Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181146
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
746 AM EDT SAT APR 18 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 AM EDT SAT APR 18 2015

ANOTHER SUNNY DAY IS EXPECTED TODAY WITH HIGHS AROUND 70. LOW
PRESSURE WILL MOVE NORTH FROM THE GULF AREA SUNDAY BRINGING QUITE A
BIT OF RAIN WITH IT. AFTER THE LOW MOVES EAST...COLDER AIR WILL MOVE
OVER LOWER MICHIGAN AND REMAIN IN PLACE NEXT WEEK. HIGHS WILL ONLY
REACH THE MID 40S TO MID 50S NEXT WEEK.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 328 AM EDT SAT APR 18 2015

FORECAST CONCERNS DEAL WITH THE LOW APPROACHING SUNDAY. AFTER
ANOTHER SUNNY AND MILD DAY TODAY CLOUDS WILL INCREASE TONIGHT AS A
PHASED NORTHERN/SOUTHERN STREAM LOW APPROACHES FROM THE SOUTH.
STRONG 60KT LLJ WILL DRAW UP ABUNDANT MOISTURE INTO THE SYSTEM.
STRONG ISENTROPIC LIFT LATE SUNDAY MORNING WILL LEAD TO RAPID RAIN
DEVELOPMENT FROM SOUTH TO NORTH. LOOK FOR THE WIND TO INCREASE AS
WELL...AT LEAST UNTIL THE LOW MOVES OVERHEAD SUNDAY EVENING. SHORT
RANGE MODELS HAVE BEEN CONSISTENT MOVING THE LOW DIRECTLY OVER THE
CWA SO CONFIDENCE IS PRETTY HIGH WE/LL SEE RAIN. QPF AROUND 3/4 INCH
LOOKS POSSIBLE AS MIXING RATIOS CLIMB TO 8G/KG BY LATE SUNDAY
AFTERNOON. THERE STILL ISN/T A STRONG SIGNAL FOR THUNDER SO WE KEPT
IT OUT OF THE GRIDS. HOWEVER GIVEN A SLIGHT DECREASE IN STABILITY
NOTED WE CAN/T RULE IT OUT EITHER.

MONDAY WILL BE MUCH COOLER AS THE LOW MOVES EAST AND WEST WINDS
DEVELOP. HIGHS IN THE MID 50S ARE EXPECTED. THE UPPER LOW WILL MOVE
OVER THE CWA MONDAY SO WE/LL CONTINUE TO SEE SCATTERED SHOWERS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 328 AM EDT SAT APR 18 2015

MOST OF NEXT WEEK WILL BE COLDER THAN NORMAL WITH SCATTERED RAIN OR
MIXED RAIN AND SNOW SHOWERS AS AN UPPER LOW BECOMES PARKED OVER THE
NORTHERN GREAT LAKES REGION. DEEP CYCLONIC FLOW AND COLD ADVECTION
WILL LEAD TO CONSIDERABLE CLOUDINESS WITH HIGHS ONLY IN THE 40S AND
FREQUENTLY BREEZY CONDITIONS.

THE MAIN RISK FOR SNOW SHOWERS WILL BE AT NIGHT AND DURING THE EARLY
MORNING WHEN THE BOUNDARY LAYER IS COOLEST... ESPECIALLY FOR HIGHER
ELEVATIONS NEAR AND NORTH OF ROUTE 10 WHERE SOME LIGHT ACCUMULATIONS
EVEN APPEAR POSSIBLE.

GFS/ECMWF DO NOT LOOK PARTICULARLY BULLISH WITH QPF AT ANY TIME NEXT
WEEK ALTHOUGH SPOKES OF VORTICITY ROTATING AROUND THE UPPER LOW
MAY LEAD TO OCCASIONAL BOUTS OF INCREASED COVERAGE OF HEAVIER
SHOWERS.

THINGS APPEAR TO DRY OUR THURSDAY NIGHT AND FRIDAY WHEN THE UPR LOW
MOVES EAST AND SFC RIDGING ARRIVES FROM THE WEST. BY FRIDAY HIGHS
COULD BE BACK UP INTO THE 50S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 745 AM EDT SAT APR 18 2015

SFC WINDS WILL INCREASE OUT OF THE NORTHEAST LATER THIS MORNING...
WITH SPEEDS OF 10 TO 20 KTS BECOMING COMMON BY AFTERNOON. THE
WINDS INCREASE FURTHER AFTER 20Z... WITH SOME GUSTS TO 30 KTS
POSSIBLE LATE TODAY INTO TONIGHT. HIGH CONFIDENCE IN VFR
CIGS/VSBYS CONTINUING TODAY AND TONIGHT.

&&

.MARINE...
ISSUED AT 328 AM EDT SAT APR 18 2015

A COLD FRONT WILL MOVE THROUGH EARLY TODAY AND TURN THE WINDS TO THE
NORTHEAST. THE OFFSHORE FLOW WILL CONTINUE TONIGHT AND STRENGTHEN. A
SCA MAY BE NEEDED TONIGHT.


&&

.HYDROLOGY...
ISSUED AT 1119 AM EDT FRI APR 17 2015

NO RIVER FLOOD ADVISORIES ARE IN EFFECT AT THIS TIME. IMPROVEMENT
IS EXPECTED TO CONTINUE AS DRY CONDITIONS WILL HOLD STRONG TODAY
THROUGH SATURDAY.

THOUGHTS ON THE NEXT ROUND OF MOISTURE ARE CONSISTENT WITH THE
PREVIOUS HYDRO UPDATE (4/16). A DECENT SOAKING RAIN IS EXPECTED TO
MOVE IN SUNDAY WITH OFF/ON WET WEATHER POSSIBLE THROUGH THE
MIDDLE OF NEXT WEEK. MUCH OF THE MOISTURE SHOULD FALL LATE IN THE
WEEKEND AND EARLY INTO THE NEW WORK WEEK. THIS COULD RESULT IN MINOR
UPTICKS FOR RIVERS. THE LACK OF CONVECTIVE ACTIVITY...OR HIGH END
HEAVIER RAINFALL...KEEPS ME SOMEWHAT CONSERVATIVE ON ANY RISES
THAT WOULD OTHERWISE BE MORE CONCERNING.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...JAM
MARINE...04





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