Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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580 FXUS63 KIND 021344 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 944 AM EDT Sun Jun 2 2024 .KEY MESSAGES... - Potential for patchy fog this morning and again tonight into Monday morning - Warmer next week with periodic thunderstorm chances. The best chances will be Wednesday. && .FORECAST UPDATE... Issued at 944 AM EDT Sun Jun 2 2024 Hi-Res soundings are showing a saturated or near rated layer from the surface up to near 10K feet. Winds were less than 10 knots through this layer, so despite a very dry layer above, mixing out of the boundary layer will be a slow process at best. So, expect little improvement through early afternoon with perhaps some improvement late in the day. This will have a big impact on temperatures. May need to lower temperatures a few degrees this afternoon. Will see how things play out and do just that for the next update if needed. Meanwhile, the weak surface system moving through has aided in generating a few very light showers over southeastern sections and they may continue for a few more hours but then ridge induced subsidence should put an end to it. && .SHORT TERM (Today and tonight)... Issued at 257 AM EDT Sun Jun 2 2024 Early this morning mid-lvl water vapor was still at a maximum over Central Indiana, with some drying noted upstream across Illinois/Missouri. The lack of a pressure field coupled with the moist boundary layer is allowing some lingering drizzle or mist to continue; however, this should become more widespread during the pre- dawn hours. This opens the door to potentially seeing fog development. The moist/damp surface from earlier showers will couple with the shallow stratus deck loosing the upward energy and sinking, then the lack of a pressure gradient to encourage mixing of saturated parcels or at least causing any additional vertical motion sets the stage for early morning fog to develop. VWP from KIND already indicating most targets under 5kts, with the only lingering wind above 3kft agl but this area is also decreasing. Some encouraging guidance is that many hi-res members displayed within DESI suggests only patchy dense fog developing and only the HRRR has been more suggestive of greater coverage. This helps with confidence to lean towards only patchy fog developing from the sinking stratus deck. But once any fog does develop, due to a lack of mixing/isallobaric field would suggest it will linger through mid- morning before burning off. Today... Boundary layer will continue to be moist through midday, perhaps into the afternoon hours. Lack of a gradient from a weak anti-cyclonic feature arriving should delay the erosion of any shallow stratus/fog from early in the morning. Which could cause a slower response for temperatures due to the shielding lingering longer. The mid-lvl flow does flatten out, with indications that perhaps an increase to the forward propagation will occur and help to push the departing moist layer east. But the caveat is that the surface remains disjointed and will not realize this upper level flow through much of the day. So temps will likely remain in the 60s perhaps around 70 by the afternoon hours, then once the stratus deck erodes enough the surface parcels should quickly respond and push temps into the mid/upr 70s quickly. Given the quasi-sinking air overhead this afternoon, not expecting development to a cumulus field. Which should inhibit our potential for seeing any convection let alone see rain become organized. So will maintain the dry forecast. Tonight... Could see a repeat setup for fog late tonight. With a lack of diurnally induced mixing scouring any moisture from the surface/boundary layer in the afternoon/evening hours, expect more optimal conditions for fog to develop. Again the wild card will be winds aloft. While the boundary layer appears to be lacking any substantial pressure gradient with guidance suggestive of minimal isallobaric pressure change in place, this should lay the foundation for fog development after sunset. But flow in the mid- lvls and aloft do appear to be more zonal and could be just enough to limit the fog growth tonight if perhaps only allowing patchy fog to occur. && .LONG TERM (Monday through Saturday)... Issued at 257 AM EDT Sun Jun 2 2024 The long term period will be warm, with highs in the 80s, for much of the week before temperatures drop back into the 70s for the weekend. There will be periodic chances for showers and thunderstorms through the week as multiple shortwaves and then a larger trough moves through into the Great Lakes region while an upper high settles into the southern plains and SW states. South to southwest flow at the surface for most of the week will advect warm and moist air into the region. Models still don`t have great agreement with precipitation through the period but generally expecting to see chances for rain Monday night into Tuesday followed by another wave Late Tuesday into Wednesday. A break between waves may be possible. As the high over Mexico moves into the south- central to southwest portion of the CONUS, the large upper low near the Dakotas will progress towards the Great Lakes. The associated cold front looks to advance through central Indiana sometime Thursday night into Friday and lower temperatures for the weekend. Additional precipitation may form along the front and another rain chance possible over the weekend. Severe weather is not expected at this time but can`t rule out a few storms producing some gusts midweek. && .AVIATION (06Z TAF Issuance)... Issued at 226 AM EDT Sun Jun 2 2024 Impacts: - Poor flying conditions through daybreak - IFR flight conditions will slowly improve to VFR midday Discussion: Stagnant airmass overhead has allowed the nearly saturated moist layer to become baggy and sink towards the surface. This has resulted in some lingering sprinkles or mist along with a shallow stratus layer that is within a few hundred feet of the surface. Guidance suggests that the shallow stratus may become in contact with the surface with fog otherwise being observed, but some guidance indicates the fog may only be scattered to perhaps patchy. The KIND VWP is still indicating some largest aloft at 10 kts, which could be enough friction to inhibit fog development, but the question is what will occur in the next few hours. Have a few points seeing fog development with VSBY down to around 3sm, but this may need to be adjusted should VWP begin to show nearly calm conditions aloft sooner. Expect after daybreak a slow and steady improvement to the CIGs with a light northerly flow helping to dry the near surface environment. This should translate into VFR conditions developing by midday or perhaps early afternoon. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...MK SHORT TERM...Beach LONG TERM...KF AVIATION...Beach