Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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095 FXUS63 KIND 291331 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 931 AM EDT Mon Apr 29 2024 .KEY MESSAGES... - Mostly Cloudy with showers and isolated thunderstorms Today - Mostly Cloudy Tonight with showers ending - Warmer than normal conditions continue through the week. - Additional thunderstorms expected late Thursday into the weekend. && .FORECAST UPDATE... Issued at 931 AM EDT Mon Apr 29 2024 Showers continue to expand across the forecast area this morning with just a few rumbles of thunder as instability is minimal. 13Z temperatures were generally in the 60s with breezy S/SW winds. The overall forecast for the rest of the day is in good shape. Showers are overspreading the region but weakening in coverage and intensity as it moves east and outruns the stronger forcing and deeper moisture hanging back to the west closer to the frontal boundary. Should see coverage expand again this afternoon as a subtle wave aloft drifts through the Ohio Valley and the weakening front moves into the forecast area. Slightly better instability arrives during the afternoon but in general...CAPE values will largely remain at or below 1000 j/kg with weak shear to boot. This would support generally disorganized showers with embedded thunder lasting into the evening as the boundary moves across the area. Even with clouds and occasional showers today...temps will rise into the 70s across the forecast area. Zone and grid updates out. && .SHORT TERM (Today and tonight)... Issued at 304 AM EDT Mon Apr 29 2024 Synopsis: Surface analysis early this morning shows strong low pressure over MN and IA with a cool front stretching south across western MO to eastern Arkansas. High pressure was found across the Carolina`s. This was resulting in continued warm southerly flow across central Indiana. Convection was found ahead of the cold front over MO and Arkansas, drifting northeast within the SW flow aloft. Aloft the upper flow showed ridging in place over the east coast, while an upper low was found over the Dakotas, pushing northeast over the ridge. Dew points across the area remained moist, in the upper 50s and lower 60s, and GOES16 shows convective debris blow off pushing into the Wabash Valley. Today... The upper low to the northwest is expected to continue to advance northeast toward Ontario. As this occurs an associated short wave trough with weak forcing is expected to push across Central Indiana through the course of the day. This upper forcing will be well ahead of the advancing cool front, which will not arrive until late tonight. Models are showing that as the precipitation advances toward and across Central Indiana through the course of the morning and afternoon, that returns become rather light and scattered. This is somewhat due to the LLJ that is depicted to weaken as the morning progresses into the afternoon. Forecast soundings fail to show a consistent surge of deep saturation, but do show enough saturation with very moist pwats over 1.4 inches that pops will still be necessary. Confidence remains high for early morning precipitation in the Wabash valley as the ongoing convection should easily advect there but continue to diminish with eastward progress through the morning. Models then hint at another area of showers arriving in the mid to late afternoon, pushing across the forecast area. Here, confidence on this feature is much lower. Nonetheless, enough ingredients remain in play today to use high pops this morning in the Wabash valley followed by lesser pops through the day due to low confidence in coverage, timing and amounts. Given the day will be spent with the warm sector once again, highs in the low to middle 70s will be expected. Tonight... Surface low pressure over WI is expected to push northeast to Lake Superior and drag a weak associated cold front across Central Indiana. Best upper support with this feature will have passed already to the east through the course of the day. However forecast soundings do not show an intrusion of dry air until after the frontal passage overnight. Pwats remain very high during the evening hours ahead of the front. Thus some rain is still expected along and ahead of the front within the first few hours after 00Z Tuesday, especially across the eastern parts of the forecast area. Thus will hold onto higher pops there in the evening before tapering to a dry forecast overnight in the wake of the front. Given the arrival of weak cold air advection, overnight lows in the upper 50s will be expected. && .LONG TERM (Tuesday through Sunday)... Issued at 304 AM EDT Mon Apr 29 2024 The long term continues to be warm and periodically stormy. Temperatures will be above normal with Thursday being the warmest day ahead of an approaching system, pulling in even more WAA. Have used a broad VCSH for much today across the TAF sites as the The period will start off with rain exiting the area Tuesday morning to midday. A quick upper ridge will allow for dry weather through Wednesday before another large upper trough sets back up over much of the U.S. and an embedded upper low makes its way through the northern Plains to north of the Great Lakes for the end of the week. This will bring another round of rain and thunderstorm chances beginning late Thursday and lasting to the end of the week. At this time we can`t rule out a chance of severe weather with the system, but there is no clear signal at this time. Models show a hint of broad negative tilting but solutions are still noisy and much could change before then. Machine learning also shows better severe potential signals well to the west of the area. While there isn`t much concern at this time, it will be something to watch for. With the noisy solutions, keeping the low PoPs given by guidance for the weekend but wouldn`t be surprised if the surface high global models show behind the end of week system brings at least one dry day this weekend. && .AVIATION (06Z TAF Issuance)... Issued at 555 AM EDT Mon Apr 29 2024 Impacts: - Showers this morning in the Wabash Valley, thunderstorms also possible. - MVFR and very brief IFR conditions possible in convection. - Variable MVFR/VFR CIGs today. - More rain chances southeast this evening before ending overnight. Discussion: Convection over IL is expected to advance to the Wabash valley, in the next few hours, including LAF and HUF near the start of the forecast period. HRRR continued to suggest weakening features on approach as the LLJ appears to exit and diminish. A weak trough is expected to linger and pass across Indiana today. Have used a broad VCSH for much today across the TAF sites as the weak features will likely produce some light rain showers or even a stray thunderstorm, but confidence on timing and location is too low. As weak high pressure build across the area tonight some MVFR cigs may return overnight at IND along with some MVFR Fog. Winds will shift to the northwest in the wake of the front tonight. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ UPDATE...Ryan SHORT TERM...Puma LONG TERM...KF AVIATION...Puma