Tuesday, April 30, 2019

Flash Flood Watch Extended for Parts of the Stateline Tuesday

A Flash Flood Watch remains in effect for Carroll and Whiteside counties but has also been issued for Lee and DeKalb counties through Wednesday morning.

Heavy rain and thunderstorms Tuesday afternoon pushed rainfall totals up near an inch in some places south of Rockford, adding on to the nearly two and a half inches that came down Monday morning.  Flash flooding might not be too great
of a concern because the thunderstorms have been fast moving but localized flooding has been occurring with standing water in ditches, fields and back yards.

The next wave of energy will pass through northern Illinois Tuesday night with showers and thunderstorms already developing over west-central Illinois, lifting into northern Illinois after 10pm.  Rainfall rates could be heavy, especially
south and southeast of Rockford, through Wednesday morning.  A break in the rain will occur Wednesday afternoon with heavier rainfall possible once again Wednesday night into Thursday. 

Monday, April 29, 2019

Flash Flood Watch Issued for Parts of the Stateline with Additional Heavy Rainfall Possible Tuesday

A Flash Flood Watch has been issued for Carroll and Whiteside counties beginning Tuesday morning and lasting through Wednesday afternoon.  It's possible the watch could be extended for additional counties within the next 24 hours.

Heavy rainfall came down Monday morning adding up to nearly two and a half inches south of Rockford.  Unfortunately another round of heavy rainfall is likely for some Tuesday night into Wednesday morning.

Skies remain mostly dry Monday night with patchy fog likely by Tuesday morning.  A few isolated showers will be possible very early Tuesday morning.  Increasing moisture from the south combined with an upper level disturbance will allow the rain to become a little more widespread Tuesday, especially during the afternoon and evening.

Low pressure will move into Iowa Tuesday night
with heavy rain and thunderstorms possible through Wednesday morning.  Additional rainfall totals could add up to over two inches in some locations.  Right now that appears to be south of Rockford, impacting parts of Whiteside, Lee and DeKalb counties.  Soils are pretty saturated following Monday's rainfall and any additional rain could not only cause river levels to rise but also cause general flooding concerns.  Especially given the amount of standing water already.

Sunday, April 28, 2019

Late April Snow Latest Snowfall for Rockford in Nearly 25 Years

A rare, late season winter storm blanketed much of northern Illinois with several inches of snow Saturday afternoon and evening.

By Sunday, most of the snow had melted away with only a few snow piles leftover in the shady areas.  Officially Rockford received 3.7 inches of snow, breaking the daily snowfall record for April 27th set back in 1979 when an inch of snow fell.

Snow totals ranged from roughly two inches, all the way up to seven inches across northern Illinois.  The 3.7 inches that fell in Rockford was the latest two inch (plus) snow event to occur since April 23rd, 1967 when 3.8 inches fell and April 23rd-24th, 1910 when 2.5 inches fell.
It was also the latest accumulating snow for Rockford since April 30th, 1994 when half an inch fell, as well as the latest snowfall since a Trace of snow fell back on May 16th, 2014.

Active Pattern Leads to Mulitple Rounds of Heavy Rainfall this Week

Record breaking snow came down over northern Illinois Saturday afternoon and evening but the focus will shift from the snow, to heavy rainfall in the upcoming week.

Several rounds of heavy rain will be likely going into the first week of May, with the first round arriving late Sunday night.  High pressure Sunday afternoon will continue to shift east of the Great Lakes Sunday evening.  Clouds will increase ahead of the rain, and isolated thunderstorms, beginning to develop over southwest Iowa and northern Missouri.  Skies will remain mostly dry through about Midnight over northern Illinois and southern Wisconsin.  Rain showers are expected to increase from the southwest after Midnight, becoming heavy at times by Monday morning.

