textproduct: Indianapolis

KEY MESSAGES

- Much cooler today with a warming trend through the workweek.

- Showers and thunderstorms possible Thursday and Thursday Night.

- Cooler on Friday, with a warming trend resuming over the weekend.

FORECAST UPDATE

Issued at 844 AM EDT Mon Mar 23 2026

Surface analysis late this morning shows strong high pressure centered over IA and MN drifting east. This cold high pressure system was providing cold northerly flow across Central Indiana. GOES19 shows plentiful stratocu streaming from Michigan across Indiana. Clearing was found over IL. Aloft, slight NW flow was in place, with a weak trough over the Great Lakes. This quick NW flow was keeping any strong polar intrusions bottled up to the north while allowing high Pacific moisture to stream across the Rockies. Temperatures across Central Indiana have plunged to the middle 30s, some 50 degrees cooler than yesterday's highs.

Forecast soundings show continued subsidence in play this afternoon in the wake of the weak upper trough as surface high pressure slowly build across the area. This will allow for the slow erosion of the stratocu deck across the area this morning, leading to skies becoming mostly sunny by this afternoon. Forecast soundings show the loss of this deck due to the subsidence and daytime heating. Thus look for skies to become mostly sunny this afternoon.

Strong cold air advection remains in play today as 850mb temps fall to around -5C by late afternoon. Thus look for highs to only reach the lower to middle 40s.

SHORT TERM (Today and tonight)

Issued at 306 AM EDT Mon Mar 23 2026

Brisk northerly flow continues behind yesterday's cold front. North- northwesterly winds between 15-20kt gusting to 30kt have been common through 06z. These winds are expected to remain brisk through sunrise, though very gradually decreasing with time. Winds continue to diminish through the morning and into the afternoon, remaining above 10kt however. Winds diminish more substantially after 00z as surface high pressure builds in from the north.

Low stratus currently blankets central Indiana within the post-front environment. Clouds stick around through the morning hours, and likely into the afternoon. Clearing is anticipated, albeit slowly, as surface flow transitions from cyclonic to anticyclonic. Additionally, diurnal mixing should help break up cloud cover to some extent (from OVC status to SCT/BKN stratocumulus) but may also allow it to persist through the afternoon. Low clouds should clear completely by 00z with high cirrus building in around the same time.

Temperatures this afternoon are expected to be much cooler than yesterday, by as much as 40 to 50 degrees. Cold air advection continues within the brisk north-northwesterly flow. Highs today are expected to be in the upper 40s to low 50s. Lows tonight should dip into the upper 20s/low 30s under good radiative cooling conditions.

LONG TERM (Tuesday through Sunday)

Issued at 306 AM EDT Mon Mar 23 2026

Anomalous ridging out west combined with low-amplitude troughing over the northeast will promote progressive northwesterly flow aloft across the Midwest. This pattern has allowed for variable conditions with periods of above-normal warmth interrupted by brief but potent cold fronts. This is expected to continue, as the cold air mass behind yesterday's front will already be moderating by the start of the Long Range.

Surface high pressure slides east of Indiana on Tuesday, with winds taking on a southerly component by the afternoon. Combined with strong sunshine and modest warm air advection aloft, temperatures are expected to rebound into the mid to upper 50s, possibly near 60. This trend continues into Wednesday, though at an accelerated rate due to a strengthening low-level jet. Highs may climb into the upper 60s/low 70s Wednesday afternoon.

MIDWEEK THUNDERSTORM POTENTIAL

The low-level jet reaches peak intensity late Wednesday night into Thursday. Some models are hinting at a subtle shortwave arriving Wednesday night. Combined with isentropic lift from warm air advection and surface convergence at the nose of the LLJ, these models show isolated convection developing before sunrise Thursday. Instability appears low, which would limit updraft intensity...but shear is plentiful and long straight hodographs suggest a non-zero hail risk.

The pattern then repeats again with another strong cold front modeled to drop south late Thursday. Temperatures may once again push 80 degrees across the region before the front arrives. The synoptic set up is actually very similar to yesterday. Strong warm/moist advection, broad synoptic-scale forcing, with moderate to high levels of shear and instability. This all points towards another round of showers and thunderstorms, with the potential for severe weather, late Thursday.

Guidance is already trending towards anafrontal convective development, with elevated storms intensifying behind a shallow but strong cold front surging southward. Details still need to be ironed out, including timing and how steep mid/upper-level lapse rates are which will determine storm intensity behind the front. Shear is plentiful, and given the elevated nature of modeled convection it would appear large hail is again the primary hazard.

THIS WEEKEND ONWARD

Another significant cool-down is likely by Friday with highs back into the 40s/50s. As with previous iterations of this pattern, the cool-down is short-lived and a warming trend begins again over the weekend. Temperatures may once again push into the 60s/70s early next week.

AVIATION (12Z TAF Issuance)

Issued at 626 AM EDT Mon Mar 23 2026

Impacts:

- NNW winds gusting to 20-30kt before 15z Monday - MVFR ceilings through 15z Monday

Discussion:

Brisk northerly winds continue behind a cold front that passed through earlier Sunday. Winds out of the north-northwest are sustained between 15-20kt gusting to 20-30kt at times. These winds should gradually diminish this morning but remain above 10kt with gusts to 25kt at times. Winds diminish further during the day Monday while gradually gaining a northeasterly direction by 00z. Winds become easterly by Tuesday morning as surface high pressure builds in to our north.

MVFR ceilings extend across central Indiana with a few breaks appearing on satellite as of 10z. Overall, a BKN to OVC sky is expected through 15z. After that, slow improvement is expected as low-level flow becomes anticyclonic. High cirrus is expected at times overnight.

IND WATCHES/WARNINGS/ADVISORIES

None.