Area Forecast Discussion
Issued by NWS Northern Indiana

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000 FXUS63 KIWX 231006 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 606 AM EDT Fri Jun 23 2017 .SYNOPSIS... Issued at 340 AM EDT Fri Jun 23 2017 Showers and thunderstorms will become more numerous early this morning. A few of the storms may produce brief periods of heavy rain and wind gusts over 30 mph. Showers and thunderstorms will diminish from northwest to southeast later this morning into this afternoon as a cold front tracks southeast across the region. Drier and cooler conditions can be expected tonight through the weekend behind the cold front. A few disturbances will bring a potential of some isolated showers at times from Saturday through Monday. High temperatures today will range from the mid 70s to around 80. Low temperatures tonight will drop back into the upper 50s. && .SHORT TERM...(Today and Tonight) Issued at 340 AM EDT Fri Jun 23 2017 Forecast still appears to be on track for greater coverage showers/storms this morning, just slightly delayed from previous thinking. Complicated flow pattern this morning with more active northern stream short wave trough beginning to increase large scale lift across the northern Great Lakes into southern Wisconsin. Additional sheared short waves continue to emanate from remnants of tropical depression Cindy across the mid MS Valley. Anomalous deep layer moisture will be in place this morning with primary moisture axis downstream of Cindy and better low level moisture pooling associated with approaching cold frontal boundary from the Corn Belt to the central Great Lakes. Frontal boundary should become more progressive over the next several hours in response to the progression of the northern stream short wave which will allow showers and storms to overspread northern Indiana/southern Lower Michigan in the 11Z-15Z timeframe. With large scale lift on the increase, pre-frontal confluence zone should also become more active through daybreak with additional showers/scattered storms expected to fill in from east central Illinois into northwest Ohio. With PWATS in the 1.75 to 2+ inch range and warm cloud depths in excess of 12K feet, will likely have to monitor for brief periods of heavier rainfall and some localized flooding potential. Currently not expecting significant hydro concerns at this time given quite dry antecedent conditions and more progressive nature of forcing mechanisms. It still appears as though axis of heaviest rainfall will be displaced south/southeast of the local forecast area where deeper moisture and more favorable low level confluence/moisture convergence persist into the afternoon hours. Destablization still looks to be rather limited today due to high coverage of clouds/precip. Other limiting factors for strong/severe storms include better shear profiles more post-frontal in nature and gradual erosion of steeper mid level lapse rates this morning. Few cells may produce wind gusts of 30 to 40 mph today, but currently not expecting any appreciable severe threat. Otherwise, diurnal swing in temps will be limited today by clouds/precip this morning followed by onset of cold air advection this afternoon. This should limit high temperatures to the 75 to 80 degree range today. Few lingering showers possible across the extreme southeast early this evening, but overall quiet weather expected tonight with cooler/drier air advecting across the Great Lakes/Ohio Valley. && .LONG TERM...(Saturday through Thursday) Issued at 340 AM EDT Fri Jun 23 2017 Longwave pattern of western CONUS ridging and eastern CONUS troughing will be maintained through much of the upcoming weekend. Several short wave are expected to translate through upstream ridge into the Great Lakes region this weekend into the first part of next week. This will allow for an extended residence time of low level thermal troughing across the region and much below normal temperatures. The coolest days of the long term period are still shaping up to be Sunday/Monday when highs may struggle to reach 70 across portions of the area. While moisture will be more limited this weekend, forcing with the series of short waves and gradual reinforcement of cold pool aloft argue for maintaining periodic slight chance/low chance shower PoPs through Monday. The strongest of these waves may affect the area Monday, where have maintained the highest chance PoPs along with chance thunder mention. Longwave pattern to break down Tue-Wed as series of Pacific waves dampen the upper ridge, eventually allowing downstream moderation of temperatures across central CONUS as this dampened upper ridge axis shifts eastward. An active northern stream wave pattern for the Wed-Fri period should result in renewed thunder chances with episodic stronger theta-e advective/frontal forcing. Have followed consensus blended solution for temps for Days 5-7 with highs back around 80 by Wed-Thu, although potential does exist for an upward adjustment in later forecast iterations, particularly by Thursday. && .AVIATION...
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(For the 12Z TAFS through 12Z Saturday Morning) Issued at 605 AM EDT Fri Jun 23 2017 Series of weak waves associated with both a cold front and remnants of Tropical Storm Cindi causing a slow expansion in showers and thunderstorms. Main thunder focus has been setting up SW to NE (Logansport to Fort Wayne). Will handle with tempo group for an hour. Focus will then shift to line of showers and storms dropping rapidly SE to bring a few hour period of impacts to both sites. Opted for tempo now as actual impacts from thunder may only last 30 to 60 minutes. Torrential rainfall and possible wind gusts to 30 kts with the strongest cells. Conditions will slowly improve through the day with a return to MVFR and eventually VFR this afternoon and evening.
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&& .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Marsili SHORT TERM...Marsili LONG TERM...Marsili AVIATION...Fisher 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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