Rainfall totals could reach three quarters of an inch, up to an inch of rain by Monday afternoon.  The first round of rain will be progressive and shouldn't cause too great of a concern for flooding.  However, ponding water on the roads and even some standing water in ditches and fields will be possible.  Skies will stay dry Monday afternoon and evening before the second round of rain moves in Tuesday.  This second round will develop ahead of a warm front that will slowly be lifting through central Illinois.  Instability won't be too high, but an isolated thunderstorm or two remain possible through Tuesday evening.

Increasing moisture with the arrival of low pressure Tuesday night will bring a greater threat for heavy rainfall to parts of northern and central Illinois.  Rainfall totals could reach over one inch by Wednesday morning.  Between Sunday night and Wednesday night rainfall totals could range between 2-3 inches across northern Illinois.  With a couple inches of rainfall possible, concerns are elevated for the potential for flooding later this week.  Something we'll need to keep an eye on in the days to come.

Friday, April 26, 2019

Late Season Winter Storm Takes Aim on Parts of the Stateline Saturday

The calendar may say late April but Mother Nature has plans of her own bringing heavy snow to parts of the Stateline Saturday afternoon and evening.

Winter Storm Warnings have been issued for Green, Rock and Walworth counties in southern Wisconsin and for Winnebago, Boone and McHenry counties in northern Illinois.  Winter Storm Watches have been issued for Jo Daviess, Stephenson, Carroll, Ogle and DeKalb counties.  Both of those winter headlines go into effect late Saturday morning.

Low pressure moving out of the northern Rockies early Saturday will quickly strengthen as it moves across Nebraska and Iowa by Saturday afternoon.  Temperatures for most Saturday morning will start off in the low to mid 40s.  As moisture increases ahead of the low during the morning precipitation will initially begin as rain.  As the low moves through southern Iowa into central Illinois temperatures will actually cool through a process called 'dynamic cooling'.  This will cause surface temperatures to fall into the low to mid 30s during the afternoon.  The cooling effect in the atmosphere will allow what is falling as rain to mix with, or transition over to, mostly snow by Saturday afternoon and evening.

Initially the snow will melt due to relatively warm road and surface temperatures.  However, a narrow band of snow will develop just north of the low track.  This narrow band looks to be between roughly I-88 and southern Wisconsin.  Within that band, snowfall rates of one to two inches per hour are possible with the potential for thundersnow!

There will be a sharp cut-off from where a heavy,
wet snow occurs to where very little snow falls at all.  It may even be as sharp of a cut-off as one part of a county experiences 4-6 inches of snow, while another part of the county only receives an inch.  Because of this trying to forecast exact snowfall totals with this system have been very difficult.

There will be impacts to the roads where the heavier snow falls as snowfall rates will be able to overcome the warm surface temperatures.  Visibility will also fall due to the heavier snow, but also because of the gusty East/Northeast wind.  At times, wind gusts could exceed 35 mph.  With a little more foliage on tree branches it's possible sporadic power outages could occur.

The good news is this is a quick moving storm system and will be out of here by Saturday night.  The bad news, temperatures will drop rather quickly Sunday morning with most falling into the upper 20s.
It's important to also note that this storm track is NOT set in stone and could very well shift north or south by Saturday morning.  Even a shift of 15-20 miles would make a big difference on who receives what Saturday.

From Spring to Winter, in Late-April ...

Once again, we would like to apologize for what is about to transpire tomorrow. Trust me when I say this, I am not as pleased about getting more snow this late into the season. Especially now that we are in "prime" severe weather season. But before we talk about the "S" word, let us take a day to enjoy the beautiful sunshine we got going on today. Clouds quickly cleared out this morning leaving us with sunny skies for as far as the eye can see.

Today will feature plenty sunshine, but also blustery conditions by this afternoon. Wind gusts right now are out of the Northwest and are ranging between 25-30 mph throughout the entire region and could gust as high as 35 mph at times this afternoon. Pin down those trashcans! Temperatures today will climb into the low 60's which is right around seasonable for this time in late April.

