Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 222030
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EST MON JAN 22 2018

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM

.SYNOPSIS...
ISSUED AT 330 PM EST MON JAN 22 2018

MORE RAIN WILL CONTINUE INTO TONIGHT, BUT OF THE LIGHTER VARIETY.
VERY LATE TONIGHT, OR AROUND DAYBREAK, THE RAIN WILL SWITCH OVER THE
SNOW.  THE SNOW WILL BE THE STEADIEST THROUGH TUESDAY MORNING,
HOWEVER WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE FREEZING, THE SNOW
ACCUMULATIONS WILL BE LIMITED.  MOST AREAS WILL SEE LESS THAN AN
INCH ON GRASSY AREAS.  AREAS TOWARD HIGHWAY 10 WILL SEE AROUND AN
INCH.  SCATTERED LIGHT SNOW SHOWERS WILL CONTINUE WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT.  THE COLDER AIR WILL HANG ON
THROUGH MID WEEK, WITH HIGHS ON WEDNESDAY ONLY AROUND 30.

ANOTHER WARM UP ARRIVES BY FRIDAY INTO SATURDAY WHEN TEMPERATURES
SHOULD ONCE AGAIN BE IN THE 40S.  THEN IT APPEARS TO COOL DOWN AGAIN
SUNDAY AND MONDAY.  LIGHT RAIN SHOULD RETURN FRIDAY NIGHT, WHICH
SHOULD SWITCH TO SNOW SATURDAY NIGHT AND LAST INTO SUNDAY NIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 PM EST MON JAN 22 2018

LOW PRESSURE WILL CROSS THE STATE LATE TONIGHT.  RAIN SHOWERS WILL
CONTINUE, THEN CHANGE TO SNOW TOWARD DAYBREAK TUESDAY.  A STEADY
SNOW IS EXPECTED TUESDAY MORNING, BUT MOST PLACES WILL SEE LESS THAN
AN INCH OF ACCUMULATION.  ROADS ARE ONLY EXPECTED TO BE WET.

PRECIPITATION WILL REMAIN SPOTTY WITHIN THE DRY SLOT WHICH WILL BE
OVER THE CWA THIS EVENING.  BUT THEN STEADIER PCPN WILL RETURN LATE
TONIGHT AND INTO TUESDAY MORNING.  THIS WILL INITIALLY START AS MORE
RAIN, BUT THEN BEGIN TO SWITCH TO SNOW FROM WEST TO EAST AS THE
COLDER AIR WRAPS IN.  STILL APPEARS WE WON`T HAVE ANY ACCUMS THROUGH
12Z TUE, SO IT APPEARS THE MORNING COMMUTE WILL GO OK, AND NO
HEADLINES ARE PLANNED.

BUT THE STEADY SNOW WILL CONTINUE THROUGH MUCH OF TUESDAY MORNING.
THIS WILL BE FALLING ON A SLOPPY WET GROUND, AFTER ROUGHLY THE INCH
OF RAIN THAT OCCURRED TODAY.  THE FAR NORTH, NEAR HIGHWAY 10 SHOULD
SEE AROUND AN INCH OF SNOW, PERHAPS TOWARD TWO INCHES IN NORTHERN
CLARE COUNTY, OTHERWISE LESS THAN AN INCH IS EXPECTED..  THE SNOW
WILL MOVE OUT TOWARD MID DAY. THIS WILL BE FOLLOWED BY SOME LIGHT
LAKE EFFECT INTO TUESDAY EVENING, THIS WILL ONLY ADD ANOTHER DUSTING
SINCE THE DELTA T`S ARE MARGINAL.

A SHORT WAVE COMES THROUGH WED MORNING, LEADING TO SLIGHTLY COLDER
AIR MOVING IN.  FEEL THIS WILL PERK UP THE LAKE EFFECT AGAIN BY
WEDNESDAY AFTERNOON AND INTO THE NIGHT.  AGAIN THE DELTA T`S ARE
MARGINAL, BUT SLIGHTLY BETTER MOISTURE ARRIVES.  ACCUMS ARE EXPECTED
TO REMAIN UNDER AN INCH IN THIS TIME FRAME AND MAINLY FOR AREAS WEST
OF U.S. 131.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM EST MON JAN 22 2018

RIDGING BOTH AT THE SURFACE AND ALOFT WILL BRING BENIGN WEATHER ON
THURSDAY AND FRIDAY. WE HAVE A DRY FORECAST THROUGH BOTH DAYS WITH
TEMPERATURES MODERATING FROM THE 30S ON THURSDAY TO THE 40S ON
FRIDAY.

