FXUS63 KGRR 270846
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
345 AM EST FRI NOV 27 2009
LATEST UPDATE...ALL BUT AVIATION...
.SYNOPSIS...(345 AM EST FRI NOV 27 2009)
SNOW SHOWES WILL DIMINISH THIS MORNING LEAVING MOSTLY CLOUDY SKIES
TODAY. SATURDAY LOOKS SOMEWHAT SUNNY BUT RAIN WILL MOVE BACK INTO
THE REGION SUNDAY AS ANOTHER COLD FRONT APPROACHES.
&&
.SHORT TERM...(345 AM EST FRI NOV 27 2009)
(TODAY THROUGH SUNDAY)
FORECAST CONCERNS DEAL WITH PCPN TRENDS. LATEST RADAR LOOP SHOWS
LAKE EFFECT SNOW SHOWERS CONTINUING TO MOVE SOUTHEAST WHILE THE
WHOLE BAND SINKS SOUTH. MODELS SHOW COLD AIR ADVECTION CONTINUING
THROUGH THE FIRST HALF OF THE MORNING BEFORE WARMER AIR BEINGS TO
PUSH IN FROM THE WEST. H8 TEMPS WILL FALL TO AROUND -9C THIS MORNING
WHICH WILL GENERATE MORE THAN ENOUGH INSTABILITY TO CONTINUE WITH
SOME SHSN. HOWEVER...BUFKIT RH PROFILES ALSO SHOW INCREASING DRY AIR
ALOFT WHICH WILL LIMIT THE PCPN. TODAY SHOULD BE PRETTY CLOUDY GIVEN
THE INSTABILITY OVER THE LAKE. HOWEVER AS WARMER AIR ARRIVES THIS
AFTERNOON WE SHOULD ALSO SEE SOME BREAKS IN THE CLOUDS DEVELOP.
SATURDAY LOOKS LIKE A DRY DAY AND THE BRIGHTEST DAY OF THE WEEKEND.
SHORT WAVE RIDGING WILL MOVE OVER THE GREAT LAKES. TEMPS WILL WARM
ABOVE AVERAGE TOO CLIMBING INTO THE MID 40S.
A COLD FRONT WILL MOVE THROUGH SUNDAY. LIGHT RAIN IS
POSSIBLE...ESPECIALLY DURING THE AFTERNOON AS H8 TEMPS FALL TO -6C
BY LATE IN THE DAY. MODERATE TO STRONG DPVA ASSOCIATED WITH THE
UPPER SHORT WAVE WILL WORK WITH THE OVER-LAKE INSTABILITY TO
GENERATE SHOWERS. BOUNDARY LAYER TEMPS MIGHT NOT BE QUITE COLD
ENOUGH BY LATE AFTERNOON TO MIX WITH SNOW...SO WE KEPT IT ALL RAIN
FOR NOW.
&&
.LONG TERM...(345 AM EST FRI NOV 27 2009)
(SUNDAY NIGHT THROUGH THURSDAY NIGHT)
MID LEVEL TROUGH TRACKS THROUGH THE GREAT LAKES REGION SUNDAY NIGHT
THROUGH MONDAY. THIS WILL KEEP THE WEATHER UNSETTLED. THE LATEST
ECMWF SHOWS ANOTHER WAVE DIGGING DOWN THE BACKSIDE OF THE TROUGH SO
WILL MAINTAIN THE RISK FOR PRECIPITATION INTO TUE. MOISTURE WITH
THESE SYSTEMS WILL BE MINIMAL...THUS ONLY CHANCE POPS WILL BE IN THE
FORECAST.
FOR WED INTO THU...IT IS STILL UNCLEAR HOW THE FORECAST WILL
EVOLVE. THE ECMWF IS CONSIDERABLY WARMER THAN THE GFS FOR WED.
HOWEVER BY FRI A RATHER DEEP UPPER LOW WILL BE OVERHEAD...AND THAT
WOULD SUPPORT SOME SNOW. I SOMEWHAT FAVOR THE ECMWF SCENARIO AS THE
GFS HAS NOT SHOWN GOOD CONTINUITY FROM THE PREVIOUS RUN. WILL KEEP
THE RISK FOR SOME PRECIPITATION GOING FOR WED NIGHT INTO THU NIGHT.
&&
.AVIATION...(1145 PM EST THU NOV 26 2009)
PRIMARILY MVFR CONDITIONS TO CONTINUE OVERNIGHT FOR CIGS AND ISOLD
VSBYS FOR MIXED RA/SN SHOWERS. LAKE EFFECT SHOWER ACTIVITY HAS BEEN
MORE WIDESPREAD AND DEEPER THAN EXPECTED EARLIER WITH CLOUD TOPS OF
12 KFT. HOWEVER...THE OVERALL TREND REMAINS THE SAME...THE COVERAGE
OF SHOWERS WILL DECREASE CONSIDERABLY AFTER MIDNIGHT AS THE UPPER
LOW RESPONSIBLE MOVES EAST OF THE STATE.
ONCE DRIER AIR MOVES IN ALOFT...STILL EXPECT A SHALLOW LAKE INDUCED
BKN/OVC LAYER WITH BASES IN THE 020-030KFT RANGE AND TOPS TO 050KFT
WILL PERSIST THROUGH MIDDAY FRI. THIS WILL SET UP A GOOD POTENTIAL
FOR LT TO MDT ICING WITH IN-CLOUD TEMPS IN THE LOWER 20S.
THE OUTLOOK FOR FRIDAY NIGHT INTO SATURDAY IS FOR VFR CONDITIONS.
THERE IS A LOW POTENTIAL FOR ISOLD IFR CONDITIONS EARLY SATURDAY
ASSOCIATED MORNING FOG AND LOW CLOUDS.
&&
.MARINE...(345 AM EST FRI NOV 27 2009)
WAVES WILL REMAIN AOA 4 FEET TODAY DUE TO GUSTY WINDS. WINDS AND
WAVES SHOULD DIMINISH BY THIS AFTERNOON.
&&
.HYDROLOGY...(345 AM EST FRI NOV 27 2009)
NO HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY ST. JOSEPH MANISTEE THROUGH FRIDAY
AFTERNOON.
&&
$$
SYNOPSIS: 93
SHORT TERM: 93
LONG TERM: MJS
AVIATION: COBB
MARINE: 93
HYDROLOGY: 93
