Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 251618
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1218 PM EDT WED MAR 25 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 330 AM EDT WED MAR 25 2015

AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE AREA TODAY. THIS LOW
WILL BRING RAIN AND FREEZING RAIN TO THE AREA THIS MORNING ALONG
WITH SOME WARMER TEMPERATURES. THE PRECIPITATION WILL THEN TAPER OFF
THIS AFTERNOON AS THE LOW PASSES NE OF THE AREA. A WAVE OF LOW
PRESSURE WILL SKIRT BY SE OF THE AREA LATE TONIGHT INTO THE DAY ON
THU. THIS COULD BRING SOME ADDITIONAL LIGHT RAIN OR SNOW TO THE FAR
SOUTHERN COUNTIES.

COLDER AIR WILL FILTER IN DURING THE DAY ON THU AND EVEN MORE SO FOR
FRI. THIS WILL LEAD TO A CHANCE OF A FEW LIGHT SNOW SHOWERS. THE
COLD AIR WILL REMAIN IN PLACE THROUGH SATURDAY. A SURGE OF SOMEWHAT
WARMER AIR WILL THEN COME IN ON SUNDAY AHEAD OF THE NEXT SYSTEM
EXPECTED TO MOVE THROUGH.

&&

.UPDATE...
ISSUED AT 920 AM EDT WED MAR 25 2015

OVERALL OUR FORECAST IS WORKING OUT NICELY. THE FREEZING RAIN
CONTINUES (AS OF 9 AM) IN OUR NORTHERN ROW OF COUNTIES...MOSTLY
EAST OF US-131 (BASED ON SURFACE TEMPERATURES). THE RAIN SHOULD BE
ENDING FROM WEST TO EAST BETWEEN 10 AM AND 11 AM. MORE THAN LIKELY
I WILL END THE ADVISORY JUST AFTER 10 AM...ASSUMING TEMPERATURES
HAVE RISEN ABOVE FREEZING BY THEN. IT SHOULD BE A DRY AFTERNOON
ACROSS ALL OF THE CWA.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED MAR 25 2015

WE WILL BE LEAVING THE WINTER WEATHER ADVISORY FOR THE FREEZING RAIN
AS IS THIS MORNING FOR THE NRN HALF OF THE CWFA. CONDITIONS REMAIN
ON TRACK FOR SOME FREEZING RAIN INITIALLY THIS MORNING...ESPECIALLY
THE FURTHER NORTH YOU GO WHERE TEMPS ARE A BIT COOLER. TEMPS ALOFT
AROUND 925 MB ARE ALREADY ABOVE FREEZING AND SHOULD PEAK OUT AROUND
4 TO 8 C BEFORE WET BULBING DOWN A BIT DUE TO THE DRY AIR IN PLACE.
SFC TEMPS RANGE FROM THE 20S UP NORTH...TO ABOVE FREEZING WELL SOUTH
AND WEST.

THE WINDOW FOR FREEZING RAIN IS SHORTER DOWN SOUTH WITH TEMPS
ALREADY NEAR FREEZING. IT IS A LITTLE LONGER UP NORTH WITH COOLER
TEMPS AND FOR IT TO TAKE A LITTLE BIT OF TIME TO MAKE IT THERE.WE
ANTICIPATE THAT ALL PCPN WILL HAVE CHANGED OVER TO PLAIN RAIN TOWARD
12Z OR JUST AFTER AS SFC TEMPS WILL JUMP UP ABOVE FREEZING. THE RAIN
WILL THEN GRADUALLY TAPER OFF FROM SOUTH TO NORTH AS THE UPPER WAVE
AND BEST MOISTURE TRANSPORT SHIFTS NORTH OF THE AREA AND THE DRY
SLOT WORKS IN.

CONDITIONS SHOULD BE RATHER BENIGN FOR MOST OF THE AREA FROM THIS
AFTERNOON THROUGH MOST OF TONIGHT. WE WILL SEE SHORT WAVE RIDGING
ALOFT BUILD IN THE WAKE OF THE WAVE THIS MORNING. WE WILL EVENTUALLY
SEE ANOTHER SHORT WAVE TROUGH DIVE SE FROM CANADA INTO THE AREA.
THIS WAVE WILL DEVELOP A WAVE ON THE SFC FRONT SOUTH OF THE AREA AND
BRING A POTENTIAL OF SOME PCPN TO THE S AND SE PORTION OF THE CWFA
VERY LATE TONIGHT AND ON THU. IF WE DO SEE PCPN OCCUR THERE...ENOUGH
COLD AIR WILL HAVE MOVED IN TO SEE AT LEAST A MIX OF RA/SN IF NOT
ALL SNOW. TEMPS WILL WARM UP ENOUGH DURING THE DAYLIGHT HOURS ON THU
TO CHANGE PCPN BACK OVER TO SOME LIGHT RAIN.

