Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 291744
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
144 PM EDT SUN MAR 29 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAR 29 2015

A COLD FRONT WILL BRING A MIX OF LIGHT RAIN AND LIGHT SNOW LATE
THIS MORNING THROUGH THIS AFTERNOON INTO THIS EVENING AND IT WILL
ALSO BECOME RATHER WINDY THIS AFTERNOON. SOME LIGHT SNOW
ACCUMULATIONS OF AROUND AN INCH OR LESS ARE ANTICIPATED FOR
CENTRAL LOWER MICHIGAN. A CLIPPER SYSTEM WILL BRING ANOTHER ROUND
OF LIGHT SNOW TO SOUTH CENTRAL LOWER MICHIGAN MONDAY NIGHT INTO
EARLY TUESDAY. TEMPERATURES WILL FINALLY MODERATE TO NEAR OR EVEN
SLIGHTLY ABOVE NORMAL BY THE MIDDLE PORTION OF THE UPCOMING WEEK.

&&

.UPDATE...
ISSUED AT 1234 PM EDT SUN MAR 29 2015

FORECAST REMAINS ON TRACK. EXPECTING A BAND OF PRECIPITATION TO
SWEEP THROUGH THE AREA THIS AFTERNOON. THE PRECIP WILL BE RAIN
ACROSS ABOUT THE SOUTHERN HALF OF THE FORECAST AREA AND WILL BE A
RAIN MIXED WITH SNOW AT TIMES ACROSS THE NORTHERN HALF. NOT
EXPECTING MUCH IN THE WAY SNOW ACCUMULATION AS TEMPERATURES HAVE
PUSHED TO NEAR 40 EVEN ACROSS CENTRAL LOWER MICHIGAN. DEW POINTS
ARE IN THE TEENS HOWEVER SO THERE WILL BE WET BULB AFFECTS COOLING
AIR TEMPS BACK INTO THE 30S AFTER THE ONSET OF THE PRECIPITATION.
HAVE POSSIBLE ACCUMULATIONS IN THE GRIDS OF A FEW TENTHS OF AN
INCH.

HIGH TEMPS IN MOST AREAS SHOULD BE IN THE 39 TO 44 DEGREE RANGE.
IT WILL BE WINDY THIS AFTERNOON WITH 20-30 MPH WINDS GUSTING TO
AROUND 40 MPH AT TIMES. THE HIGHEST WINDS IN THE FORECAST AREA
WILL BE FOUND UP ALONG THE LAKESHORE NEAR BIG AND LITTLE SABLE
POINTS. GUSTS ARE NOW UP TO 44 MPH AT THE BIG SABLE POINT
OBSERVATION SITE IN LUDINGTON STATE PARK. WINDS WILL TAPER OFF
THROUGH THE COURSE OF THE EVENING.

A SECOND WAVE OF PRECIPITATION...MAINLY RAIN SHOWERS WILL WORK
THROUGH THE AREA THIS EVENING BETWEEN 600PM AND 1000PM. THIS
PRECIPITATION IS ASSOCIATED WITH A TRAILING/SECOND UPPER
SHORTWAVE DIVING INTO THE BACKSIDE OF THE UPPER TROUGH.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT SUN MAR 29 2015

PRIMARY SHORT TERM FCST CHALLENGES INVOLVE DETERMINING POTENTIAL
FOR LIGHT SNOW LATER TODAY AND AGAIN MONDAY NIGHT INTO EARLY TUESDAY.

A CONSENSUS OF LATEST SHORT RANGE 00Z GUIDANCE CONTINUES TO
INDICATE PCPN WILL DEVELOP FROM WEST TO EAST LATE THIS MORNING
THROUGH THE AFTERNOON. PCPN WILL BEGIN AS A MIX OF LIGHT RAIN AND
LIGHT SNOW AND MAY TRANSITION TO A PERIOD OF MAINLY LIGHT RAIN
THIS AFTERNOON OVER OUR SOUTHERN FCST AREA NEAR TO SOUTH OF I-96
AS THERMAL PROFILES MODERATE.

AROUND AN INCH OR LESS OF SNOW IS ANTICIPATED NORTH OF I-96 WITH
RELATIVELY HIGHEST AMOUNTS OF AROUND AN INCH OR SO EXPECTED OVER
HIGHER ELEVATIONS OF OUR NORTHERN FCST AREA. HOWEVER IMPACTS WILL
BE VERY MINIMAL GIVEN THE LIGHT NATURE OF PCPN AND TEMPS EVEN UP
NORTH SHOULD REACH THE LOWER 40S SUCH THAT SOME MELTING WILL
OCCUR.

IT WILL BECOME WINDY THIS AFTERNOON WITH FREQUENT WIND GUSTS IN THE
35 TO 40 MPH RANGE. A FEW SLIGHTLY HIGHER GUSTS ARE POSSIBLE MAINLY
RIGHT ALONG THE LAKE MI SHORELINE ESPECIALLY FROM KMKG NORTH TO
KLDM. BREEZY CONDITIONS WILL THEN CONTINUE THROUGH THE EVENING.

PCPN WILL LINGER INTO THE EVENING BEFORE ENDING OVERNIGHT. HIGH
PRESSURE WILL BUILD IN TO PRODUCE FAIR WX WITH SEASONABLY COOL
TEMPS MONDAY. A CLIPPER SYSTEM WILL BRING LIGHT SNOW TO SOUTH CENTRAL
LOWER MI LATE MONDAY NIGHT INTO EARLY TUESDAY WITH POTENTIAL FOR
AROUND AN INCH OR TWO OF SNOW NEAR TO MAINLY NE OF KGRR.

