Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 181615
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1215 PM 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.

&&

.UPDATE...
ISSUED AT 1055 AM EDT SAT APR 18 2015

I INCREASED THE HIGH TEMPERATURE AROUND 5 DEGREES FOR THIS
AFTERNOON BASED ON MORNING SOUNDING DATA. THE RAP MODEL SEEMS TO
BE DOING A BETTER JOB OF SHOWING CURRENT TEMPERATURES...DEW POINTS
AND WINDS SO I USED THAT TO INCREASE THE WIND SPEED...TEMPERATURES
AND LOWER THE DEW POINTS. THAT ALL BEING SO... WE COULD SEE HIGHS
IN THE MID TO UPPER 70S OVER THE WESTERN SECTIONS OF THE CWA THIS
AFTERNOON. WE WILL BE GETTING CLOSE TO RED FLAG CONDITIONS IF THIS
HAPPENS. FOR NOW I WILL LET OUR HWO AND POST OF FACEBOOK COVER
THIS ISSUE.

&&

.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 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1215 PM EDT SAT APR 18 2015

VFR CONDITIONS WILL CONTINUE THROUGH 18Z SUNDAY. ENE WINDS WILL GUST
TO AROUND 20 KTS AT TIMES THIS AFTERNOON AND BECOME EASTERLY AND
GUST TO 20 TO 25 KTS SUNDAY MORNING AND AFTERNOON. SHOWERS WILL
GRADUALLY MOVE IN FROM SOUTH TO NORTH AT ALL THE TERMINALS BETWEEN
18Z AND 21Z SUNDAY AFTERNOON WHEN CONDITIONS WILL DETERIORATE TO
PRIMARILY MVFR WITH POCKETS OF IFR POSSIBLE IN HEAVIER SHOWERS.

&&

.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 1126 AM EDT SAT APR 18 2015

A GOOD SOAKING RAINFALL IS STILL ON TRACK TO AFFECT THE ENTIRE AREA
BEGINNING SUNDAY. THE BULK OF THE MOISTURE WILL LIKELY FALL
BETWEEN SUNDAY AFTERNOON INTO MONDAY MORNING WITH SOME GUIDANCE
HINTING AT OVER AN INCH IN SPOTS. ADDITIONAL CHANCES FOR RAIN WILL
SPAN THROUGH THE MIDDLE OF THE WEEK BUT ARE NOT EXPECTED TO BE
QUITE AS ABUNDANT WITH MOISTURE.

RIVERS WILL MAINLY RESPOND IN THE MANNER OF MINOR RISES. THIS SHOULD
MOSTLY CONSIST OF WITHIN BANK RISES. I HAVE A LITTLE MORE CONFIDENCE
IN THINKING MAPLE RAPIDS COULD FLIRT WITH ADVISORY CRITERIA ONCE
AGAIN.
THIS IS PENDING THE AMOUNT OF RAINFALL RECEIVED THROUGH EARLY MONDAY.
OTHERWISE...WE ARE LOOKING PRETTY GOOD WITH THIS NOT BEING A
CONVECTIVE
MODE OF PRECIPITATION...NO REAL SURPRISES AT THIS POINT.

&&

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

$$

UPDATE...WDM
SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...LAURENS
HYDROLOGY...JAM
MARINE...04






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.