000
FXUS63 KGRR 090826
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
327 AM EST MON DEC 9 2013

.SYNOPSIS...
ISSUED AT 327 AM EST MON DEC 9 2013

TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE WEEK WITH SEVERAL
ROUNDS OF LAKE EFFECT SNOW SHOWERS. TEMPERATURES WILL STAY BELOW
FREEZING THROUGH THE WEEK AND LAKE EFFECT SNOW SHOWERS WILL BE MOST
PREVALENT TODAY THROUGH THURSDAY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY AFTERNOON)
ISSUED AT 327 AM EST MON DEC 9 2013

THE ENTIRE SHORT TERM FORECAST PERIOD WILL BE CHARACTERIZED BY BELOW
NORMAL TEMPERATURES AND SEVERAL ROUNDS OF LAKE EFFECT SNOW SHOWERS.
THE ACCUMULATING SYNOPTIC SNOW HAS EXITED OUR AREA. HOWEVER LAKE
EFFECT SNOW SHOWERS WILL DEVELOP LATER TODAY AS H8 TEMPS FALL FROM
-8 TO -10 C AT 12Z THIS MORNING TO AROUND -16 TO -18 C BY THIS
EVENING. DEEP LOW LEVEL MOISTURE IS NOTED AND INCREASING WEST WINDS
WILL CARRY THE SNOW SHOWERS WELL INLAND. HOWEVER ACCUMULATIONS TODAY
SHOULD BE RATHER LIGHT... ON THE ORDER OF AN INCH OR TWO WITH HIGHER
END AMOUNTS NEAR TO WEST OF US-131.

LAKE EFFECT SNOW SHOWERS WILL LINGER TONIGHT BUT MAY DECREASE A BIT
IN COVERAGE AND INTENSITY FOR A BRIEF PERIOD AS DEEPER MOISTURE
MOVES OUT. HOWEVER A FAIRLY STRONG SHORTWAVE MOVING IN FROM THE NW
WILL CAUSE SNOW TO RAMP BACK UP TUESDAY MORNING. MANY OF THE 00Z
BUFKIT TIME HEIGHT RH/OMEGA PROFILES SHOW OMEGAS ON THE ORDER OF 10
TO EVEN 15 MICROBARS/SEC TUESDAY MORNING AND INVERSION HEIGHTS
SHOULD RISE TO AT LEAST 7 TO 8 KFT. AN ADDITIONAL 1 TO 3 INCHES OF
SNOW WITH HIGHER AMOUNTS WEST OF US-131 IS EXPECTED TUESDAY.

LAKE EFFECT SNOW SHOWERS WILL CONTINUE TUESDAY NIGHT WITH ANOTHER
BURST OF HEAVIER LAKE EFFECT LIKELY FOR WEDNESDAY MORNING AND EARLY
AFTERNOON WHEN DEEPER MOISTURE MOVES IN ONCE AGAIN LONG WITH STRONG
OMEGAS ON THE ORDER OF 15 MICROBARS/SEC IN THE DGZ AS ANOTHER STRONG
SHORTWAVE MOVES THROUGH. SOME OF THE HEAVIEST SNOW WEDNESDAY MORNING
SHOULD FALL ACROSS ROUGHLY THE SOUTHERN HALF OF OUR FCST AREA WHERE
THERE ARE ALSO SUGGESTIONS IN LOW LEVEL FCST WIND FIELDS THAT
I-94/I-96 CONVERGENCE BANDS WILL SET UP.

SO... MID WINTER CONDITIONS WITH BELOW NORMAL TEMPS AND SEVERAL
ROUNDS OF ACCUMULATING SNOW ARE ANTICIPATED THROUGH THE SHORT TERM
FORECAST PERIOD.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 327 AM EST MON DEC 9 2013

LAKE EFFECT SHOULD PERSIST WITH RELATIVELY DECENT INTENSITY ON
WEDNESDAY NIGHT EVEN THOUGH THE DEEPER MOISTURE IS PROGGED TO BAIL
OUT BEHIND A DEPARTING SHORTWAVE. THANKS TO THE COLD AIR MASS... THE
DGZ REMAINS SQUARELY IN THE CLOUD LAYER BETWEEN ROUGHLY 1K AND 5K
FEET WEDNESDAY NIGHT WITH ABOUT A 290 DEGREE FLOW PATTERN. THIS
FAVORS AREAS WEST AND SOUTH OF GRR SUCH AS MKG/BIV/LWA/AZO WHERE
ADDITIONAL FLUFFY ACCUMULATIONS ARE LIKELY.