IT IS NOTED THAT 00Z ECMWF GUIDANCE REMAINS FURTHER SOUTH WITH
PCPN PLACEMENT WITH THIS SYSTEM AND WOULD BRING POTENTIAL FOR
LIGHT SNOW ACCUMULATIONS OF AN INCH OR TWO INTO KGRR/KLAN WHEREAS
00Z NAM/GFS GUIDANCE SUGGESTS THE LIGHT SNOW WOULD ONLY AFFECT OUR
FAR NORTH TO NE FCST AREA.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAR 29 2015

AFTER A LENGTHY STRETCH OF CHILLY WEATHER... A COUPLE OF MILD
SPRING-LIKE DAYS ARE LIKELY FOR THE MIDDLE PART OF NEXT WEEK. HIGHS
IN THE LOW TO MID 50S ARE EXPECTED ON WEDNESDAY... WITH READINGS
LIKELY REACHING OR EXCEEDING 60 ON THURSDAY AWAY FROM LAKE MICHIGAN.

THE MAIN FEATURE OF INTEREST WILL BE A COLD FRONT EXTENDING SOUTH
FROM A LOW IN SOUTHERN CANADA... WHICH EDGES IN FROM THE WEST LATE
WEDNESDAY NIGHT OR THURSDAY. SCATTERED TO NUMEROUS RAIN SHOWERS
WILL ACCOMPANY THIS FRONT.

THE ECMWF IS MUCH SLOWER WITH THE SFC FRONT THAN THE GFS AND HAS
RAIN HOLDING OFF UNTIL AFTER 18Z THURSDAY. THE GFS HAS THE RAIN
ARRIVING AS EARLY AS 06Z THURSDAY AND EXITING ALREADY AFTER 18Z
THURSDAY. THESE TIMING DIFFERENCES IN THE MODELS ARE CRITICAL
BECAUSE IF THE ECMWF IS CORRECT WE COULD SEE HIGH TEMPERATURES
APPROACH OR EXCEED 70 DEGREES ON THURSDAY SOUTH AND EAST OF GRR.

THE OTHER BIG DIFFERENCE IS THAT THE ECMWF WANTS TO STALL THE FRONT
THURSDAY NIGHT AS A WAVE MOVES ALONG IT. THE GFS IS MUCH MORE
PROGRESSIVE WITH THE FRONT AND WITH THE ARRIVAL OF THE COLD DRY AIR
BEHIND IT. IF THE SLOWER ECWMF IDEA OF A WAVE ALONG THE FRONT IS
CORRECT...WE COULD SEE OVER A HALF INCH OF RAIN THURSDAY NIGHT
INTO EARLY FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 144 PM EDT SUN MAR 29 2015

THE MAIN PERIOD OF CONCERN WITH THE 18Z FCSTS WILL BE THE FIRST 12
HOURS OR SO WITH LOWER CONDITIONS WITH PCPN EXPECTED. THE LEADING
EDGE OF THE INITIAL BAND OF PCPN HAS REACHED KMKG AS OF 1740Z.
THIS STARTED AS RAIN AND SLEET/PL AT KMKE AND WE EXPECT THE SAME
HERE. GENERALLY MVFR CONDITIONS ARE EXPECTED.

WE EXPECT THAT SOME SNOW MAY MIX IN AT KMKG AND KGRR FOR AN HOUR
OR TWO AS THE AIR COOLS OFF WHILE MOISTENING UP. FURTHER SOUTH A
SUFFICIENT WARM LAYER AT THE SFC SHOULD KEEP MOST PCPN RAIN. PCPN
MAY DIMINISH TO DRIZZLE BEHIND THE FIRST BAND...AND AHEAD OF A
SECONDARY BAND THAT WILL COME THROUGH. THE SECONDARY BAND SHOULD
BE ALL RAIN FOR ALL OF THE TERMINALS.

PCPN SHOULD END LATE IN THE EVENING OR VERY EARLY IN THE OVERNIGHT
PERIOD. MVFR CLOUDS WILL LINGER INTO THE OVERNIGHT HOURS BEFORE
SKIES SHOULD CLEAR.

WIND GUSTS WILL REMAIN UP INTO THE 30 KNOT RANGE INTO 02-04Z. WIND
GUSTS WILL DIMINISH A LITTLE...WITH GUSTS AROUND 20-25 KNOTS
EXPECTED THROUGH THE END OF THE FCST PERIOD.

&&

.MARINE...
ISSUED AT 741 AM EDT SUN MAR 29 2015

NEARSHORE MARINE FORECASTS BETWEEN ST. JOSEPH AND MANISTEE WILL
BEGIN TOMORROW...MONDAY MARCH 30TH. THE MARINE SECTION OF THE AREA
FORECAST DISCUSSION WILL START UP THEN AS WELL.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT SAT MAR 28 2015

RIVERS REMAIN BELOW BANKFULL AND ARE HOLDING STEADY OR SLOWLY
FALLING. PRECIPITATION AMOUNTING UP TO SEVERAL TENTHS OF AN
INCH OVER THE NEXT SEVERAL DAYS IS NOT EXPECTED TO CAUSE A
SIGNIFICANT RISE IN RIVER LEVELS.

&&

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

$$

UPDATE...DUKE
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...MEADE
AVIATION...NJJ
HYDROLOGY...CAS
MARINE...99






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