PUBLIC INFORMATION STATEMENT   
   NATIONAL WEATHER SERVICE LITTLE ROCK AR   
   600 AM CST TUE NOV 12 2013   
      
   ...WINTER PRECIPITATION TYPES...   
      
   NOVEMBER 11TH THROUGH 15TH IS WINTER WEATHER AWARENESS WEEK   
   IN ARKANSAS. PEOPLE ARE ASKED TO TAKE SOME TIME TO PREPARE FOR    
   THE UPCOMING WINTER SEASON.   
      
   TODAYS TOPIC IS WINTER PRECIPITATION TYPES.   
      
   SNOW -- SNOW FORMS IN THE CLOUDS AND REMAINS AS SNOW ALL THE WAY TO   
   THE GROUND. IT MOST COMMONLY TAKES THE FORM OF SNOWFLAKES...WHICH   
   ARE THE FAMILIAR SIX-SIDED ICE CRYSTALS. IT MAY ALSO FALL IN THE   
   FROM OF SNOW PELLETS OR SNOW GRAINS.   
      
   SNOW FLURRIES ARE NORMALLY SEEN AS A FEW SNOWFLAKES FALLING...   
   ALTHOUGH VISIBILITIES CAN BE REDUCED AT TIMES. IN ARKANSAS...THE   
   TERM SNOW FLURRIES IS USED TO INDICATE THAT NO ACCUMULATION IS    
   EXPECTED.   
      
   SNOW SHOWERS IS A TERM NOT OFTEN USED IN ARKANSAS. IN THIS TYPE OF   
   PRECIPITATION...THE SNOW FALLS AT VARYING INTENSITIES...OFTEN    
   CHANGING INTENSITIES OVER BRIEF PERIODS. ACCUMULATION MAY OCCUR...   
   ESPECIALLY DURING MODERATE TO HEAVY SNOW SHOWERS.   
      
   BLOWING SNOW REFERS TO SNOW THAT IS ALREADY ON THE GROUND AND IS    
   LIFTED INTO THE AIR BY THE WIND.   
      
   IN ARKANSAS...HEAVIER SNOWS USUALLY OCCUR WHEN COLD AIR IS   
   ALREADY IN PLACE OVER THE STATE AND A STRONG UPPER LEVEL LOW    
   PRESSURE SYSTEM MOVES OUT OF THE SOUTHWESTERN UNITED STATES. THE    
   LOW SERVES TO PULL MOIST AIR FROM THE GULF OF MEXICO NORTHWARD INTO    
   THE COLD AIR. LIGHT SNOW OR SNOW FLURRIES CAN ALSO OCCUR IN THE COLD    
   AIR THAT FOLLOWS THE PASSAGE OF AN ARCTIC COLD FRONT.   
      
   SLEET -- SLEET CONSISTS OF PELLETS OF ICE. IN FACT...FOR PEOPLE WHO   
   HAVE TROUBLE WITH THE DIFFERENCE BETWEEN SLEET AND FREEZING RAIN...   
   IT MAY BE EASIER TO ASSOCIATE SLEET WITH ITS TECHNICAL NAME...WHICH   
   IS ICE PELLETS. FOR SLEET TO FORM...SNOW BEGINS FALLING FROM THE   
   CLOUDS BUT THEN GOES THROUGH A LAYER OF ABOVE-FREEZING AIR THOUSANDS   
   OF FEET ABOVE THE GROUND. THIS CAUSES THE SNOW TO CHANGE TO RAIN.    
   THEN...THE RAIN GOES THROUGH A LAYER OF BELOW-FREEZING AIR...USUALLY   
   AT LEAST TWO TO THREE THOUSAND FEET THICK...AND THE PRECIPITATION    
   TURNS INTO PELLETS OF ICE.   
      
   SLEET TYPICALLY OCCURS IN A FAIRLY NARROW BAND. THIS BAND USUALLY   
   MOVES...BUT AT TIMES MAY REMAIN NEARLY STATIONARY...RESULTING IN   
   ACCUMULATIONS OF SLEET.   
      
