840 FXUS63 KIND 270702 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 302 AM EDT Sun Apr 27 2025 .KEY MESSAGES... - Patchy frost possible across portions of northwest central IN this morning - Above normal temperatures return Monday with highs in the upper 70s to low 80s - Active and stormy pattern from Tuesday through Thursday, with the potential for severe weather Tuesday afternoon and evening - Cooler temperatures return by next weekend && .SHORT TERM (Today and tonight)... Issued at 301 AM EDT Sun Apr 27 2025 Quiet weather conditions are expected through the period as surface high pressure remains centered over the region. Current satellite and surface observations show mostly clear skies with light winds promoting efficient cooling. Passing high clouds may be slightly limiting diurnal cooling, but temperatures have still fallen well into the 40s. Patchy frost could develop over far northwest central Indiana towards daybreak as temperatures continue cooling into the upper 30s. Look for temperatures to quickly rebound later today thanks to plentiful sunshine and a very dry airmass. Forecast soundings depict deep PBL mixing during the day with a subsidence inversion. Dewpoint depressions near the 850-700mb layer are around 40C which is impressively dry. The NBM tends to have a moist bias when forecasting dewpoints in these setups so CAMs were incorporated to more accurately forecast strong thermal mixing today. RH values may fall to near 30%, but fire concerns are very low due to recent rainfall and light winds. Southeasterly winds remaining slightly elevated and increasing clouds from a weakening disturbance may limit diurnal cooling to some degree tonight. Look for temperatures to range from the low 50s across the southwest to mid 40s over northeast central Indiana. No precipitation is expected as a dry airmass remains in the low-levels. && .LONG TERM (Monday through Saturday)... Issued at 301 AM EDT Sun Apr 27 2025 An upper level ridge will bring warm and dry weather to start on Monday before an unsettled pattern develops for much of the rest of the week as a frontal boundary becomes nearly stationary over the Ohio Valley with multiple opportunities for rain and thunderstorms and two chances for scattered severe weather on Tuesday. An omega block upper level pattern will develop for the weekend anchored by deep troughs over the eastern U S and along the Pacific west coast...placing central Indiana within a dry and cooler regime. Monday and Monday Night Southerly flow develops Monday as the warm front lifts north and high pressure shifts off to the east. Much warmer air will advect into the region with highs near 80 degrees across central Indiana. A tightening surface pressure gradient supports a breezy afternoon across the forecast area. Clouds and moisture will increase Monday night as low pressure tracks into the Great Lakes with a trailing cold front extending southwest into the Missouri Valley. Scattered convection will move into the northwest half of the forecast area in the predawn hours on Tuesday. Tuesday through Friday The low will lift northeast into Quebec on Tuesday with the cold front shifting into the region from the northwest. The overall model trends have sped up the arrival of the frontal boundary into central Indiana by early afternoon. While the potential for robust convection remains on Tuesday afternoon and evening focused especially over the southern half of the forecast area...the faster arrival of the boundary coinciding with increased cloud coverage and scattered showers earlier in the day complicates the overall severe weather risk. Ample instability with SBCAPEs peaking near 2000-500 j/kg and sufficient low level moisture with precip water values in excess of 1.5 inches remain supporting factors for more intense convection. Model soundings showing unidirectional shear and broad instability profiles through the depth of the column suggesting damaging winds and large hail as the most likely threat from convection. A few tornadoes are possible but the lack of more substantial directional shear and overall low level storm relative helicity make it a secondary concern that will likely be predicated on boundary interactions. Forcing aloft appear subtly out of phase with the peak instability and moisture however which may keep the severe threat more scattered than originally thought. The low level jet will lift away to the northeast by early afternoon with weaker flow present during the expected timeframe for most widespread convective coverage. The region remains within the right rear quad of the upper jet Tuesday afternoon but the orientation of the strongest upper level flow has shifted slightly further north from previous model runs. At this point...anticipate numerous showers and storms during the afternoon and evening with scattered severe potential in a messy convective mode that will likely be multicellular clusters with embedded supercells. Periodic showers and storms will continue as the front stalls over southern Indiana Tuesday night then lifts back north across the entire forecast area by late Wednesday. An axis of deeper low level moisture and enhanced forcing in the vicinity of the boundary will lead to locally heavy rain becoming the primary impact from storms through Wednesday evening. Low pressure will track into the Great Lakes Thursday with another round of stronger storms ahead of the cold front. The front will clear the region Thursday night with additional showers lingering on Friday as an upper trough amplifies over the Great Lakes. Highs in the lower 80s Tuesday will fall back into the 70s Wednesday and Thursday then into the upper 60s for Friday. Saturday and Sunday The aforementioned upper trough will become the primary influence into next weekend bringing cooler and drier air into the Ohio Valley. Highs may slide back into the lower and mid 60s Saturday with scattered diurnal clouds under the cold pool aloft. The upper trough will shift east on Sunday into early next week with seasonable temperatures returning. && .AVIATION (06Z TAF Issuance)... Issued at 1256 AM EDT Sun Apr 27 2025 Impacts: - None expected Discussion: VFR conditions are expected through the period. High and some mid clouds will pass through at times. Winds will become southeasterly after daybreak and remain light through the period. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Melo LONG TERM...Ryan AVIATION...Melo