Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 152024
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
324 PM EST MON DEC 15 2014

LATEST UPDATE...
SHORT TERM/LONG TERM

.SYNOPSIS...
ISSUED AT 215 PM EST MON DEC 15 2014

A STORM SYSTEM CURRENTLY CENTERED OVER WESTERN MISSOURI WILL TRACK
THROUGH MICHIGAN TONIGHT INTO TUESDAY. THIS WILL BRING RAIN TO THE
AREA BY LATE EVENING. RAIN SHOWERS WILL PREVAIL MOST OF THE DAY
TIME HOURS OF TUESDAY. THEN THE COLD FRONT... THAT TRAILS THE
SYSTEM... CROSS THE AREA LATE TUESDAY EVENING. THAT WILL CHANGE
THE RAIN SHOWERS TO SNOW SHOWERS BY MIDNIGHT. THE SNOW SHOWERS
WILL CONTINUE INTO EARLY THURSDAY MORNING. SOME MINOR
ACCUMULATIONS ARE EXPECTED NEAR AND WEST OF US-131 WEDNESDAY AND
WEDNESDAY NIGHT. IT WILL TURN COLDER THEN WITH HIGHS NEAR 30 ON
WEDNESDAY.

HIGH PRESSURE WILL THEN MOVE OVER THE AREA BY THURSDAY AND THAT
WILL REMAIN IN CONTROL OF THE WEATHER OVER SOUTHWEST MICHIGAN
THROUGH THE WEEKEND. TEMPERATURES WILL BE NEAR NORMAL TROUGH
THURSDAY THROUGH SUNDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 324 PM EST MON DEC 15 2014

THE WARM WEATHER IS ABOUT TO COME TO AN ABRUPT END TUESDAY
AFTERNOON. PRIOR TO THAT HOWEVER WE GET ABOUT 24 MORE HOURS OF
TEMPERATURES IN THE 40S. THERE WILL BE A PERIOD OF SHOWERS FROM
MID EVENING THROUGH MOST OF THE DAY TUESDAY. BEHIND THE COLD FRONT
RAIN SHOWERS CHANGE TO SNOW SHOWERS AND I WOULD EXPECT LAKE
ENHANCED SNOW SHOWERS TO CONTINUE INTO EARLY THURSDAY.

OUR OCCLUDED SURFACE LOW AND ASSOCIATED CLOSED CIRCULATION UPPER LOW...
CONTINUES TO TRACK NORTHEAST FROM NORTHERN MISSOURI THIS AFTERNOON
TOWARD LOWER MICHIGAN LATE TONIGHT. IS EXPECTED TO CROSS THE
CHICAGO AREA AROUND MIDNIGHT. FROM THERE IT WILL TRACK EAST ACROSS
SOUTHERN LOWER MICHIGAN. THE SYSTEM STILL LOOKS RATHER IMPRESSIVE
ON THE IR AND WATER VAPOR LOOPS. NORMALLY THIS SYSTEM WOULD HAVE
TRACKS WEST OF THE GREAT LAKES BUT A DIGGING NORTHERN STREAM
SYSTEM IS BLOCKING THAT. IN FACT THAT NORTHERN STREAM SYSTEM
MERGES WITH SOUTHERN STREAM SYSTEM BY WEDNESDAY. THIS RESULTS IN A
SLOW MOVING MUCH LARGER CLOSED OFF UPPER LOW OVER THE CENTRAL GREAT
LAKES. THE CONTINUITY IN THE MODELS FOR THIS SYSTEM HAS BEEN VERY
GOOD FOR DAYS NOW SO LITTLE QUESTION THE SYSTEM WILL DO AS WE
EXPECT IT TO IN TERMS OF THE TRACK AND UPPER LEVEL SYSTEM EVOLUTION.

SINCE THE SYSTEM WILL BE TRANSITIONING TONIGHT AS THE NORTHERN
STREAM SYSTEM COMES INTO PLAY... THAT CUTS OFF THE DEEP MID LEVEL
INFLOW TO THE SYSTEM KEEP THE HIGHER PRECIPITABLE WATER VALUES AND
THE BETTER 1000 TO 850 MB MOISTURE TRANSPORT. ALL OF THAT IN TURN
CUTS BACK ON THE EXPECTED QPF FROM THE SYSTEM OVERNIGHT. EVEN SO
IT WILL RAIN ACROSS THE AREA TONIGHT... MOST LOCATIONS SEEING
BETWEEN A TENTH AND THIRD OF AN INCH OVERNIGHT.

TUESDAY WE ARE IN THE WRAP AROUND MOISTURE FROM THE SYSTEM WITH
DEEP MOISTURE STILL IN PLACE SO SHOWERS WILL CONTINUE. THE COLD
ARRIVES BEHIND THE SECONDARY COLD FRONT THAT MOVES THROUGH THE AREA
LATE IN THE AFTERNOON. THAT WILL CHANGE THE RAIN TO SNOW BETWEEN
SUNSET AND MIDNIGHT.