THE REST OF THE AREA WILL SEE A LOW CHC OF A FEW LIGHT SHOWERS THU
INTO EARLY FRI. THESE WILL BE THE RESULT OF A BETTER TROUGH AND THE
COLD POOL ALOFT MOVING OVERHEAD. SOME DIURNAL INSTABILITY WILL BUILD
DURING THE DAY. MOST SHOWERS DURING THIS TIME FRAME WOULD BE MAINLY
SNOW. ENOUGH WARMING AT THE SFC ON THU WOULD HELP TO MIX IN SOME
RAIN WITH THE SNOW. WE SHOULD SEE A DECREASE IN PCPN CHCS DURING THE
DAY ON FRI AS A SHORT WAVE RIDGE IS EXPECTED.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED MAR 25 2015

CHILLY WEEKEND WEATHER IS IN STORE...FOLLOWED BY A MODERATING TREND
EARLY NEXT WEEK. TEMPERATURES WILL BE A GOOD 15 DEGREES BELOW NORMAL
SATURDAY... RECOVERING TO AROUND NORMAL BY TUESDAY. NORMAL HIGHS FOR
THIS TIME OF YEAR ARE AROUND 50. THE BEST CHANCE OF PRECIPITATION IN
THE LONG TERM PERIOD IS ON SUNDAY.

COLD AND DRY SFC HIGH PRESSURE AND A DEEP UPPER TROUGH WILL BE OVER
THE REGION FOR THE FIRST HALF OF THE WEEKEND. A PACIFIC SHORTWAVE
AND ASSOCIATED SFC FRONTAL SYSTEM RACING RAPIDLY EAST ACROSS SRN
CANADA AND THE NRN U.S. WILL BRING A GOOD CHANCE OF MIXED RAIN AND
SNOW SUNDAY AND SUNDAY NIGHT.

DESPITE STRONG WARM ADVECTION AHEAD OF THE APPROACHING SYSTEM ON
SUNDAY... THE DRY AIR MASS/LOWER SFC DEW POINTS LEFT BEHIND BY THE
DEPARTING SFC HIGH IS WHY A MIXTURE SEEMS APPROPRIATE WITH THIS
SYSTEM RATHER THAN JUST RAIN.

BEHIND THE SUNDAY SYSTEM...THE UPPER LEVEL FLOW BECOMES LESS
AMPLIFIED WITH A BIT MORE ZONAL/FLATTER LOOK AND WEAK HIGH PRESSURE
AT THE SFC. THIS SHOULD RESULT IN DRY WEATHER WITH MILDER
TEMPERATURES MONDAY AND TUESDAY OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 755 AM EDT WED MAR 25 2015

CIGS/VSBYS WILL CONTINUE TO LOWER EARLY THIS MORNING... WITH
WIDESPREAD IFR/LIFR LIKELY THROUGH EARLY AFTERNOON. CONDITIONS ARE
EXPECTED TO IMPROVE TO MVFR AFTER 18Z AS RAIN/DRIZZLE ENDS
ALTHOUGH SFC WINDS WILL INCREASE OUT OF THE SOUTHWEST WITH GUSTS
TO 25 KTS THIS AFTERNOON. LOOK FOR CIGS TO GRADUALLY LIFT TO VFR
LEVELS TONIGHT ALTHOUGH SOME MVFR MAY LINGER LONGER AT LAN AND
JXN. SFC WINDS WILL DIMINISH TONIGHT TO AROUND 10 KTS.

&&

.HYDROLOGY...
ISSUED AT 1218 PM EDT WED MAR 25 2015

FALLING RIVER LEVELS HAVE FOR THE MOST PART LEVELED OFF DUE TO
THE RAIN FROM THIS MORNING. RIVER LEVELS MAY CREEP BACK UP... BUT
ARE EXPECTED TO PEAK BELOW BANK FULL. FLOODING IS A VERY LOW
PROBABILITY. ONLY A LITTLE PRECIPITATION IS FORECAST THIS WEEK...
SO RIVER LEVELS SHOULD BE LOWER NEXT WEEK.

&&

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

&&

$$

UPDATE...WDM
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...63





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