FXUS63 KGRR 100758
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
358 AM EDT SUN MAY 10 2009
LATEST UPDATE...ALL SECTIONS EXCEPT AVIATION...
.SYNOPSIS...(358 AM EDT SUN MAY 10 2009)
A WEAK WAVE OF LOW PRESSURE WILL MOVE ACROSS LOWER MICHIGAN THIS 
AFTERNOON AND BRING A CHANCE OF A FEW SPRINKLES TO THE AREA. HIGH 
PRESSURE WILL THEN BUILD IN BEGINNING TONIGHT. CLEARING SKIES...
LIGHT WINDS...AND A COOL AIR MASS IN PLACE WILL ALLOW FROST TO 
DEVELOP ACROSS THE AREA WITH FREEZING TEMPERATURES LIKELY NORTH OF 
I-96. 
HIGH PRESSURE WILL REMAIN IN PLACE THROUGH TUESDAY...AND BRING DRY 
WEATHER AND SLIGHTLY BELOW NORMAL TEMPERATURES TO THE AREA. THE NEXT 
CHANCE OF SHOWERS AND STORMS WILL COME IN BEGINNING LATE TUESDAY 
NIGHT AND CONTINUE INTO WEDNESDAY NIGHT AS A SYSTEM MOVES THROUGH.
&&
.SHORT TERM...(358 AM EDT SUN MAY 10 2009)
(TODAY THROUGH TUESDAY)
PESKY SPRINKLES THAT HAVE BEEN AFFECTING PORTIONS OF THE AREA LAST 
EVENING AND VERY EARLY THIS MORNING HAVE MOVED OUT OF THE AREA. 
SHORT WAVE LIKELY RESPONSIBLE IS NOW OVER LAKE HURON AND MOVING 
EAST. UPPER JET IS EXPECTED TO REMAIN JUST SOUTH OF THE CWFA THROUGH 
THE DAY TODAY AND INTO THE DAY ON MON. THIS WILL OCCUR AS SHORT 
WAVES EMBEDDED IN THE FLOW WILL BE MOVING THROUGH THE AREA.
NEXT SHORT WAVE IN THE SERIES IS NOW ACROSS MN AND WRN WI. THIS 
SHORT WAVE IS EXPECTED TO MOVE INTO THE AREA AFTER 18Z THIS 
AFTERNOON AND EXIT BY 00Z TONIGHT. EVEN THOUGH THE SHORT WAVE IS 
NOTEWORTHY...ATMOSPHERE IT WILL BE ACTING ON IS NOT CONDUCIVE FOR 
MUCH PCPN. MID LEVEL LAPSE RATES ARE ABOVE 6 C/KM AND THE WAVE WILL 
BE COMING IN DURING PEAK HEATING. HOWEVER DEW POINTS WILL BE 
DROPPING TODAY. WE WILL BE IN THE ENTRANCE REGION OF THE UPPER JET 
AND GENERAL RIDGING BUILDING IN AT THE SFC...HELPING TO KEEP A LID 
ON ANY CONVECTIVE ACTIVITY. FCST SOUNDINGS SHOW A CAP AROUND 7-8K 
FEET...SO CLOUDS WILL NOT HAVE MUCH CONVECTIVE DEPTH. WE FELT THAT 
SPRINKLES ARE THE BEST WAY TO GO ATTM.
SKIES ARE EXPECTED TO CLEAR OUT RATHER QUICKLY THIS EVENING AS THE 
SHORT WAVE MOVES EAST OF THE AREA...AND DIURNAL INSTABILITY IS LOST. 
HIGH PRESSURE IS EXPECTED TO MOVE ALMOST DIRECTLY OVER THE AREA BY 
12Z MON. LOOKS LIKE ALMOST AN IDEAL SET UP FOR FROST AND FREEZE 
ACROSS THE AREA. AREAS NORTH OF INTERSTATE 96 LOOK PRIMED FOR A 
SOLID FREEZE...WHILE FROST LOOKS LIKELY ELSEWHERE.
THE REMAINDER OF THE PERIOD THROUGH TUE THEN LOOKS RATHER QUIET AND 
UNEVENTFUL. A WEAKER SHORT WAVE IS EXPECTED TO MOVE TOWARD THE AREA 
ON MON AFTERNOON. LESS LOW LEVEL MOISTURE AND HIGH PRESSURE IN PLACE 
AT THE SFC SHOULD KEEP CONDITIONS DRY. MON NIGHT LOOKS LIKE ANOTHER 
COLD NIGHT WITH SOME FROST/FREEZE HEADLINES POSSIBLE...ESPECIALLY UP 
NORTH. RETURN FLOW SETTING UP VERY LATE AND SLIGHTLY WARMER TEMPS ON 
MON SHOULD KEEP TEMPS A COUPLE OF DEGREES WARMER MON NIGHT. MILDER 
WEATHER IS EXPECTED ON TUE WITH WAA BEGINNING ON SRLY FLOW. 
