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000
FXUS63 KGRR 092200
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
458 PM EST TUE FEB 9 2010

LATEST UPDATE...ALL EXCEPT AVIATION...

.SYNOPSIS...(458 PM EST TUE FEB 9 2010)
LOW PRESSURE WILL PIVOT ACROSS WESTERN LAKE ERIE TONIGHT AND MOVE
OFF THE EAST COAST OF THE UNITED STATES BY WEDNESDAY MIDDAY. THE LOW
WILL AID IN CONTINUING THE SNOW ACROSS LOWER MICHIGAN THROUGH
TONIGHT. AS THE LOW CLOSES IN ON THE SOUTHERN GREAT LAKES THIS
EVENING A BURST OF HEAVIER SNOW WILL OCCUR FROM THE LATE AFTERNOON
HOURS THROUGH THE EVENING. THE SNOW WILL LIGHTEN UP OVERNIGHT AND
TAPER OFF CONSIDERABLY TOWARD DAYBREAK ON WEDNESDAY. NORTHERLY WINDS
WILL INCREASE INTO THE 15 TO 30 MPH RANGE LATE TONIGHT AND WEDNESDAY
THOUGH CREATING AREAS OF BLOWING AND DRIFTING SNOW WHICH WILL
PERSIST THROUGH THE DAY ON WEDNESDAY. HIGH PRESSURE SLIDING THROUGH
THE GREAT LAKES REGION WILL PROVIDE QUIET...DRY WEATHER FOR THURSDAY
AND FRIDAY WITH TEMPERATURES IN THE 20S FOR HIGHS.

&&

.SHORT TERM...(458 PM EST TUE FEB 9 2010)
(TONIGHT THROUGH WEDNESDAY NIGHT)
STORM SYSTEM EVOLVING ABOUT AS EXPECTED THIS AFTERNOON WITH PERIODS
OF LIGHT TO OCCASIONALLY MODERATE SNOW HAVING OCCURRED THROUGH THE
DAY. SNOWFALL TOTALS RANGE FROM 1-3 INCHES SO FAR ACROSS THE CENTRAL
LOWER MICHIGAN TO 2-4 INCHES THROUGH THE INTERSTATE 96 CORRIDOR AND
3-5 INCHES DOWN ALONG INTERSTATE 94.

A MORE PERSISTENT MODERATE TO OCCASIONALLY HEAVY SNOW WILL NOW OCCUR
THROUGH ABOUT 1000PM. THE SNOW HAS PICKED UP IN INTENSITY ALREADY
THIS AFTERNOON AND THIS SHOULD CONTINUE FOR THE NEXT 4-6 HOURS.
AFTER 1000-1100 PM THE SNOW WILL BEGIN TO GRADUALLY LIGHTEN UP WITH
ACCUMULATING SNOW CONTINUING INTO THE OVERNIGHT HOURS. THE SNOW WILL
THEN TAPER OFF SIGNIFICANTLY BETWEEN 500AM-900AM.

THE FORECAST LOOKS ON TRACK FOR STORM TOTAL SNOW AMOUNTS IN THE 3 TO
6 INCHES RANGE ACROSS THE ADVISORY AREA WITH 6 TO 10 INCHES OF SNOW
FALLING IN THE WARNING AREA.

THE SNOW IS BEING AIDED BY THE PERSISTENT ISENTROPIC UPGLIDE THAT
DOES NOT SHUT DOWN UNTIL LATE TONIGHT. THE MODELS HAVE BEEN VERY
CONSISTENT WITH THIS. ALSO...THIS EVENING THE 850MB LOW SLIDES BY TO
THE SOUTH MOVING FROM FORT WAYNE TO NEAR TOLEDO...WHICH IS A VERY
FAVORABLE TRACK FOR MODERATE TO HEAVY SNOW FOR LOCATIONS FROM
INTERSTATE 96 TO THE SOUTH.

DURING THE LATE OVERNIGHT HOURS AND WEDNESDAY TIME FRAME WINDS WILL
BEGIN TO INCREASE. IN GENERAL...A NORTHERLY WIND OF 15 TO 30 MPH IS
EXPECTED DURING THIS TIME FRAME. AREAS OF BLOWING AND DRIFTING SNOW
WILL OCCUR WITH THE HIGHEST LIKELIHOOD TOWARD THE LAKE MICHIGAN
COAST.

AFTER THE SYNOPTIC SNOW PUSHES EAST EARLY WEDNESDAY WE WILL SEE LAKE
EFFECT SNOW FIRE UP...BUT WITH A NORTHERLY FLOW WE ARE NOT EXPECTING
MUCH IN OUR FORECAST AREA. A DOMINANT BAND WILL LIKELY FORM PUSHING
INTO AREAS LIKE MICHIGAN CITY INDIANA. TEMPERATURES ACTUALLY BECOME
MARGINAL FOR LES INTO WEDNESDAY NIGHT.

&&

.LONG TERM...(458 PM EST TUE FEB 9 2010)
(THURSDAY THROUGH TUESDAY)
MAIN CONCERN IN THE LONG TERM WILL BE THE NEXT SYSTEM THAT IS
EXPECTED TO DROP SOUTH OUT OF CANADA THIS WEEKEND.

N/NW FLOW WILL HANG ON THROUGH THU NIGHT ON THE FAR WRN PERIPHERY OF
THE SYSTEM NOW AFFECTING THE AREA. AIR BEHIND THIS SYSTEM IS NOT
EXPECTED TO BE ALL THAT COLD...ONLY AROUND -8C TO -10C. THIS WILL
PROVIDE ONLY A LOW CHC OF SOME LIGHT LAKE EFFECT SNOW SHOWERS FOR
THE WRN HALF OF THE CWFA INTO THU EVENING WITH DELTA T/S ONLY 9 TO
12C. RIDGING WILL MOVE IN FOR FRI AND BRING DRY WX AND THE POTENTIAL
FOR SOME SUNSHINE.

