Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
057 FXUS63 KIND 170655 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 255 AM EDT Fri May 17 2024 .KEY MESSAGES... - Patchy fog will be around parts of the northwest early this morning - Scattered showers and storms will continue into the evening hours - More fog possible tonight - Very warm Sunday-Tuesday with highs in mid to upper 80s...before increasing threat of strong/severe t-storms next Tuesday-Wednesday && .SHORT TERM (Today and tonight)... Issued at 255 AM EDT Fri May 17 2024 Early this morning, showers with some embedded thunder were across much of the southeastern half of the forecast area. Forcing for these was coming from upper energy in a broad upper trough along with some influence a couple of upper jet streaks. Much of this forcing will gradually shift east during the predawn hours, but some will linger across the south. By 12Z, will only have likely PoPs across the far south with PoPs diminishing farther northwest. Will continue to watch hi-res hourly guidance as some of these hint at another band developing near the I-70 corridor, which would warrant higher PoPs there at 12Z. Will have to watch for any fog development, mainly northwest where cloud cover will be thinnest. Forcing during the day today will weaker. While the area will remain in broad upper troughing, heights will be on the rise, and the jet streaks will have less influence having moved east. At the surface, no strong boundaries will be around. However, smaller boundaries, some from previous convection, will linger. Moisture will continue to be available, and even with clouds around, heating will add instability. Thus, expect scattered convection to continue throughout the day. Will go chance PoPs most areas, with lower confidence on specific timing and location of highest PoPs. Instability and shear won`t be enough for a severe storm threat. With some breaks in the clouds expected this afternoon, temperatures will rebound into the middle and upper 70s. Tonight... Any lingering forcing will remain weak with not much change in the synoptic setup. Will keep some lower PoPs around, mainly during the evening when instability is highest. Similar to this afternoon, instability/shear will be weak enough so that severe storms are not expected. Lingering low level moisture could lead to some fog overnight tonight. Will add a mention to the forecast and continue to monitor. Low temperatures will be around 60 degrees. && .LONG TERM (Saturday through Thursday)... Issued at 255 AM EDT Fri May 17 2024 Saturday through Monday Night... The long term will start out with chances for scattered, mainly light rain across central Indiana...from the northern portions of a rather weak southern wave lifting from the Lower Mississippi Valley to near Kentucky. Around 500-1000 J/kg of CAPE and 0.90-1.20 inches of precipitable water could promote a few t-storms with more impressive rainfall rates, especially over southeastern counties, yet appears lack of wind shear and next to no low-level convergence...will lead to less than 0.25 inches of precipitation for most locations. Dry conditions should be the rule by pre-dawn Sunday as rather weak yet broad surface high pressure builds in from the Great Lakes to the Mid-Atlantic under an arriving upper ridge. A late spring transitional-type pattern will then feature broad troughiness across much of southern Canada, whose occasionally- plunging short waves over western North America will likely direct increasing heights into the Midwest. There has not been the best run-to-run model consistency with placement/tilt of both the overall trough as well as embedded vorts, yet latest trends are for disturbed weather to hang well to the north/west and the upper ridge axis to build near Indiana. Overall light northeasterly surface winds from the passing, weak surface ridge will likely veer to southerly breezes Monday ahead of strengthening surface low pressure over the central Plains. Moderation through the weekend will yield an unseasonably warm and rather humid early week more indicative of early summer, with mid to upper 80s likely Sunday and Monday. Tuesday through Thursday... The middle of next week should see an increasingly active mid-level pattern with at least two vort maxs spinning around the overall deepening western North America trough...before ejecting to the Upper Midwest and/or Central Plains. Surface cyclogenesis would result along a strengthening cold frontal zone from the Upper Mississippi Valley to the southern Plains...while the antecedent surface ridge departs to the Atlantic coast. Rain chances are expected to cross the region around the Tuesday- Wednesday timeframe, although there is so far low confidence in when the front, connecting what may be multiple areas of low pressure from the various vort maxs, will actually pass the CWA. Multiple rounds of convection are certainly possible ahead of this eventual passage...with ample instability fueled by dewpoints into the 60s, as well as probably a third day in the 80s Tuesday...and what should be increasing wind shear under the eastern extents of the trough arriving from the west. Greater confidence for Thursday following the cold frontal passage which would return dry conditions and drop readings back closer to seasonal. The normal max/min at Indianapolis through the short term is 75/55. && .AVIATION (06Z TAF Issuance)... Issued at 114 AM EDT Fri May 17 2024 Impacts: - MVFR conditions developing early. Some IFR at KLAF. - VFR returning after 18Z. - Scattered light rain showers much of the period. Discussion: An area of showers will be moving across KIND/KBMG early in the period. Embedded thunder looks to remain between the 2 sites. Additional showers will develop overnight and may impact all but KLAF. Thunder cannot be ruled out but coverage is too low to mention. Ceilings will deteriorate during the night, mainly staying MVFR but a period of IFR is expected at KLAF. Some fog is also likely at KLAF with lower odds elsewhere given rain/clouds. Scattered showers will continue during the daytime, mainly at the southern sites. A slow improvement in ceilings will occur. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...50 LONG TERM...AGM AVIATION...50