Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 301930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
329 PM EDT THU APR 30 2015

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

.SYNOPSIS...
ISSUED AT 329 PM EDT THU APR 30 2015

HIGH PRESSURE WILL BRING FAIR WEATHER THE REMAINDER OF THE WEEK AND
INTO MUCH OF THE WEEKEND. TEMPERATURES WILL GRADUALLY MODERATE EACH
DAY...REACHING THE UPPER 60S ON FRIDAY AND THE LOWER 70S ON SATURDAY
AND SUNDAY. THE PATTERN LOOKS TO TURN WET LATE IN THE WEEKEND AND
EARLY NEXT WEEK AS A FRONTAL BOUNDARY WILL BE DRAPED ACROSS THE
REGION. SHOWERS AND STORMS ARE IN THE FORECAST FROM SUNDAY AFTERNOON
THROUGH WEDNESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 329 PM EDT THU APR 30 2015

VERY LITTLE IN THE WAY OF SHORT TERM FORECAST ISSUES WITH HIGH
PRESSURE IN CONTROL OF THE WEATHER. THERE MAY BE A STRAY SHOWER THIS
EVENING TOWARD BATTLE CREEK AND JACKSON...BUT OTHERWISE EXPECTING
DRY WEATHER FROM TONIGHT THROUGH SATURDAY NIGHT. TEMPERATURES WILL
BE SLIGHTLY ABOVE SEASONAL NORMS FOR THIS TIME OF YEAR WHICH WILL BE
A CHANGE FROM WHERE WE HAVE BEEN OF LATE. OVERALL SKIES WILL BE
MOSTLY CLEAR TO PARTLY CLOUDY THROUGH THE PERIOD.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 329 PM EDT THU APR 30 2015

ITS CONTINUING TO LOOK RATHER ACTIVE THROUGH THE LONG TERM PERIOD
WITH SHOWERS AND THUNDERSTORMS BEING THE MAIN FOCUS.

THE INITIAL ONSET OF PRECIPITATION IS LOOKING TO HOLD OFF RATHER
LATE IN THE WEEKEND. AS HAS BEEN THE CASE FOR THE LAST FEW
DAYS...THE GFS AND ECMWF HAVE THEIR DISAGREEMENTS WITH TIMING AND
PLACEMENT OF THE FRONTAL BOUNDARY THAT WILL ULTIMATELY BE
RESPONSIBLE FOR WET CONDITIONS. THE ECMWF IS QUITE PERSISTENT ON
PUSHING AN AREA OF LOW PRESSURE EAST OF THE HUDSON BAY. A WEAKER
DISTURBANCE DEVELOPS AND ROTATES AROUND THE MAIN LOW AND ATTEMPTS TO
PUSH COOLER AIR SOUTHWARD. THE GFS IS SLOWER AND FURTHER WEST WITH
THIS MAIN LOW AND KEEPS THE BOUNDARY FURTHER NORTH. THIS WOULD PLAY
A LARGE ROLE IN NOT ONLY PRECIPITATION AMOUNTS THROUGH THE AREA BUT
ALSO THE TEMPERATURE SPREAD FROM NORTH TO SOUTH. THE PERSISTENCE OF
THE ECMWF WOULD NORMALLY BE COMFORTING...BUT RECENT EVENTS HAVE
ACTUALLY BEEN WON OUT BY THE GFS. THEREFORE...THE CONFIDENCE ON THE
FRONTAL BOUNDARY PLACEMENT IS STILL RATHER LOW.

WHILE THE ECMWF IS LESS AMPLIFIED WITH THE UPPER LEVEL RIDGE...THE
GFS HAS A TROUGH OVER THE WEST...WHICH WOULD EXPLAIN THE REASONING
FOR THE NORTHWARD EXTEND OF THE FRONTAL BOUNDARY AND MORE AMPLIFIED
PATTERN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 139 PM EDT THU APR 30 2015

THE PATTERN HAS SHIFTED IN MORE OF AN OPTIMISTIC DIRECTION. VFR
CONDITIONS ARE EXPECTED THROUGH A LARGE PORTION OF THE AREA. THERE
IS SOME QUESTION TO THE EXTENT AND DURATION OF CLOUD COVER AT OUR
SOUTHEASTERN SITES. A BROKEN DECK IS EXPECTED TO ROTATE THROUGH
THESE LOCATIONS THROUGH EARLY EVENING...BUT THE MOISTURE FOR THIS
DECK IS THIN AND EVACUATES RATHER QUICKLY THROUGH LATE EVENING.

WINDS WERE ANOTHER AREA I TRENDED DOWN ON AS IT SEEMS WE ARE
UNDER-PERFORMING FROM PREVIOUS THOUGHTS. BY LATE EVENING
CONDITIONS SHOULD CONTINUE TO IMPROVE AS WINDS DIE DOWN AND ANY
CLOUD COVER AROUND KLAN AND KJXN ERODES.

&&

.MARINE...
ISSUED AT 329 PM EDT THU APR 30 2015

MAINTAINED THE SMALL CRAFT ADVISORY WITH THIS FORECAST PACKAGE...BUT
IT LOOKS LIKE IT IS SOMEWHAT MARGINAL UP NORTH TOWARDS BIG AND
LITTLE SABLE POINTS. THAT SAID...BIG SABLE OB IS SHOWING GUSTS OF
21-24 KNOTS THE LAST FEW HOURS. THE HRRR CONTINUES TO SHOW A CORE OF
WIND WORKING DOWN THE SHORE THIS AFTERNOON AND EVENING WITH GUSTS TO
AROUND 25 KNOTS. WAVES SHOULD COME UP INTO THE 3-5 FOOT RANGE FOR A
FEW HOURS AS THE WIND SHIFTS SOUTH. EXPECTING PORT SHELDON TO COME
UP OVER THE NEXT 1-3 HOURS.

WINDS AND WAVES SHOULD BE FAIRLY TAME AFTER THIS EVENING AS HIGH
PRESSURE BUILDS IN THE NEXT COUPLE DAYS.

&&

.HYDROLOGY...
ISSUED AT 139 PM EDT THU APR 30 2015

RIVERS ARE RUNNING NEAR TO BELOW NORMAL. NO ISSUES ARE EXPECTED
THROUGH THE WEEKEND. WE ARE MONITORING THE POTENTIAL FOR OVER AN
INCH OF RAINFALL DURING THE FIRST HALF OF NEXT WEEK. CONFIDENCE IS
CURRENTLY NOT HIGH ON WHERE THE AXIS OF HEAVIEST RAIN WILL BE. WITH
THE GREEN-UP UNDERWAY... PLANTS AND SOIL ARE ABLE TO ABSORB A
GREATER AMOUNT OF RAIN THAN EARLIER IN THE SPRING. THIS WILL BUFFER
RIVER RESPONSE TO SOME EXTENT.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR LMZ847>849.

     SMALL CRAFT ADVISORY UNTIL 3 AM EDT FRIDAY FOR LMZ844>846.

&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...JAM
AVIATION...JAM
HYDROLOGY...CAS
MARINE...DUKE









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