Skip Navigation Links www.nws.noaa.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
Storm Prediction Center
 
   

Search SPC
 

Mesoscale Discussion 6
MD 6 graphic
   
   MESOSCALE DISCUSSION 0006
   NWS STORM PREDICTION CENTER NORMAN OK
   0621 PM CST SAT JAN 01 2005
   
   AREAS AFFECTED...SERN MN...NCNTRL/NERN IA...MUCH OF WI...FAR NRN IL
   AND MUCH OF LOWER MI/SRN UPPER MI
   
   CONCERNING...FREEZING RAIN AND SLEET 
   
   VALID 020021Z - 020615Z
   
   SIGNIFICANT ICE/SLEET EVENT WILL CONTINUE TO DEVELOP WHILE
   PROGRESSING ENEWD FROM THE UPPER MS VALLEY ACROSS THE WRN/NRN GREAT
   LAKES REGION THROUGH 06Z. TWO CORRIDORS OF HEAVIEST ACCUMULATIONS
   ARE ANTICIPATED TO OCCUR DURING THIS TIME. ONE AXIS IS ANTICIPATED
   TO EXTEND FROM NCNTRL/NERN IA NEWD ACROSS SERN MN...CENTRAL/NERN WI
   AND THE WRN U.P. OF MI. THE OTHER AXIS ACROSS PORTIONS OF WCENTRAL
   WI EWD INTO CENTRAL LOWER MI. IN BOTH OF THESE AREAS...ISOLATED 0.15
   TO 0.25 IN/HR LIQUID EQUIVALENT PRECIPITATION RATES ARE POSSIBLE
   THROUGH 06Z.
   
   RECENT WV IMAGERY SHOWS A WELL DEFINED UPPER LVL JET MAX ROTATING
   OUT OF THE CENTRAL ROCKIES INTO THE CENTRAL HIGH PLAINS OF WRN
   KS/NEB. UPPER DIVERGENCE IN THE LEFT EXIT REGION OF THIS JET HAS
   ALREADY ENHANCED CLOUD TOP COOLING ON IR IMAGERY OVER WRN IA/SWRN MN
   AND INCREASING CONVECTIVE PRECIPITATION IN THESE AREAS. AS THE UPPER
   JET MAX CONTINUES TO MOVE NEWD...IT WILL CONTINUE TO SUPPORT NEWD
   ENHANCEMENT OF ALREADY MODERATE TO STRONG LIFT IN RIGHT ENTRANCE
   REGION OF NRN JET MAX OVER THE U.S/CANADIAN BORDER AND LOW LEVEL
   ISENTROPIC ASCENT ALONG AND NORTH OF SFC WARM FRONT BOUNDARY. THUS A
   DEEP LAYER OF VERTICAL MOTION WILL EXTEND ALONG AND NORTH OF THE SFC
   LOW/WARM FRONTAL TRACK FROM NCENTRAL IA NEWD INTO NCENTRAL WI
   THROUGH 06Z. THE TRANSITION ZONE FOR FREEZING RAIN/SLEET IN THIS
   REGION HAS BEEN SOMEWHAT MUDDLED BY THE CONVECTIVE NATURE OF THE
   PRECIPITATION. THUS A MIX OF FREEZING RAIN/SLEET IS ANTICIPATED TO
   OCCUR THROUGH THE PERIOD WITH A CONTINUATION OF THE CONVECTIVE
   NATURE OF PRECIPITATION GIVEN THE DEGREE OF FORCING...STEEP MID
   LEVEL LAPSE RATES AND 100-200 J/KG OF MUCAPE.  STRONGEST VERTICAL
   MOTION DUE TO COUPLED JET STRUCTURE WILL EXIST FROM NCENTRAL IA NEWD
   INTO NCENTRAL WI/WRN U.P OF MI THROUGH 06Z.
   
   ELSEWHERE...AS THE SFC LOW LIFTS NEWD INTO SERN MN THROUGH 06Z...THE
   SFC FREEZING LINE IS ANTICIPATED TO LIFT NWD TO A ALO TO MSN TO MKE
   LINE BY 06Z. THUS FREEZING RAIN OVER ERN IA/FAR NRN IL AND FAR SRN
   WI WILL GRADUALLY CHANGE TO RAIN FROM SOUTH/NORTH THROUGH THIS
   PERIOD. FARTHER ENE...A DRY BOUNDARY LAYER WILL CONTINUE TO AID IN A
   SLOW DEVELOPMENT OF SIGNIFICANT FREEZING RAIN AND/OR SLEET OVER MUCH
   OF ECENTRAL WI THROUGH 02Z AND WRN/CENTRAL LOWER MI THROUGH 03Z.
   WELL REMOVED FROM THE SFC LOW DRY ELY FLOW WILL LIMIT THE NWD
   MOVEMENT OF THE SFC FREEZING ISOTHERM BEFORE AND AFTER ONSET OF
   PRECIPITATION OVER CENTRAL/SRN LOWER MI. INITIAL PRECIPITATION OVER
   ECENTRAL WI EWD INTO WRN/CENTRAL LOWER MI WILL LIKELY FORM IN THE
   FORM OF SLEET DUE TO THE DRY BOUNDARY LAYER. HOWEVER...INCREASING
   MOISTURE ADVECTION ON THE HEELS OF A 40-50 KT LOW LEVEL JET/SUBTLE
   MID LEVEL SHORTWAVE CURRENTLY AIDING IN MODERATE PRECIPITATION OVER
   ERN IA/WRN IL WILL AID IN QUICK SATURATION IN THE LOW LEVELS FROM
   SW-NE FROM 02-06Z. COMBINED WITH MODERATE INSTABILITY...MUCAPES FROM
   100-300 J/KG...MODERATE TO HVY FREEZING RAIN IS ANTICIPATED TO OCCUR
   ACROSS THIS REGION BETWEEN 02-06Z. THE LEADING EDGE OF THE HEAVIEST
   PRECIPITATION GIVEN CURRENT EXTRAPOLATION WILL REACH A JXN TO HTL
   LINE BY 06Z.
   
   ..CROSBIE.. 01/02/2005
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
   SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
   06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
   RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
   USED FROM DECEMBER 1 THROUGH FEBRUARY 28.
   
   ATTN...WFO...DTX...APX...IWX...GRR...MQT...GRB...LOT...MKX...DVN...DLH...ARX...MPX...DMX...
   
   46119001 46188721 45658586 44888475 44258404 43428350
   42588355 42338420 42208600 41888777 41859080 42389303
   42889359 43719385 45219321 45699205 
   
Top/All Mesoscale Discussions/Forecast Products/Home