Clouds will increase throughout the overnight hours tonight as this potent system draws closer to the region. Temperatures tomorrow morning will drop down into the upper 30's to low 40's before the event begins which will make for a chilly start to our morning.Precipitation will begin to make its way into the Stateline after sunrise and will start out as a chilly rain.
As this low pressure system tracks to the southwest and then eventually to the south of the region, winds will switch from the northwest to out of the east. This strong easterly flow will provide enough lift or forcing in the atmosphere for much colder air to feed into the system. Temperatures mid morning will climb into the low 40's before steadily dropping into the 30's as we head towards noontime.

By the time we enter the afternoon, temperatures will continue to be falling into the 30's and winds could gust as high as 35 mph at times into tomorrow evening. Model trends this morning for the most part continued to show a quick transition to snow as we head into the afternoon. With that said, there will be a period of a wintry mix before things changeover to a heavy wet snow by the early evening.
Once the transition to snow is complete, models continue to show a heavy band of snow forming from central Wisconsin into Northern Illinois. The farther north you live, the higher chance you see accumulating snow. The further south you are, the lighter snow totals will be. In fact, the prime area to watch during this event is along or north of Highway 20, this is where significant snowfall is possible.
So far, only our counties in Southern Wisconsin, Rock, Green, and Walworth, have been placed in a Winter Storm Watch. This will go into effect starting mid-morning on Saturday. As I said in my weather casts, I wouldn't be surprise if we see a few of our Northern Illinois counties placed under some sort of watch or advisory before the late-April shenanigans unfolds (later today or tomorrow morning specifically).

Biggest impacts with this system:

1. Roadways: We will definitely have to watch and see how the snow interacts with the warm ground temperatures. During our last snowstorm (April 14th where we got 2.9" of snow), it didn't take long for the snow to overcome the warm ground here in the Stateline. If it starts to stick early on into the event, roads will definitely be slick and hazardous to drive on by tomorrow afternoon and evening.

2. Winds: The winds tomorrow could also bring impacts to the Stateline during this event. Winds will begin to ramp up starting tomorrow morning and last into the evening and could top out around 35 mph at times. This along with accumulating, wet, heavy snow could cause light tree branches to snap and fall. Another thing to keep in mind with the blustery conditions is power outages.

Luckily, the combination of the Late-April sun angle and temperatures in the 50's both Sunday and Monday, will quickly aid in the melting of whatever amount of snow we get from this storm system.

Thursday, April 25, 2019

Rare Late Season Snow Possible for Saturday

Say it isn't SNOW!

A potent low pressure system moving in from the northwest Saturday morning will bring with it the chance for snow Saturday afternoon and evening.  For some, the snow could accumulate quite a bit by Saturday night.

High pressure will briefly move in Friday afternoon but then shift into the southeast Friday night.  This will allow low pressure moving out of the Plains to sweep across Iowa and west-central
Illinois by Saturday evening.  Initially precipitation will start out as a chilly rain Saturday morning but will then mix with, or completely change over to, snow Saturday afternoon and evening.  Temperatures stuck in the 30s during the afternoon will allow the snow to be a heavy, wet snow - wherever it falls.  As it looks right now the heaviest will fall over southern Wisconsin where several inches of snow could accumulate.  However, a slight shift in the track could shift the heaviest band of snow either north or south.  This is definitely something we'll be keeping a close eye on in the days to come. 

Rain Moves In Thursday Evening

A line of showers is currently moving through southern Wisconsin and northern Illinois Thursday evening following the passage of a cold front.

Temperatures Thursday warmed into the low 70s but have quickly fallen into the 60s, and even 50s, now that the front has passed.  Winds are also increasing from the North gusting close to 30-35 mph.  There were a few isolated thunderstorms earlier but the rain is movng into an environment with little instability.  The rain will, however, become more widespread through the evening before coming to and end from west to east by 10pm.  Skies will then turn partly cloudy overnight.

Skies will quickly turn partly cloudy with temperatures falling into the low 40s.  Rainfall amounts won't be much and should remain right around a quarter of an inch.

