Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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899
FXUS63 KGRR 301756
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
156 PM EDT SAT APR 30 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SAT APR 30 2016

LOW PRESSURE OVER THE PLAINS WILL MOVE TOWARD THE GREAT LAKES
TODAY. CLOUDS WILL INCREASE AND RAIN WILL DEVELOP THIS AFTERNOON
FROM SOUTH TO NORTH AND CONTINUE INTO SUNDAY BEFORE DIMINISHING
LATE IN THE DAY. COOLER THAN NORMAL WEATHER WILL CONTINUE INTO
NEXT WEEK WITH HIGHS IN THE 50S THIS WEEKEND RISING TO THE LOWER
TO MID 60S FOR THE FIRST HALF OF NEXT WEEK.

&&

.UPDATE...
ISSUED AT 1226 PM EDT SAT APR 30 2016

FORECAST GOING AS PLANNED TODAY WITH RAIN GRADUALLY SPREADING IN
FROM THE SOUTH. STRONG ISENTROPIC LIFT IS NOTED IN THE MODELS IN A
ZONE OF WARM AIR ADVECTION. AN 850MB WARM FRONT WHICH SETS UP THIS
EVENING ACROSS SOUTHERN LOWER MICHIGAN SHOULD BE A FOCUS FOR
LIGHT TO MODERATE RAIN DEVELOPMENT. TEMPS THIS AFTERNOON WILL HOLD
IN THE 50S IN MANY AREAS GIVEN THE THICKENING MID AND HIGH CLOUDS.
IT WILL FEEL A BIT COOLER WITH A STIFF BREEZE FROM THE EAST.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 330 AM EDT SAT APR 30 2016

FORECAST CONCERNS DEAL WITH RAINFALL EXPECTED TODAY.

LOW PRESSURE OVER THE PLAINS WILL MOVE NORTHEAST TOWARD THE GREAT
LAKES TODAY AND GENERATE LIGHT RAIN THIS AFTERNOON. STRONG
ISENTROPIC LIFT WILL RESULT IN GOOD SATURATION WHICH WILL OVERCOME
THE DRY AIR AT THE SFC. LIGHT RAIN SHOULD MOVE INTO THE SOUTHERN CWA
BY 18Z AND GRADUALLY SPREAD NORTHEAST BY LATE IN THE DAY. SHOWERS
WILL LINGER THROUGH SUNDAY NIGHT AS THE LOW SLOWLY MOVES EAST.
ROUGHLY A QUARTER INCH OF RAIN IS EXPECTED NORTH OF I-96 AND AROUND
A HALF INCH SOUTH OF THERE. SHOWERS FALLING INTO THE DRY AIR TODAY
SHOULD PRODUCE SOME WET BULBING AND KEEP HIGHS IN THE MID TO UPPER
50S.

A CHILLY DAY IS EXPECTED SUNDAY WITH LINGERING SHOWERS. HIGHS IN THE
LOWER TO MID 50S WILL BE AT LEAST 10 DEGREES BELOW NORMAL. HIGH
PRESSURE WILL BUILD INTO THE CWA MONDAY AND WE/LL SEE SOME SUNSHINE
AND HIGHS AROUND 60.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EDT SAT APR 30 2016

THE GFS IS QUICKER THAN THE ECMWF WITH THE COLD FRONT PRESSING SOUTH
FROM CANADA ON TUESDAY... BUT CONSENSUS IS THAT MOST OF THE DAY
WILL BE DRY AND MILD WITH HIGHS WELL INTO THE 60S. THE MAIN CHANCE
OF SHOWERS WITH THE FRONTAL PASSAGE HOLDS OFF UNTIL TUESDAY NIGHT.

BEHIND THE COLD FRONT IT TURNS COLDER FOR THE REST OF THE WEEK AS A
DEEP UPR TROUGH EVOLVES OVER THE ERN UNITED STATES. BY FRIDAY AN
OMEGA PATTERN IS PROGGED ALOFT WITH LARGE UPPER LOWS OVER THE ERN
AND WRN U.S. AND A RIDGE IN BETWEEN OVER THE CENTER OF THE NATION.

CONFIDENCE IS CURRENTLY LOW REGARDING THE PROXIMITY OF THE UPR LOW
ON THURSDAY AND FRIDAY... WITH THE LATEST ECMWF SHOWING IT CLOSE BY
OVER THE ERN GRTLKS RGN BUT THE GFS SENDING IT TOWARD THE
APPALACHIANS AND MID ATLANTIC RGN. IF THE ECMWF IS CORRECT WE
WILL SEE MORE IN THE WAY OF CLOUDS AND SHOWERS THURSDAY AND FRIDAY
THAN WE ARE CURRENTLY FORECASTING... ESPECIALLY EAST OF HIGHWAY
131 IN THE AFTERNOON AND EARLY EVENING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 156 PM EDT SAT APR 30 2016

CONDITIONS WERE VFR ACROSS THE REGION EARLY THIS AFTERNOON.
HOWEVER RAIN AND LOWERING CEILINGS AND VSBYS WILL BE THE RULE AS
WE APPROACH THE EVENING. THE SYSTEM WAS MOVING IN FROM THE SOUTH
SO THE I-94 TAF SITES WILL COME DOWN SOONER. EXPECT MVFR BY
21-22Z...AND IFR OR EVEN LIFR DEVELOPING 00-02Z. IT WILL OCCUR
SLIGHTLY SLOWER FOR THE I-96 TAF SITES...WITH MVFR BY 23-00Z AND
IFR BY 01-03Z.

ONCE THE LOWER CONDITIONS ARRIVE IT IS EXPECTED THAT THE IFR/LIFR
WILL HANG AROUND THROUGH SUNDAY MORNING. SOME IMPROVEMENT WILL BE
POSSIBLE AS WE GET TOWARD MID DAY SUNDAY...HOWEVER THE MIXING
SEEMS LIGHT SO THIS COULD BE A VERY SLOW PROCESS.

&&

.MARINE...
ISSUED AT 330 AM EDT SAT APR 30 2016

NORTHEAST WINDS WILL BE ON THE INCREASE LATER TODAY AND
ESPECIALLY TONIGHT. WHILE THE OFFSHORE FLOW WILL LIMIT WAVE
HEIGHTS... THE WIND SPEEDS COULD STILL APPROACH THE SMALL CRAFT
ADVISORY CRITERIA OF 22 KTS.


&&

.HYDROLOGY...
ISSUED AT 118 PM EDT SAT APR 30 2016

RECENT RAINFALLS HAVE RESULTED IN MINOR RISES ON STREAMS AND RIVERS.
SIGNIFICANT RISES ON MAIN STEM RIVERS ARE NOT LIKELY. ADDITIONAL
RAINFALL INTO MONDAY MAY KEEP SMALLER STREAMS AND RIVERS ELEVATED...
WITH A SMALLER CHANCE FOR ELEVATED MAIN STEM RIVERS. FLOODING IS NOT
EXPECTED.

&&

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

$$

UPDATE...DUKE
SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...JK
HYDROLOGY...63
MARINE...04



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