We will end up not dropping below 10 for December 2020 in Greater Lafayette. In 141 years of data, only 19.9% of the Decembers have failed to drop below 10 degrees during the month.
This, after our record high of 63 on December 23 & the incredibly warm November (5th warmest in 141 years).
Mean temperatures are running 1.5-3 degrees above normal over the past month.
Interestingly, we haven't been able to switch on the consistently above normal precipitation yet.
We are running about 50-70% of normal precipitation for the past month.
Long-term drought continues for a chunk of the Corn Belt.
Long-term Moderate Drought continues over the northwestern half of the viewing area from northwestern Warren to Fulton counties & northwestward.
Round of showers will occur this evening in the 7 p.m. to 2 a.m. time frame with strong southwest winds to 32 mph becoming northwest behind cold front.
This, after mild highs today of 45-52.
Rainfall of 0.04-0.22" is expected. The lightest totals look to be in our southwestern counties.
Monday looks gray & dreary until skies clear from west to east in the afternoon. Highs will run 31-36 with some increasing clouds Monday night with lows 17-23.
Northwest winds of 15-25 mph are likely Monday making it feel more like upper teens to mid 20s than 31-36.
Clouds will continue to thicken Tuesday (gradually dimming & blurring sun away with time) with wind turning to the southeast at 10-20 mph. Highs of 33-38.
Storm system will be approaching from the west with wind turning to the south-southeast by Tuesay night.
Rain may begin as brief period of freezing rain along & north of a Kentland to Monon to Peru line Tuesday night with temperatures 32-38 over the area.
Rain is likely Wednesday with highs 47-54 with southerly winds.
January 1-2 or Friday-Saturday looks interesting.
Storm track is extremely important.
Whether we see substantial to significant wintry precipitation (ice/snow) or mostly snow or rain end as snow or just a mix of ice to rain to snow are all dependent on the track of a surface low riding the front northeastward.
This is also tied to the position of the front as the cold air will be behind the front.
If it is far enough to the east, it is mostly snow here, a bit farther west & it is a mix. Farther west set-up, still, will be more rain than ice & snow.
Looks like a gusty storm system with gusts +30 mph at times, so if we do get in on the snowy or icy side, it would lead to lots of travel impacts.
WHAT WE KNOW:
1. Winter storm will pivot northeastward through the Mississippi to Ohio Valleys & Great Lakes.
2. Winds gusting +30 mph at times will occur with the storm.
3. Band of heavy snowfall will occur with the storm.
4. Some ice will occur with the storm.
5. Moisture-rich, liquid values of 0.75-1.00" are possible with the system atop the 0.60-0.80" rainfall amounts the day prior.
6. It does not look excessively cold behind the system with highs 20s to 30s with temperatures also in the 20s & 30s on the colder side of the system.
7. Impacts would occur January 1-2.
WHAT WE DON'T KNOW:
1. The exact storm track or position of cold front (largely due to Bermuda-type high off of the East Coast strengthening).
2. How impactful the wintry side of the storm will be in our area.
3. Precipitation types here.
4. Whether we will see much accumulating snow &/or ice.
5. The dominant precipitation types here (rain, snow or ice).
6. Where band of heaviest snowfall will occur.
7. Where highest potential of icing will occur.
8. Exact hours of passage of precipitation whether it be rain, snow, ice.
9. IF there are different precipitation types, what time frame each will occur.
WHAT TO DO:
1. Be careful of posts on social media regarding storm system & do not believe all you see from various forecast posts on-line. Rumors & confusion all tend to begin with absurd winter weather posts from online (like a blizzard forecasted for the viewing area at the beginning of December from several online outlets).
2. Just be aware. Know we need to watch January 1-2 for POTENTIAL of wintry weather.
3. Keep in mind whether it is impactful winter storm or mostly RAIN is in question & it could change.
4. Know it is a tedious forecast with potential of a very sharp cut-off between substantial winter impacts & little/none (for example, heavy, wind-driven snow in Illinois & mostly rain here).
5. Know the forecast will be tweaked with time & more details will be forthcoming.
Interestingly, this system will pull up unseasonably warm air from the Northeast to Southeast U.S with severe weather risk Ohio & Pennsylvania to the Gulf Coast. 60s may reach as far north as the Northeast with flooding rainfall from Mississippi to Maine.
Here are the potential different outcomes via U.S. GFS model Ensembles:
Ensemble snowfall amounts (band of ice may occur with the system as well):
There may be one minor snow system after this one through January 10.
After that, it looks overall very mild with three systems of rain in the January 11-25 time frame.
We may reach the 50s to 60s.
Both systems may produce some vigorous severe weather development from southeastern Texas to Alabama.