Breezy & Warm

As April comes to a close, it'll go down as a rainy and cool one.  So far we've racked up 4.90 inches of rain at O'Hare this month.  That's 1.34 inches above average!  And highs have averaged 55.6 degrees.  We'll end the month on the mild side with temps topping into the low 70s today.  It'll be a breezy day as well with S/SE winds 15-20 mph gusting to 30 mph.  After a warm front passes today, a cold front quickly follows with a chance of rain early evening through the overnight hours tonight.  Sunday promises to be a cooler day with highs only around 60 degrees, but the sunshine reappears after a mostly cloudy to partly sunny day on Saturday.  The trend this upcoming week is leaning to the drier side compared to weeks past, but there still are some chances of rain later in the week.  Here's the rest of the week's forecast.  Monday-mostly sunny (high/low) 58/42, Tuesday-mostly sunny 60/41, Wednesday-sunny skies 67/42, Thursday-partly sunny with a chance of rain 65/47, and for Friday-mostly cloudy with a chance of rain 64/50.  Enjoy your weekend!  MARK BISHOP

A quiet day

...And that applies locally as well as across the battered South.  High pressure is off to our east, protecting us for a short while from wet weather and clouds.  That same high is camped right over the hardest-hit parts of the country, where the death toll has exceeded 300.  A word of caution: We keep hearing reporters and anchors referring to "150 tornadoes that ripped through the Southeast..."  That's not necessarily true.  In fact, the actual number of twisters will likely be MUCH lower.  Why the error?  They are referring to statistics from the Storm Prediction Center (SPC) where reports of severe weather are catalogued. Here's the map for Wednesday. http://www.spc.noaa.gov/climo/reports/110427_rpts.html  Notice how 211 tornado "reports" are listed.  Well that could mean 211 individual and unique tornadoes, 211 sightings of the SAME tornado in different locations, or most likely, some combination in between.  I expect when all of the damage assessment is completed (and this will take several more days to do properly) the actual number of tornadoes will go down as the tracks are identified and duplicate reports are negated.  No matter... this will go down as one of the top five tornado outbreaks in terms of deaths.  The worst is still the Tri-State outbreak of March 18, 1925 while killed 747 people, including more than 650 from the single deadliest tornado in U-S history. 

On to brighter news.  The sun is making a rare April appearance today.  This month has featured plenty of rainfall (it's the 23rd wettest April so far) and when it hasn't been raining it's been cloudy much of the time.  We might not be done with April rainfall yet, however. A storm system will drag a cold front through here tomorrow night, sweeping away Saturday highs in the 70s and ushering in 50s for Sunday.  A few showers and thunderstorms will accompany the front... especially tomorrow night.  For the first week of May, early indications point to pleasant weather and seasonable temperatures.

Mike

A Sad Day

In the news business, it's difficult to best serve everyone's interests.  I'm sure many viewers are going to be thrilled to focus on the Royal Wedding early Friday our time.  Meanwhile, cleanup will be ongoing across a large portion of our country in the wake of one of the deadliest tornado outbreaks ever.  To me, that should be of the highest importance.

As I write this blog, the death toll is 249 and rising.  Most of those deaths were in Alabama, where amateur and professional video captured one of the best-documented tornadoes ever as it leveled parts of Tuscaloosa.  I watched a portion of a broadcast featuring a friend, fellow TV meteorologist James Spann, as the deadly tornado scoured away the city live on ABC 33/40 in Birmingham. He's one of the best in the business, but he was clearly disturbed by what he was seeing.  That storm was born from a supercell thunderstorm whose deadly power was first unleashed in Neshoba County, MS.  By chance, I had picked that storm yesterday afternoon as a textbook example of a tornado vortex signature on radar, and posted pictures of it on my facebook page. That same storm would cross eastern Mississippi, Alabama, northern Georgia, then finally weaken over the mountains of North Carolina.  Weather Service damage assessment teams will later give this tornado an EF rating (I expect it'll top out at EF5) and determine how long a single tornado spawned by the storm stayed on the ground.  The record is 219 miles set by the Tri-State Tornado on March 18, 1925.  This may have exceeded that incredible distance.

Many today are wondering why there were so many fatalities.  No one can say the public wasn't warned. The Storm Prediction Center (SPC) telegraphed the unusually high risk of tornadoes several days in advance.  SPC and local National Weather Service offices were spot-on with their issuance of watches and pre-emptive warnings.  Sirens blared.  TV coverage showed tornadoes AS THEY WERE OCCURING.  People had to know what was coming. What went wrong? 