MODELS DIVERGE ON SATURDAY WHICH LEADS TO A LOWER CONFIDENCE
FORECAST FOR THE WEEKEND. THE GFS AND CANADIAN HAVE A WEAKENING
SURFACE TROUGH AND THEREFORE LITTLE IN THE WAY OF PRECIPITATION
ASSOCIATED WITH IT. THE ECMWF DEVELOPS A WAVE OF LOW PRESSURE ON A
FRONT WHICH MOVES NORTHEAST THROUGH OUR AREA. WE HAVE A CHANCE FOR
SHOWERS IN THE FORECAST FOR SATURDAY AND SATURDAY NIGHT FOR NOW AND
WE WILL SEE HOW THE MODELS TREND. THE PRECIPITATION IN THE FORECAST
IS A NOD TO THE ECMWF.

COLDER AIR FLOWS IN FOR SUNDAY AND MONDAY AND WE HAVE SOME SMALL
CHANCES FOR SNOW SHOWERS IN THE FORECAST. THE SURFACE PATTERN
FEATURES A HIGH BUILDING IN SO NOT EXPECTING ANYTHING SIGNIFICANT IN
REGARD TO SNOW. HIGHS COOL BACK INTO THE UPPER 20S AND LOWER 30S BY
NEXT MONDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 150 PM EST MON JAN 22 2018

CHANGEABLE AVIATION CONDITIONS ARE EXPECTED THE NEXT 24 HOURS, AS
AN AREA OF LOW PRESSURE MOVES THROUGH THE STATE. MVFR CONDITIONS
HAVE REPLACED THE IFR AND LIFR CONDITIONS THAT WERE IN PLACE
EARLIER IN THE DAY. KMKG STILL HOLDS ON TO THE LOW AVIATION
CONDITIONS AS OF 18Z. IMPROVEMENT AT ALL SITES IS EXPECTED LATE
THIS AFTERNOON HOWEVER AHEAD OF A COLD FRONTAL PASSAGE. LOWER
AVIATION CONDITIONS WILL RETURN TONIGHT AND INTO TUESDAY MORNING
HOWEVER BEHIND THE COLD FRONT. THE RAIN WILL MIX WITH SOME SNOW
TOWARDS DAYBREAK ON TUESDAY AND CHANGE OVER TO SNOW FOR TUESDAY
MORNING. IFR CONDITIONS ARE LIKELY TUESDAY MORNING IN ALL AREAS.

&&

.HYDROLOGY...
ISSUED AT 214 PM EST SUN JAN 21 2018

A COMPLETE MELTING OF THE NATURAL SNOWPACK IS EXPECTED BY MONDAY
IN THE GRAND, KALAMAZOO, AND MUSKEGON RIVER BASINS. THIS WILL
RELEASE A QUARTER TO PERHAPS HALF INCH OF WATER. RAIN TOTALS ON
MONDAY WILL MOSTLY RANGE BETWEEN 0.6 AND 1.2 INCHES (ECMWF AND
ENSEMBLE HAVE BEEN CONSISTENTLY LOWER THAN GFS AND ENSEMBLE).
DEPTH OF FROZEN SOIL VARIES BUT OVERALL EXPECT THE GROUND TO
REMAIN FROZEN ENOUGH TO ALLOW EFFICIENT RUNOFF.

A NUMBER OF RIVER FORECAST POINTS WILL LIKELY RISE ABOVE BANKFULL
IN THE UPCOMING WEEK. THERE IS A CHANCE OF MINOR FLOOD STAGE BEING
REACHED AT A FEW SITES (OF EARLIEST CONCERN ARE HOLT AND EAGLE),
PARTICULARLY IF HIGHER RAINFALL TOTALS VERIFY. A BREAKUP OF RIVER
ICE IS EXPECTED, AND ANY ICE JAMS THAT FORM CAN CAUSE
UNPREDICTABLE FLUCTUATIONS IN WATER LEVELS. ROAD CLOSURES ARE
POSSIBLE IN LOW SPOTS NEAR RIVER BANKS. WATER COULD ALSO APPROACH
BUILDINGS IN FLOOD PRONE AREAS.

&&

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

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...CAS



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