Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 202310
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
710 PM EDT WED MAY 20 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 329 PM EDT WED MAY 20 2015

COOLER THAN NORMAL WEATHER WILL CONTINUE THE REST OF THE WORK
WEEK...WITH FROST A GOOD BET EACH NIGHT ACROSS PORTIONS OF CENTRAL
LOWER MICHIGAN. SOME LIGHT RAIN SHOWERS OR SPRINKLES ARE POSSIBLE
ALONG INTERSTATE 94 THIS EVENING INTO TONIGHT. ANY RAINFALL AMOUNTS
WILL BE VERY LIGHT. AFTER A DRY AND PARTLY TO MOSTLY SUNNY DAY ON
THURSDAY SOME LIGHT RAIN SHOWERS WILL MOVE THROUGH THE AREA THURSDAY
NIGHT ALONG AND AHEAD OF A COLD FRONTAL PASSAGE. WARMER AIR WILL
MOVE IN FOR THE HOLIDAY WEEKEND WITH CHANCES FOR SHOWERS AND STORMS
RETURNING FOR SUNDAY INTO MEMORIAL DAY. HIGHS WILL REMAIN IN THE 60S
THE REST OF THE WORK WEEK RISING INTO THE 70S FOR SUNDAY AND
MEMORIAL DAY.

&&

.UPDATE...
ISSUED AT 604 PM EDT WED MAY 20 2015

ADDED CHANCE OF A MIX OF LIGHT RAIN AND SLEET TO THE FORECAST
THIS EVENING ACROSS THE SOUTHERN CWA PER NUMEROUS REPORTS OF A
RAIN/SLEET MIX IN THE CHICAGO AREA. AFTER THE PRECIP MOVED
IN...SOUTH HAVEN DROPPED TO 41 DEGREES REPORTING UP. THE FORECAST
IS DRY AFTER 06Z.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 329 PM EDT WED MAY 20 2015

SHORT TERM FOCUS WAS ON CHANCES FOR RAIN IN THE SOUTH THIS
EVENING...FROST POTENTIAL ACROSS CENTRAL LOWER MI TONIGHT AND THE
CHANCE FOR RAIN THURSDAY NIGHT WITH THE NEXT FRONT.

DECIDED TO ADD A MENTION OF LIGHT RAIN SHOWERS ALONG INTERSTATE 94
THIS EVENING AFTER ALL. HI-RES MODELS LIKE THE HRRR CONTINUE TO
INDICATE RAIN MAKING IT INTO OUR CWA...AND UPSTREAM RADAR TRENDS
WOULD AGREE. THAT SAID DRY AIR OVER LOWER MICHIGAN WILL TRY TO ERODE
IT AS IT MOVES IN. DEW POINT DEPRESSIONS AT THE SURFACE ACROSS THE
GRR CWA ARE IN EXCESS OF 20F IN MOST AREAS. PRECIP IS JUST TOO CLOSE
AT THIS POINT TO IGNORE. HAVE 20 PCT WORDING ALONG I-94 FOR NOW. WE
WILL BE WATCHING TO SEE IF IT MAKES IT INTO THE CWA AS WELL AS IF IT
TRENDS FURTHER NORTH TOWARDS I-96 WHICH THE HRRR CONTINUES TO SHOW
AS WELL.

OPTED TO ISSUE A FROST ADVISORY ACROSS THE FAR NORTHERN ROW OF
COUNTIES ALONG U.S. 10. CLOUDS WILL CLEAR OUT UP THERE OVERNIGHT
WITH VERY DRY AIR IN PLACE. VERY COLD READINGS OCCURRED LAST NIGHT
UP THERE AND THE AIR MASS HAS NOT CHANGED. FROST AND FREEZING
TEMPERATURES WILL BE POSSIBLE THE NEXT COUPLE NIGHTS UP THERE AS
WELL...THURSDAY NIGHT AND FRIDAY NIGHT.

A COLD FRONT WILL SWING THROUGH LOWER MICHIGAN THURSDAY NIGHT WITH
ALL OF THE SHORT TERM MODELS KICKING OUT SOME LIGHT PRECIPITATION.
THE COLD FRONT IS ASSOCIATED WITH AN UPPER LOW DRIFTING SOUTHEAST
ACROSS ONTARIO. MAY BE JUST ENOUGH MOISTURE AND LIFT FOR A FEW
SHOWERS. WILL CARRY 30 PCT CHANCES FOR RAIN THURSDAY NIGHT.

OTHERWISE QUIET WEATHER IS EXPECTED DURING THE DAY ON THURSDAY AND
AGAIN FRIDAY AND FRIDAY NIGHT.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 329 PM EDT WED MAY 20 2015

MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE LATE
SUNDAY THROUGH WEDNESDAY. THE WEATHER WILL TREND WARMER AND MORE
HUMID THIS WEEKEND INTO THE MIDDLE OF NEXT WEEK.

