Sunday, April 22, 2018

Chilly April Nights

Finally!  A weekend where we could get out and enjoy the outdoors without having to bundle up.  While a few showers came down on Saturday, Sunday was dry and mild with temperatures reaching the mid 60's.

Temperatures through the last week of April will remain seasonable but there are some signals that point to the possibility of temperatures falling slightly below average once again within the first week or two of May.  Average highs at the beginning of May should be in the upper 60's, to near 70 degrees.

Even though temperatures will be warming through the end of the month, April as a whole will likely go down in the books as below average.  Mostly because of just how cold it was during the first half of the month.  Not only were high temperatures well below average, but overnight lows were below average as well.  Through the first 22 days of the month, 17 of those days had overnight lows either at or below 32 degrees, putting this April as the fourth most of record for freezing temperatures.  The record was 20 days set back in 1907!  The fact that the third highest April was 18 days set back in 1926 just proves that the cold we were dealing with hasn't been felt in quite some time.

Saturday, April 21, 2018

A Warming Trend Finally Settles into the Stateline

Minus the isolated rain we had move through today, it was still nice seeing some warmer temperatures, and even getting a few peaks of sunshine early on this evening.  These conditions will stay the same for early evening, with temperatures staying on the warmer side around 50°, before temperatures drop during the overnight into the mid 30's.

Skies will clear up during the overnight, allowing us to wake up to some sunshine tomorrow morning, which will help warm our temperatures quickly heading through Sunday morning.  We can thank this high pressure system for that, as it'll be in full control once that mid-level trough pushes southeast tonight.  However, that trough will pull some warmer air into our area on Sunday, helping temperatures warm up even more.

All that sunshine will bring temperatures into the mid 60's Sunday afternoon, and we keep the sunshine the entire day, so definitely make some outdoor plans for tomorrow! 

Once we get into the work week, that high pressure system stays in control, keeping the sunshine for Monday and allowing temperatures to warm up even more into the upper 60's, possibly hitting 70° Monday afternoon.

Afterwards we'll have an upper-level disturbance track into the Stateline on Tuesday, bringing chances for some showers, but we'll still be warm at around 70°.

Temperatures cool off afterwards, but we'll still be on the warmer side in the 60's for Wednesday and Thursday.  Our coldest day next week will be Friday, only hitting the mid 50's, which will still feel nice.  This just gives you more reassurance that spring is here to stay!

Friday, April 20, 2018

Spring is Settling In

We finally got some nice weather in the Stateline, hitting 60° this afternoon and getting plenty of sunshine!  A well-deserved end to the work week after dealing with winter for so long.  Compared to last year, we've had a pretty cold start to 2018, only seeing 3 60° days so far, and getting only one 70° day.  Both being way outdone by last year's numbers.

As we head into the evening this high pressure system will keep our skies clear.  This will cool us down to the mid 40's by 10pm, but before 7pm we'll get to experience the 50's, so it's shaping us to be a pretty nice evening.  The high will continue cooling us down even after 10pm, bringing us to around 40° heading into the overnight.

During the overnight a mid-level low will move near our area, increasing our cloud cover during the overnight.  Despite the cloud cover, temperatures will still manage to cool to the mid 30's overnight, but luckily winds stay calm, so wind chill won't be a factor.  The low will keep us cloudy as we head into Saturday, bringing us chances for a quick passing shower early Saturday afternoon.

The low will keep us cloudy through late Saturday evening, but afterwards the high pressure system will take back over as the mid-level low moves out.  The high will stay in control for the rest of the weekend afterwards, bringing us more sunshine, and allowing our temperatures to warm into the mid 60's during Sunday afternoon.

This high will continue staying dominate heading into the work week, with Monday being pretty much the same as Sunday.  Tuesday we'll be near 70°, before rain chances move in Tuesday night into Wednesday.  Temperatures briefly cool off afterwards for the rest of the week, hitting the mid 50's on Wednesday, mid 60's on Thursday, and low 60's on Friday. 

However, even those temperatures will feel nice to us, considering we've been dealing with winter weather for far too long.