MODELS ARE ALL IN AGREEMENT IN DROPPING A FAIRLY SIGNIFICANT PIECE
OF ENERGY SOUTH OUT OF CANADA LATE ON SAT AND DURING THE DAY ON SUN.
THIS SYSTEM HAS TRENDED STRONGER AND IS NOW EXPECTED TO PASS SOUTH
AND EVENTUALLY SOUTH OF THE AREA. THIS IS NOT SURPRISING CONSIDERING
SYSTEMS OUT OF CANADA USUALLY END UP STRONGER. WE HAVE A LOW CHC OF
SNOW IN FOR THE WEEKEND AND EVEN MON AS THE WRAP AROUND MOISTURE ON
THE BACKSIDE OF THE SYSTEM COULD IMPACT THE AREA. WE THINK THAT
MOST...IF NOT ALL OF THE PCPN WITH THIS SYSTEM SHOULD MISS THE AREA.

COOLER AIR WILL REMAIN IN PLACE THROUGH THE PERIOD...ALTHOUGH THERE
COULD BE A SLIGHT MODERATING TREND TOWARD THE END OF THE PERIOD. WE
HAVE STARTED NEXT TUE OUT DRY AS RIDGING BUILDS IN BEHIND THE
WEEKEND SYSTEM.

&&

.AVIATION...(1245 PM EST TUE FEB 9 2010)
INITIAL BURST OF HEAVIER SNOW THIS MORNING HAS MOVED OUT/DIMINISHED
OVER THE PAST HOUR. WE ARE CURRENTLY IN A RELATIVE LULL IN SNOWFALL
INTENSITY. THIS IS PROVIDING IFR VSBYS WITH SOME MVFR CIGS ACROSS
THE AREA. WE EXPECT THIS TREND TO CONTINUE FOR THE NEXT 2 TO 4
HOURS.

A MORE INTENSE BAND OF SNOW IS EXPECTED TO DEVELOP TOWARD 21Z TO 00Z
TONIGHT AS THE LOW TO OUR SOUTH INTENSIFIES AND MOVES TOWARD LAKE
ERIE. LIFR TO VLIFR CONDITIONS ARE EXPECTED TO DEVELOP AT THAT TIME
AND CONTINUE INTO THE OVERNIGHT HOURS. THE HEAVIEST SNOW WILL BE THE
FURTHER SOUTHEAST YOU GO.

SNOW WILL BEGIN TO DIMINISH FROM NORTHWEST TO SOUTHEAST TOWARD
DAYBREAK WED MORNING. CONDITIONS WILL TRY AND IMPROVE...HOWEVER
LIGHT SNOW WILL CONTINUE TO FALL AND INCREASING WINDS WILL START TO
PRODUCE BLOWING AND DRIFTING SNOW. WE ARE NOT CONFIDENT HOW LOW
VSBYS WILL GO IN THE BLOWING SNOW...BUT WE HAVE ACCOUNTED FOR THIS
WITH SOME MVFR VSBYS ON WED THROUGH 18Z.

&&

.MARINE...(458 PM EST TUE FEB 9 2010)
DROPPED THE GALE WATCH EARLIER AND EXTENDED THE SMALL CRAFT ADVISORY
INTO THURSDAY MORNING. WINDS DO NOT LOOK STRONG ENOUGH IN THE LOWEST
2K FEET TO PUSH A SUSTAINED WIND OR A LONG PERIOD OF FREQUENT GUSTS
TO GALE FORCE. THE MAY BE A FEW BRIEF GUSTS TO GALE FORCE LATE
TONIGHT AND EARLY WEDNESDAY MORNING...BUT NOT PERSISTENT ENOUGH TO
REQUIRE A GALE. SMALL CRAFT ADVISORIES SHOULD COVER THINGS WITH
WAVES BUILDING INTO THE 5 TO 10 FOOT RANGE IN THE NEARSHORE WATERS
ON WEDNESDAY.

&&

.HYDROLOGY...(458 PM EST TUE FEB 9 2010)
ALL AREA RIVERS ARE WITHIN BANK. ICE ON RIVERS CONTINUES TO
INCREASE SOME. RECENT OBSERVATIONS INDICATE THAT SYCAMORE CREEK AT
HOLT IS NOW COMPLETELY ICED OVER...BUT THE ICE IS SOLID AND NO ICE
JAMS EXIST. THE GRAND RIVER AT ROBINSON TOWNSHIP IS ALSO ICED
OVER...BUT THE ICE LOOKS STABLE. BELOW NORMAL TEMPS WILL PERSIST
INTO THE WEEKEND...BUT WE ARE NOT ANTICIPATING TO DEAL WITH ANY ICE
JAM PROBLEMS AT THIS POINT. NO KNOWN ICE JAMS EXIST PER RIVER
OBSERVATIONS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING ENTIRE CWA EXPECT FOR MASON...LAKE...
     OSCEOLA AND CLARE COUNTIES WHICH ARE UNDER A WINTER WEATHER
     ADVISORY. TIME FRAME OF BOTH HEADLINES IS THROUGH 18Z WED.
LM...SMALL CRAFT ADVISORY THROUGH WEDNESDAY NIGHT FROM ST. JOSEPH TO
     MANISTEE.

&&

$$

SYNOPSIS:     DUKE
SHORT TERM:   DUKE
LONG TERM:    NJJ
AVIATION:     NJJ
MARINE:       DUKE
HYDROLOGY:    DUKE