Sunrise 6:40 AM   Sunset 8:42 PM Moonrise 3:21 AM   Moonset 2:34 PM

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FXUS63 KIND 030657 AFDIND

Area Forecast Discussion National Weather Service Indianapolis IN 257 AM EDT Fri May 3 2024

KEY MESSAGES

- Damp and mild today, with widespread showers and a few thunderstorms, especially this morning.

- Potential for fog late tonight.

- Multiple chances for showers and storms throughout most of the forecast period, with continued above normal temperatures.

- Potential for severe weather during the middle of next week, highest chances Tuesday evening and Wednesday night.

.SHORT TERM (Today and tonight)...
Issued at 257 AM EDT Fri May 3 2024

A fairly ordinary damp spring day is expected across central Indiana today, with weak surface low pressure to our northwest pushing a frontal boundary through the region as a modest upper level disturbance slides through the area.

Despite the presence of a fairly moist airmass, with precipitable water values toward the upper end of climatology, modest forcing and what should be very weak destabilization given fairly widespread cloud cover throughout the morning and into the afternoon will limit intensity of showers and coverage of thunderstorms, though a slight uptick in the latter may be seen along the boundary this afternoon if some clearing can occur. Very weak deep layer shear will limit the intensity of these storms even in the presence of some slightly more modest instability.

Total rainfall across the area through tonight should be light, around a third of an inch or less.

Fairly good dry advection throughout much of the column will bring an end to any lingering showers and storms during the evening hours, with most of the area dry throughout tonight. Depending on the degree of lingering high cloud cover, the damp ground may promote fog development late tonight, and will have to keep an eye out for dense fog if more significant clearing occurs.

Widespread clouds and precip, especially early in the day, will limit insolation and keep highs today no warmer than about the mid 70s, with lows tonight in the mid 50s to low 60s.

.LONG TERM (Saturday through Thursday)...
Issued at 257 AM EDT Fri May 3 2024

Saturday Through Sunday.

For much of the long term, the Ohio Valley will be well positioned within an unstable atmosphere, leading to unsettled weather and higher uncertainty than usual.

For Saturday, the surface moisture will recover quickly behind a weak cold front with steady low to mid level lapse rates leading to widespread 1000-2000 J/kg of CAPE by the afternoon. There will not be much in the way of forcing given the short wave still well off to the east, but weak subtle waves from upstream convection should be enough for isolated to scattered thunderstorms (With a focus over S.
IN) for much of Saturday afternoon and evening. Severe weather looks unlikely for Saturday (Given negligible dynamics), but cannot be ruled due to a shallow midlevel dry layer and a deep instability profile. This should allow a few isolated thunderstorm cores to reach >25kft, of which could produce small hail and strong wind gusts.

A boundary out ahead of the aforementioned wave will progress eastward throughout the day Saturday, leading to a continued threat for convection on Saturday night. This boundary is expected to initiate an MCS over IA/IL during the day on Saturday, but mid to upper level dynamics will be weak, and will make eastward propagation more challenging, especially as diurnal temperature inversions develop Saturday night. With that said, if updrafts can sustain themselves into western Indiana, an isolated severe threat (although unlikely) is possible Saturday evening. Regardless, this boundary should pass throughout Saturday night, with showers/thunderstorms weakening as they progress across the state.
Barring a few lingering showers Sunday morning, the remainder of the day should be quiet with highs in the mid 70s.

Monday Through Thursday.

By early next week, another shortwave is expected to develop within the subtropical jet and push E/N into the Ohio Valley. High pressure in the wake of the previous system could hinder northward progression of the wave, creating some uncertainty if showers and thunderstorms will reach this far north on Monday. Given the short period of potential rainfall, QPF isnt expected to be high, but long range soundings are hinting at rather efficient rain producers leading to a marginal concern for flooding. Details are still very hazy at this point, leading to low confidence in any hazards for Monday

The next round of unsettled weather will push into the region shortly after, with another trough, albeit deeper, over the Inter- Mountain West by Tuesday. This time around, a more organized low pressure system is expected to develop, rapidly deepening as it reaches the Great Plains. As the low develops, convergence east of the low should create a weak warm-frontal region and associated isentropic ascent. This lift is expected to reach the Great Lakes and Ohio Valley sometime Monday night into Tuesday, leading to showers and some elevated thunderstorms.

Following this warm front passage, central Indiana will be within a moderately unstable environment with a mid and upper level jet aloft. Although uncertainty is high on timing and specifics, this should lead to a few rounds of more organized convection Tuesday through Thursday, including a threat for severe convection. Greatest chances for severe weather looks to be Tuesday and Wednesday evenings. The thunderstorm and severe threat should decrease late week as AVA and modest CAA returns leading to high pressure and a drier overall airmass.

.AVIATION (06Z TAF Issuance)...
Issued at 115 AM EDT Fri May 3 2024

Impacts:

- MVFR ceilings in scattered showers and isolated thunderstorms as early as 08-09Z in some spots, more widespread between 12-19Z.

Discussion:

Scattered showers and isolated thunderstorms will overspread the TAF sites overnight into Friday morning, with ceilings gradually diminishing to MVFR at all sites, primarily from around daybreak to early afternoon on Friday, though periods of MVFR will be possible in showers as early as 08-09Z.

These showers will begin to move out during the afternoon hours, with VFR conditions returning fairly rapidly and persisting through the remainder of the period.

Winds will be below 10KT throughout, initially somewhat variable but primarily southerly, becoming westerly and then northerly through the period.

Despite the potential for a few thunderstorms, uncertainty is too high for an explicit mention at this time. Will stick with VCSH or - SHRA.

IND WATCHES/WARNINGS/ADVISORIES
None.

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