Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 280812

Area Forecast Discussion
National Weather Service Northern Indiana
412 AM EDT Fri Apr 28 2017

Issued at 356 AM EDT Fri Apr 28 2017

High pressure will move out of the area this morning and a warm
front over the southern U.S. will lift north into the Ohio Valley
this afternoon, likely causing showers and scattered
thunderstorms to move into our area by tonight. The warm front
will move slowly north across our area over the weekend as a
strong low pressure system moves slowly northeast from the
southern plains, resulting in showers and scattered thunderstorms
with locally heavy rainfall across our area. The low will move
slowly northeast across the Great Lakes early next week resulting
in windy and cool conditions across our area with a chance of


.SHORT TERM...(Today and Tonight)
Issued at 356 AM EDT Fri Apr 28 2017

Ridge passing through the area early this morning. Low cloud deck
over the area eroding and should gone entirely by 12z, hwvr high
clouds already streaming in from the w-sw and this should cont
through the day as warm front over the srn plains/lwr ms valley
lifts north into the lwr OH valley. Should be sufficient filtered
sunshine to allow temps to rise into the 60s in the aftn. Over-
running of the warm front by a very warm/moist airmass to the
south, should result in scattered showers developing over our area
this aftn, with best chances across the south. As higher theta-e
air conts to advect north tonight via a LLJ, convection should
intensify allowing tstms to develop. CAMs differ on location and
duration of deep convection tonight ranging from the OH River to
over our srn CWA. If boundary does lift this far north (per NAM
solution), rotating storms producing large hail and training
echoes/locally heavy rainfall psbl over srn portion of our cwa,
but confidence in this scenario is low given Hires model
differences. Lows expected to range from the mid 40s nw to the
m50s se.


.LONG TERM...(Saturday through Thursday)
Issued at 356 AM EDT Fri Apr 28 2017

Warm front expected to lift slowly north over the weekend as
deepening upr low moves into the srn plains and associated sfc
low lifts northeast to MO. Backing/strengthening flow will allow
a very warm/moist airmass to continue to impinge on the frontal
boundary resulting in persistent/widespread showers and sct tstms
with the potential for heavy rainfall. Front will gradually
transition from a w-e to sw-ne orientation in this timeframe
resulting in longer duration and thus higher rainfall
amounts/flooding potential across nw 1/2 of our cwa. There is also
a low threat of svr storms over the weekend. On Saturday we will
remain north of the warm front so main threat would be for hail
storms. On Sunday as front lifts ne into nw IN/sw MI, moderate sfc
based instability may develop with contd strong deep layer shear
in place. Lack of sgfnt forcing in the warm sector along with
potential capping or cloud cover are limiting factors. Cdfnt will
wrap around the low and lift ne across our area Sunday night.
Diurnal cooling should limit instability at that time but wind
fields will be very strong so even wk convection could result in
some pockets of damaging wind gusts with the fropa.

Occluded/vertically stacked low will lift slowly ne Mon-Tue
resulting in cool/windy conditions with a chc of showers in our
area. Another shrtwv expected to dive se into the srn plains Wed
with subsequent sfc low expected to track farther to the se than
this weekend`s system with associated precip shield prbly just
skimming our se or bypassing us altogether. This scenario will
keep cool airmass in place across the grtlks with temps in our
area remaining a bit blo normal through the end of the work week.


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 137 AM EDT Fri Apr 28 2017

Patches of cu were drifting across both TAF sites on the leading
edge of some slightly moister air. VFR conditions expected to
persist through at least 18Z with forecast becoming rather
uncertain with regards to not only precip chances but flight
conditions through the remainder of the period.

At least a small period of showers appears in store possibly as
early as 21Z with better chances more in the 00z-06z Sat window.
Models show steady decrease in cigs with low end MVFR/Upper end
IFR cigs possible after 00Z. Not exactly sure how much moistening
will occur and some models suggest deeper moisture could be pushed
back south of both sites. Have opted to go with tempo mention for
showers and excursion to MVFR cigs for the time being.





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