Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 311521
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1121 AM EDT TUE MAR 31 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 312 AM EDT TUE MAR 31 2015

A MIX OF RAIN AND SNOW WILL EXIT SOUTHWEST LOWER MICHIGAN BY 8 AM
THIS MORNING. SLICK TRAVEL CONDITIONS ARE POSSIBLE THIS MORNING
MAINLY NORTH OF I-96. QUIET WEATHER FOLLOWS FOR THIS AFTERNOON
THROUGH WEDNESDAY. HIGHS AROUND 50 TODAY WILL WARM INTO THE MID
50S TO LOWER 60S ON WEDNESDAY.

A COLD FRONT WILL BRING RAIN AND A CHANCE FOR THUNDERSTORMS LATE
WEDNESDAY NIGHT INTO THURSDAY. DRY WEATHER FOLLOWS ON FRIDAY...BUT
SNOW OR A MIX COULD CLIP SOUTHERN LOWER MICHIGAN FRIDAY NIGHT.
AFTER A WARM THURSDAY...MUCH COOLER AIR MOVES IN FOR FRIDAY AND
SATURDAY WITH HIGHS IN THE 40S.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 312 AM EDT TUE MAR 31 2015

LATEST REGIONAL RADAR TRENDS AND A CONSENSUS OF SHORT TERM GUIDANCE
SUGGEST ONGOING PRECIP WILL BE EAST OF THE CWA BY 8 AM. THE MAIN
IMPACT WITH THIS CLIPPER SYSTEM IS THE TRANSITION OF RAIN TO SNOW
ACROSS CENTRAL LOWER MICHIGAN. SURFACE TEMPS HAVE DROPPED INTO THE
MID 30S ACROSS CENTRAL LOWER AS OF 2:15 AM. ASOS INDICATES LIGHT
SNOW IN BIG RAPIDS AND ALMA. WITH MODERATE FGEN FORCING...MAIN
CONCERN IS A PERIOD OF MODERATE SNOW THROUGH 6 AM CENTERED ON A
BALDWIN TO MT. PLEASANT AXIS. A FEW INCHES OF ACCUMULATION IS NOT
OUT OF THE QUESTION...AND SLICK AND SLUSHY TRAVEL CONDITIONS ALONG
WITH REDUCED VISIBILITIES ARE POSSIBLE FOR THE TUESDAY MORNING
COMMUTE IN THESE AREAS.

CLOUDS WILL SCATTER OUT LATER THIS MORNING AND MOST AREAS SHOULD SEE
SOME SUN IN THE AFTERNOON AND EVENING. HIGHS WILL BE IN THE UPPER
40S TO LOWER 50S INLAND...WITH MID 40S ALONG THE IMMEDIATE
LAKESHORE. QUIET WEATHER IS EXPECTED TONIGHT AND WEDNESDAY. A WEAK
SHORTWAVE DOES TRACK TO OUR NORTHEAST TONIGHT...WITH SOME CLOUDS THE
ONLY RESULT.

RIDGING BUILDS IN ON WEDNESDAY AND LOW LEVEL FLOW TURNS SOUTHERLY BY
THE EVENING. EXPECT A BEAUTIFUL DAY WITH HIGHS IN THE MID 50S TO
LOWER 60S. LATE WEDNESDAY EVENING INTO WEDNESDAY NIGHT...A 50-55 KT
LOW LEVEL JET WILL DEVELOP AHEAD OF A FAIRLY STRONG COLD FRONT.
SIGNIFICANT TIMING DIFFERENCES REMAIN BETWEEN THE ECMWF AND
GFS...BUT A COLD FRONT WILL MOVE THROUGH LOWER MI ON THURSDAY.
925-850 MB MOISTURE TRANSPORT RAMPS UP CONSIDERABLY WEDNESDAY
NIGHT...WITH PWATS SLIGHTLY OVER 1 INCH ON THURSDAY. SURFACE
DEWPOINTS MAY BE ABLE TO GET UP INTO THE MID 50S BY THURSDAY
AFTERNOON.