I have some possible thoughts on that matter. First: Apathy.  Ever see a tornado warning for your county go by on your tv set and do absolutely nothing?  It's easy to become complacent and I suspect many folks in the south simply ignored the warnings. Second: Storm speed.  I'm not referring to the wind speed here.. but actual speed of storm propagation. Many of those supercells were racing across the countryside at 50-70 miles per hour yesterday. If you live in Oak Park and a friend calls you from Forest Park to tell you a tornado just hit her neighborhood and that storm is moving at 70mph... you don't have much time to react.  Third, and I think most importantly: Strength of tornadoes. Look at the tornado video and damage aftermath on the news, youtube, wherever.  It's horrific.  The worst of the twisters yesterday likely had winds in excess of 200 mph.  Many of the people who died probably went to the safest place in their home, well ahead of the storm, and it simply wasn't safe enough.  When a monster like the one that hit Tuscaloosa roars through, the only relatively safe place is under ground... away from everything blowing around above ground at 200mph. Not everyone had access to a basement or storm cellar.  Very little any of them could do in the face such power.

Gino Izzi out at the NWS in Romeoville put out a great reminder about Chicago's risk of severe storms.  Here's the link: http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=67386&source=0

Read it.  Consider your own safety plans and willingness to act when severe storms threaten.  I reflect back on James Spann's terrific coverage yesterday and hope I can maintain similar composure for that day when our area is in the crosshairs.

Mike

Morning Washout!

Last night, between watching Dancing With the Stars, flipping over to the Weather Channel to monitor the southern storms, switching over to the Bulls victory then the crushing Hawks OT defeat, I was fairly confident that my forecast of minimal shower activity here would pan out.  Our in-house MicroCast model showed no rain.  The beloved NAM model showed no rain.  Then... somewhere around 5 a.m., what looked like a feeble area of sprinkles ballooned into a rain shield covering the entire viewing area most of the morning. At least that rain is outbound as drier air wraps in from the southwest.  Only a few showers are expected this afternoon and tonight, but a new disturbance threatens renewed shower activity tomorrow... a Thursday which will find temperatures struggling to get out of the 40s.  Beyond that, warmer temps loom for Friday and Saturday. I think Saturday we'll enjoy 70s before a cold front cuts through the warmth with a line of showers and thunderstorms at night or Sunday morning.

Speaking of storms, yesterday brought 57 new tornado reports to what will almost certainly go down as the most tornadic April ever.  Seven states had twisters from TX to KY.  Sadly, at least 3 more fatalities came as a result of the deadly storms in Mississippi.  The atmosphere appears ready to re-load again today. In fact, tornado watches and warnings are in effect as I write this at a time of day when you'd expect things to be quieting down. The highest risk of tornadoes will be in eastern MS, much of AL, southern TN and northwest GA.  This is part of the diagnosis from the Storm Prediction Center... highlighting the risk:

   THE VERTICAL SHEAR ENVIRONMENT WILL BECOME VERY FAVORABLE FOR
   TORNADIC SUPERCELLS...CHARACTERIZED BY LONG/CURVED HODOGRAPHS WITH
   EFFECTIVE BULK SHEAR IN EXCESS OF 70 KT AND EFFECTIVE SRH OF 300-600
   M2/S2 IN THE UNSTABLE WARM SECTOR.  GIVEN THE EXPECTATION OF SEVERAL
   HOURS OF DISCRETE SUPERCELL DEVELOPMENT IN THE WAKE OF THE MORNING
   STORMS...A VERY MOIST BOUNDARY LAYER...THE STRONG INSTABILITY...AND
   INTENSE VERTICAL SHEAR...THE SCENARIO APPEARS FAVORABLE FOR MULTIPLE
   LONG-TRACK SUPERCELLS WITH THE POTENTIAL TO PRODUCE INTENSE/DAMAGING
   TORNADOES IN THE HIGH RISK AREA.

I realize not all of you are weather geeks, so I'll paraphrase a bit.  Shear is a change of wind speed and direction, most importantly with height.  Meteorologists use a graphic tool called a hodograph to map how much shear will be present.  Shear is a vital ingredient in severe thunderstorm development, especially "supercells" capable of producing tornadoes. The meteorologist here also refers to SRH... which stands for Storm Relative Helicity. Imagine helicity this way: Take a roll of paper towels and place it lengthwise on a table.  Now push the top side of the roll... causing it to roll over the table.  Air works the same way... if the wind is stronger above the ground than close to it, there will be a horizontal tube of rotating air.  What if we could get that horizontal motion into a more vertical orientation?  We can.  Through vigorous updrafts in a thunderstorm, that rolling motion can be converted into a vertical spin... and that's helicity.  Thunderstorm cells with such rotation are the ones most apt to produce a tornado. The forecaster talks about discrete supercell development.  OK... storms can form and arrange themselves in many ways.  Sometimes they form into lines.  Sometimes they are separated by many miles.  Research has found that often times, a supercell that is "on its own" so to speak, can grow stronger and generate more powerful tornadoes that last longer.  Supercells which end up interracting with each other, while potentially damaging, seem to put down weaker tornadoes.  I suspect that might have been the case last night, when there were so many storms in close proximity that they sapped some of the energy from each other, limiting the potential that any single storm cell might have attained.  And that's quite a statement when you look at the damage wrought by the storms anyway. Today will be dangerous again, and there is clearly a fear it could be worse than yesterday where the storm mode is more discrete. I'll have the latest on the multi-day outbreak and our own forecast at 4, with JT taking over starting at 5.

