Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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289 FXUS63 KIWX 091906 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 306 PM EDT Thu May 9 2024 .KEY MESSAGES... -Rain chances continue into tonight before sliding south and east. -A quick moving system provides another chance for rain later tonight into Saturday morning -Yet another chance for rain slowly slides southeast Monday night and Tuesday. Some thunder is possible Monday afternoon. && .DISCUSSION... Issued at 257 PM EDT Thu May 9 2024 A trough continues swinging southeastward through the Great Lakes and Ohio Valley areas today and this pushes a surface low pressure system eastward towards the Mid Atlantic States today. Large scale ascent begins to wane this afternoon and dry air advection gets under way in the low levels as the main moisture plume shifts southeastward as well. As such, we`ll see a reduction in rain chances into tonight, especially after a final vort max swings through after 00z and northern stream flow gets underway. Friday is expected to be dry, but with cloudy skies in the morning scattering out by the afternoon. Height rises ensue especially midday Friday with noticeable mid level ridging moving through. As mixing commences Friday morning, could see some gusty winds to start, achieving 15 to 20 mph, before the gradient begins to relax for the midday and afternoon hours. Temperatures will be slightly warmer with the increased mixing and diminished rain, allowing for low to mid 60s for highs. Those aformentioned mid level height rises become height falls again Friday night as another trough moves into the area with a potent vort max embedded within it. An thin area of large scale ascent associated with the surface low pressure and its attendant frontal system provides ample forcing for this event. However, the wave is fairly quick-moving and the moisture plume is rather thin, which will help to restrict total precipitation output to a quarter inch or less before it departs. Mid level height rises ensue midday Saturday and subsidence occurs during the morning hours allowing a transition back to drier weather through the morning. As such, cloud cover decreases through the afternoon Saturday. Expect similar to slightly warmer high temperatures to Friday with low to mid 60s. Additionally, a lingering tight gradient allows for gusts between 20 and 30 mph Saturday. Mid level height rises and ridging provide a drier day Sunday as surface high pressure edges into the area. This is the pick of the weekend with plenty of sunshine expected along with some high clouds. Warm advection ensues during the daytime Sunday allowing high temperatures to rise back into the 70s. Monday is expected to be affected by a moisture stream in from the south with a Gulf of Mexico connection. With forcing far enough away from the area, am a little hard pressed to have PoPs associated with it Sunday night into Monday morning, especially given the relatively dry atmospheric column in that area. However, instability does appear to build to between 900 and 1200 J/kg on the ECMWF so perhaps a stray shower/storm could be around during the afternoon/evening. During this time, a boundary slows down just into MI as an upper level low pressure system passes by to our south. On Tuesday, a surface low pressure system develops through the Ohio River/ Tennessee River valley area and there`s a disjointed setup similar to a TROWAL as this occurs. However, the placement of the upper low to our south is in question to some extent with the ECMWF out on a limb with it farther south, but also a little bit odd in that it could siphon all of the moisture away from its northern periphery as long as surface convergence doesn`t further enhance that northern periphery. There is still time for this get smoothed out over the coming days. This timing and placement of the energy for the Tuesday system affects what happens later Wednesday and Thursday with the GFS currently out on its own with rain on Thursday. The NBM will be allowed to handle this period for now given the disagreement in modeling. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 140 PM EDT Thu May 9 2024 Weak surface low is currently moving across the area. Precip has temporarily ended at KSBN and will temporarily end at KFWA in the next two hours as a midlevel dry slot moves overhead. Ceilings are also expected to improve slightly though remain low MVFR through the evening. Additional wraparound showers are expected later this evening but ceilings will continue to slowly rise as dry air advection and mixing increase slightly. Return to VFR expected by late tonight with tranquil weather on Friday. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Roller AVIATION...AGD