FXUS63 KGRR 281138
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
645 AM EST SAT NOV 28 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(346 AM EST SAT NOV 28 2009)
HIGH PRESSURE OVER THE AREA WILL RESULT IN QUITE A BIT OF SUNSHINE
TODAY AND MILD TEMPERATURES. A COLD FRONT WILL MOVE THROUGH LOWER
MICHIGAN LATE SUNDAY BRINGING LIGHT RAIN SHOWERS WITH IT. COLDER AIR
BEHIND THE FRONT MAY GENERATE SOME LAKE EFFECT SNOW SHOWERS LATE
SUNDAY NIGHT AND MONDAY BUT SIGNIFICANT SNOW IS NOT EXPECTED.
ANOTHER SURGE OF COLDER AIR IS EXPECTED TUESDAY NIGHT. LAKE EFFECT
SNOW SHOWERS ARE POSSIBLE FOR THE LATTER HALF OF THE WEEK.
&&
.SHORT TERM...(346 AM EST SAT NOV 28 2009)
(TODAY THROUGH MONDAY)
FORECAST CONCERNS DEAL WITH PCPN TRENDS SUNDAY AND MONDAY. WE SHOULD
SEE ABUNDANT SUNSHINE TODAY. LATEST IR LOOP SHOWS THE BACK EDGE OF
THE STRATOCU HAS JUST CLEARED THE EASTERN CWA. HOWEVER...A SMALL
AREA OF STRATOCU STILL EXISTS ALONG THE LAKE SHORE BUT THIS WILL MIX
OUT SOON. H8 TEMPS CLIMBING TO +4C WILL HELP SFC TEMPS CLIMB INTO
THE MID 40S TODAY AND SUNDAY.
A COLD FRONT WILL MOVE THROUGH SUNDAY. ALOFT...A SHARP TROUGH WILL
ALSO MOVE ACROSS LOWER MICHIGAN. MOISTURE IS LIMITED WITH THIS
SYSTEM BUT DPVA IS PRETTY STRONG SO WE/LL HAVE A CHC POP IN THE
FORECAST. THE SHRA WILL MIX WITH AND CHANGE TO SNOW OVERNIGHT AS
COLDER AIR FLOWS IN BEHIND THE FRONT. NOT LOOKING FOR MUCH. IN
FACT...GIVEN THAT OMEGA IS NEGLIGIBLE AND THE DGZ LOOKS LIKE IT WILL
NOT BE SATURATED SUNDAY NIGHT OR MONDAY...WE MIGHT SEE MORE
FZDZ/FLURRIES THAN ANYTHING. HIGH TEMPS WILL COOL OFF INTO THE 30S
BY MONDAY.
&&
.LONG TERM...(346 AM EST SAT NOV 28 2009)
(MONDAY NIGHT THROUGH FRIDAY)
THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH TIMING THE
ARRIVAL OF THE COLD AIR. DIFFERENCES ARE RATHER CONSIDERABLE AMONGST
THE MODELS IN TERMS OF WHEN THE COLD AIR WILL ARRIVE. THE GFS SHOWS
A WEAK AND FAST MOVING MID LEVEL SHORTWAVE PUSHING THROUGH THE GREAT
LAKES REGION TUE INTO TUE NIGHT. THIS WOULD DRAW THE COLD AIR IN
FOR WED. THE ECMWF IS SLOWER AND STRONGER WITH THIS WAVE AND IS
PHASING IT WITH THE SOUTHERN STREAM SYSTEM WED INTO THU. THE ECMWF
SCENARIO SUPPORTS A SURFACE LOW TRACKING UP WEST OF THE
APPALACHIANS. THIS TRACK WOULD DELAY THE ARRIVAL OF THE COLD AIR
UNTIL THU INTO FRI.
I FAVOR THE ECMWF SOLUTION GIVEN THAT IT INITIALIZED THE MID TO
UPPER LEVEL SYSTEM IN TERMS OF STRENGTH AND LOCATION...BETTER THAN
THE GFS. AS A RESULT I WILL FEATURE A RISE IN THE TEMPERATURES FOR
WED...FOLLOWED BY COLDER AIR FOR THU AND FRI.
THE ECMWF SUPPORTS A BAND OF SNOW NORTHWEST OF THIS LOW TRACK ACROSS
PARTS OF LOWER MICHIGAN LATER WED INTO WED NIGHT. THIS WILL NEED TO
BE MONITORED. FROM ALL MODELS...LOOKS LIKE A SET UP FOR LAKE EFFECT
SNOW AT SOME POINT IN THE THU TO FRI TIMEFRAME. ALL MODELS SHOW
MAINLY WESTERLY FLOW...SO THE LAKE EFFECT SNOW MAY END UP BEING
LIMITED IN COVERAGE AND INTENSITY. MOST MODELS SHOW WARM AIR
ADVECTION BY FRI NIGHT...BUT THE FIM SUPPORTS A LONGER DURATION OF
THE COLD AIR.
&&
.AVIATION...(645 AM EST FRI NOV 27 2009)
SOUTH TO SOUTHWEST AHEAD OF AN APPROACHING COLD FRONT ARE EXPECTED
TO KEEP THE WEATHER MAINLY VFR INTO THIS EVENING AT ALL TAF SITES.
ONE TIMEFRAME OF CONCERN IS LATER TONIGHT...AFT 06Z WHEN THE WINDS
BECOME LIGHTER AND THE ATMOSPHERE COOLS. THIS IS WHEN SOME FOG OR
STRATUS COULD DEVELOP...LEADING TO MVFR OR LOWER CONDITIONS. WILL
NEED TO MONITOR TRENDS THROUGH THE DAY.
&&
.MARINE...(346 AM EST SAT NOV 28 2009)
HIGH PRESSURE OVER THE AREA WILL RESULT IN LIGHT WINDS AND 1-3 FT
WAVES TODAY.
&&
.HYDROLOGY...(346 AM EST SAT NOV 28 2009)
NO HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: 93
SHORT TERM: 93
LONG TERM: MJS
AVIATION: MJS
MARINE: 93
HYDROLOGY: 93
