553  
FXUS63 KGRR 010550  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
150 AM EDT WED OCT 1 2014  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 325 PM EDT TUE SEP 30 2014  
 
THE WEATHER WILL REMAIN QUIET TONIGHT AND WEDNESDAY. WE WILL SEE  
MORE SUNSHINE WEDNESDAY WHICH WILL BOOST TEMPERATURES INTO THE MID  
AND UPPER 60S. HOWEVER WE WILL BE ENTERING A WET PERIOD STARTING  
LATE WEDNESDAY NIGHT INTO THURSDAY AND LASTING THROUGH SATURDAY. A  
SOAKING RAIN APPEARS LIKELY WITH SOME AREAS SEEING UP TO TWO INCHES  
OF RAINFALL.  
 
AFTER A WARMER DAY ON THURSDAY...WITH HIGHS FROM 70 TO 75...WE WILL  
COOL DOWN FOR THE WEEKEND WITH HIGHS ONLY IN THE 50S. WE SHOULD SEE  
TEMPERATURES WARM BY TUESDAY WITH HIGHS REACHING AROUND 60.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY NIGHT)  
ISSUED AT 325 PM EDT TUE SEP 30 2014  
 
QUIET WEATHER FOR THE NEXT 24 HOURS. WE WILL HANG ON TO THE CLOUDS  
THROUGH MUCH OF THE NIGHT AS THE LOW LEVELS REMAIN MOIST. HOWEVER  
WITH UPPER RIDGING MOVING IN CLEARING WILL START BY MID MORNING  
WEDNESDAY FROM THE SW...AND BY MID AFTERNOON OVER THE NE CWA. THIS  
CLEARING IS SLIGHTLY DELAYED SO TEMPS MAY STRUGGLE A BIT. I TRIMMED  
MAX TEMPS SLIGHTLY...BUT STILL FEEL MID AND UPPER 60S WILL BE  
ACHIEVED.  
 
THEN WE WILL ENTER A WET PERIOD...OVER THE WESTERN CWA LATE  
WEDNESDAY NIGHT...AND ADVANCING TO THE EASTERN CWA BY THURSDAY.  
DEEP SOUTHWEST FLOW WILL SET UP OVER THE GREAT LAKES AS RIDGING IS  
SEEN OVER THE EASTERN SEABOARD...WITH UPPER TROUGHING OVER THE  
PLAINS. A SURFACE COLD FRONT WILL ONLY SLOWLY PROGRESS EAST ACROSS  
THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES FROM WED NIGHT INTO  
THU NIGHT. UPPER DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF THE  
UPPER JET SETS UP OVER LOWER MICHIGAN THURSDAY AFTERNOON AND IS  
MAINTAINED THROUGH THURSDAY NIGHT WHEN THE BULK OF THE RAIN IS  
EXPECTED. INCREASED POPS FOR THURSDAY NIGHT AND ALSO BUMPED MINS UP  
GIVEN THE STRONG SOUTHERLY FLOW AND CLOUD COVER.  
 
WITH THE DEEP SW FLOW GULF MOISTURE WILL BECOME ABUNDANT AS  
PRECIPITABLE WATER VALUES SPIKE TOWARD 1.75 INCHES THURSDAY  
EVENING. WITH THE SLOW NATURE OF THE SYSTEM THE NW CWA APPEARS MOST  
LIKELY TO SEE THE HEAVIEST RAINS...WHICH COULD APPROACH TWO INCHES  
BY FRIDAY MORNING. THE SEVERE WEATHER THREAT APPEARS LOW AT THIS  
POINT DUE TO WEAK INSTABILITY...AND THE FACT THAT THE BEST UPPER  
DYNAMICS DOES NOT COME IN UNTIL THURSDAY NIGHT. 45 KNOTS OF WIND IS  
PROGGED OVER SW MI AT 2K FEET THURSDAY NIGHT...WHICH A STRONGER  
STORM COULD MIX DOWN...MAKING FOR ISOLATED STRONG WIND GUSTS.  
   
LONG TERM
 
(FRIDAY THROUGH TUESDAY)  
ISSUED AT 325 PM EDT TUE SEP 30 2014  
 
THE COLDEST WEATHER WE HAVE SEEN SINCE THE MIDDLE OF MAY SHOULD MOVE  
INTO THE AREA FRIDAY. THE CHILLY AIR APPEARS TO PERSIST THROUGH THE  
WEEKEND INTO EARLY NEXT WEEK BEFORE THE SYSTEM FINALLY MOVES OUT OF  
THE AREA AND ANOTHER WARM UP STARTS. LAKE EFFECT RAIN SHOWERS  
SHOULD CONTINUE THROUGH THE WEEKEND.  
 