Tornado Watch Issued

The Storm Prediction Center has noted a risk for supercell thunderstorms south and east of Chicago late this afternoon and into the evening.  Consequently a Tornado Watch is in effect until 9pm CDT for all of northern Indiana and southwest Michigan. Here's a map defining the area.  I'll have the latest on the storm threat starting at 4:00.

Mike

http://www.spc.noaa.gov/products/watch/ww0216.html

TUESDAY, APRIL 26, 2011

Good afternoon.  Aaaaaaaaa...can you feel the warmth?  Sixties are in the air today...but if for some reason you are longing for the days of snow, cold and all that went with the winter just past, the National Weather Service office has put out a detailed recap for you.  Here is a link to that data:

http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=67256&source=0

Tracy

Showery week.. but how much?

April is almost over, and in terms of cloud cover and rainfall... good riddance.  The rainfall today so far has been light anyway, with just some drizzle lingering early this afternoon. However, as an area of low pressure organizes to our west today, it will bring showers back into the area tonight and into the morning hours Tuesday.  While a few embedded thunderstorms are possible, I think overall the rainfall will be light.  In fact, what looked to be a VERY wet week here during our forecasts last week, now looks much less soggy, at least in terms of total precipitation.  In other words, while it may rain several times between now and Sunday, amounts should not be that great.  The higher risk of drenching rainfall is across the Ohio Valley where several inches of additional rainfall will accumulate this week. In addition, a high risk of severe thunderstorms will exist over the next few days spreading out of the Southern Plains today, into much of the eastern third of the country from New York to New Orleans by Wednesday.  I do not see a severe weather threat here for at least the next 5 days. 

So for today, it'll be mostly cloudy, with more peeks of sun the farther north you live, followed by showers tonight. Rainfall should exit during rush hour Tuesday as we get dry slotted in the storm system.  The passage of a warm front will send highs into the 70s over the southern half of the viewing area so tomorrow is not a total washout!

Mike

Another wet week????

We finally got a break from the rain this weekend after seeing measurable rain for eight days in a row. The breief dry spell will likely end as it looks like we will see more rain early this work week. An active frontal boundary to our south will lift northward bringing us the threat for substantial rain late Monday into Monday night. Right now it looks like the heaviest rain will fall south and east of of our area with probably about a half inch for our most of us. The question mark is will the rain return on Wednesday? A seconday storm will move along the front bringing heavy rain across Central Illinois into Northern Indiana and possibly clipping our area. By Thursday we should start to dry out and Friday looks like the nicest day of the week.

 The big weather story this week will likely be flooding along the Ohio River Valley. Some areas along the Ohio and Indiana border have already seen 2 to 4 inches of rain the last couple of days and will likely see another 2 to 5 inches of additional rainfall.

                                            Phil

Easter weekend a little warmer

After topping in the mid-40s for highs on Friday, Easter weekend promises to be warmer.  With highs averaging this month at around 55-degrees (compared to April 2010 with averages around 65-degrees), our low to mid-60s will feel nice for your Saturday.  Coming off a rainy week, we'll have a few days of dry weather then back into the rainy trend into the new week.  Easter Sunday looks mostly cloudy but overall dry this year.  Areas especially south of I-80 could have a shot of rain for Sunday, but the overall Chicagoland area will not see rain for Easter.  Next chances for more widespread rain will creep in starting Sunday night and carrying throuh with chances of rain Monday-Tuesday-and Wednesday.  Here's your forecast for the next week.  Sunday-Mostly cloudy (high/low) 59/45, Monday-Rain likely 55/43, Tuesday-Chances of rain 62/47, Wednesday-Chance of rain 51/41, Thursday-Partly sunny 56/42, Friday-Mostly sunny 64/44.  I hope you enjoy your weekend and enjoy warmer weather (compared to last week that is).  MARK BISHOP

FRIDAY, APRIL 22, 2011

Good morning.  It is another chilly, windy, raw, damp day in Chicago.  WHAT'S NEW?  I was looking over the stats from April 2010.  For April 2010, we had reached at least 80 degrees four times and 70 degrees five times.  This April, we hit 70 once and 80 once!!!  WHAT GIVES?  Our pattern has been one in which we have had a chilly wind off of the lake and persistant and unending cloud cover!...not to mention the rain and snow too.

But, I have to mention that...again...this afternoon, expect heavy rain in the area mainly south.  This evening, it is possible there may be a few thunderstorms at anytime and in any suburb.  But, Saturday is looking beautiful for any Easter Egg hunts....let's hope we find some sunshine hidden in our Easter baskets!!!

Tracy