Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271935
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
235 PM EST SAT DEC 27 2014

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

.SYNOPSIS...
ISSUED AT 235 PM EST SAT DEC 27 2014

A COLD FRONT WILL MOVE THROUGH THIS EVENING. COLDER AIR WILL
FOLLOW FOR THE REST OF THE WEEK WITH OCCASIONAL LAKE EFFECT SNOW
SHOWERS. NO BIG STORMS ARE EXPECTED THROUGH NEW YEARS.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 235 PM EST SAT DEC 27 2014

SFC LOW AND COLD FRONT MOVE EAST WITH RAIN SHOWERS ENDING. KEPT A
SLIGHT CHANCE OF RAIN/SNOW SHOWERS THIS EVENING ACROSS THE
NORTHWEST FORECAST AREA WHICH COULD BE CLIPPED BY THE SOUTHERN
EDGE OF DEFORMATION ZONE PRECIP. THIS AREA COULD ALSO SEE SOME
LAKE EFFECT SNOW SHOWERS LATER TONIGHT INTO SUNDAY MORNING.

FLOW GOES NORTHWEST THIS EVENING WITH INVERSION HEIGHTS FALLING
BLO 5 KFT...SO SNOW SHOWERS SHOULD BE LIGHT. SNOW SHOWERS SHOULD
TAPER OFF SUNDAY MORNING AS DRYING AND SUBSIDENCE CONTINUE. SNOW
SHOWERS COULD FLARE UP A BIT SUNDAY NIGHT AS AN ARCTIC FRONT SAGS
SOUTH WITH SOME SFC CONVERGENCE HELPING THE CAUSE. THE FLOW GOES
MORE NORTHERLY ON MONDAY BEHIND THE FRONT...SO ANY SNOW SHOWERS
WILL BE CONFINED CLOSE TO THE COAST.

SNOW SHOWERS COULD BE MOVING FURTHER INLAND LATE MONDAY NIGHT AS
FLOW STARTS TO GO MORE NORTHWEST. INVERSION HEIGHTS ARE STILL AOB
5 KFT...SO ACCUMS WILL BE LIMITED.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 218 PM EST SAT DEC 27 2014

WE CONTINUE TO EXPECT A TREND TOWARD COLDER TEMPERATURES WITH CHCS
OF LAKE EFFECT SNOW SHOWERS THROUGH MUCH OF THE LONG TERM. WE WILL
THEN HAVE A CHC OF PCPN NEXT WEEKEND AS A STORM SYSTEM EJECTS FROM
THE SW PORTION OF THE COUNTRY.

NO REAL CHANGE TO THE TUE THROUGH THU TIMEFRAME WITH AN ARCTIC AIR
MASS COMING IN ALONG WITH CHCS OF LIGHT LAKE EFFECT SNOW SHOWERS.
THE RIDGE AXIS IN THE LOWER LEVELS WILL BE SHIFTING SOUTH OF THE
AREA BY TUE. THIS WILL TRANSITION THE MEAN LOW LEVEL FLOW TO THE NW
AND EVENTUALLY WEST. TEMPS AT H850 IN THE NEGATIVE TEENS C WILL BE
SUFFICIENT FOR LAKE EFFECT. THE LAKE EFFECT IS NOT EXPECTED TO BE
SIGNIFICANT AS THE NRN STREAM OF THE JET REMAINS NORTH...LEADING TO
LO INVERSION HEIGHTS AND SHALLOW MOISTURE. A COUPLE OF SHORT WAVES
WILL BE MOVING JUST NORTH OF THE CWFA TRYING TO HELP THE SNOW SHOWER
CHCS OUT.

IT LOOKS LIKE THE BRUNT OF THE SYSTEM THAT HAS BEEN SHOWN TO DEVELOP
IN THE MODELS FOR NEXT WEEKEND WILL MISS MOST OF THE CWFA FOR NOW.
THE TREND OVER THE PAST 24 HOURS IS FOR THE PARALLEL GFS AND EURO TO
SLOW THE EJECTION OF THE SW ENERGY AS EXPECTED. THIS ALLOWS THE NRN
STREAM OF THE JET TO MOVE IN AND SHUNT THE SRN STREAM SYSTEM TO THE
SE. PLENTY OF TIME FOR THE MODELS TO RESOLVE THE INTERACTION OF THE
TWO BRANCHES. FOR NOW WE WILL GO WITH A CHC OF SNOW AND FEATURE
COOLER TEMPS COMPARED TO THE WARMER AND MORE WET SOLUTIONS OF THE
PREVIOUS FEW DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1230 PM EST SAT DEC 27 2014

IFR AND LOWER CONDITIONS ARE CURRENTLY IN PLACE AT ALL OF THE
TERMINALS ACROSS SW LOWER MICHIGAN EARLY AFTERNOON. THIS IS MAINLY
DUE TO LOW CLOUDS IN PLACE AND DUE TO DRIZZLE/FOG WITH A FEW
SHOWERS AROUND. WE EXPECT THE LOW CONDITIONS TO HOLD ON FOR A FEW
HOURS BEFORE CIGS LIFT AND VSBYS IMPROVE TO MVFR FROM WEST TO EAST LIKE
WHAT IS CURRENTLY HAPPENING UPSTREAM ACROSS WI AND IL. THE BETTER
CONDITIONS APPEAR TO BE OCCURRING AFTER THE PASSAGE OF THE COLD FRONT.

THE AREA WILL REMAIN UNDER MVFR CONDITIONS FOR MOST OF THE NIGHT
WITH CIGS OF AROUND 1500 FT EXPECTED. THESE CLOUDS SHOULD TEND TO
BREAK UP BY MID-LATE SUN MORNING AS HIGH PRESSURE BUILDS IN ACROSS
THE AREA.

&&

.MARINE...
ISSUED AT 328 AM EST SAT DEC 27 2014

A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH 11 AM SUNDAY. WINDS
WILL VEER WEST TO 30 KNOTS THIS EVENING. WAVES WILL BUILD TO 4 TO
8 FEET NORTH OF HOLLAND AND 3 TO 5 FEET SOUTH OF HOLLAND. WEST
WINDS WILL VEER NORTHWESTERLY OVERNIGHT.

&&

.HYDROLOGY...
ISSUED AT 328 AM EST SAT DEC 27 2014

NO HYDRO ISSUES.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST SUNDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...EBW
MARINE...EBW




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