FXUS63 KGRR 270452
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1145 PM EST THU NOV 26 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(330 PM EST THU NOV 26 2009)
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL EXIT THE AREA THIS EVENING.
A COLD FRONT WILL MOVE ACROSS LOWER MICHIGAN THIS THANKSGIVING
DAY...ALLOWING SOME LAKE EFFECT PRECIPITATION TO DEVELOP NEAR THE
LAKESHORE OVERNIGHT INTO EARLY FRIDAY MORNING. RAIN MIXED WITH SNOW
IS EXPECTED...ALTHOUGH LITTLE IF ANY ACCUMULATIONS ARE EXPECTED.
COLDER WEATHER IS EXPECTED TOWARDS THE END OF NEXT WORK WEEK WITH
SOME LAKE EFFECT SNOW POSSIBLE.
&&
.SHORT TERM...(950 PM EST THU NOV 26 2009)
(TONIGHT THROUGH FRIDAY AFTERNOON)
UPDATED FORECAST TO ACCOUNT FOR WIDESPREAD LAKE EFFECT RAIN/SNOW
SHOWERS THIS EVENING. LATEST SAT IMAGERY INDICATES CLOUD TOPS TEMPS
OF AROUND -17C/11.0 KFT SO SHOULD BE PRODUCING SNOW ALOFT. SO WILL
LIKELY SEE SNOW IN WITH THE HEAVIER SHOWERS OVERNIGHT. TEMPS SHOULD
STAY JUST ABOVE FREEZING MOST AREAS SO ACCUMULATIONS ARE A LOW
PROBABILITY.
PERSISTENT LAKE EFFECT ACTIVITY CURRENTLY OVER
OTTAWA...ALLEGAN...VAN BUREN...KALAMAZOO...WRN BARRY..AND WRN KENT
COUNTIES WILL CONTINUE WITH NW FLOW THROUGH LATE EVENING. LAST
SEVERAL RUNS OF HRRR RUC INDICATE AREA WILL SLOWLY DIMINISH IN
EXTENT AND INTENSITY AFTER MIDNIGHT WITH CORE OVER
OTTAWA...ALLEGAN...VAN BUREN..AND WRN KALAMAZOO AFTER MIDNIGHT.
GENERALLY EXPECT LESS THAN /0.10/ INCHES BUT COULD SEE LOCALLY
/0.25/ INCHES. IF IT SNOWS THIS WOULD BE ENOUGH TO BRIEFLY COVER
GRASSY SURFACES.
STILL EXPECT MOISTURE TO BECOME SHALLOWER WITH THE SHOWERS DRYING UP
COMPLETELY FRI MORNING AS THE UPPER LOW PULL WELL EAST OF THE STATE.
RIDGING SFC AND ALOFT EXPECTED TO DRY OUT BOUNDARY LAYER FRI
AFTERNOON BUT MAY NOT SEE SC COMPLETELY BREAK UP UNTIL SUNSET.
&&
.LONG TERM...(330 PM EST THU NOV 26 2009)
(FRIDAY NIGHT THROUGH THURSDAY)
DRY WX IS ANTICIPATED FRIDAY NIGHT THROUGH SATURDAY AS RIDGING AT
THE SFC AND THEN ALOFT BUILDS IN. A WEAK COLD FRONT WILL MOVE
THROUGH SUNDAY BRINGING THE POTENTIAL FOR A FEW LIGHT SHOWERS.
HOWEVER MOISTURE WITH THIS SYSTEM WILL BE QUITE LIMITED SO DRY
CONDITIONS WILL PREVAIL MOST OF THE DAY. A NORTHERN STREAM SHORTWAVE
MAY BRING A FEW MIXED LIGHT RAIN/LIGHT SNOW SHOWERS SUNDAY NIGHT AND
MONDAY.
A SFC HIGH PRESSURE RIDGE CENTERED OFF TO OUR SOUTH WILL PRODUCE
MAINLY DRY WX FOR TUESDAY INTO WEDNESDAY. MOST OF OUR LATEST MEDIUM
RANGE GUIDANCE CONTINUES TO ADVERTISE POTENTIAL FOR A MUCH COLDER
AIRMASS TO ADVECT IN LATE NEXT WEEK. THIS COULD ALSO RESULT IN
POTENTIAL FOR LAKE EFFECT SNOW SHOWERS BY NEXT THURSDAY/FRIDAY.
&&
.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...(330 PM EST THU NOV 26 2009)
NO CHANGES TO THE CURRENT SCA HEADLINES. WINDS ARE NOT AS STRONG AS
PREVIOUSLY FORECAST...BUT STILL EXPECT SCA WIND AND WAVE CONDITIONS
TO REMAIN THROUGH FRIDAY AFTERNOON.
&&
.HYDROLOGY...(330 PM EST THU NOV 26 2009)
DUE TO NEGLIGIBLE PRECIPITATION AMOUNTS...NO HYDRO ISSUES ARE
ANTICIPATED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY ST. JOSEPH MANISTEE THROUGH FRIDAY
AFTERNOON.
&&
$$
SYNOPSIS: TJT
SHORT TERM: COBB
LONG TERM: LAURENS
AVIATION: COBB
MARINE: TJT
HYDROLOGY: TJT
