Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 242344
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
744 PM EDT TUE MAR 24 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 PM EDT TUE MAR 24 2015

CLEAR SKIES EARLY THIS EVENING WILL GIVE WAY TO CLOUDS AND RAIN BY
EARLY WEDNESDAY MORNING. AREAS NORTH OF INTESTATE 96 WILL SEE
FREEZING RAIN EARLY WEDNESDAY MORNING WITH AROUND A TENTH OF AN
INCH OF ICE ACCUMULATION NEAR ROUTE 10 BEFORE TEMPERATURES RISE
ABOVE FREEZING AROUND SUNRISE. THE RAIN SHOULD END ACROSS THE AREA
BY MID MORNING. IT WILL TURN WINDY WITH TEMPERATURES NEAR 50
DURING THE AFTERNOON.

AN ARCTIC FRONT WILL BRING AFTERNOON TEMPERATURES BELOW FREEZING
BY THURSDAY EVENING AND TEMPERATURES WILL STAY BELOW FREEZING INTO
SATURDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM EDT TUE MAR 24 2015

I HAVE ISSUED A WINTER WEATHER ADVISORY FOR FREEZING RAIN FROM 2
AM TILL 11 AM WEDNESDAY. MOST OF THE FREEZING RAIN WILL BE NEAR
AND NORTH OF ROUTE 46. IT WILL BE WINDY WEDNESDAY ONCE THE RAIN
ENDS BY MID MORNING.

WE HAVE BEEN FOLLOWING THIS SYSTEM FOR WELL OVER A WEEK NOW AND
FINALLY WE HAVE A SOUTHERN STREAM SYSTEM THAT TRACKS FAR ENOUGH
NORTH AND HAS ENOUGH DYNAMICS TO BRING SIGNIFICANT PRECIPITATION TO
THIS AREA...WHICH HAS NOT SEEN ANY SIGNIFICANT PRECIPITATION SINCE
THE 3RD OF MARCH. WE HAVE A DIGGING NORTHERN STREAM WAVE THE
MERGES WITH THE SOUTHERN STREAM WAVE AFTER THE SYSTEM IS EAST OF
MICHIGAN. HOWEVER... THE UPPER LEVEL SYSTEM GOES NEGATIVE TILT AS
IT MOVES THROUGH MICHIGAN TONIGHT. THIS PROCESS FOCUSES THE LOW
LEVEL JET AND 1000 TO 850 MB TRANSPORT VECTORS ON LOWER MICHIGAN
BETWEEN MIDNIGHT AND SUNRISE WEDNESDAY. WITH THE AID OF A 55 TO 60
KNOT LOW LEVEL JET... THE 850 TEMPS RISE TO 3C TO 4C ACROSS MOST
OF THE LOWER PENINSULA TONIGHT. THAT OF COURSE MAKES IT TO WARM
FOR SNOW TO REACH THE GROUND BUT THE STRONG DYNAMICS AND DECENT
MOISTURE TRANSPORT AND STRONG WARM ADVECTION ASSURES US IT WILL
INDEED RAIN ACROSS THE AREA TONIGHT.

OUR PROBLEM THROUGH IS THE AIR AT THE SURFACE IS COOL AND VERY
DRY. AFTERNOON DEW POINTS OVER LOWER MICHIGAN A 2 PM WERE MOSTLY
BETWEEN 5F AND 15F. AIR TEMPERATURES ARE JUST ABOVE FREEZING.
AFTER SUNSET MOST AREAS NORTH AND EAST OF GRAND RAPIDS WILL FALL
BELOW FREEZING BEFORE THE CLOUDS GET THICK ENOUGH TO STOP THE
TEMPERATURE FALL. WITH THE EAST WINDS AHEAD OF THE SYSTEM AT THE
SURFACE WET BULB COOLING WILL ALSO AID THE PROCESS SO I SEE
SEVERAL HOURS OF FREEZING RAIN NORTH OF GRAND RAPIDS
TONIGHT...WHICH IS WHY I ISSUED THE ADVISORY. NEAR INTERSTATE 96
THIS WILL BE LESS OF AN ISSUE BUT I STILL THINK EVEN HERE WE COULD
SEE AN HOUR OR TWO OF FREEZING RAIN.

AS A SIDE NOTE...THERE IS SOME MID LEVEL INSTABILITY WITH THIS
SYSTEM BUT THE AIR UNSTABLE ENOUGH FOR THUNDERSTORMS IS EXPECTED
TO STAY SOUTH WELL SOUTH OF INTERSTATE 94. SO I DO NOT SEE
THUNDERSTORMS IMPACTING THE AREA TONIGHT OR EARLY WEDNESDAY
MORNING. THIS ALSO AGREES WITH THE SPC OUTLOOK FOR THUNDERSTORMS
(WHICH IS ALL SOUTH OF THE GRR CWA IN MICHIGAN).