 
&&
.LONG TERM...(358 AM EDT SUN MAY 10 2009)
(TUESDAY NIGHT THROUGH SATURDAY)
ONLY MADE MINOR TWEAKS TO THE EXTENDED FORECAST. SHADED BACK POPS 
LATE TUESDAY NIGHT AS MODEL CONSENSUS IS FOR THE LEADING EDGE OF THE 
SHOWERS TO ARRIVE AFTER 12Z WEDNESDAY. BUMPED POPS UP FOR WEDNESDAY 
NIGHT AS THE COLD FRONT PUSHES THROUGH. ALSO DECIDED TO GO WITH A 
DRY FORECAST FOR SATURDAY WITH A SLOWER ARRIVAL OF DEEP MOISTURE AS 
SEEN IN THE GFS RH CROSS SECTION. ONLY ONE CHANGE TO TEMPS...TWEAKED 
MAXES DOWN A BIT FOR THURSDAY WITH COLD ADVECTION PATTERN SEEN 
FOLLOWING THE FROPA.
&&
.AVIATION...(740 PM EDT SAT MAY 9 2009)
UPSTREAM SURFACE AND SATELLITE OBSERVATIONS SUGGEST THAT MVFR CIGS 
CAN BE EXPECTED AT MOST SITES THROUGH 06Z...WHICH IS SLIGHTLY MORE 
PESSIMISTIC THAN THE PREVIOUS SET OF TAFS. AN AREA OF LIGHT RAIN 
CROSSING LAKE MI AT 23Z SHOULD CONTINUE TO SHRINK...RESULTING IN 
NEGLIGIBLE IMPACTS TO THE LOCAL TERMINALS. MODEL GUIDANCE AND 
OBSERVATIONS SUGGESTS THAT LOWER CIGS WILL BE MORE LIKELY AT THE 
KAZO...KBTL...AND POSSIBLY KJXN TERMINALS COMPARED TO SITES FARTHER 
N...GIVEN THE LOCATION OF THE NW TO SE FETCH OF MOISTURE INDICATED 
ON VISIBLE SATELLITE.  STILL AGREE THAT VFR CONDITIONS SHOULD BE 
SEEN AREAWIDE AFTER 10Z.
  
&&
.MARINE...(358 AM EDT SUN MAY 10 2009)
NO SIGNIFICANT WINDS OR WAVES EXPECTED THROUGH THE DAY ON TUESDAY. 
HIGH PRESSURE SETTLING IN WILL BRING WINDS AT OR BELOW 15 KNOTS AND 
WAVES BELOW 3 FEET. AS THE NEXT MAJOR SYSTEM APPROACHES TUESDAY 
NIGHT...WINDS WILL INCREASE AS THE WINDS IN THE LOWEST 2K FEET 
INCREASE TO AS HIGH AS 35 KNOTS. THIS IS NOT EXPECTED TO BE REALIZED 
AT THE SURFACE WITH THE COLD LAKE WATERS AND WARM AIR MOVING IN. 
&&
.HYDROLOGY...(358 AM EDT SUN MAY 10 2009)
THE RAIN THAT OCCURRED ACROSS THE AREA FRIDAY NIGHT AND SATURDAY 
MORNING HAS CAUSED RIVER LEVELS TO STABILIZE FROM THEIR FALLS OVER 
THE PAST WEEK OR SO. A FEW LOCATIONS SAW A LITTLE BUMP AS A RESULT 
OF THE RAINFALL...HOWEVER NO MAJOR RISES ARE EXPECTED. NEXT CHANCE 
OF RAINFALL THAT WOULD AFFECT THE RIVERS AND STREAMS WILL COME 
MAINLY ON WEDNESDAY AND WEDNESDAY NIGHT. 
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FREEZE WARNING FOR THE NORTHERN HALF OF THE CWFA EXCEPT 
MUSKEGON COUNTY FROM 06Z MON TO 12Z MON. FROST ADVISORY FOR THE 
REMAINDER OF THE CWFA 06Z MON TO 12Z MON. 
LM...NONE.
&&
$$
SYNOPSIS:     NJJ
SHORT TERM:   NJJ
LONG TERM:    OSTUNO
AVIATION:     TJT
MARINE:       NJJ
HYDROLOGY:    NJJ