ASK TOM: Is the humidity always 100 percent when it is raining?

Posted on: May 22nd, 2013 12:44 AM by CWC Staff

 

Dear Tom,

Is the humidity always 100 percent when it is raining?

-- Janis Norm, Rockford?

 

Dear Janis,
No, it is not. Rain can occur in many different kinds of weather situations. For example, consider the situation that meteorologists refer to as “overrunning.” It’s an atmospheric event that occurs most frequently during the colder portion of the year.

 

Warm, moist air (with a humidity of 100 percent) from which rain (or snow) is falling spreads up and over a layer of cooler air at ground level. Typically, the cool layer is several hundred to a few thousand feet deep, and it is usually relatively dry in comparison with the warmer air above. Relative humidity at the surface, sometimes below 80 percent, reflects the moisture content of the surface air into which rain is falling from warmer, saturated air above.

Moon over puffy cumulus

Posted on: May 21st, 2013 7:21 PM by Steve Kahn No Comments

 

Thanks to Tracy Schonberger who sent this great shot of  puffy cumulus clouds visible over St. Boniface Cemetery  with the moon rising in the background.

 

Photo by Tracy Schonberger

Photo by Tracy Schonberger

The tornado warning issued for the deadly EF-5 Moore Tornado on Monday May 20, 2013

Posted on: May 21st, 2013 6:47 PM by Steve Kahn No Comments

 

Below is a copy of the actual tornado warning issued for what was to become the
deadly EF-5 Moore tornado. the warning was issued with a 36 minute lead time before
the twister struck the area and was issued 16 minutes  before the twister first touched
down.

 

The warning contains verbiage of the new impact-based warnings being issued by
the National Weather Service which employs tougher language in the call to
action statements to urge people to take protective action NOW. The enhanced
wording is bolded in the text below.



BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE NORMAN OK
301 PM CDT MON MAY 20 2013





THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A


 





* TORNADO WARNING FOR...


  NORTHWESTERN MCCLAIN COUNTY IN CENTRAL OKLAHOMA...


  SOUTHERN OKLAHOMA COUNTY IN CENTRAL OKLAHOMA...


  NORTHERN CLEVELAND COUNTY IN CENTRAL OKLAHOMA...


 





* UNTIL 345 PM CDT


 




* AT 259 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM


  SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS TORNADO NEAR


  NEWCASTLE. DOPPLER RADAR SHOWED THIS TORNADO MOVING NORTHEAST AT 20


  MPH.


 





THIS IS A TORNADO EMERGENCY FOR MOORE AND SOUTH OKLAHOMA CITY.


 





IN ADDITION TO A TORNADO...LARGE DESTRUCTIVE HAIL UP TO TENNIS BALL


SIZE IS EXPECTED WITH THIS STORM.


 




* LOCATIONS IMPACTED INCLUDE...


  MIDWEST CITY...MOORE...NEWCASTLE...STANLEY DRAPER LAKE...TINKER AIR


  FORCE BASE AND VALLEY BROOK.


 




PRECAUTIONARY/PREPAREDNESS ACTIONS...


 





THIS IS AN EXTREMELY DANGEROUS AND LIFE THREATENING SITUATION. IF YOU


CANNOT GET UNDERGROUND GO TO A STORM SHELTER OR AN INTERIOR ROOM OF A


STURDY BUILDING NOW.


 






TAKE COVER NOW IN A STORM SHELTER OR AN INTERIOR ROOM OF A STURDY


BUILDING. STAY AWAY FROM DOORS AND WINDOWS.


&&



						

					

				
				

			
			

			
				
			

			
				

				
					

						
Last night’s lightning as seen from Yorkville

						

    Posted on: May 21st, 2013 5:01 PM by Steve Kahn    No Comments

					

					
					
					
					
					
 

					
					

						

							
Thanks to Liz Fox for this great lightning shot from last night's storms.


 


Photo by Liz Fox
Photo by Liz Fox

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Lightning, Aurora style

						

    Posted on: May 21st, 2013 4:52 PM by Steve Kahn    No Comments

					

					
					
					
					
					
 

					
					

						

							
 


This stacked photo depicts multiple lightning discharges last evening and looks toward the Aurora Airport from about a mile south in Sugar Grove.


Photo by Kelly Gustafson
Photo by Kelly Gustafson


 

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Waukegan’s Monday night lights

						

    Posted on: May 21st, 2013 4:17 PM by Steve Kahn    No Comments

					

					
					
					
					
					
 

					
					

						

							
Storms produced this dramatic lightning discharge in Waukegan last night. This photo comes to us from David Andrews whose son Jeremy snapped this remarkable shot.


Photo by David and Jeremy Andrews
Photo by David and Jeremy Andrews

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Monday night lightning

						

    Posted on: May 21st, 2013 4:16 PM by Steve Kahn    No Comments

					

					
					
					
					
					
 

					
					

						

							
Thanks to Nick Ulivieri who shares with us this double lightning strike photo he took last evening. One is in contact with the Willis Tower---the second in the distance is striking antennae on the Hancock Building.


Photo by Nick Ulivieri
Photo by Nick Ulivieri


 

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Shot of yesterday’s tragic tornado approaching Moore, Oklahoma

						

    Posted on: May 21st, 2013 4:47 PM by Steve Kahn    No Comments

					

					
					
					
					
					
 

					
					

						

							
Thanks to Tom Pastrano who captured this shot of yesterday's massive EF-5 tornado as it was approaching Moore.


 


Photo by Tom Pastrano
Photo by Tom Pastrano


 


 


 


 


 

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Main focus for severe weather this afternoon is east of Chicago

						

    Posted on: May 21st, 2013 12:26 PM by Mike Hamernik    No Comments

					

					
					
					
					
					
 

					
					

						

							
A few gusty thunderstorms may yet develop across the Chicago area this afternoon, but the threat of organized severe weather remains very low.


 


The Storm Prediction Center has removed Chicago from the "Slight Risk" categorization.  For the Midwest, the main severe weather risk this afternoon is centered over Michigan, Ohio and eastern Indiana.


 


spc 521


 


 

						

					

				
				

			
			

			
				
			

			
				

				
					

						
Chicago area on western edge of severe storm risk area today

						

    Posted on: May 21st, 2013 6:37 AM by Paul Dailey    No Comments

					

					
					
					
					
					
 

					
					

						

							
The greatest threat of severe storm development today is expected to be in the southern plains with northeastern Texas, northwest Louisiana, the southeast tip of Oklahoma and southwestern Arkansas under a moderate risk of severe storms (see red-shaded area on map below).


A good portion of Lower Michigan, Indiana and southern and eastern Illinois have been placed in the slight risk area today with the immediate Chicago area and south on the western edge of the outlined area (yellow-shaded area on map below). With normal daytime heating showers and thunderstorms may develop primarily this afternoon and evening with strongest storms likely east of a line from Pontiac, Illinois to Gary, Indiana.