173  
FXUS63 KGRR 250100  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
900 PM EDT FRI APR 24 2015  
 
LATEST UPDATE...  
UPDATE  
   
SYNOPSIS
 
 
ISSUED AT 325 PM EDT FRI APR 24 2015  
 
RAIN SHOWERS WILL SLOWLY ENCROACH UPON WEST MICHIGAN TONIGHT AND  
SATURDAY ALTHOUGH ONLY LIGHT AMOUNTS ARE EXPECTED MOST PLACES. THE  
STEADIER RAIN WILL BE ACROSS FAR SOUTHERN LOWER MICHIGAN. THEN  
FAIR WEATHER RETURNS FOR SUNDAY AND MUCH OF NEXT WEEK.  
 

 
   
UPDATE
 
 
ISSUED AT 900 PM EDT FRI APR 24 2015  
 
WE HAVE UPDATED THE FCST THIS EVENING TO FEATURE HIGHER CHCS OF  
RAIN FOR AREAS MAINLY SOUTH OF I-96. LATEST RADAR IMAGERY SHOWS A  
BANDED AREA OF RAIN MOVING IN ACROSS THE WRN PORTION OF THE CWFA.  
A LOT OF THIS IS LIKELY ALOFT WITH THE DRIER AIR INITIALLY IN  
PLACE. HOWEVER IT IS INTENSE ENOUGH ALOFT THAT SOME OF IT WILL  
MAKE IT TO THE GROUND WITH SOME LIGHT...YET MEASURABLE AMOUNTS  
POSSIBLE.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH SUNDAY NIGHT)  
ISSUED AT 325 PM EDT FRI APR 24 2015  
 
VERY DRY ATMOSPHERE WILL SLOWLY MOISTEN UP THIS EVENING AS WARM  
ADVECTION WING OF SHOWERS MOVES IN FROM THE WEST. EXPECT SOME OF  
THE RAIN TO REACH THE GROUND THIS EVENING...PRIMARILY ACROSS  
WESTERN ZONES FROM MUSKEGON TO KALAMAZOO BY LATE EVENING.  
 
THEN THERE WILL BE A BRIEF LULL UNTIL SATURDAY MORNING WHEN THE  
NORTHERN EDGE OF THE PRECIP SHIELD OF LOW LOW TRACKING INTO THE  
OHIO VALLEY REACHES THE SOUTHERN ZONES. QPF SHOULD BE A TENTH OF  
AN INCH OR LESS.  
 
ANY PRECIP SHOULD BE ENDING SATURDAY EVENING WITH SFC RIDGING  
NOSING DOWN ONCE AGAIN FROM CENTRAL CANADA...ALTHOUGH THIS AIRMASS  
IS NOT AS COLD AS THE LAST ONE. THERE STILL COULD BE SOME FROST  
AND FREEZING TEMPERATURES SUNDAY MORNING AND POSSIBLE MONDAY  
MORNING AS THE SFC RIDGE HOLDS SWAY.  
   
LONG TERM
 
(MONDAY THROUGH FRIDAY)  
ISSUED AT 325 PM EDT FRI APR 24 2015  
 
THE LONG TERM PORTION CONTINUES TO LOOK RATHER QUIET WITH A SLIGHT  
WARM UP INTO THE MIDDLE OF NEXT WEEK.  
 
THE BLOCKED PATTERN WE HAVE SEEN OVER THE MUCH OF SECOND HALF OF  
THIS WEEK...GIVING US THE CHILLY WEATHER...WILL FINALLY BREAK DOWN  
BY MONDAY/MONDAY NIGHT. A NORTHERN NEW ENGLAND UPPER LOW WILL  
FINALLY PUSH OFFSHORE ALLOWING SURFACE AND UPPER RIDGING TO TAKE  
PLACE OVER THE GREAT LAKES. THIS WILL GIVE US DRY WEATHER AND  
SLIGHTLY WARMER TEMPS BY TUESDAY.  
 
HOWEVER THE WEAK UPPER RIDGE BREAKS DOWN RATHER QUICKLY WITH BROAD  
TROUGHING DEVELOPING OVER THE EASTERN U.S. BY WEDNESDAY. THIS  
SHOULD CAUSE TEMPS TO LEVEL OFF TO NEAR NORMAL FOR THE SECOND HALF  
OF THE WORK WEEK. DESPITE THE UPPER TROUGH FEEL WE WILL REMAIN DRY  
MUCH OF THE WEEK AS SURFACE RIDGING SHOULD SUPPRESS MOST SHOWERS.  
WE MAY SEE A FEW SHOWERS WEDNESDAY AS THE TROUGH AXIS COMES  
THROUGH...BUT THESE LOOK RATHER MINIMAL AT THIS POINT.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)  
ISSUED AT 526 PM EDT FRI APR 24 2015  
 
VFR WEATHER EXPECTED TO PREVAIL THROUGH SATURDAY. RAIN SHOWERS  
WILL BE MOVING IN OVERNIGHT...BUT DUE TO THE DRY AIRMASS IN  
PLACE...VISIBILITIES AND CEILINGS ARE FORECASTED TO REMAIN AT VFR LEVELS.  
KAZO WILL BE CLOSEST TO THE LOW LEVEL MOISTURE...AND WILL NEED TO  
BE MONITORED FOR POSSIBLE MVFR CEILINGS LATE TONIGHT OR SATURDAY.  
 

 
   
MARINE
 
 
ISSUED AT 325 PM EDT FRI APR 24 2015  
 
WINDS AND WAVES WILL BE LIGHT INTO EARLY NEXT WEEK.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1027 AM EDT FRI APR 24 2015  
 
RIVER LEVELS ACROSS SOUTHWEST LOWER MICHIGAN ARE STEADY OR SLOWLY  
FALLING. RAIN IS POSSIBLE ACROSS SOUTHERN LOWER MICHIGAN SOUTH OF  
INTERSTATE 96 LATE TONIGHT INTO SATURDAY NIGHT. ACCUMULATIONS SHOULD  
BE UNDER A HALF INCH. DRY WEATHER RETURNS LATE SATURDAY NIGHT  
THROUGH NEXT WEEK. BRIEF RISES ARE POSSIBLE ON THE SOUTHERN  
RIVERS... BUT RIVER FLOODING IS NOT EXPECTED.  
 

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

 
 

 
 
UPDATE...NJJ  
SYNOPSIS...OSTUNO  
SHORT TERM...OSTUNO  
LONG TERM...JK  
AVIATION...MJS  
HYDROLOGY...63  
MARINE...OSTUNO  
 
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