Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 211742
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1242 PM EST WED JAN 21 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 329 AM EST WED JAN 21 2015

LIGHT SNOW WILL CONTINUE TODAY WITH TOTAL ACCUMULATIONS OF 1 TO 2
INCHES. SNOW WILL TAPER OFF THIS EVENING. FAIR WEATHER IS EXPECTED
FOR FRIDAY AND SATURDAY BUT SNOW WILL RETURN BY SUNDAY.

&&

.UPDATE...
ISSUED AT 956 AM EST WED JAN 21 2015

WILL LET THE ADVISORY EXPIRE AT 10 AM. THE I-94 CORRIDOR IS
LOOKING AT IMPROVING CONDITIONS. THE I-96 CORRIDOR WILL SEE
ANOTHER HOUR OF LIGHT TO MODERATE SNOW BUT SFC TEMPS IN THE MID TO
UPPER 20S WILL ALLOW TREATED ROADS TO BE WET RATHER THAN ICY.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 329 AM EST WED JAN 21 2015

THE MAIN IMPACTS IN THE SHORT TERM WILL BE RELATED TO THIS
MORNINGS DEVELOPING SNOWFALL AND A RESULTING SLICK WEDNESDAY
MORNING COMMUTE.

RADAR CONTINUES TO SHOW SNOW DEVELOPMENT OVER PORTIONS OF
SOUTHWEST LOWER MICHIGAN THIS MORNING AND THIS AREA IS EXPECTED TO
CONTINUE TO EXPAND. SOME OF THE INITIAL PRECIPITATION MIXED IN
WITH SOME PATCHY FREEZING DRIZZLE JUST AFTER MIDNIGHT. EXTRA
CAUTION MAY BE NEEDED ON AREA ROADWAYS AS SOME REPORTS WERE
RECEIVED THAT A LIGHT GLAZE RESULTED. THE DGZ WILL CONTINUE TO
SATURATE...THUS MINIMIZING CONCERN OF ADDITIONAL FREEZING DRIZZLE
THROUGH THE MORNING HOURS.

THE BEST MOISTURE IS JUST STARTING TO APPROACH THE AREA OUT AHEAD
OF THE MAIN SYSTEM TO OUR WEST. AS THE SYSTEM SLIDES TO THE SOUTH
AND EAST IT WILL LEAD TO INCREASING LIFT THAT WILL AID IN ADDITIONAL
DEVELOPMENT THROUGH THE MORNING HOURS. THE GREATEST POTENTIAL FOR
ACCUMULATING SNOW WILL BE CONCENTRATE ALONG I-94 RUNNING FROM
ABOUT BATTLE CREEK...EASTWARD TO JUST SOUTH OF LANSING AND THROUGH
JACKSON. SOME LOWERING VISIBILITY MAY RESULT THROUGH THE FIRST
HALF OF THE DAY IN THESE AREAS WITH THE POTENTIAL FOR SOME LOCALIZED
AREAS NEAR 3 INCHES.

THE MAIN QUESTION TO ANSWER THEN IS HOW QUICKLY...OR SLOWLY...THIS
ALL DEPARTS. THOUGH LITTLE RUN TO RUN MODEL DIFFERENCES EXISTED IN
TIMING AND SNOW AMOUNTS THERE HAS BEEN A BOUNCE BETWEEN HOW LONG
THE SYSTEM REMAINS CLOSED OFF. THAT SAID...SNOW IS EXPECTED TO
BECOME LIGHTER THROUGH THE AFTERNOON AND EVENTUALLY TAPER OFF
LATE WEDNESDAY EVENING. THE REMAINDER OF THE SHORT TERM IS RATHER
UNEVENTFUL WITH SOME LIGHT LAKE EFFECT SNOW SHOWERS POSSIBLE INTO
EARLY THURSDAY AND MILDER CONDITIONS AND POSSIBLE SUNSHINE ON FRIDAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 329 AM EST WED JAN 21 2015

MODELS ARE IN DECENT AGREEMENT IN SHOWING THE COLD FRONT PUSHING
THROUGH SOUTHWEST LOWER MI SATURDAY WITH HIGH PRESSURE BUILDING INTO
ONTARIO.  THIS WILL ACT TO DRAW DOWN COLDER AIR FROM CANADA.  THIS
FRONTAL PASSAGE DOES NOT SUPPORT MUCH IN THE WAY OF PRECIPITATION.
WHAT MOISTURE IS THERE IS SHALLOW...ALMOST A DRIZZLE LOOK TO IT.
SOUNDINGS ARE LARGELY BELOW FREEZING...BUT SURFACE TEMPS STILL
SHOULD REACH FREEZING.

WILL NEED TO MONITOR THE SUNDAY MID LEVEL WAVE DROPPING DOWN FROM
THE NORTHWEST.  THE MODELS LOOK STRONGER WITH THIS FEATURE AND THE
HIGH RES EURO WOULD SUPPORT A BAND OF SNOW HERE IN SOUTHERN LOWER
MI.  I DID BUMP UP POPS GIVEN THE TREND IN THE MODELS.  AS THIS WAVE
BUILDS EAST OF MI GOING INTO MONDAY MID LEVEL HEIGHT FALLS CONTINUE
OVER THE GREAT LAKES REGION WITH CYCLONIC FLOW. THE LOW LEVEL FLOW
WILL BE FROM THE NORTHEAST SUNDAY NIGHT INTO MONDAY...WHICH WOULD
LIMIT ANY LAKE EFFECT POTENTIAL.

THE HIGH RES EURO HAS ANOTHER MID LEVEL WAVE ARRIVING FOR TUE WHILE
THE GFS DOES NOT.  THE MODELS DO AGREE IN THAT BELOW NORMAL
TEMPERATURES ARE LIKELY TO ARRIVE FOR THE MIDDLE PART OF THE WEEK.
I WILL KEEP POPS RELATIVELY LOW FOR THIS PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1240 PM EST WED JAN 21 2015

A SLOW MOVING TROUGH WILL KEEP LOW LEVEL MOISTURE IN PLACE ACROSS
THE TAF SITES THROUGH MUCH OF THE PERIOD. LIGHT SHOW IS
DIMINISHING BUT CIGS WILL REMAIN IFR/MVFR THROUGH TONIGHT. WINDS
WILL GRADUALLY TURN FROM THE NORTHEAST TO THE NORTTHWEST BY THU
AM BUT REMAIN AROUND 5 KNOTS.

&&

.HYDROLOGY...
ISSUED AT 330 PM EST TUE JAN 20 2015

NEAR TO A LITTLE ABOVE NORMAL TEMPERATURES AND A LACK OF SIGNIFICANT
PRECIPITATION THIS WEEK WILL RESULT IN LIMITED ICE AND SNOW MELT.
THIS SHOULD RESULT IN A GRADUAL FALL IN RIVER LEVELS. ICE BREAKUP
IS NOT EXPECTED.

&&

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

$$

UPDATE...OSTUNO
SYNOPSIS...JAM
SHORT TERM...JAM
LONG TERM...MJS
AVIATION...93
HYDROLOGY...63






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