops along with slightly more nw reach. Blend of prior forecast and
latest model consensus yields about 70f today which given a decent
amount of insolation again today especially n-nern cwa. Sufficient
offshore component flow should minimize lake shadow in contrast to


.LONG TERM...(Saturday through Thursday)
Issued at 438 AM EDT Fri May 20 2016

High plains mid level ridging to overspread eastward into upper
great lakes in wake of friday night systems passage into new
england that drives significant coastal cyclogenesis. Very dry
/pwat on order of 0.40 inches/ subsident airmass for moderating
temperatures to above normal/near 80 by tuesday. Again as yday
have held line with respect to onset of higher pops/shra/tsra chcs
as initial wave ejection from deep/expansive wrn conus cyclone
likely deflects nw-n of cwa and initial gomex feed lacking/shunted
well westward. Gradual ramp to mid level chance pops starting tue
aftn...though best chances in wed/wed night timeframe as cwa
becomes poised for additional upstream shortwave ejections in deep
swrly flow as large scale trof opens/broadens and transitions from
highly pos tilt to neg tilt axis /BC into corn belt/ by dy7.
Models hint at shallow frontal passage late thu that could provide
convective focus to linger into next weekend.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 100 PM EDT Fri May 20 2016

Surface low pressure centered over northern Mississippi has spread
high cloud shield over the forecast area. This system will lift
northeast into the Ohio Valley tonight and is expected to lower
ceilings at KFWA but still remain VFR. Latest HIRES guidance still
indicating potential for a stray shower to work back into KFWA
overnight so will keep mention of VCSH going. Easterly flow this
afternoon 10-15kts as gradient strengthens initially as low
approaches...then becoming more northeast and generally less than
10kts by Saturday morning.


.IWX Watches/Warnings/Advisories...


LONG TERM...Murphy

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