WITH THE UPPER LOW MOVING DIRECTLY OVER SOUTHWEST LOWER MICHIGAN
WE WILL HAVE THE DEEP COLD AIR IN PLACE AND WHILE THE MOIST LAYER
IS NOT ALL THAT DEEP WEDNESDAY... THE DGZ DOES GET INTO THE TOP OF
THE CLOUD LAYER SO I EXPECT SNOW SHOWERS TO PREVAIL ALL DAY
WEDNESDAY MIDNIGHT THROUGH MIDNIGHT. THE SHALLOW NATURE OF THE
MOISTURE WILL LIMIT AMOUNTS BUT IT WILL SNOW NONE THE LESS. AIR
TEMPERATURES WILL FALL BELOW FREEZING AND STAY THAT WAY AT THE
SURFACE SO IT WILL BE COLD ENOUGH FOR SNOW TOO.

BOTTOM LINE... SHOWERS TONIGHT AND TUESDAY THEN SNOW SHOWERS
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT.



.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 324 PM EST MON DEC 15 2014

TRANQUIL WEATHER WITH SEASONABLE TEMPERATURES IS ANTICIPATED
THROUGH THE LONG RANGE FORECAST PERIOD AS A HIGH PRESSURE RIDGE
TAKES HOLD OF THE WEATHER PATTERN. A FEW LIGHT LAKE EFFECT SNOW
SHOWERS AND FLURRIES MAY LINGER INTO THURSDAY MORNING BEFORE  THE
HIGH BUILDS IN.

A LOW PRESSURE SYSTEM TRACKING NE FROM THE GULF COAST REGION
SATURDAY SHOULD STAY WELL TO THE SE OF OUR REGION. 12Z GFS GUIDANCE
HAS TRENDED FURTHER SOUTH AND NOW ALSO KEEPS ALL PCPN SOUTH OF OUR
AREA IN LINE WITH A CONSENSUS OF MOST MEDIUM RANGE GUIDANCE THE PAST
SEVERAL DAYS. THE 12Z ECMWF IS ALSO FURTHER SOUTH AND SHOWS PCPN
WOULD STAY WELL SE OF OUR AREA SATURDAY

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1130 AM EST MON DEC 15 2014

MIXED LIFR/IFR/MVFR CIGS LATE THIS MORNING WILL GRADUALLY TRANSITION
TO PRIMARILY MVFR THIS AFTERNOON. HOWEVER WIDESPREAD IFR/LIFR
CONDITIONS WILL RETURN THIS EVENING AND OVERNIGHT DUE TO LOW CIGS
AND PATCHY FOG AND AS RAIN DEVELOPS FROM SW TO NE AT ALL THE
TERMINALS THIS EVENING AND CONTINUES OVERNIGHT AND TUESDAY MORNING.
IFR/LIFR CONDITIONS WILL PERSIST THROUGH 18Z TUESDAY DUE TO LOW
CIGS/VISBYS.

SOUTHEAST TO SOUTH WINDS AROUND 10 KTS THIS AFTERNOON WILL BECOME SE
TONIGHT BEFORE GRADUALLY VEERING TO THE SW TO WEST LATE TUESDAY
MORNING AND EARLY AFTERNOON.


&&

.MARINE...
ISSUED AT 215 PM EST MON DEC 15 2014

WE WILL LIKELY NEED A SMALL CRAFT ADVISORY FOR TUESDAY AFTERNOON
THROUGH WEDNESDAY AS THE COLD AIR COMES BACK IN INCREASING WINDS
TO AS HIGH AS 30 KNOTS. THERE MAY EVEN BE A BRIEF PERIOD OF GALES
ON THE LEADING EDGE OF THE COLD AIR. AFTER COORDINATING WITH NEAR
BY OFFICES WE DECIDED TO HOLD OFF ON ISSUING HEADLINES FOR THIS
EVENT JUST YET.


&&

.HYDROLOGY...
ISSUED AT 215 PM EST MON DEC 15 2014

NO HYDRO IMPACTS ARE EXPECTED OVER THE NEXT WEEK. LIGHT RAIN WILL
MOVE IN FROM THE SOUTHWEST THIS EVENING AND SPREAD NORTHEAST
OVERNIGHT AND CONTINUE INTO TUESDAY. AROUND A QUARTER INCH OR LESS
OF RAINFALL IS EXPECTED...WHICH WON`T HAVE A SIGNIFICANT IMPACT ON
RIVER LEVELS. STREAMFLOW ON ALL RIVERS IN SOUTHWEST LOWER MICHIGAN
IS CURRENTLY NORMAL FOR THIS TIME OF YEAR.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...EBW
MARINE...WDM






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