Scary, Non-Spook-tacular Halloween Weather for Central Indiana

A wet start to the day as showers and thunderstorms invade this Thursday. This is definitely not one of our greatest Halloween but mother nature is certainly bringing a scarier look to parts of the U.S. today. Some monster rainfall totals and howling winds are in the headlines w/ a side of electrifying lightning (low threat). Will need to watch for the potential for any storms to become severe today including isolated tornadoes. SPC has placed all of Indiana under a slight risk for severe thunderstorms today.
The powerful autumn storm striking the state today is not only bringing more than 7" of rain in parts of Texas but here in Indianapolis this could put us in record setting rainfall territory. We are looking at one of the wettest Halloweens not only since 0.49" fell 40 years ago (1973) but also since the last record of 1.30" was set 72 years ago in 1941. Besides 1941, our last 1+" rain on Halloween was 94 years ago in 1919 with 1.09". Model averages are certainly hinting at more than an inch of precipitation, some could come out on the high end at more than 2" to 3" total when this is all done.

There was a slow climb in temperatures yesterday due to the thick stratus cloud deck and fog but temperatures began to respond a little after a warm front lifted North Wednesday evening. Temperatures went from 49° (official low) in the pre-dawn hours to 59° by sunset. By midnight, we finally reached the 60s. Yesterday's official high was 61. We finally snapped a 14 consecutive day streak of below normal temps. It was the longest cool streak since March 12th-30th (19 days). The average high for this time of the year is 60 and the average low is 41.
I'm skeptical if we'll actually warm up today w/ rain around all day. Temperatures this morning have held between 60°-61°. At one point we actually peaked at 62°. I'm going to stick with that 62 for today's high temp. If we do manage to warm up I don't think we get beyond the mid 60s.
Rain will primarily be on the light side during the morning hours picking up in intensity as the day progresses. We officially recorded 0.19" yesterday you can almost multiply that times ten for today. Some areas in the state may receive over 2" of rain. The thing to note is, not everyone is going to see the same amount and will vary North to South but everyone will likely receive enough rain to finish October above normal. Not only is rain going to be an issue today but so will the winds. We look to see gusts in excess of 30mph peaking as high as 50mph in some spots. Here's a look at forecast wind speeds for 2pm & 8pm. These are not wind gusts!



Here are snapshots of HRRR and NAM models that show a heavier push of rain & storms (some severe) around 8pm. Right behind this line of heavy storms is where a cold front is expected to push through tonight. Winds may also be at its heaviest at this time though not shown in the wind maps above in Indianapolis but you can see the darker colors farther North (in Ohio) showing the heavier winds.



At the beginning of the blog I mentioned a low threat for lightning. CAPE (Convective Availabe Potential Energy) values are expected to be low for most of the day but increase with that stronger push of rain/wind tonight I showed above. The increase is favorable for supercells to form. You only need about 300 j/kg for a weak THUNDERSTORM. Values lower than that have no convective potential. Values of over 1000 j/kg have moderate convective potential supportive of some strong thunderstorms. 2500 j/kg is the threshold for more severe thunderstorms. We aren't expected values that high. Today's main threat though is DAMAGING WINDS and HEAVY RAIN.



I also mentioned an isolated chance for Tornadoes as well. Here's a look at helicity values. The higher the value the higher the risk is for tornadic activity. Anything 400+ could favor it, and values are forecasted that high in Central Indiana. This is a look at the NAM model.



A cold front pushes through tonight so temperatures will drop back into the mid to upper 40s for Friday morning lows.




Here's my Halloween Forecast and a look at my 10 day outlook for November 1st-10th. Rain/Storms clears out early tomorrow morning. We should get back into some sunshine tomorrow afternoon. After a surge of warmth, the next storm appears to come in the middle of next week. Still working out the timing. This may come Wednesday evening. Temps slide back into the 50s and remain fairly steady for a wet Thursday then dropping back into the upper 30s for Friday morning low temps. More details to come.