Jet stream becomes more active the last week of March

The wave train of storm systems is set to increase heading into the weekend and through the last week of March. 

An active jet stream will allow a series of storm systems to move in from the Pacific and travel across the middle of the country.  The first will arrive this weekend with an area of low pressure becoming cut-off from the main flow of the jet stream.  This will allow periodic rain and storm chances through Sunday.  The next system

will be quick to move in early next week with another following later in the week.  With a nearly every other day rain threat, precipitation could be running on the higher end giving us a high probability of above average precipitation through the end of the month.  This may even carry over into the first few days of April.

With each of these systems arriving from the west, the chance for temperatures cooling is fairly low.  Highs through the end of the month

will either be right around or above average.  Average highs through the end of the month are in the upper 40's to right around 50 degrees.

Potentially Soggy Weekend

Chief Meteorologist Candice King talked in the previous post about a closed low pressure system that will detach from the jet stream and meander through Illinois this weekend. This will bring somewhat gloomy conditions with mild temperatures, however, it has the potential to bring quite a bit of rain.

Ahead of the low, moisture will be drawn in from the Pacific, but also from the Gulf of Mexico. With higher levels of moisture to work with, soggy conditions are looking more likely. Right now the timing of the rain will be later Friday afternoon, with storms also possible. Rain would continue through the overnight and into Saturday morning. Models then take the low through Illinois, and with no support from the upper levels of the atmosphere, it will take it's time moving through.

It's possible that some areas close by, near Green Bay, could receive almost 2" of rain. In and around the Stateline, the Weather Prediction Center outlooks anywhere between .75" to 1.25" of rain between Friday and Sunday.

The track and strength of the low will dictate how much rain we get, so we will make sure to keep you updated as we get closer to the weekend!

Clouds and rain may linger for the upcoming weekend

The first day of spring did not disappoint!  Even though a cold front moved through, temperatures were still able to climb into the low to mid 60's - nearly 20 degrees above average.

There will be a brief dip in the temperature the next couple of days as a cold high pressure system moves over the eastern Great Lakes Tuesday and Wednesday.  This will cause temperatures to fall back into the 40's on Tuesday, but still above average, and then right around 40 degrees on Wednesday.

By the end of the week southerly winds will give temperatures another boost into the 60's Friday afternoon.  But an approaching low pressure system from the west will bring a chance for rain and thunderstorms by Friday evening and the weekend.

This low will get cut-off from the main flow of the northern branch of the jet stream.  With nothing significant in the atmosphere to give it a push, the low will meander through Illinois Saturday and Sunday.  There isn't a lot of cold air associated with this low, but there is quite a bit of moisture.  This will lead to cloudy, and possibly rainy, skies through the weekend.  And if the low stays far enough to the south our surface winds will be from the east keeping temperatures a bit cooler than the forecast high of the low 50's for Saturday and Sunday.

Hail producing storms possible late Sunday

Strong southerly winds Sunday gave temperatures almost a ten degree boost over Saturday's high.  Incoming cloud cover and a south wind will keep overnight lows in the 40's Sunday with highs warming back into the 50's Monday.

An approaching warm front from the south will fall short of reaching northern Illinois and southern Wisconsin.  Already this front had been the focus for thunderstorms over central Missouri Sunday afternoon.  As the front begins to shift north, instability and moisture will increase and lift north with it.  Strong winds within the lower level of the atmosphere will increase and interact with the increase in moisture.  This will likely cause thunderstorms to develop over central or northern Iowa late Sunday evening, likely after 10pm.  Those storms are then expected to move east into Illinois after midnight.  These storms will be elevated and could produce marginally severe hail.

The image on the left is a simulated radar image around 2am.  Most short term forecast models suggest the bulk of storm activity staying south of Rockford.  Most of the thunderstorms will be southeast of the Stateline by Monday morning, but an approaching cold front could help redevelop a few showers/storms mid-morning Monday to the southeast of Rockford.

Spring Right Around the Corner

Spring is right around the corner with the solstice coming up on Tuesday.  We've been seeing some spring-like weather the past couple of weeks, with warm temperatures and some strong thunderstorms.  We'll be seeing more of those warm temperatures as we progress through the weekend as a high pressure system will move through our area tonight.  It will cool our temperatures for the overnight, but warm us up as we move into Sunday with temperatures in the low 50°s.  A warm front will move in Sunday evening and bring us some light rain for the overnight, but the front will also keep our temperatures warm as we head into the work week.  We'll be in the upper 50°s on Monday and the low 50°s on Tuesday, before cooling to the 40°s for Wednesday and Thursday.  Some light rain will move through for the overnight Thursday night followed by some thunderstorms on Friday, where temperatures will warm back up in the low 60°s.

The Fight for Spring

For the past month we've been going on quite the roller coaster ride as temperatures have been all over the place.  This has lead to a large variability in our weather with severe thunderstorms one day, followed by snow the next, and then repeating the cycle.  This week was fairly cold, but another hill comes up on the roller coaster as we climb up into the 50°s for the end of the weekend and early next week.  Warm air will start filtering in Sunday morning with a warm front moving through at night.  The front will keep our temperatures warm for the overnight, but it will also bring some light rain with it.  The accumulation will be small and it will only be a light rainfall.  The rain moves out Monday morning where temperatures will climb to the mid 50°s for the afternoon.  We slightly cool down Tuesday and Wednesday into the 40°s, but warm right back up at the end of the week with another chance of rain on Thursday and Friday.

Spring Outlook

Yesterday the Climate Prediction Center issued it Seasonal outlook for April, May, and June. If you are a fan of warmer weather then you will like this outlook.

They indicate most of the country with a probability of above average temperatures predicted. For the Stateline, that probability is anywhere between about 40-50%. The Climate Prediction Center uses a variety of tools to determine this outlook, including drought conditions, the status of ENSO (El Nino Southern Oscillation), and various other products.

There is no strong signal to support a probability of above or below precipitation
for that time.