Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 270458
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1158 PM EST FRI DEC 26 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EST FRI DEC 26 2014

ONE MORE UNSEASONABLY MILD DAY IS IN STORE FOR SATURDAY AS A LOW
PRESSURE SYSTEM OVER MISSOURI TRACKS NORTHEAST THROUGH WISCONSIN AND
NORTHERN MICHIGAN.

MOISTURE STREAMING NORTH AHEAD OF THIS SYSTEM WILL BRING CLOUDS AND
OCCASIONAL LIGHT RAIN OR DRIZZLE BEGINNING LATE TONIGHT AND
CONTINUING THROUGH SATURDAY. THE RAIN MAY MIX WITH A LITTLE LIGHT
SNOW SATURDAY NIGHT BEFORE ENDING AS A COLD FRONT PASSES THROUGH.

WE WILL SEE SOME CHILLY AIR AND LIGHT LAKE EFFECT SNOW SHOWERS
ARRIVE THIS WEEK WITH HIGHS MAINLY IN THE 20S. NO SIGNIFICANT SNOW
ACCUMULATIONS ARE EXPECTED AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 330 PM EST FRI DEC 26 2014

NO MAJOR CHANGES IN THINKING TO THE GOING FORECAST. WIDESPREAD LOW
CLOUDS DEVELOP LATER THIS EVENING AS SFC DEW POINTS AROUND 40 STREAM
IN FROM THE SOUTHWEST. LATEST RUNS OF THE HRRR SHOW SCATTERED LIGHT
CONVECTIVE LOOKING RAIN SHOWERS DEVELOPING THIS EVENING ACROSS
MISSOURI AND ILLINOIS. THESE SHOULD WILL LIKELY TRACK INTO THE AREA
FROM THE SOUTHWEST OR DEVELOP OVERHEAD OVERNIGHT AND PERSIST
SATURDAY WITHIN THE WARM ADVECTION ZONE AHEAD OF THE APPROACHING SFC
LOW AND COLD FRONT. IN ADDITION TO THE CONVECTIVE RAIN SHOWERS...
SOME PATCHY DRIZZLE MAY BE SQUEEZED OUT OF THE LOW CLOUDS AT TIMES
LATE TONIGHT AND SATURDAY.

DEEPER MOISTURE MOVES EAST OF THE AREA AFTER 00Z SUNDAY ABOUT THE
TIME THE COLDER AIR IS ARRIVING. PRECIPITATION BEHIND THE SFC COLD
FRONT SHOULD TREND TOWARD JUST SOME VERY LIGHT MIXED RAIN AND SNOW
SHOWERS. NO SNOW ACCUMULATIONS EXPECTED LATE SATURDAY NIGHT INTO
EARLY SUNDAY DUE TO VERY SHALLOW MOISTURE PROFILES AND QUESTIONABLE
DGZ SATURATION. ADDITIONALLY...SURFACE RIDGING/ANTICYCLONIC FLOW IS
QUICK TO BUILD IN WHICH ACTUALLY LEADS TO DECENT PROSPECT FOR
SUNSHINE DEVELOPING SUNDAY AFTERNOON.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 330 PM EST FRI DEC 26 2014

WE CONTINUE TO EXPECT A TREND TOWARD COLDER WEATHER IN THE LONG TERM
WITH CHCS OF SNOW SHOWERS THROUGH THE PERIOD. SNOW ACCUMULATIONS DO
NOT LOOK TO BE ANYTHING SIGNIFICANT IN THE FCST PERIOD FOR NOW. WE
WILL CONTINUE TO MONITOR THIS POTENTIAL AS IT WOULD NOT TAKE MAJOR
CHANGES TO BRING A BETTER POTENTIAL OF LAKE EFFECT.

THE CHC OF SNOW FOR SW LOWER ON MON DOES NOT LOOK REAL GOOD AT THIS
TIME. A SHORT WAVE TROUGH WILL BE MOVING INTO THE GREAT LAKES REGION
FROM THE WNW ON MON. HOWEVER A STRONG 1050+ MB RIDGE TO OUR WEST
WILL BE IN CONTROL OF THE LOWER LEVELS HERE. NE FLOW AND AN
EXTENSION OF THE SFC RIDGE IN PLACE WILL LIMIT PCPN POTENTIAL.

