Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 221130
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
630 AM EST THU JAN 22 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 315 AM EST THU JAN 22 2015

A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE LOWER GREAT LAKES REGION
AND BRING TRANQUIL WEATHER TODAY THROUGH FRIDAY. TEMPERATURES WILL
UNDERGO A SLIGHT MODERATING TREND FRIDAY THROUGH SATURDAY AND A
WEAK SYSTEM MAY BRING A FEW LIGHT SNOW SHOWERS AND FLURRIES FRIDAY
NIGHT AND SATURDAY. AN ALBERTA CLIPPER SYSTEM WILL BRING POTENTIAL
FOR SEVERAL INCHES OF ACCUMULATING SNOW FOR SUNDAY.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 315 AM EST THU JAN 22 2015

A FEW LIGHT SNOW SHOWERS AND FLURRIES WILL LINGER EARLY THIS
MORNING. OTHERWISE TRANQUIL WX IS ANTICIPATED TODAY THROUGH
FRIDAY AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE LOWER GREAT
LAKES REGION.

TEMPS WILL AVERAGE NEAR NORMAL TODAY BEFORE MODERATING SLIGHTLY
FOR FRIDAY AS LOW LEVEL WINDS BACK TO THE SW. A WEAK SYSTEM WILL
MOVE IN FROM THE NW FRIDAY NIGHT AND BRING POTENTIAL FOR A FEW
LIGHT SNOW SHOWERS AND FLURRIES BUT WITH VERY LITTLE TO NO SNOW
ACCUMULATION.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 315 AM EST THU JAN 22 2015

THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE POTENTIAL FOR
ACCUMULATING SNOW SUNDAY.

MODELS CONTINUE TO SHOW LOW PRESSURE TRACKING SOUTHEAST FROM MN TO
OH SATURDAY NIGHT INTO SUNDAY.  THE GFS IS FURTHER NORTH WITH THE
TRACK OF THIS LOW AS COMPARED TO THE HIGH RES EURO AND WOULD SUPPORT
WIDESPREAD ACCUMULATING SNOW FOR SOUTHWEST LOWER MI AS THE LOW
DEEPENS.  THE HIGH RES EURO IS WEAKER AND FURTHER SOUTH...SUGGESTING
ANY ACCUMULATIONS WILL BE CONFINED TO THE REGION SOUTHWEST OF A
MUSKEGON TO LANSING LINE.  THE HIGH RES EURO IS TRENDING FURTHER
SOUTH WITH THE TRACK THIS SYSTEM.  THE TREND OF THE GFS IS FOR A
DEEPER SYSTEM.  SO WE WILL NEED TO MONITOR THIS POTENTIAL SYSTEM
CLOSELY AS ACCUMULATIONS ARE POSSIBLE.  I WILL KEEP THE POPS
RELATIVELY HIGH FOR SUN...ESPECIALLY FOR GRAND RAPIDS...MUSKEGON AND
KALAMAZOO.

COLD AIR ADVECTION STRENGTHENS BEHIND THE DEPARTING SYSTEM SUNDAY
NIGHT INTO MONDAY.  BELOW NORMAL TEMPERATURES ARE LIKELY AS THE LOW
LEVEL THERMAL TROUGH WITH ITS SOURCE FROM CENTRAL CANADA MOVES IN.
THIS COLD AIRMASS MAY PERSIST INTO TUESDAY...BUT WARM AIR ADVECTION
IS SHOWN BY TUESDAY NIGHT.  WILL REBOUND TEMPERATURES CLOSER TO
NORMAL BY WEDNESDAY.

GOOD AGREEMENT AMONGST THE MODELS ON THE ARRIVAL OF AN IMPRESSIVE
SURGE OF ARCTIC AIR FOR THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 624 AM EST THU JAN 22 2015

GENERALLY MVFR CONDITIONS TO PREVAIL THROUGH THE PERIOD...ALTHOUGH
SOME VFR WILL BE AROUND THIS MORNING. LOW LEVEL MOISTURE GENERALLY
REMAINS HIGH...THUS THE CLOUD BASES WILL REMAIN LOW. THERE COULD
BE ICING IN THE CLOUDS THROUGH TONIGHT. THE LIGHT SNOW WILL
CONTINUE TO DIMINISH THIS MORNING.

A RISK FOR IFR EXISTS TONIGHT. I DID NOT PUT IT IN THE FORECAST
AS CONFIDENCE WAS NOT HIGH ENOUGH. WE WILL NEED TO MONITOR TRENDS
ON THIS RISK.

&&

.HYDROLOGY...
ISSUED AT 328 PM EST WED JAN 21 2015

THE ONLY CONCERN AT THIS TIME IS THE ICE JAM POTENTIAL AROUND THE
AREA. MILD WEATHER OVER THE NEXT FEW DAYS COULD POTENTIALLY ALLOW
SOME ICE TO BREAK UP AND START TO MOVE. IT APPEARS ICE IS AFFECTING
THE GAGE AT EVART...BUT NO OTHER SPECIFIC CONCERNS AT THIS TIME.

OTHER THAN ICE JAMS...WE EXPECT NO SIGNIFICANT AMOUNT OF RUN OFF
INTO THE RIVERS OVER THE NEXT WEEK. WE COULD BE LOOKING AT A COLD
PERIOD LATE NEXT WEEK THAT COULD HELP TO INCREASE ICE FORMATION.

&&

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

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...NJJ






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