THE MODELS HAVE COME TOGETHER NOW ON HOW THIS WILL PLAY OUT. ALL OF  
THEM NOW SHOW A CLOSED UPPER LOW OVER THE GREAT LAKES SATURDAY INTO  
SUNDAY. HOWEVER AS IT LIFTS OUT SATURDAY NIGHT ANOTHER SHORTWAVE  
FOLLOWS IT...WHICH KEEPS SOUTHWEST LOWER MICHIGAN IN THE COLD  
UNSTABLE AIR INTO EARLY TUESDAY.  
 
850 MB TEMPERATURES FALL INTO THE -1C TO -3C RANGE BY FRIDAY NIGHT  
THEN CONTINUING INTO MONDAY NIGHT. GIVEN THE MOSTLY WESTERLY WINDS  
THROUGH THE PERIOD....LITTLE QUESTION LAKE EFFECT RAIN SHOWERS WILL  
CONTINUE INTO MONDAY. WATER SPOUTS MAY BE AN ISSUE TOO.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 150 AM EDT WED OCT 1 2014  
 
CONDITIONS WILL DETERIORATE A LITTLE BIT THROUGH DAYBREAK THIS  
MORNING BEFORE CONDITIONS THEN IMPROVE THROUGH THE REMAINDER  
OF THE PERIOD.  
 
MVFR CIGS CONTINUE TO DOMINATE ACROSS MOST OF THE AREA EARLY THIS  
MORNING. SOME LOCAL IFR SPOTS ARE PRESENT ACROSS THE EAST WHERE  
THERE IS A FLOW OFF OF LAKE HURON. WE EXPECT CONDITIONS TO REMAIN  
RATHER STABLE WITH LITTLE CHANGE OTHER THAN MAYBE CLOUDS DROPPING  
A FEW HUNDRED FEET TONIGHT. CIGS WILL THEN LIFT TO MVFR BY MID  
MORNING...AND THEN CLEAR OUT THIS AFTERNOON AS DRIER AIR MOVES IN  
AND THE MOISTURE MIXES OUT.  
 

 
   
MARINE
 
 
ISSUED AT 325 PM EDT TUE SEP 30 2014  
 
WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE NORTH OF SOUTH HAVEN  
AND ALSO CANCEL THE AREA NORTH OF PENTWATER. BUOY DATA SHOWS WAVES  
HAVE DIMINISHED TO 3-4 FEET OFFSHORE OF LUDINGTON AS WINDS ARE  
SLOWLY PIVOTING TO THE NE. PORT SHELDON AND SOUTH HAVEN BUOYS ARE  
DOWN TO 2-3 FEET....WHILE BRIDGEMAN STILL SHOWS 4-5 FEET. WILL  
ALLOW THE SCA SOUTH OF SOUTH HAVEN TO EXPIRE AT 8 PM AS WINDS  
CONTINUE TO DIMINISH AND TURN MORE NE.  
 
ANOTHER PERIOD OF HIGHER WINDS AND WAVES IS EXPECTED BY THURSDAY  
MORNING NORTH OF GRAND HAVEN AS SOUTH WINDS INCREASE. THIS WILL  
LIKELY EXTEND INTO THURSDAY NIGHT AND EXPAND ACROSS ALL THE  
NEARSHORE WATERS AS SOUTHERLY WINDS ARE EXPECTED TO CONTINUE TO  
INCREASE.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 325 PM EDT TUE SEP 30 2014  
 
THE RAIN FROM LATE WEDNESDAY NIGHT INTO FRIDAY IS EXPECTED TO BE  
HEAVY...BUT SINCE IT WILL FALL OVER A LONG PERIOD OF TIME...HYDRO  
ISSUES ARE NOT EXPECTED. MUCH OF THE CWA SHOULD SEE BETWEEN ONE AND  
TWO INCHES OF RAIN. ONE POSSIBLE SCENARIO WOULD BE DRAINS CLOGGED  
WITH LEAVES MAY RESULT IN PONDING OF WATER.  
 

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

 
 

 
 
SYNOPSIS...JK  
SHORT TERM...JK  
LONG TERM...WDM  
AVIATION...NJJ  
HYDROLOGY...JK  
MARINE...JK  
 
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