Thursday, April 19, 2018

Record Cold the First Half of April

That is not a statistic you want to hear when temperatures are supposed to be warming up.  But the first 18 days of the month have been well below average.  In fact, it's been the coldest first half of April on record for Rockford!

When factoring in the high and low temperatures from April 1st-18th, the average temperature was 33.9 degrees.  That last time it was this cold for the first half of April was back in 1907, just two years after record-keeping started in Rockford!

High temperatures Thursday warmed into low 50's which was a vast improvement from Wednesday afternoon.  Temperatures will continue to climb into the weekend and early next week, reaching the mid 60's by next Monday.

The overall pattern will change to a warmer one next week and that pattern may last through the start of May.

Above Average Snow surprise here...but we've received way more snow this April then we're supposed to. With snow falling yesterday and last night, we added another inch to Rockford's tally for snow.

So far this month we've added up 4.1" of snow, but the average is only 0.8". That brings our monthly total to 3.3" above average! could be worse. In Green Bay, 36.7" have fallen this month with a couple large systems dumping snow. The highest amount was 11" on the 14th, and they had a snow depth of 19" on the 16th.

The good news is, if you aren't a fan of 'Sprinter' is that the forecast over the next seven days gets better and better. Upper 40's for highs today with mostly sunny skies, 50's Friday and Saturday, and then 60's through next week!

Wednesday, April 18, 2018

Different Types of Wintry Weather

That title just doesn't sound right in the middle of April, does it?  But we had quite the range of wintry weather Wednesday morning and early afternoon.  From heavy sleet, rain, freezing rain, thunder, small hail and eventually snow, Mother Nature gave it all to us.

But what caused the quickly changing weather over northern Illinois and southern Wisconsin?  Well, it all has to do with what the temperatures were like from the bottom of the atmosphere (near the surface) to the very top.  Let's think of the atmosphere as a column of air.  If the column of air above us is below freezing then the precipitation will fall in the form of snow.  But if a 'warm layer' of air is introduced into that column, different types of precipitation will occur.

Air flowing around low pressure systems flows counter-clockwise.  The southerly wind will bring warmer air northward, but it doesn't necessarily happen at the surface.  Sometimes the warm air can ride, or move overtop, the cold air near the surface.  As precipitation falls from the cloud it will initially fall as snow because temperatures at that level are below freezing.  But if the snow falls into a shallow, warm layer of air above the surface the snow will partially melt within that layer.  However, as it moves out of the warm layer it refreezes and will fall as sleet.

If the warm layer of air is a little more deep throughout the atmosphere the snow will completely melt, becoming all liquid.  During freezing rain situations rain falls through the atmosphere but will refreeze on a surface that is below 32 degrees.  And for all rain to form the entire column of air is above freezing.  We had all four, and then some, scenarios Wednesday morning and early afternoon.  But now with the passage of low pressure the transition over to light snow occurred and will continue into the overnight.

Wednesday Evening Weather Update


8pm Update: Light snow continues to fall Wednesday evening, with a little more steady snow from Janesville, Monroe and Freeport.  Accumulations have already started, but are mostly on grassy surfaces.  Snow totals will still range from 1" to 2" through the overnight.

The transition over to light snow has started now that the upper level low is moving over northern Illinois.  There may still be some sleet/drizzle mixing in with the snow, but I do expect a transition to all snow by 7pm this evening.

Snow accumulations will remain light and mostly confined to grassy surfaces.  But slush filled roads can be expected through early Thursday morning.  Most of the snow will be done between Midnight and 3am Thursday morning, but cloud cover will stick around through Thursday morning.  Even though the precipitation will be done before sunrise Thursday, untreated roads will still be slick.  Be careful on bridges and overpasses, around curves and on/off ramps.

Visibility has also been a concern this evening and has actually lowered with more moisture wrapping in around the upper level low.  Falling snow will help to lower the visibility even further this evening and overnight.  It's already down to under a mile in Galena/Dubuque.  Fog may linger for some early Thursday with temperatures climbing back into the mid 40's.