THE PERIOD FROM TUE THROUGH THU THEN WILL FEATURE THE COLDEST TEMPS
OF THE LONG TERM. THE MON SHORT WAVE WILL COMPLETE THE TRANSITION OF
THE UPPER AIR PATTERN TO MORE OF A NW FLOW ALOFT OVER THE AREA.
COLDER AIR WILL CONTINUE TO FILTER IN ON THE NRLY AND EVENTUALLY NW
LOW LEVEL FLOW. THE AIR WILL BE PLENTY COLD ENOUGH FOR LAKE
EFFECT...HOWEVER WE WILL REMAIN ON THE SOUTH SIDE OF THE NRN BRANCH
OF THE JET. SHORT WAVES DIVING SE ARE EXPECTED TO REMAIN JUST NORTH
OF THE CWFA. THIS WILL LIMIT MOISTURE DEPTH SIGNIFICANTLY AND ALSO
THE DEEP LAYER INSTABILITY.

LAKE EFFECT COULD BE MORE ROBUST IF THE UPPER JET AND THE ASSOCIATED
SHORT WAVES ARE ABLE TO DIVE JUST A LITTLE FURTHER SOUTH. WE BELIEVE
THAT THE STRONG CUTOFF UPPER LOW ACROSS THE SW U.S. AND THE RIDGE
AHEAD OF IT WILL HOLD THE NRN BRANCH OF THE JET JUST NORTH OF THE
AREA.

WE COULD SEE THE INITIAL EFFECTS OF THE CUTOFF UPPER LOW START TO
MOVE IN AS EARLY AS NEXT FRI AS WARM AND MOISTURE ADVECTION AHEAD OF
IT STARTS TO OVERRUN THE COLDER AIR EXPECTED TO BE IN PLACE. THE
MODELS TYPICALLY EJECT THESE SYSTEMS OUT TOO QUICK...SO WE WILL KEEP
THE CHC OF PCPN LOW AT THIS TIME FOR NEXT FRI.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1157 PM EST FRI DEC 26 2014

CEILING WILL SLOWLY LOWER TO IFR BY MORNING AND PERIOD OF LIGHT
RAIN OR DRIZZLE WILL ALSO DEVELOP BY THEN ALSO LOWERING
VISIBILITIES TO IFR. THE FRONT WILL COME THROUGH DURING THE
AFTERNOON AND WILL END THE PRECIPITATION AND IMPROVE VISIBILITIES.
CEILINGS WILL ONLY SLOWLY LIFT DURING THE EVENING.

&&

.MARINE...
ISSUED AT 330 PM EST FRI DEC 26 2014

THE PRESSURE GRADIENT RELAXES TONIGHT SO WINDS AND WAVES ARE
EXPECTED TO SUBSIDE. HOWEVER THEY WILL RAMP UP AGAIN LATE SATURDAY
AND SATURDAY NIGHT AS A COLD FRONT PASSES ACROSS LK MI.


&&

.HYDROLOGY...
ISSUED AT 330 PM EST FRI DEC 26 2014

HAVE CANCELED THE ADVISORY FOR THE MAPLE RIVER AT MAPLE RAPIDS AS
LATEST FORECAST HAS IT CRESTING A HALF FOOT BELOW BANKFULL SUNDAY.
SYCAMORE CREEK AT HOLT CRESTED LAST NIGHT AND IS FALLING BELOW
BANKFULL AT THIS TIME. ABOUT A TENTH OF AN INCH OF PRECIPITATION IS
EXPECTED ON SATURDAY WHICH WILL NOT AFFECT THE RIVERS MUCH. A LACK
OF SIGNIFICANT PRECIPITATION INTO THE NEW YEAR WILL ALLOW THE LARGER
RIVERS TIME TO CREST AND FALL WITHOUT MUCH IMPACT.

&&

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

$$

SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...CAS
MARINE...MEADE





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