Rain Chances Increase This Evening

Clear skies and light winds helped temperatures this morning drop down into the upper 30s in most spots. It was definitely a chilly start to the morning, but the sunshine is already making up for it. Temperatures so far have climbed into the upper 50s and we look to warm up into the upper 60s this afternoon. Today looks to be mostly dry and mild with plenty of sunshine before things begin to change up this evening. Not only do you want to take your sunglasses, but it would also be a good idea to have an umbrella on hand.

Clouds will then increase later on today as a cold front begins to approach the region. This frontal boundary will bring a chance for showers as well as a few embedded thunderstorms. Instability will be on the low side throughout this event so we aren't expecting anything severe. But a few rumbles of thunder are possible.

Timing out the rain, the first half of the day looks to remain dry. Our highest chances for rain will occur between 5 PM and 10 PM this evening. The cold front should press through the region by midnight tonight as that is when we will see rain chances decrease substantially. Clouds will begin to go on the decrease the further we go into Friday morning.  Friday will feature much drier conditions and plenty of sunshine, but it will feel a tad bit cooler than what we will see today. Temperatures will be seasonable with highs in the low 60s. That is all before a potent low pressure system swings in for the weekend not only bringing a chance for rain and thunderstorms, but also below average temperatures. 

Tuesday, April 23, 2019

Clouds Clearing Out, Sunny Afternoon

The low pressure system that brought strong to severe storms to the Stateline area yesterday has pushed off to the northeast. The atmosphere looked to be a little overworked as we entered the evening yesterday. With a limited amount of energy in the atmosphere, the main line of thunderstorms began to break apart and weaken as it made its way towards the Rockford area. Some areas off towards the west and the south did receive heavy rain as thunderstorms rolled on by as well as observe small hail.

The cold front associated with that low pressure system passed through our region earlier this morning not only bringing a chilly start to the day, but also a breezy one. It wouldn't be a bad idea to grab a light jacket as you make your way out this morning. We do have some leftover cloud cover from yesterday's system, but that looks to clear out as we head into the afternoon. And it's all thanks to that high pressure system sitting in the upper Midwest!

This high pressure system will begin to slide in this afternoon and will help keep things quiet into tomorrow. Today will feature much cooler temperatures than what we have have experienced the past two days. Highs yesterday and on Easter Sunday both warmed up to 80°. Now that the winds are out of the north, temperatures this afternoon will only climb into the low 60s.

On the bright side, temperatures in the low 60s are considered to be seasonable for this time in April. Once the clouds clear out, our afternoon will be filled with plenty of sunshine. With that said, it will be a beautiful day to do some yard work, run some errands, or even take the pup out for a walk or to take them to the dog park. 

Monday, April 22, 2019

Isolated Severe Storms Monday Afternoon

6:00pm Update: New Severe Thunderstorm Warning for Carroll County until 6:45pm.  Storm located over Delmar, IA is currently moving east at 50mph.  60mph and penny sized hail possible with this storm.

Severe Thunderstorm Warning canceled for Jo Daviess County.

(5:47:00 PM) nwsbot: Local Storm Report by NWS DVN: 3 E Rock Grove [Stephenson Co, IL] public reports HAIL of pea size (E0.25 INCH) at 05:30 PM CDT -- half inch hail 530-540 pm cdt.

The Severe Thunderstorm Warning for Lee County has been canceled.  Storm still capable of dime to nickel sized hail. 

5:20pm Update: Severe Thunderstorm Warning for south-central Lee County until 5:45pm.  Storm is moving to the east around 35 mph.  Quarter sized hail will be the biggest threat. 

4:10pm Update: Severe Thunderstorm Warning for Lee County until 4:45pm.  Storm located west of Dixon is currently moving east at 35 mph and capable of producing quarter sized hail.

A Severe Thunderstorm Warning remains in effect for Whiteside County until 4pm Monday afternoon.  A cluster of thunderstorms capable of quarter sized hail has been moving through Whiteside County, with several reports of hail across eastern Iowa and northwest Illinois.

The storm is moving to the northeast/east around 45 mph.  It may weaken a little as it approaches western Lee County as the environment is a little more stable.  However, an approaching cold front will allow for an increase in storm coverage through the evening.  Any strong to severe thunderstorm will be capable of producing large hail and damaging winds. 

