Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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690 FXUS63 KIND 280137 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 937 PM EDT Mon May 27 2024 .KEY MESSAGES... - Partly cloudy and cooler Tonight and Tuesday - Dry and Seasonable Thursday and Friday, Rain chances late Saturday into Sunday && .FORECAST UPDATE... Issued at 936 PM EDT Mon May 27 2024 Radar was showing a couple of strong to severe thunderstorms moving southeast across Illinois from just southwest of Aurora to just southeast of Peoria. That said, downstream instability is very weak to non-existent. So, think this convection will run out of steam around or shortly after moving into the Wabash Valley. This convection was aided along by an upper wave over SW Wisconsin and NW Illinois embedded in the broad cyclonic flow. With instability lacking and sunset at hand, will only keep small PoPs in across the upper Wabash Valley and only through Midnight. Otherwise, upstream obs, GOES-16 IR satellite and soundings are supportive of some patches of mid and high clouds with otherwise breaks in the cloud cover. Winds will also drop off and allow for decent cooling and overnight lows should approach upstream dew point temperatures in the 50s. && .SHORT TERM (This evening through Tuesday)... Issued at 234 PM EDT Mon May 27 2024 Synopsis: Surface analysis early this afternoon shows low pressure northeast of Lake Huron. This system was providing cyclonic lower level flow across the Great Lakes and central Indiana. A weak trough pivoting around the low was found entering Ohio, and a second weak trough was found over northern IL. GOES16 imagery shows a stratocu deck in the wake of the trough across most of Central Indiana. Aloft, water vapor shows an upper trough over Michigan extending south across eastern Indiana. Another upper low was found over Minnesota. Subsidence was shown over Indiana and Illinois and Ohio. Dew points have fallen to the middle 50s and cooler westerly flow was in place. Tonight - Models suggest that tonight the upper low near Lake Huron will push east and away from Central Indiana. However the other upper low over MN will also push east, pushing another upper trough axis across MI and Indiana overnight. Moisture for this next system will be limited as subsidence that has been occurring through the day along with the prevailing west to northwest lower level flow. Forecast soundings are showing a relatively dry column through the night, so mainly some passing high clouds will be mainly expected. With cooler northwest flow in place, lows in the mid 50s will be expected Tuesday - The upper flow will remain cyclonic across the Great Lakes and Ohio valley on Tuesday as strong ridging builds aloft over Rockies and high plains. An embedded short wave looks to pass within this cyclonic flow aloft through the afternoon, but once again, moisture remains lacking. Forecast soundings fail to show deep saturation, but do hint at CU deck development in the late afternoon. An inversion aloft will prevent any deep growth. Thus expect mainly partly cloudy sky through the course of the day, as Indiana will lie between departing surface low pressure and approaching high pressure. An isolated afternoon shower or sprinkle cannot be ruled out in the late afternoon. Any amounts will be very light and isolated, mainly across the north and east parts of central Indiana during the late afternoon and early evening. Overall there will be many dry hours. Cold air advection will still be ongoing, although it will be rather weak. Look for highs in the lower to middle 70s. && .LONG TERM (Tuesday night through Monday)... Issued at 234 PM EDT Mon May 27 2024 Wednesday and Thursday... The broad upper trough that was in place for the early half of the week begins to push east with one final shortwave moving across the area Wednesday. Steep low level lapse rates and very limited instability combined with a cold front moving in from the NE should allow for some afternoon showers to develop. Any thunder chances would be limited and mainly focused along the IN/OH border. A secondary shortwave moves over the eastern Great Lakes on Thursday keeping conditions on the cooler side with winds remaining out of the NE/E. Highs on both Wednesday and Thursday should stay in the lower 70s for much of the area with the exception of the far southern portions of the area where mid 70s are possible. Overnight lows may drop into the lower 50s to upper 40s with clear skies, light winds, dewpoints in the lower 40s, which will setup some good radiational cooling. Friday through Sunday... High pressure over the area on Friday will keep skies clear and temps near normal. Upper level ridging over far southern TX and into northern Mexico will allow for a fairly wavy zonal flow pattern over the central US as we head into the weekend and into the following week. Increasing return flow off of the Gulf of Mexico will bring upper 60 to lower 70 degree dewpoints back to the region this weekend with highs gradually warming into the 80s by Sunday. A shortwave moving out of the Rockies will push into the Ohio Valley/Great Lakes region on Saturday but there remains a lot of spread amongst ensemble members on the timing of any precipitation into central IN. Expect increasing rain chances Saturday evening through Sunday as the shortwave moves through. Lapse rates aloft and wind shear aren`t overly impressive and the position of the potential surface wave would suggest general thunderstorm potential for the weekend. && .AVIATION (00Z TAF Issuance)... Issued at 553 PM EDT Mon May 27 2024 Impacts: - Small chance of brief MVFR or worse fog 09z-12z at the smaller airports Discussion: Surface high pressure will build in from the west in the wake of the low pressure system departing northeast and currently over southwestern Quebec. That combined with a mostly dry column will provide mostly or all VFR flying conditions. The only caveat would be the small chance of MVFR and worse conditions in fog toward daybreak at the smaller airports. Also, would not rule out a brief light shower at KLAF and KIND 00z-06z as an upper waves dives down out of southern Minnesota. Winds will be from the west with modest gusts through 01z tonight and then become light to calm late tonight before mixing allows for more modest gusts Tuesday afternoon. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...MK SHORT TERM...Puma LONG TERM...Stumpf AVIATION...MK