   IN ARKANSAS...SLEET MOST COMMONLY OCCURS IN A NARROW BAND BETWEEN   
   AN AREA OF RAIN TO THE SOUTH AND AN AREA OF SNOW TO THE NORTH.   
      
   FREEZING RAIN -- THIS WEATHER PHENOMENON IS SOMETIMES CALLED GLAZE...   
   BECAUSE OF THE GLAZE OF ICE IT PUTS ON SURFACES AT THE GROUND.   
   FREEZING RAIN NORMALLY OCCURS WHEN PRECIPITATION FALLS FROM THE    
   CLOUDS AS SNOW...THEN GOES THROUGH AN ABOVE-FREEZING LAYER...WHICH    
   TURNS THE PRECIPITATION TO RAIN. THEN...THE RAIN REACHES THE GROUND    
   WHERE TEMPERATURES ARE BELOW FREEZING. THE RAIN THEN FREEZES AS IT    
   HITS EXPOSED OBJECTS. IN THE WORST CASES...EVERYTHING BECOMES COATED    
   WITH A LAYER OF ICE.   
      
   IN ARKANSAS...FREEZING RAIN COMMONLY OCCURS AS AN ARCTIC HIGH    
   PRESSURE SYSTEM BEGINS TO MOVE AWAY FROM THE STATE. IN THIS    
   SITUATION...COLD AIR IS STILL LINGERING AT THE GROUND...BUT WARMER    
   SOUTHERLY WINDS FROM THE GULF OF MEXICO BEGIN BRINGING MOISTURE BACK    
   OVER THE TOP OF THE COLD AIR. SINCE THE AIR AT THE GROUND HAS NOT    
   WARMED ABOVE FREEZING...THE RAIN THAT FALLS FREEZES ON THE GROUND    
   AND OTHER OBJECTS. FREEZING RAIN...AND ITS COUSIN FREEZING DRIZZLE...   
   OFTEN DEVELOP DURING THE LATE NIGHT HOURS...CREATING ICY CONDITIONS    
   FOR MORNING RUSH HOUR.   
      
   FREEZING FOG -- WHILE THIS IS NOT PRECIPITATION FALLING FROM THE    
   CLOUDS...IT IS ANOTHER WINTER WEATHER HAZARD. FREEZING FOG TYPICALLY   
   DEVELOPS ON CLEAR...CALM NIGHTS WHEN TEMPERATURES ARE BELOW FREEZING.   
   FOG FORMS AND FREEZES...USUALLY ON BRIDGES...OVERPASSES...AND OTHER   
   ELEVATED ROADWAYS. IT CAN CREATE QUITE A SURPRISE FOR MOTORISTS...DUE   
   TO THE PRESENCE OF CLEAR SKIES OVERHEAD.   
      
   FROST -- FROST DESCRIBES THE FORMATION OF THIN ICE CRYSTALS ON THE   
   GROUND OR OTHER SURFACES IN THE FORM OF SCALES...NEEDLES...   
   FEATHERS...OR FANS. FROST FORMS WHEN WATER VAPOR IN THE AIR TURNS    
   DIRECTLY TO ICE CRYSTALS ON AN OBJECT. THE TEMPERATURE OF THE OBJECT    
   MUST BE BELOW FREEZING FOR FROST TO OCCUR. HOWEVER...FROST IS    
   SOMETIMES SEEN ON THE GROUND WHEN OFFICIAL TEMPERATURES ARE REPORTED    
   TO BE ABOVE FREEZING. THIS IS BECAUSE THE OFFICIAL TEMPERATURE IS    
   TAKEN ABOUT FIVE FEET ABOVE THE GROUND...WHERE THE AIR CAN BE A FEW    
   DEGREES WARMER THAN THE TEMPERATURE AT GROUND LEVEL.   
      
   &&   
      
   PLEASE VISIT OUR WEB SITE AT   WWW.SRH.NOAA.GOV/LZK   
      
   $$    
      
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