Severe Weather Possible This Evening

After receiving our first 80° day of the year yesterday, today will be slightly cooler with highs in the upper 70's. The only difference is, the dry spell looks to end this evening. A strong low pressure system off towards the west will help bring in a large amount of moisture to the viewing area this afternoon and evening. This will help dew points rise in to the mid to upper 50's and temperatures into the upper 70's.

The Storm Prediction Center has placed the entire viewing area under a Marginal Risk (Dark Green) for severe weather. That is level 1 of 5 in the categorizes for severe weather. The main severe hazards for this evening look to be damaging wind gusts and large hail up to quarter size. The tornado risk is very small, but is non-zero. So just in case, make sure you are weather ready.
The main time frame for thunderstorm chances will be right after peak heating (12PM - 4 PM) this afternoon. Most models show thunderstorms starting to move into our western counties right around the start of the evening commute. This main line will then track through the Rockford area between 6-8 PM so definitely have the rain gear on hand as you are leaving work or are heading home. And while you are out on the roads, if a thunderstorm is creating hazardous conditions, use extra caution. The thunderstorms should exit the viewing area by at least 10 PM tonight leaving around a few lingering showers as we go into tomorrow morning.

This would be a great time to make sure that your severe weather plan is set and ready to go. Also, make sure that you have multiple ways to receive watches and warnings as severe weather rolls through your area. Whether it's through a weather radio, or your cell phone by downloading the First Warn Weather App, or by watching our weather casts. It is crucial to be have the latest information during a severe weather event. Happy Earth Day Stateline and be weather aware!

Sunday, April 21, 2019

First 80 Degree Day of the Season

Plenty of sunshine and warmth Sunday afternoon pushed temperatures across northern Illinois and southern Wisconsin into the upper 70s and low 80s.  Rockford reached 80 degrees for the first time this season/year. 

This actually isn't too far from when we typically achieve our first 80 degree day.  The long-term average for the first 80 degree day in Rockford typically occurs on or around Aprill 22nd.  The last time the temperature was 80 degrees, or higher, was last October 7th, 2018.
The earliest the temperature has reached 80 degrees was back on March 15th, 2012.  The latest Rockford ever reached 80 degrees was June 1st, 1973.

Monday will be another warm, summer-like, afternoon.  A little more cloud cover during the afternoon will keep temperatures from hitting the 80 degree mark, but highs should warm into the mid and upper 70s.  Showers and thunderstorms will be possible ahead of a cold front late afternoon and evening.

Saturday, April 20, 2019

Warm Easter Sunday

Winds shifting around to the south Sunday morning will give temperatures a nice little boost during the afternoon, bringing highs into the mid and upper 70s!

High pressure centered over the western Great Lakes Saturday left most of the Midwest with northing but sunshine and warmth.  Officially the high in Rockford reached 68 degrees!  Clear skies continue into Easter Sunday morning with temperatures starting off in the mid 40s. 

Winds will increase a little during the afternoon pulling in a very warm air mass.  This will bring temperatures into the mid 70s for most, if not the upper 70s to near 80 degrees Sunday afternoon.  Since Easter doesn't fall on the same day every year there is no 'normal high' for that day.  The warmest Easter day ever recorded was April 12th, 1925 and April 10th, 1977 when the temperature reached 84 degrees.  Last year Easter fell on April 1st and the high temperature that afternoon was only 32 degrees.

Thursday, April 18, 2019

Breezy Today, Windy Tomorrow!