THE UPPER LEVEL TROUGH COMES THROUGH MID MORNING WEDNESDAY
BRINGING AND OCCLUDED FRONT THROUGH THE AREA. THAT WILL QUICKLY
END THE RAIN FROM SOUTHWEST TO NORTHEAST AND EVEN BRING SOME
CLEARING TO THE AREA BY EARLY WEDNESDAY AFTERNOON. BEING IN THE
SOUTHWEST QUAD OF THIS SYSTEM MEANS THE DRY SLOT AND STRONGER
WINDS. THE MIXED LAYER TAPS WINDS TO NEAR 40 KNOTS... I BELIEVE
THIS WILL NOT BE QUIET STRONG ENOUGH FOR A WIND ADVISORY BUT NONE
THE LESS IT WILL BE VERY WINDY WEDNESDAY AFTERNOON. TEMPERATURES
SHOULD RISE TO NEAR 50 AT GRR...MAYBE NEAR 60 AT JXN BUT ONLY IN
THE 40S NORTH AND WEST OF GRR.

COLDER AIR FOLLOWS THURSDAY BUT THE ARCTIC FRONT DOES NOT COME
THROUGH TILL THURSDAY EVENING SO THURSDAY SHOULD BE QUIET AND
COOLER DAY. A WAVE ON THE COLD FRONT MAY BRING PRECIPITATION AS
FAR NORTH AS INTERSTATE 94 EARLY THURSDAY MORNING BUT MOST OF THE
PRECIPITATION WITH THAT WILL STAY SOUTH OF MICHIGAN.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 328 PM EDT TUE MAR 24 2015

VERY COLD TEMPERATURES FOR LATE MARCH AND MAINLY DRY WEATHER WILL BE
THE THEME FRIDAY AND SATURDAY. TEMPERATURES GRADUALLY MODERATE
SUNDAY INTO TUESDAY...AND THE BEST CHANCE FOR SNOW AND RAIN ARRIVES
SUNDAY.

A DEEP UPPER TROUGH WILL BE IN PLACE OVER THE GREAT LAKES REGION
FRIDAY AND SATURDAY. HIGHS ON FRIDAY WILL STRUGGLE TO REACH 30
DEGREES. THERE IS A SLIGHT CHANCE FOR LAKE EFFECT SNOW SHOWERS ON
FRIDAY WITH MODERATE INSTABILITY OVER THE LAKE. MOISTURE WILL BE
RATHER SHALLOW. SHORTWAVE RIDGING BUILDS IN FRIDAY NIGHT AND
SATURDAY AS A SURFACE HIGH DROPS FROM WISCONSIN INTO THE OHIO
VALLEY. LOW TEMPERATURES SATURDAY MORNING ARE EXPECTED TO BE IN THE
SINGLE DIGITS TO MID TEENS. NORMAL LOWS FOR LATE MARCH ARE IN THE
UPPER 20S TO LOWER 30S. SATURDAY WILL FEATURE PLENTIFUL SUNSHINE
WITH HIGHS RECOVERING INTO THE MID 30S...STILL 15 DEGREES BELOW
NORMAL.

SIGNIFICANT MODEL SPREAD EXISTS ON THE 12Z ECMWF/GFS FOR THE SUNDAY
SYSTEM. THE GFS BRINGS THE SURFACE LOW QUITE A BIT FURTHER
SOUTH...CENTERED JUST NORTH OF MACKINAC BRIDGE AT 00Z MONDAY. THE
GFS IS A LITTLE MORE BULLISH ON QPF...WHICH WOULD RESULT IN MORE
SNOW DURING THE SUNDAY MORNING HOURS...CHANGING TO RAIN TOWARD
MIDDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 743 PM EDT TUE MAR 24 2015

VFR CONDITIONS ARE EXPECTED THROUGH 06Z BEFORE MVFR CONDITIONS
ARRIVE. THERE MAY BE A PERIOD OF FREEZING RAIN AFTER 06Z...BUT
THIS SHOULD LAST AN HOUR OR LESS AND NOT CAUSE ANY SIGNIFICANT
ICING. THEN RAIN SHOWERS AND CEILINGS AROUND 1000 FEET AGL ARE
EXPECTED FROM AROUND 08Z TO ABOUT 15Z. CONDITIONS SHOULD IMPROVE
BACK TO VFR DURING THE AFTERNOON.

WINDS WILL BE SOUTHEAST AND INCREASING TONIGHT WITH GUSTS OVER 20
KNOTS AT TIMES. WINDS WILL GO SOUTHWEST TO WEST DURING THE
AFTERNOON AND GUSTS OVER 25 KNOTS ARE POSSIBLE.

&&

.HYDROLOGY...
ISSUED AT 1238 PM EDT TUE MAR 24 2015

RIVER LEVELS WILL CONTINUE TO FALL THROUGH WEDNESDAY. THE GROUND
HAS THAWED AND SOILS ARE DRYING OUT. A RAIN AND FREEZING RAIN
EVENT TONIGHT INTO EARLY WEDNESDAY IS EXPECTED TO HAVE
PRECIPITATION TOTALS OF AROUND A HALF INCH. LOCALLY HIGHER
AMOUNTS ARE POSSIBLE... IF THUNDERSTORMS OCCUR. THIS MAY CAUSE
RIVER LEVELS TO LEVEL OFF OR EVEN CREEP BACK UP TO NEAR BANK
FULL... BUT FLOODING IS NOT A HIGH PROBABILITY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 2 AM TO 11 AM EDT WEDNESDAY FOR
     MIZ037>040-043>046-050>052.

LM...NONE.
&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...EBW
AVIATION...OSTUNO
HYDROLOGY...63





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