WITH MLCAPE VALUES AROUND 100-300 J/KG AND 0-6 KM BULK SHEAR VALUES
AROUND 40-50 KTS...THIS APPEARS TO BE THE FIRST SUBSTANTIAL RISK FOR
THUNDER THIS SPRING. THUNDERSTORM RISK ALONG WITH GUSTY WINDS AND
HEAVY RAINFALL POTENTIAL WILL NEED TO CONTINUE TO BE MONITORED AS WE
MOVE CLOSER TO THIS EVENT.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 312 AM EDT TUE MAR 31 2015

SFC LOW IS MOVING AWAY THURSDAY EVENING AND THE TRAILING COLD FRONT
SHOULD BE CLEARING THE SOUTHERN FORECAST AREA BY MIDNIGHT. WILL GO
WITH SLIGHT CHANCE POPS ACROSS THE SOUTHEAST FOR THURSDAY NIGHT.

DECIDED TO GO WITH A DRY FORECAST ON FRIDAY AS THE FRONT REMAINS
WELL TO THE SOUTH...BUT WE WILL HAVE TO WATCH HOW THINGS PLAY OUT
FRIDAY NIGHT. THE FRONT REMAINS STALLED OVER THE OHIO VALLEY AND
SOUTHERN PLAINS CYCLOGENESIS WILL MOVE NORTHEAST ALONG IT. THE
PRECIP SHIELD COULD CLIP LOWER MICHIGAN WITH EITHER SNOW OR A MIX.

ONCE THAT GOES BY...A COLDER AIR ARRIVES ON SATURDAY ALONG
WITH A WEAK SHORTWAVE TROUGH THAT MAY BRING SOME SNOW SHOWERS. THIS
IS FOLLOWED BY ANOTHER PLAINS LOW MOVING EAST TOWARDS THE LAKES AND
BRINGING RAIN BY MONDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 740 AM EDT TUE MAR 31 2015

AREAS OF IFR WITH PATCHY LIFR WILL CONTINUE THROUGH AROUND 15Z
THEN CONDITIONS SHOULD BEGIN TO IMPROVE...BECOMING VFR BY THIS
AFTERNOON. WINDS WILL BE EAST THIS MORNING AROUND 10 KNOTS THEN
GOING NORTHEAST AND NORTH LATER THIS EVENING.


&&

.MARINE...
ISSUED AT 312 AM EDT TUE MAR 31 2015

NORTHEAST WINDS AROUND 10-15 KNOTS WILL BACK WESTERLY LATE IN THE
DAY. WAVES AROUND 1 FOOT EXPECTED TODAY. FAIRLY LIGHT WINDS WILL
KEEP WAVES AROUND 1 FOOT OR LESS TONIGHT THROUGH WEDNESDAY.
SOUTHERLY WINDS WILL RAMP UP CONSIDERABLY BEGINNING WEDNESDAY
EVENING. WAVES ARE EXPECTED TO BUILD TO 3 TO 6 FEET WEDNESDAY
NIGHT.


&&

.HYDROLOGY...
ISSUED AT 1120 AM EDT TUE MAR 31 2015

RIVERS CONTINUE TO REMAIN WELL BELOW ADVISORY LEVELS WITH ONLY SMALL
AND MOMENTARY RESPONSES NOTED FROM RECENT PRECIPITATION. NORTHERN
SECTIONS OF THE FORECAST AREA WILL SEE SLOWER RESPONSES DUE TO
SNOW MELT WITH LAST NIGHTS SNOWFALL.

WE WILL SEE A RATHER ACTIVE PATTERN SET UP THROUGH THE NEXT 7
DAYS. MUCH OF THIS COMES IN TWO WAVES...ONE THURSDAY THEN THE
SECOND VERY LATE IN THE WEEKEND AND INTO THE NEXT WORK WEEK. GENERAL
AMOUNTS ON TOTAL PRECIPITATION THROUGH THE PERIOD ARE AROUND ONE
INCH OR SO. THIS IS FAIRLY EVENLY DIVIDED BETWEEN THE TWO WAVES
WHICH SHOULD BE FAVORABLE FOR RESPONSE TIMES. NO FLOODING IS
EXPECTED AT THIS TIME. HOWEVER...THE HEAVIER RAIN THAT IS
ANTICIPATED TO OUR SOUTH THROUGH THE OHIO VALLEY SHOULD BE WATCHED
IN THE EVENT THAT ANY ADJUSTMENTS ARE NEEDED IN PRECIPITATION
AMOUNTS.

&&

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

$$

SYNOPSIS...EBW
SHORT TERM...EBW
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...JAM
MARINE...EBW





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