FXUS63 KGRR 050112
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
812 PM EST FRI DEC 4 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(258 PM EST FRI DEC 4 2009)
SNOW SHOWERS WILL SLOWLY TAPER OFF THIS EVENING BUT AN INCH OR TWO
OF SNOW IS POSSIBLE FROM LUDINGTON TO SOUTH HAVEN AND INLAND TO
GRAND RAPIDS AND KALAMAZOO. WINTER LOOKS LIKE IT IS HERE TO STAY AS
A CLIPPER STORM COULD BRING SOME LIGHT SNOW ON MONDAY.
THEN OUR ATTENTION TURNS TO THE POSSIBLE BIG STORM COMING FOR LATE
TUESDAY INTO WEDNESDAY...WHICH COULD BRING HIGH WINDS AND LOTS OF
SNOW OR MIXED PRECIPITATION.
&&
.SHORT TERM...(258 PM EST FRI DEC 4 2009)
(TONIGHT THROUGH SUNDAY NIGHT)
WILL LET THE HEADLINES EXPIRE AT 4 PM AS ROAD CONDITIONS HAVE
IMPROVED THIS AFTERNOON AS SNOW HAS SLOWLY TAPERED OFF. EXPECT
ANOTHER INCH OR TWO TONIGHT AND SATURDAY AS LES SHOWERS CONTINUE BUT
INVERSION HEIGHTS ARE AOB 5 KFT SO ACCUMS WILL BE LIMITED.
AFTER A QUICK BREAK WITH SFC RIDGING SUNDAY...A WEAK CLIPPER ARRIVES
FOR LATE SUNDAY NIGHT WITH LIGHT SNOW SPREADING OVER LOWER MICHIGAN
IN AREA OF WEAK ISENTROPIC ASCENT. MAIN ACCUMS SHOULD OCCUR ON
MONDAY.
&&
.LONG TERM...(258 PM EST FRI DEC 4 2009)
(MONDAY THROUGH FRIDAY)
12Z MEDIUM RANGE GUIDANCE CONTINUES TO SHOW POTENTIAL FOR A COUPLE
OF LOW PRESSURE SYSTEMS TO IMPACT OUR AREA MONDAY AND THEN FROM
TUESDAY NIGHT THROUGH THURSDAY. LONG RANGE FCST TWEAKS INCLUDED
LOWERING THE MAX TEMP FCST BY SEVERAL DEGREES LATE NEXT WEEK BASED
ON GUIDANCE TRENDS.
THE WEAKER OF THE TWO SYSTEMS WILL MOVE THROUGH MONDAY BRINGING
POTENTIAL FOR SOME SYNOPTIC SNOW FOLLOWED BY LAKE EFFECT SNOW
SHOWERS. THIS SHOULD NOT BE A STRONG SYSTEM BUT COULD NEVERTHELESS
PRODUCE A FEW INCHES OF SNOW.
THERE IS POTENTIAL FOR A ROBUST LOW PRESSURE SYSTEM TO IMPACT OUR
AREA TOWARD THE MIDDLE OF NEXT WEEK. 12Z ECMWF GUIDANCE TAKES THE
SFC LOW FROM THE SOUTHERN PLAINS AT 12Z TUE NE THROUGH OHIO ON
WEDNESDAY. 12Z GFS GUIDANCE INTENSIFIES THE LOW FASTER AND BRINGS IT
FURTHER NORTH (984 MB NEAR DTW BY WEDNESDAY AFTERNOON). NEARLY ALL
OF OUR OTHER MEDIUM RANGE GUIDANCE ALSO HINTS AT POTENTIAL FOR A
SIGNIFICANT MIDWEEK SYSTEM... BUT THERE ARE LARGE DISCREPANCIES THAT
REGARDING STRENGTH AND TRACK AS WE WOULD EXPECT THAT FAR OUT IN
TIME.
THIS SYSTEM WILL HAVE POTENTIAL TO PRODUCE STRONG TO SEVERE STORMS
OUT AHEAD OF THE COLD FRONT IN THE WARM SECTOR AND HEAVY SNOW NORTH
AND NORTHWEST OF THE LOW TRACK. THERE IS ALSO POTENTIAL FOR VERY
WINDY CONDITIONS AND SNOW SHOWERS ON THE BACK SIDE OF THE SYSTEM
LATE WEDNESDAY INTO THURSDAY. SO WE WILL NEED TO MONITOR MEDIUM
RANGE GUIDANCE TRENDS REGARDING THIS SYSTEM CLOSELY.
&&
.AVIATION...(812 PM EST FRI DEC 4 2009)
VFR CONDITIONS PERSIST AT ALL THE TAF SITES AT 800 PM. QUESTIONS
REVOLVE AROUND MVFR CEILINGS UPSTREAM OF THE TAF SITES THOUGH AND
HOW WILL THE CURRENT LAKE EFFECT MORPH THE NEXT 24 HOURS. FEEL THAT
THE LAKE EFFECT WILL PERK UP OVERNIGHT...TAKING
CONDITIONS...PROBABLY BOTH CEILING AND VISIBILITY BACK INTO THE MVFR
RANGE AT KMKG AND KGRR IN SOUTHWEST FLOW OFF THE LAKE. KAZO...KLAN
AND KBTL WILL TO TO REMAIN VFR THE NEXT 24 HOURS. KJXN IS DOWNSTREAM
OF A PATCH OF MVFR CEILINGS THAT ARE DRIFTING NORTHEAST OUT OF
NORTHERN INDIANA. SO...BROUGHT THESE CEILINGS INTO KJXN RIGHT OFF
THE START THINKING THEY WILL PRESS IN SHORTLY. LAKE EFFECT SHOULD
TONE DOWN ON SATURDAY AFTER ABOUT 15Z...WITH ALL SITES TRENDING TO
VFR.
&&
.MARINE...(258 PM EST FRI DEC 4 2009)
SCA CONTINUES THROUGH FRIDAY NIGHT THEN THINGS WILL TEMPORARILY CALM
DOWN.
&&
.HYDROLOGY...(258 PM EST FRI DEC 4 2009)
NO HYDROLOGY ISSUES EXPECTED THROUGH THE WEEKEND. ALL PRECIPITATION
THROUGH THE WEEKEND WILL BE SNOW...AND VERY LITTLE...IF ANY RUNOFF
IS EXPECTED WITH HIGHS EXPECTED ONLY TO BE AROUND OR SLIGHTLY ABOVE
FREEZING. THE STORM NEXT WEEKEND MAY BE RAIN OR SNOW...IT IS STILL
TOO EARLY TO TELL HOW MUCH IF ANY RUNOFF WILL OCCUR.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY ST. JOSEPH TO MANISTEE THROUGH TONIGHT.
&&
$$
SYNOPSIS: OSTUNO
SHORT TERM: OSTUNO
LONG TERM: LAURENS
AVIATION: DUKE
MARINE: OSTUNO
HYDROLOGY: OSTUNO