SATURDAY IS SHAPING UP TO BE A BEAUTIFUL DAY WITH SURFACE HIGH
PRESSURE SLIDING OFF TO THE SOUTHEAST AND AN UPPER RIDGE BUILDING
INTO THE GREAT LAKES REGION. SOUTHWESTERLY RETURN FLOW SETS UP ON
SATURDAY...AND LOWER MICHIGAN WILL FINALLY START TO WARM UP AFTER A
COOL WEEK. HIGHS SHOULD BE AROUND 70 ON SATURDAY.

TEMPS WILL BE WARMER STILL ON SUNDAY AS A WARM FRONT APPROACHES FROM
THE SOUTH. TIMING DIFFERENCES EXIST BETWEEN THE LATEST GFS AND EURO.
THE 12Z EURO KEEPS SW LOWER MI MOSTLY DRY ON SUNDAY...WITH PERHAPS
SOME LIGHT RAIN MOVING INTO THE EXTREME SW CWA SUNDAY EVENING. THE
GFS IS MUCH WETTER SUNDAY. I WOULD DEFINITELY FAVOR A DRY SUNDAY
MORNING WITH PRECIP CHANCES INCREASING SUNDAY EVENING AND ESPECIALLY
SUNDAY NIGHT. SHOWERS AND THUNDERSTORMS ARE EXPECTED SUNDAY NIGHT
THROUGH WEDNESDAY...WITH SOME BREAKS IN THERE OF COURSE. CONFIDENCE
IN SEVERE WEATHER IS LOW AT THIS TIME...BUT SOME INSTABILITY DOES
DEVELOP MONDAY AFTERNOON AND EVENING PRIMARILY SOUTH OF I-96 ALONG
WITH 30-40 KNOTS OF 0-6 KM BULK SHEAR. HIGHS MONDAY THROUGH
WEDNESDAY OF NEXT WEEK SHOULD BE IN THE MID TO UPPER 70S. 80
DEGREES SEEMS POSSIBLE ON WEDNESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 706 PM EDT WED MAY 20 2015

BASED ON RADAR TRENDS...WENT WITH MORE RAIN IN THE TAFS FOR THIS
EVENING. BY MIDNIGHT MOST OF THE RAIN SHOULD BE EAST OF THE TAF
SITES. IMPACTS SHOULD BE LIMITED GIVEN THE LACK OF LOW LEVEL
MOISTURE...HOWEVER KLWA EARLIER DID GO IFR WITH LIKELY GS. THE IS
LOOKING VFR WITH DRY AIR ADVECTION OCCURRING.

&&

.MARINE...
ISSUED AT 329 PM EDT WED MAY 20 2015

NOT EXPECTING SIGNIFICANT WINDS OR WAVES THE NEXT SEVERAL DAYS.
WINDS WILL COME UP A BIT THIS EVENING FROM HOLLAND SOUTH AND THEN
AGAIN THURSDAY AFTERNOON AND EVENING AHEAD OF A COLD FRONTAL
PASSAGE. IN BOTH CASES EXPECTING WINDS AND WAVES TO REMAIN BELOW
SMALL CRAFT ADVISORY THRESHOLDS. WAVES MAY RISE INTO THE 2-3 FOOT
RANGE DURING THE AFOREMENTIONED TIMES.


&&

.HYDROLOGY...
ISSUED AT 1139 AM EDT WED MAY 20 2015

NO REAL IMPACTS ARE EXPECTED IN THE NEAR FUTURE. RIVERS ARE STABLE
OR SLOWLY FALLING. ONLY SLIGHT CHANCES OF RAIN EXIST LATE THURSDAY
INTO EARLY FRIDAY. ANY MEANINGFUL PRECIPITATION IS EXPECTED TO
HOLD OFF UNTIL AT LEAST SUNDAY.

BY SUNDAY...CHANCES FOR PRECIPITATION WILL INCREASE AS A WARM
FRONT LIFTS NORTH AND BECOMES STATIONARY SOMEWHERE OVER THE GREAT
LAKES REGION. THE PLACEMENT OF THIS BOUNDARY...AND THE POSSIBILITY
OF IT MEANDERING A BIT...MAY PROVIDE MULTIPLE CHANCES FOR RAIN
THROUGH MUCH OF NEXT WEEK. THIS WILL BE SOMETHING TO MONITOR AND
UPDATES WILL BE PROVIDED AS WE GET CLOSER TO THE WEEKEND.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FROST ADVISORY FROM 2 AM TO 8 AM EDT THURSDAY FOR MIZ037>040.

LM...NONE.
&&

$$

UPDATE...EBW
SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...EBW
AVIATION...MJS
HYDROLOGY...JAM
MARINE...DUKE


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