It took a while for thunderstorms to break through the cap and materialize yesterday. We dodged the severe weather threat as only a few strong storms formed right after sunset and moved into Southern Wisconsin. As we were all waking up this morning, a cold front was making its way through the Stateline. This has set the stage for a chilly, cloudy, and breezy day for the Stateline. 
We have been mostly cloudy and breezy for most of our Thursday morning. A recent look at satellite and radar shows a band of showers now moving through the eastern half of the viewing area. This is all due to a upper-level trough that is currently moving through the Great Plains. The shower activity should decline as we head into this afternoon. but a shower or two still cannot be ruled out.
Did you enjoy the 75° temperatures yesterday? Well, we are sad to say that today is going to feel the total opposite. With the passing of this mornings cold front, temperatures will be fluctuating in the upper 40's-low 50's throughout the afternoon. Not only that, its going to be breezy as there will be an uptick in winds this afternoon. Winds will gust out of the northwest at 20 to 25 mph at times.
Now heading into Friday, a low pressure system will slowly track southeast of the region to start of the morning. This low will strengthen and deepen causing a tight pressure gradient at the surface. The tighter the pressure gradient is, the stronger the wind gusts. Tomorrow, we can expect wind gusts a little bit stronger than today. Temperatures stay below average as well making it a chilly and windy start to the weekend.

Wednesday, April 17, 2019

Isolated Thunderstorm Wednesday Evening - Severe Threat Quickly Ending

 9:10pm Update: Our overall severe threat has pretty much come and gone Wednesday evening.  While an isolated strong/severe storm can't be ruled out only a few showers and isolated storms are expected during the overnight. 

Storms over the southern Plains will lift northeast after Midnight impact parts of central Illinois early Thursday morning.  Those could produce some gusty winds but the biggest threat looks to remain south of I-80.  A few showers will last into Thursday morning with mostly cloudy skies expected Thursday afternoon.

Isolated thunderstorms have developed Wednesday evening over northern Illinois and southern Wisconsin.  The storms have remained below severe limits, but did produce pea to penny sized hail in Beloit and South Beloit.

Isolated thunderstorms continue to move east of I-39 this evening with a line of weakening showers and thunderstorms moving into eastern Iowa.  The severe threat continues to quickly decrease this evening as a cold front advances from the west.

Thunderstorms developing over the southern Plains will lift northeast overnight into central Illinois.  These storms will pose a wind threat but mostly south of the area and are expected to move in after Midnight.  A few showers will linger into Thursday with temperatures holding steady in the mid and upper 50s.

Severe Potential Later Today

After almost having a "sunny & 75" forecast yesterday, our attention turns to the potential for thunderstorms this evening. The Storm Prediction Center (SPC) in Norman, OK has placed the Western half of the Stateline is under a Slight Risk, while the other is under a Marginal Risk. Now, don't pay attention to the category. Just know that there is the potential for severe weather throughout this afternoon and evening.

There are two key features that we need to keep an eye on for today's severe weather potential. The first is the stationary front in central Illinois, and the second is a low pressure system out in the Midwest. Models continue to show this stationary boundary lifting northward as a warm front. If this does occur, the viewing area will be placed in the warm sector of the low pressure system. This is where a large amount of moisture and warmer air is brought up from the south. This will provide a potent environment for severe storms to form. With that said, if the warm front fails to lift north and stays to our south, than that drops our severe weather chances drastically.

There's one other factor into whether we will encounter severe storms this evening. It's something meteorologists call "the cap". Normally, temperatures decrease the further up you go in the atmosphere. But sometimes, there will be layer of relatively warm air aloft, usually several thousand feet above the surface. This acts as a blocker and delays the development of thunderstorms. 

Thunderstorms rising into this warm layer become much cooler than the surrounding air, which inhibits their ability to rise and fully mature.If thunderstorms can break "the cap" this afternoon, the severe weather potential for our area will increase.

The time frame in which we have the best chance to see severe thunderstorms will be from 4 PM to 11 PM. Storms will initially develope out to our west. They will then move in during the evening commute, so make sure you take your time heading home this evening. Most likely will see gusty winds and large hail, but a tornado or two cannot be ruled out!

And with severe weather in mind, here are a few severe weather safety tips. Always have multiple ways to receive watches and warnings issued by the National Weather Service. That could be with a weather radio, your local meteorologist, or on your cell phone. Then, make sure that you have a safe place and a severe weather kit ready to go!