000
FXUS63 KGRR 141918
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
318 PM EDT FRI JUN 14 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 239 PM EDT FRI JUN 14 2013

HIGH PRESSURE WILL DRIFT EASTWARD THROUGH LOWER MICHIGAN TONIGHT
KEEPING THE WEATHER DRY. AN AREA OF LOW PRESSURE WILL APPROACH
FROM THE WEST SATURDAY. THIS SYSTEM WILL BRING WITH IT SOME
UNSETTLED WEATHER THAT WILL PERSIST INTO SUNDAY MORNING.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 239 PM EDT FRI JUN 14 2013

THE MAIN CHALLENGE IN THE FORECAST DEALS WITH THE POTENTIAL FOR
RAIN OVER THE WEEKEND. OVERALL WILL KEEP THE POTENTIAL FOR RAIN
CLOSE TO WHAT WE HAD PREVIOUSLY FORECASTED.

ELEVATED INSTABILITY WORKS ITS WAY INTO SOUTHWEST LOWER MI DURING
THE DAY ON SATURDAY. THE LOW LEVEL JET ACCOMPANYING THE ARRIVAL OF
THE INSTABILITY DOES WEAKEN...BUT IT IS SHOWN TO ARRIVE IN MI
SATURDAY AFTERNOON. IN ADDITION...THE MODELS SHOW MOISTURE AND
LIFT IN THE DGZ AT THIS TIME. AS A RESULT WILL KEEP THE MENTION OF
PRECIPITATION IN THE FORECAST...MAINLY FOR THE AFTERNOON. SOME
CONCERN THAT THE PRECIPITATION COULD ARRIVE IN THE MORNING EXISTS.

I DID BUMP UP POPS SLIGHTLY FOR MOST LOCATIONS SATURDAY NIGHT.
MOST MODELS SHOW A MOIST DGZ ALONG WITH LIFT DURING THE NIGHT. THE
NAM DOES LIMIT THIS POTENTIAL SOMEWHAT ACROSS NORTHERN COUNTIES.
STILL WITH THE COLD FRONT PRESSING IN AND ELEVATED INSTABILITY
AROUND WE SHOULD SEE SEVERAL HOURS OF SHOWERS WITH A RISK FOR
THUNDERSTORMS.

ON SUNDAY THE SURFACE FRONT PUSHES THROUGH IN THE MORNING. SO WILL
HOLD ONTO THE PRECIPITATION POTENTIAL THEN. PERHAPS A SECONDARY
COLD FRONT ARRIVES SUNDAY AFTERNOON. AT THIS TIME IT LOOKS TOO
WEAK TO LEAD TO ANY ADDITIONAL SHOWERS SO WILL KEEP THE AFTERNOON
DRY FOR NOW.





.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 239 PM EDT FRI JUN 14 2013

A SHORT WAVE CONTINUES TO BE PROGGED TO PASS THROUGH THE REGION
MONDAY NIGHT.  SEEMS LIKE A FAIRLY WEAK SYSTEM...BUT CERTAINLY
ENOUGH LIFT TO INCLUDE CHC POPS MONDAY INTO MONDAY NIGHT.  BEST CHCS
OF RAIN SHOULD OCCUR ACROSS THE INTERIOR NORTHERN CWA.  KEPT POPS IN
FOR TUESDAY FOR THE CHC OF A FEW DIURNAL AFTERNOON SHOWERS AS
REMNANT MOISTURE IS INDICATED.  IT APPEARS MAINLY QUIET FROM TUESDAY
NIGHT THROUGH FRIDAY AS A LARGE AREA OF HIGH PRESSURE SETTLES IN.

TEMPS SHOULD COOL AFTER MONDAY/S SHORT WAVE AND STAY COOLISH THROUGH
MID WEEK.  WE SHOULD WARM THURSDAY AND FRIDAY AS RETURN FLOW SETS UP
ON THE BACK SIDE OF THE HIGH PRESSURE CENTER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 137 PM EDT FRI JUN 14 2013

VFR CONDITIONS WITH PLENTIFUL SUNSHINE AND DRY AIR EXPECTED FOR
THE REST OF THE DAY. LIGHT WINDS CONTINUE INTO THE EVENING AND
OVERNIGHT. THUNDERSTORMS OVER IOWA OVERNIGHT ARE EXPECTED TO BRING
DEBRIS CLOUDS INTO SOUTHWEST LOWER MICHIGAN SATURDAY MORNING.
CEILING HEIGHTS ARE EXPECTED TO REMAIN ABOVE 4K FT. WARM FRONT
LIFTS NORTH INTO LOWER MI AND SOUTHERLY WINDS INCREASE IN SPEED AT
THE TAIL END OF THE TAF PERIOD.

SOME UNCERTAINTY AS TO WHETHER THUNDERSTORMS WILL BE IMPACTING THE
WESTERN TAF SITES CLOSER TO 18Z SATURDAY...BUT KEPT THE
SIGNIFICANT WEATHER OFF TO THE WEST FOR NOW. CHANCES FOR SHOWERS
AND THUNDERSTORMS WILL INCREASE BEYOND 18Z SATURDAY INTO THE
OVERNIGHT PERIOD.


&&

.MARINE...
ISSUED AT 239 PM EDT FRI JUN 14 2013

WINDS WILL REMAIN WEAK THROUGH THE NIGHT AND INTO SATURDAY
MORNING. AS A RESULT THE WAVES WILL REMAIN LOW. THE PASSAGE OF A
COLD FRONT SATURDAY NIGHT WILL RESULT IN WINDS AND WAVES
INCREASING...BUT AT THIS TIME THE PRESSURE GRADIENT IS FORECASTED
TO REMAIN TO WEAK TO SUPPORT SMALL CRAFT ADVISORY CONDITIONS.

&&

.HYDROLOGY...
ISSUED AT 239 PM EDT FRI JUN 14 2013

CRESTS CONTINUE TO WORK THEIR WAY DOWNSTREAM ON THE AREA RIVERS
AS A RESULT OF THE EARLIER HEAVY RAIN THIS WEEK. RAIN WILL RETURN
TO THE REGION LATER SATURDAY INTO SATURDAY NIGHT. LOCALLY HEAVY
AMOUNTS EXPECTED. AT THIS TIME IT APPEARS THAT NOT ENOUGH BASIN
AVERAGE RAIN WILL FALL TO CAUSE FLOODING. WILL NEED TO MONITOR TRENDS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...JK
AVIATION...JK/EBW
HYDROLOGY...MJS
MARINE...MJS