660  
FXUS63 KGRR 192345  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
745 PM EDT SUN MAY 19 2013  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
THUNDERSTORMS ARE EXPECTED TO IMPACT SOUTHERN LOWER MICHIGAN  
MONDAY THROUGH WEDNESDAY....WITH SOME SEVERE WEATHER POSSIBLE EACH  
DAY. COOLER AIR WILL RETURN LATE IN THE WEEK WITH LOW TEMPERATURES  
POTENTIALLY IN THE UPPER 30S FOR SOME OF THE HOLIDAY WEEKEND.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY NIGHT)  
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
SHORT TERM SEVERE WEATHER POTENTIAL REMAINS FOR MONDAY AFTERNOON  
THROUGH TUESDAY NIGHT. LOCALIZED FLOODING MAY BE POSSIBLE IF  
SEVERAL ROUNDS OR CONTINUOUS HEAVIER RAINFALL MOVES OVER THE SAME  
LOCATIONS IN SHORT SUCCESSION.  
 
STORMS RIGHT NOW LOOK LIKE THEY WILL DEVELOP BY EARLY TO MID MONDAY  
AFTERNOON NEAR THE LAKE SHORE AND MOVE EAST/NORTHEAST INTO THE  
EVENING. ADDITIONAL WAVES OF STORMS WILL BE POSSIBLE EARLY IN THE  
EVENING AS THE BROAD SYSTEM CONTINUES TO EJECT ENERGY INTO LOWER  
MICHIGAN FROM THE SOUTHWEST. SOME SEVERE STORMS WILL BE POSSIBLE  
WITH POTENTIAL FOR DAMAGING WINDS AND HAIL. NOT OUT OF THE  
QUESTION A QUICK TORNADO COULD SPIN UP...BUT TORNADOES DO NOT  
APPEAR TO BE MUCH OF A THREAT AT THIS TIME.  
 
UNCERTAINTIES THAT REMAIN IN THE FORECAST CENTER AROUND IF ANY  
DEBRIS CLOUDS FROM ONGOING STORMS TO OUR SOUTHWEST WILL LIMIT  
WARMING AND INSTABILITY MONDAY. ALSO IN PLAY IS THE LOCATION OF A  
STALLING WARM FRONT THAT PUSHES NORTH THROUGH LOWER MICHIGAN THIS  
EVENING/EARLY MONDAY. SEVERAL OF THE SHORT RANGE MODELS ARE INDICATING  
THIS FRONT STALLING ACROSS NORTHERN LOWER AND KEEPING BEST FORCING  
NORTH FOR MONDAY AFTERNOON INTO EARLY EVENING. SHOULD THESE TWO  
THINGS OCCUR...ESPECIALLY THE CLOUD COVER...SOUTHWEST LOWER MICHIGAN  
COULD MISS OUT ON MOST OF THE SEVERE WEATHER MONDAY AFTERNOON.  
 
LATE MONDAY NIGHT INTO TUESDAY EVENING SEES SEVERAL MORE CHANCES OF  
POTENTIAL THUNDERSTORMS WITH SLIGHTLY BETTER JET DYNAMICS WORKING  
INTO LOWER MICHIGAN AND SEVERAL SHORTWAVES FROM THE UPPER SYSTEM  
EJECTING TOWARD THE REGION. UNCERTAINTIES REMAIN HERE AS WELL...BUT  
SEVERE POTENTIAL REMAINS...ESPECIALLY FOR TUESDAY AFTERNOON.  
   
LONG TERM
 
(WEDNESDAY THROUGH SUNDAY)  
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
WEDNESDAY LOOKS LIKE THE MOST ACTIVE DAY OF THE PERIOD. LOW PRESSURE  
MOVING ACROSS THE SRN CWA WILL RESULT IN SHOWERS AND PERHAPS STORMS  
WEDNESDAY AND WEDNESDAY EVENING. THE MOST LIKELY LOCATION FOR STORMS  
WILL BE SOUTH OF I-96. NOT LOOKING FOR SEVERE STORMS AS INSTABILITY  
WILL BE DECREASING. THE UPPER TROUGH FOLLOWING THE SFC LOW MAY  
PRODUCE SOME SHOWERS THROUGH THURSDAY.  
 
AS MEMORIAL DAY WEEKEND APPROACHES...HIGH PRESSURE OVER THE NRN  
GREAT LAKES WILL PRODUCE A COOL AND DRY AIR FLOW FROM CANADA  
RESULTING IN SUNNY DAYS FRIDAY/SATURDAY WITH HIGHS IN THE 60S. FROST  
MAY BE A POSSIBILITY FRIDAY NIGHT ACROSS THE NRN TWO ROWS OF  
COUNTIES WITH LIGHT WINDS AND CLEAR SKIES AS TEMPS FALL INTO THE MID  
TO UPPER 30S.  
 
THE HIGH WILL DRIFT EAST SUNDAY AND A WARM FRONT APPROACHING FROM  
THE WEST MAY PRODUCE SOME SHOWERS AND PERHAPS STORMS.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 745 PM EDT SUN MAY 19 2013  
 
EXPECT VFR CONDITIONS THROUGH MUCH OF THE NIGHT. THERE IS STILL A  
CHANCE OF SOME SHOWERS WITH MVFR CONDITIONS AFTER MIDNIGHT...BUT  
THIS MAY BE IN THE FORM OF DISSIPATING SHOWERS AND SO COVERAGE MAY  
BE SPARSE UNTIL MORE MOISTURE ARRIVES LATER ON MONDAY AFTERNOON.  
 

 
   
MARINE
 
 
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
THUNDERSTORMS TO POSE HAZARD TO MARINERS MONDAY THROUGH  
WEDNESDAY. FOG IS ALSO EXPECTED TO BE A HAZARD EACH NIGHT FROM  
TONIGHT THROUGH TUESDAY NIGHT.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
WARM AND SLIGHTLY MORE HUMID WEATHER WILL CONTINUE THROUGH THE  
WEEK. THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES  
MONDAY THROUGH WEDNESDAY AFTERNOON.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 305 PM EDT SUN MAY 19 2013  
 
LOCALIZED FLOODING COULD OCCUR IF SEVERAL ROUNDS OF RAIN AND  
THUNDERSTORMS MONDAY THROUGH WEDNESDAY OCCUR IN THE SAME LOCATION  
IN SHORT SUCCESSION. OTHERWISE...NO LARGE SCALE FLOODING ISSUES  
ARE EXPECTED AT THIS TIME.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...NONE.  

 
 

 
 
SYNOPSIS...MACZKO  
SHORT TERM...MACZKO  
LONG TERM...93  
AVIATION...OSTUNO  
FIRE WEATHER...MACZKO  
HYDROLOGY...LAURENS  
MARINE...MACZKO  
 
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