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000
FXUS63 KGRR 230459
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1159 PM EST THU JAN 22 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 321 PM EST THU JAN 22 2015

MOSTLY FAIR WEATHER WILL PREVAIL INTO SATURDAY. A CLIPPER WILL
BRING SOME SNOW FOR SUNDAY THEN IT WILL TURN COLDER ON MONDAY AND
TUESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 321 PM EST THU JAN 22 2015

ONLY REAL FORECAST CONCERN IN THE NEAR TERM IS FOR PRECIPITATION
TYPE LATE FRIDAY NIGHT AS MODEL SOUNDINGS SHOW THE DGZ IS NOT
SATURATED AFTER 06Z SATURDAY. KEPT THE PRECIP TYPE AS SNOW FOR
NOW BUT MAY HAVE TO ADD FREEZING DRIZZLE IF DGZ IS DRY IN FUTURE
RUNS DURING THE 06Z TO 12Z SATURDAY PERIOD. WITH THE SFC LOW
PASSING WELL NORTH OF THE FORECAST AREA...THE FORCING FOR ANY
PRECIP IS WEAK AND THERE DOES NOT APPEAR TO BE MUCH LIFT IN THE
STRATUS DECK...SO ANY PRECIP SHOULD BE LIGHT.

ONE OTHER POTENTIAL ISSUE IS FOR POPS LATE SATURDAY NIGHT. AT THIS
POINT IT APPEARS THAT BULK OF THE SNOW WITH THE APPROACHING
CLIPPER WILL HOLD OFF UNTIL AFTER 12Z SUNDAY. WENT WITH CHANCE
POPS FOR NOW WITH HIGHER CHANCES TO THE WEST. POPS WILL HAVE TO BE
RAISED FOR THE 06Z TO 12Z SUNDAY PERIOD IF A FASTER TREND DEVELOPS
AS WE GET CLOSER TO THE EVENT...AS HAPPENED WITH THE CLIPPER THAT
MOVED THROUGH YESTERDAY.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 321 PM EST THU JAN 22 2015

THE MAIN CONCERN DURING THE LONG TERM IS THE POTENTIAL FOR
ACCUMULATING SNOW SUNDAY. THE MODELS ARE PRETTY MUCH ON TRACK AND
CONVERGING ON A TRACK THAT TAKES A CLIPPER SOUTHEASTWARD ACROSS NW
INDIANA. THIS TRACK PLACES THE CWA ON THE COLD AND SNOWY SIDE. THE
LATEST ECMWF IS CLOSER TO ITS ENSEMBLE MEAN POSITION AND WILL
GENERALLY BE FOLLOWED.

ISENTROPIC LIFT WILL BEGIN EARLY SUNDAY AHEAD OF THE CLIPPER AND
CONTINUE THROUGH THE DAY. AS THE CLIPPER APPROACHES THE GREAT LAKES
A COLD FRONT WILL DROP SOUTH AND THE RESULTING BAROCLINIC ZONE WILL
BE CONDUCIVE FOR PCPN DEVELOPMENT. QPF AROUND A QUARTER INCH SHOULD
RESULT IN SNOWFALL ACCUMULATIONS IN THE 2-4 INCH RANGE GIVEN SNOW
RATIOS AROUND 14/15-1. THERE IS DEEP LIFT WITHING THE CLOUD LAYER
INCLUDING THE DGZ. HOWEVER...THE STRONGEST LIFT IS BELOW THE DGZ
WHICH MAY PRECLUDE THE SYSTEM FROM OVERPERFORMING. SNOWFALL WILL
WIND DOWN BY LATE AFTERNOON/EARLY EVENING SUNDAY.

HIGHS IN THE LOWER 30S ARE EXPECTED SUNDAY THEN COOLING TO AROUND 20
BY MONDAY BEHIND THE CLIPPER THEN BEGIN A WARMING TREND THROUGH THE
REST OF THE PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1158 PM EST THU JAN 22 2015

MVFR CEILINGS PREVAIL AT MOST TAF SITES AT MIDNIGHT...BUT A HOLE
IN THE OVERCAST HAS DEVELOPED FROM KGRR AND KLAN NORTHEASTWARD
TOWARDS SAGINAW BAY. THE EXPECTATION IS THAT THESE CLOUDS WILL
FILL BACK IN AT KGRR AND KLAN WITHIN THE NEXT FEW HOURS. EXPECTING
MVFR CEILINGS TO BE WIDESPREAD AGAIN BY DAYBREAK AS SOUTHWEST
WINDS PUSH THESE CLOUDS BACK INTO THE AREA.

THE CLOUD FORECAST ON FRIDAY IS TRICKY AS CURRENT SATELLITE
IMAGERY WOULD INDICATE WE SHOULD SEE PLENTY OF MVFR CLOUDS
CONTINUING. CLIMATOLOGY WOULD AGREE WITH THIS BEING A CLOUDY TIME
OF THE YEAR. SOME MODEL PROGS BREAK UP THE LOWER CLOUDS HOWEVER.
AT THIS POINT WILL SIDE WITH CLIMATOLOGY AND SATELLITE PICS AND
KEEP THE CLOUDS IN. WILL TREND UP JUST A BIT HOWEVER AND TAKE
CEILINGS VFR IN THE AFTERNOON. LOW CONFIDENCE EXISTS ON CLOUD
TRENDS ON FRIDAY. WINDS WILL INCREASE OUT OF THE SOUTHWEST ON
FRIDAY WITH 10-20 KNOT SUSTAINED WINDS IN THE AFTERNOON GUSTING TO
25 KNOTS AT TIMES.

&&

.HYDROLOGY...
ISSUED AT 321 PM EST THU JAN 22 2015

ALL GAUGES SHOW RIVER LEVELS BELOW BANKFULL. WILL CONTINUE
MONITORING FOR POTENTIAL ICE JAMS WHICH CAN CAUSE WATER LEVEL RISE
AT ANY TIME. SIGNIFICANT ICE JAM FLOODING IS UNLIKELY FOR THE TIME
BEING. A SMALL AMOUNT OF ICE MELT MAY OCCUR WITH MILDER TEMPERATURES
FRIDAY AND SATURDAY BEFORE COLDER AIR ARRIVES NEXT WEEK.

&&

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

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...93
AVIATION...DUKE
HYDROLOGY...CAS