Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 211701
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1201 PM EST SUN DEC 21 2014

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 325 AM EST SUN DEC 21 2014

DRY WEATHER IS EXPECTED THROUGH MIDDAY MONDAY BEFORE A LOW PRESSURE
SYSTEM BRINGS A CHANCE OF RAIN SHOWERS BEGINNING MONDAY AFTERNOON.
RAIN IS LIKELY MONDAY NIGHT THROUGH TUESDAY. PRECIPITATION WILL
TAPER OFF TUESDAY NIGHT INTO WEDNESDAY.

&&

.UPDATE...
ISSUED AT 1200 PM EST SUN DEC 21 2014

GOING FORECAST LOOKS TO BE IN GOOD SHAPE THIS AFTERNOON. EXPECTING
DRY CONDITIONS AND MAINLY CLOUDY SKIES. THERE MAY BE A FEW BREAKS
IN THE CLOUD COVER THAT MOVE INTO SOUTHERN LOWER MICHIGAN...SOUTH
OF INTERSTATE 96...BUT THINKING WE WILL KEEP A FAIR AMOUNT OF
CLOUDS.

SOME VERY LIGHT RETURNS ON THE KGRR RADAR NEAR MUSKEGON WITH SLIGHTLY
HIGHER REFLECTIVITY SHOWING UP ON WISCONSIN 88D/S. NO REPORTS OF
PRECIPITATION HOWEVER WITH SITES REPORTING JUST LIGHT FOG OR
HAZE. EVEN IT THE PRECIP NEAR MUSKEGON IS REACHING THE GROUND IT
WOULD BE DRIZZLE. GIVEN TEMPERATURES SLOWLY WARMING FROM THE LOWER
30S TO THE MIDDLE 30S THIS AFTERNOON NOT EXPECTING ANY ISSUES.

THE RETURNS ON WISCONSIN RADARS ARE MOVING TOWARD WEST CENTRAL
LOWER MICHIGAN...BUT GIVEN NO REPORTS OF UPSTREAM PRECIP AND THE
HRRR SHOWING PRECIP EVAPORATING...KEPT THE FORECAST DRY.


&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 325 AM EST SUN DEC 21 2014

SKIES WILL BE MOSTLY CLOUDY TODAY THROUGH TONIGHT WITH DRY WEATHER.
THE SOUTHERLY WINDS ON THE BACK SIDE OF THE RIDGE OVER THE EASTERN
CONUS WILL HELP TO BOOST MAX TEMPS INTO THE MIDDLE 30S THIS
AFTERNOON.

LIGHT WAA SHOWERS WILL DEVELOP AS EARLY AS MONDAY AFTERNOON WELL
OUT AHEAD OF THE WEAKENING LOW PRESSURE SYSTEM IN THE PLAINS
STATES. THIS SYSTEM WILL BRING STEADIER LIGHT TO MODERATE RAIN
SHOWERS ACROSS OUR FCST AREA MONDAY NIGHT AND TUESDAY. THE STRONG
SOUTHERLY FLOW WAA TUESDAY WILL HELP TO BOOST MAX TEMPS WELL INTO
THE 40S IN SPITE OF THE RAINFALL.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN DEC 21 2014

00Z MODEL GUIDANCE CONTINUES THE TREND FOR A WEAKER STORM WITH FEWER
IMPACTS FOR LOWER MICHIGAN. IN FACT...THERE MIGHT NOT EVEN BE
SIGNIFICANT PRECIP DURING TUESDAY NIGHT AND WEDNESDAY WITH THE WAY
THINGS ARE TRENDING. BASED ON THE PAST COUPLE DAYS EVOLUTION OF THE
FORECAST...THE CURRENT THINKING IS THAT THE SFC LOW DOES NOT RAPIDLY
DEEPEN UNTIL IT IS WELL INTO CANADA.

THE 00Z GFS SHOWS THE NORTHERN AND SOUTHERN STREAMS STAYING SEPARATE
AND IT TRACKS A SFC LOW ACROSS OHIO LATE WEDNESDAY. THIS WOULD BRING
SOME F-GEN BANDS OF RAIN OR SNOW ACROSS THE EASTERN HALF OF THE
FORECAST AREA. WHILE THIS CANNOT BE DISCOUNTED...THE CONFIDENCE IN
THIS HAPPENING IS LOW UNLESS IT GETS MORE SUPPORT IN COMING DAYS.

THERE IS STILL GOOD AGREEMENT THAT THE COLD AIR WILL BE COMING IN
WEDNESDAY EVENING...SO WHATEVER PRECIP IS AROUND WILL BE GOING OVER
TO SNOW. 850MB TEMPS ARE DOWN TO ABOUT MINUS 8C BY 12Z ON THE 25TH
AND THERE SHOULD BE SOME LIGHT LAKE EFFECT SNOW SHOWERS.

WARM AIR ADVECTION IS ALREADY UNDER WAY BY THURSDAY NIGHT AND SOME
LIGHT SNOW OR MIXED PRECIP COULD FOLLOW BY FRIDAY AS A WEAK
SHORTWAVE TROUGH MOVES THROUGH. THERE IS GOOD MODEL AGREEMENT THAT
ARCTIC AIR ARRIVES ON SATURDAY FOR THE FIRST TIME THIS MONTH WITH
850 MB TEMPS PROGGED TO BE MINUS 15 TO 20C.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 647 AM EST SUN DEC 21 2014

MVFR CONDITIONS ARE EXPECTED MUCH OF TODAY WITH LIGHT FOG OR HAZE
AND CEILING HEIGHTS AROUND 2500 FEET AGL. WINDS WILL BE SOUTH TO
SOUTHEAST AOB 10 KNOTS. SOME FLURRIES OR FREEZING DRIZZLE IS
POSSIBLE AT TIMES BUT SHOULD NOT CAUSE ANY ACCUMULATION OR ICING.


&&

.MARINE...
ISSUED AT 325 AM EST SUN DEC 21 2014

A SMALL CRAFT ADVISORY WILL BE IN EFFECT FROM HOLLAND NORTH TO
MANISTEE FROM THIS AFTERNOON THROUGH TONIGHT AS SOUTHERLY WINDS
WILL CAUSE WAVE HEIGHTS TO REACH SCA CRITERIA NORTH OF HOLLAND.


&&

.HYDROLOGY...
ISSUED AT 325 AM EST SUN DEC 21 2014

NO HYDRO ISSUES ANTICIPATED WITH DRY WEATHER TODAY THROUGH MIDDAY
MONDAY. A LOW PRESSURE SYSTEM WILL BRING RAIN SHOWERS AS EARLY AS
MONDAY AFTERNOON AND MAINLY FOR MONDAY NIGHT THROUGH TUESDAY NIGHT
WITH POTENTIAL FOR RAINFALL AMOUNTS OF A QUARTER TO THREE QUARTERS
OF AN INCH TO PERHAPS AS MUCH AS AN INCH. HOWEVER THIS PROLONGED
PERIOD OF LIGHT TO MODERATE RAINFALL WILL NOT BE SIGNIFICANT ENOUGH
TO CAUSE HYDRO ISSUES.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ846>849.

&&

$$

UPDATE...DUKE
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...LAURENS
MARINE...LAURENS





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