Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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280 FXUS63 KIND 011849 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 249 PM EDT Mon Jul 1 2024 .KEY MESSAGES... - Mostly Clear and pleasant tonight. - Partly Cloudy and warmer on Tuesday. - Heat and humidity continues through Friday. - Rain and thunderstorm chances Wednesday through Friday, A few strong to severe storms are possible on Wednesday and Thursday. && .SHORT TERM (This evening through Tuesday)... Issued at 243 PM EDT Mon Jul 1 2024 Surface analysis early this afternoon shows strong high pressure in place over MI. Cool and dry easterly flow was in place over Central Indiana. GOES16 shows only a few high clouds across Central Indiana, and dew points were mainly in the 50s. Aloft, water vapor imagery showed strong ridging in place over the plains states. This was resulting in NW flow aloft and subsidence over Indiana. Upper level moisture was spilling over the ridge into Illinois, but subsiding over Indiana. Tonight... Models suggest the large area of high pressure over the Great Lakes will drift to the eastern Great Lakes and New England. Ridging and high pressure aloft will continue to protect Indiana from any upper support to the west and subsidence remains in play. Thus mostly clear skies will be expected. Warm air advection is expected to begin late tonight as the ridge axis aloft reaches the east coast. This will start the beginning of warm air advection into Wednesday. Lows overnight should be warmer than previous night as the pool of cooler air drifts east. Thus expect lows in the middle to upper 50s. Tuesday... Increasing clouds and and heat are expected on Tuesday. The upper ridge axis is expected to drift to the east of coast, allowing warmer southerly and southwesterly flow to push into Indiana. 850MB levels show a surge of warm air advection and the development of a thermal ridge across Indiana as temps there approach 20C. Forecast soundings remain dry and show a mid level inversion that should prevent much CU development. However with the southwest flow in place aloft and a lack of wide subsidence, some passing high clouds seems reasonable. Given the expected warm air advection, highs in the upper 80s seem on the mark. && .LONG TERM (Tuesday night through Monday)... Issued at 243 PM EDT Mon Jul 1 2024 Tuesday night through Friday night... The latter half of this week looks rather active with showers and thunderstorms likely Wednesday through Friday. A decaying complex of storms ahead of an approaching front could move into the area around daybreak Wednesday. Deep-layer shear quickly weakening with eastward extent and a narrow corridor of deep moisture are limiting factors for the aforementioned storms to survive as they move into central Indiana. Model guidance is in good agreement that convection will quickly weaken with little to no impacts during the morning hours due to this. By Wednesday afternoon, moisture advection and daytime heating should promote moderate-strong destabilization ahead of the aforementioned frontal boundary. This along with low-level convergence will likely lead to the development of thunderstorms. Lingering cloud cover from convective debris in the morning may limit destabilization some, but latest model runs continue to show strong destabilization occurring. Modest effective bulk shear around 25-30 knots supports the potential for organized convection. The primary threat is damaging wind gusts, but large hail and locally heavy rainfall cannot be ruled out. Heat/humidity will also be concerning as heat index values could reach or exceed 100F. Forcing primarily confined along the front should allow for upscale growth to occur with time. If an organized cold pool can form, then expect the frontal boundary to briefly be shunted southward towards the Ohio River. Precipitation chances remain high Wednesday night, but POPs may need to be lowered depending on where the front ends up. The front looks to return north Thursday as a low amplitude shortwave moves into the region. Increasing dynamics and moderate to strong destabilization once again will likely promote thunderstorm development during the afternoon. Slightly stronger deep-layer shear suggest another round of strong to severe storms is possible. However, there are some caveats to the forecast. There are signs that clouds could stick around for much of the day with convection possible in the morning. This may augment the thermodynamic environment potentially limiting the severe weather threat. Damaging wind gusts and locally heavy rainfall are the primary threats. A third day of storms is expected on Friday with another deeper trough moving in which will finally kick the annoying frontal boundary out of the area. Favorable dynamics combined with destabilization during the day could promote organized convection once again. There is even greater uncertainty in this setup for multiple reasons. Thursday night/early Friday morning potential convection, location of the frontal boundary, and larger model spread limit confidence for the threat of strong storms on Friday. Mostly dry conditions are expected over the weekend as weak surface high pressure settles in. Rain chances then begin to increase late Sunday into next week with another system potentially approaching. Outside of hot conditions on Wednesday, temperatures generally look near seasonal through the extended. Daily chances for showers/storms mid-late week could limit diurnal heating to some degree. && .AVIATION (18Z TAF Issuance)... Issued at 1216 PM EDT Mon Jul 1 2024 Impacts: - VFR Conditions expected. Discussion: Surface high pressure moving across the Great Lakes will continue to provide a dry easterly flow to Central Indiana. Forecast soundings remain dry through the period under the influence of this high pressure system. Winds will become a bit more southerly as the high reaches the eastern Great Lakes on Tuesday. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Puma LONG TERM...Melo AVIATION...Puma