Area Forecast Discussion
Issued by NWS Northern Indiana

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000 FXUS63 KIWX 272342 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 742 PM EDT Thu Apr 27 2017 .SYNOPSIS...
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Issued at 740 PM EDT Thu Apr 27 2017 Mostly cloudy, cool, and dry conditions are expected overnight and Friday. Lows tonight will drop into the lower to middle 40s...with highs on Friday recovering into the 60s. A frontal boundary will bring periods of rain and perhaps a few thunderstorms to the region late Friday through Monday. The heavier, more widespread, rain is expected to fall later Saturday into early Sunday. Highs on Saturday will generally range between the mid 50s to mid 60s...with temperatures warming into 70s on Sunday. Cooler conditions are then expected behind this system next week.
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&& .SHORT TERM...(This Evening through Saturday) Issued at 303 PM EDT Thu Apr 27 2017 Cooler/drier air will continue to funnel in post-frontal late this afternoon and evening as low pressure lifts north into Ontario. The only real adjustment to the forecast was to increase sky cover due to expected slower erosion of low clouds and increase in mid-high level clouds later tonight into Friday morning as warm advection commences. Strong Northeast Pacific upper jet will carve out a negative height anomaly Friday into Saturday across the Four Corners...with subsequent downstream mid/upper ridging across the Eastern US and a strengthening low level baroclinic zone materializing across the Mid MS/OH Valleys. This combined with ample GOM moisture return in deepening southwest flow will set the stage for periods of rain later tomorrow into Saturday. A disjointed lead wave and initial surge of elevated moisture/isentropic ascent will bring chances for lighter rain later Friday into Friday evening, though some more moderate rain and perhaps some embedded thunder will be possible mainly along/south of US 24 on the nose of the associated weak LLJ. Seasonable temps and mainly cloudy otherwise tomorrow. An active low level frontal boundary will then lay/stall out over the Mid MS/Northern OH Valleys later Friday night into Saturday morning as high pressure nudges into the Great Lakes and low pressure organizes over the Southern Plains. The result will be a trend toward drier/cooler conditions northwest of US 24 and continued higher chances for periods of rain/elevated thunder along/southeast of US 24 near the frontal slope. && .LONG TERM...(Late Saturday through Thursday) Issued at 303 PM EDT Thu Apr 27 2017 12z model suite continued to point to the late Saturday through Sunday morning periods as the best opportunity for more widespread/heavier rainfall as moisture transport/convergence maximizes in response to northeast ejection of deepening low into the Central US. As mentioned in previous discussions it is difficult to pinpoint where the heaviest swath of rain will occur given smaller scale elements that cannot be resolved at this forecast range. With that said will continue to highlight the potential for a swath of 1-3" and possible low lying/river flooding in the ESF (Hydrologic Outlook), with favored models hinting at our nw IN/sw Lower MI counties for heavier totals. Active frontal boundary likely lifts north into Lower MI/far nw IN Sunday into Sunday evening in response to deep low eventually lifting into Iowa. This will allow warmer/more unstable air to briefly advect back into the local area during this time. Chances for occasional showers/storms will likely persist into Sunday as height falls overspread warm sector and convectively induced/smaller scale waves lift northeast in strong southwest flow, especially over nw IN/sw Lower MI near frontal zone. System cold front/occlusion then swings through sometime Sunday night/early Monday with additional chances for showers/storms. The main threat will continue to be locally heavy rain as marginal instability and late arrival of cold front likely limits the severe threat. The early week period will feature breezy/cooler conditions and chances for a few light showers post-frontal as wrap around moisture rotates through under filling low meandering northeast through the Upper Midwest/Northern Great Lakes. Drier with temps remaining below normal into the middle of next week. && .AVIATION...
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(For the 00Z TAFS through 00Z Friday Evening) Issued at 733 PM EDT Thu Apr 27 2017 Primarily VFR conditions to persist through the forecast period. Some brief excursions to MVFR due to cigs through this evening...however do not anticipate any cigs blo 2kft for impact. Otherwise attention on backing surface flow and a more elevated ceiling into Friday. While rain chances non-zero, they do not appear sufficient for inclusion at this time as a more significant chance with impact potential holding off until just beyond current forecast period.
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&& .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...Small Craft Advisory until 8 PM EDT this evening for LMZ043-046. && $$ SYNOPSIS...Murphy SHORT TERM...Steinwedel LONG TERM...Steinwedel AVIATION...Murphy Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana

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