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000
FXUS63 KGRR 030840
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
341 AM EST TUE DEC 3 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 341 AM EST TUE DEC 3 2013

A WARM FRONT MOVING THROUGH LOWER MICHIGAN WILL BRING LIGHT SNOW
POSSIBLY MIXED WITH SLEET AND FREEZING RAIN THIS MORNING. WE DON/T
EXPECT MUCH IF ANY ACCUMULATION. HOWEVER A FEW ROADS COULD BECOME
SLICK. THE PCPN WILL BECOME LIGHT RAIN THIS AFTERNOON AS WARMER AIR
MOVES INTO THE REGION.

A STRONG COLD FRONT WILL MOVE THROUGH WEDNESDAY NIGHT BRINGING AN
ABRUPT END TO THE 50 DEGREE TEMPERATURES EXPECTED WEDNESDAY. SNOW
SHOWERS AND HIGHS IN THE 20S ARE EXPECTED FRIDAY THROUGH THE
WEEKEND.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 341 AM EST TUE DEC 3 2013

FORECAST CONCERNS DEAL WITH MIXED PCPN MAINLY THIS MORNING.

LATEST RADAR SHOWS A BAND OF PCPN STRETCHING FROM OCEANA COUNTY
SOUTHEAST TOWARD NW OHIO MOVING NEWD THROUGH THE CWA. MOST OF THIS
IS LIGHT SHOW BUT LOCAL OBS HAVE SHOWN SOME SLEET TOO. THIS WAS
CORROBORATED BY DUAL POL. LATEST HRRR AND FCST SOUNDINGS SUGGEST
SOME
LIGHT FREEZING RAIN IS POSSIBLE TOO THIS MORNING BEFORE TEMPS WARM
UP ENOUGH TO RESULT IN LIGHT RAIN. PCPN IS FAIRLY LIGHT AND ANY
ACCUMS SHOULD REMAIN LESS THAN AN INCH. THAT SAID...A FEW ROADS MAY
BECOME SLICK.

A WARM FRONT WILL CONTINUE TO PUSH NORTH THROUGH THE CWA TONIGHT. H8
TEMPS RISING TO 7C SHOULD RESULT IN SFC TEMPS IN THE 50S TOMORROW.
MODELS CONTINUE TO BE AT ODDS ON COLD FRONTAL TIMING. WE/LL BE
CONSISTENT THOUGH IN FOLLOWING THE SLOWER ECMWF DUE TO THE OCCLUDING
NATURE OF THE SYSTEM. THAT MEANS A FROPA WEDNESDAY NIGHT. HIGHS
THURSDAY WILL BE IN THE MID 30S. LIGHT SNOW SHOWERS POSSIBLE
THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 AM EST TUE DEC 3 2013

TWO MAIN HEADLINES OF THE LONG TERM REMAIN THE COLD AND LAKE EFFECT
SNOW SHOWERS. THE COLD MAY BE THE BIGGER STORY AS THE LAKE EFFECT
LOOKS TO BE SOMEWHAT MOISTURE DEPLETED.

COLD AIR ADVECTION WILL BE IN FULL SWING THURSDAY NIGHT AS WE BEGIN
THE LONG TERM WITH THE LOW MOVING AWAY ACROSS ONTARIO. DELTA T/S
WILL BE IN THE MIDDLE TEENS...PROVIDING DECENT INSTABILITY. MOISTURE
LOOKS LIMITED SO NOT EXPECTING ANYTHING IN THE WAY OF SIGNIFICANT
LAKE EFFECT. MINOR ACCUMULATIONS AT BEST.

THAT REALLY REMAINS THE CASE FOR FRIDAY THROUGH SATURDAY. CONTINUED
COLD AIR ADVECTION WILL PUSH DELTA T/S INTO THE LOWER 20S C...BUT
MOISTURE REMAINS A LIMITING FACTOR. WE NEVER DEEPLY PLUNGE INTO
CYCLONIC FLOW TO THE NORTH SIDE OF THE UPPER JET AXIS...INSTEAD
REMAINING IN A BROAD SOUTHWEST TO WEST FLOW. 1000-700MB RH VALUES
FROM FRIDAY THROUGH SATURDAY REMAIN IN THE 40-60 PCT RANGE WHICH IS
NOT IDEAL. 20-40 PCT CHANCES FOR SNOW SHOWERS THURSDAY NIGHT THROUGH
SATURDAY SEEM WARRANTED. AT THIS POINT NOT EXPECTING ANY BIG
ACCUMULATIONS...JUST PERSISTENT LIGHT SNOW SHOWERS.

LOW PRESSURE IS FORECAST BY THE ECMWF (STILL THE MODEL OF CHOICE
TONIGHT) TO SWING NORTH THROUGH THE AREA SUNDAY NIGHT INTO MONDAY
WHICH BRINGS A GENERAL LIGHT SYNOPTIC SNOW TO THE AREA.

LOWS IN THE TEENS THROUGH THE PERIOD WITH HIGHS IN THE 20S WILL BE
COMMON. THIS IS COLDER THAN NORMAL...BUT BY NO MEANS RARE FOR EARLY
DECEMBER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1058 PM EST MON DEC 2 2013

THE MAIN AVIATION ISSUE TONIGHT IS WITH THE LIGHT MIXTURE OF
SNOW... FREEZING RAIN.. AND SLEET WHICH IS EXPECTED FROM ROUGHLY
08Z TO 14Z. THIS WILL IMPACT THE MORNING RUSH WITH THE LIKELIHOOD
FOR ICING AS WELL AS SLIPPERY RUNWAY CONDITIONS. THE ICING THREAT
IS EXPECTED TO END BY 15Z AS SFC TEMPS WARM ABOVE FREEZING AND THE
PRECIPITATION CHANGES TO ALL LIGHT RAIN.

WIDESPREAD VFR CONDITIONS AT 04Z WILL LOWER FAIRLY QUICKLY INTO
THE MVFR/IFR CATEGORY 06Z-09Z AS THE LIGHT WINTRY MIX DEVELOPS AND
SPREADS EAST/NORTHEAST. PRECIPITATION WILL CHANGE TO ALL RAIN BY
MID MORNING TUESDAY ALTHOUGH WIDESPREAD IFR CONDITIONS ARE EXPECTED
FOR TUESDAY AFTERNOON AND EVENING DUE TO PERSISTENT LOW CIGS/VSBYS
IN LINGERING LIGHT RAIN/FOG.


&&

.MARINE...
ISSUED AT 341 AM EST TUE DEC 3 2013

SOUTH TO SOUTHEAST WINDS WILL INCREASE TO 15 TO 25 KNOTS TODAY. THE
OFFSHORE NATURE OF THE WINDS SHOULD PRECLUDE WAVES FROM GETTING
HIGHER THAN 3 FEET.

&&

.HYDROLOGY...
ISSUED AT 341 AM EST TUE DEC 3 2013

NO HYDRO ISSUES TODAY. HOWEVER THE ARCTIC AIR EXPECTED BY THE END OF
THE WEEK COULD CAUSE ICE TO DEVELOP ON STREAMS AND RIVERS.

&&

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

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...DUKE
AVIATION...MEADE
HYDROLOGY...93
MARINE...93