THURSDAY AND THURSDAY NIGHT ARE INTERESTING BECAUSE ANOTHER SLUG OF
DEEPER MOISTURE IS PROGGED TO ARRIVE FROM THE NORTHWEST. THIS LOOKS
RELATED TO MID LEVEL ISENTROPIC LIFT OCCURRING ALONG A TIGHT NW TO
SE ORIENTED BAROCLINIC ZONE WHICH WILL EXTEND FROM NORTH DAKOTA TO
LWR MI. AT THE SAME TIME THE LOW LEVELS WILL PROBABLY STILL BE COLD
ENOUGH TO SUPPORT LAKE EFFECT. WE COULD BE LOOKING AT ONE OF THOSE
COMBINATION WARM ADVECTION/WEST SOUTHWEST FLOW LAKE ENHANCED EVENTS
IMPACTING THE WRN AND NRN CWFA.

IT SEEMS LIKE EVERY PERIOD IN THE LONG TERM WILL OFFER A CHANCE OF
SNOW. ON FRIDAY THERE IS A 140KT UPR LVL JET CORE ZIPPING ALONG THE
U.S./CANADIAN BORDER WHICH COULD BRING A QUICK ENTRANCE REGION EVENT
COUPLED WITH FGEN FORCING TO THE CENTRAL AND NRN CWFA. THEN FOR NEXT
WEEKEND IT LOOKS LIKE A SRN STREAM SYSTEM PASSING BY TO OUR SOUTH
COULD BRING SOME LIGHT SNOW SATURDAY... WHICH IS FOLLOWED BY A
POTENT CLIPPER SYSTEM DROPPING DOWN IN THE NW FLOW ON SUNDAY. THE
ECMWF IS MORE AGGRESSIVE THAN THE GFS WITH THIS FEATURE AND IS
BRINGING DOWN MORE -20C TYPE AIR AT H8 BEHIND IT NEXT SUNDAY NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1151 PM EST SUN DEC 8 2013

I EXPANDED THE MENTION OF FZDZ IN THE TAFS. KGRR AND KMKG ARE NOW
INCLUDED MAINLY FOR A PERIOD AFTER 08Z. THE DEEPER CLOUDS AND
ASSOCIATED SNOW ARE MOVING OUT OF SW LOWER MI AT THIS TIME.
UPSTREAM IN ILLINOIS THERE WAS SOME FZDZ...WHICH SHOULD MOVE INTO
THE TAFS SITES LEADING TO SOME IMPACT. CONDITIONS WILL TREND
TOWARD MVFR...BUT STILL SOME IFR AROUND THROUGH DAYBREAK.

WINDS SHIFT TO THE WEST ON MONDAY AND THAT WILL HELP TO CREATE
LAKE EFFECT SNOW SHOWERS. MVFR WEATHER TO PREVAIL.

&&

.MARINE...
ISSUED AT 327 AM EST MON DEC 9 2013

HAVE DECIDED TO HOIST A GALE WATCH FROM MID MORNING TUESDAY THROUGH
LATE TUESDAY EVENING. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE ENTIRE NEARSHORE TODAY THROUGH EARLY TUESDAY MORNING. WINDS WILL
RAMP UP TO AROUND 30 KNOTS TODAY INTO TONIGHT. WINDS MAY APPROACH
GALE FORCE BUT WILL MOST LIKELY STAY JUST BELOW TODAY. GALE FORCE
WINDS ARE POSSIBLE BY MIDDAY TUESDAY.

&&

.HYDROLOGY...
ISSUED AT 327 AM EST MON DEC 9 2013

THE COMBINATION OF COLD AIR TEMPERATURES...SLIGHTLY ABOVE FREEZING
WATER TEMPERATURES AND FALLING SNOW WILL RESULT IN POTENTIAL FOR ICE
JAMS ACROSS THE AREA THROUGH THE WEEK.  BELOW NORMAL TEMPERATURES
ARE ANTICIPATED THROUGH AT LEAST THE NEXT WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR LMZ844>849.
     GALE WATCH 9 AM TUESDAY THROUGH 10 PM TUESDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...MEADE
AVIATION...MJS
HYDROLOGY...LAURENS
MARINE...LAURENS