Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 201152
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
752 AM EDT MON APR 20 2015

LATEST UPDATE...
AVIATION/MARINE

.SYNOPSIS...
ISSUED AT 330 AM EDT MON APR 20 2015

A CHILLY WEEK IS DEVELOPING AS LOW PRESSURE HAS MOVED OVER THE GREAT
LAKES. COOLER AIR WILL FLOW INTO WEST MICHIGAN BEHIND THE LOW. RAIN
SHOWERS MAY MIX WITH WET SNOW AT TIMES. MINOR ACCUMULATIONS ARE
POSSIBLE TUESDAY NIGHT NEAR US 10. HIGHS WILL BE IN THE MID 40S TO
MID 50S THROUGH THE END OF THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT MON APR 20 2015

FORECAST CONCERNS CONTINUE TO DEAL WITH THE EVOLUTION OF THE LOW
MOVING ACROSS LOWER MICHIGAN. OVERALL...THE FORECAST IS UNFOLDING AS
EXPECTED.

LOCAL AND REGIONAL RADAR SHOWS RAIN SHOWERS MOVING NORTH ACROSS THE
CWA. OVERALL COVERAGE THOUGH IS BEGINNING TO DECREASE SOUTH OF THE
MI/IN BORDER AS THE LOW MOVES NORTH. SREF SHOWS THAT PCPN WILL FILL
BACK IN ACROSS THE SOUTHERN CWA LATER THIS MORNING AS A SHORT WAVE
ALOFT PIVOTS TOWARD LOWER MICHIGAN BEFORE DIMINISHING AGAIN LATER
THIS AFTERNOON. AT THIS POINT THE HEAVIEST AND STEADIEST RAIN
APPEARS TO BE WINDING DOWN. WHAT WE/LL BE LEFT WITH IS SCATTERED TO
NUMEROUS SHOWERS TODAY AND A BIT LESS TONIGHT.

TUESDAY THE CORE OF THE UPPER LOW MOVES OVERHEAD. LOOK FOR PCPN TO
INCREASE IN COVERAGE AGAIN AS INSTABILITY ALOFT INCREASES A BIT DUE
STEEPENING LAPSE RATES COURTESY OF H5 TEMPS NEAR -30C MOVING OVER
THE CWA. THE COLDER AIR WILL REMAIN WITH US THROUGH TUESDAY NIGHT.
THAT/S WHEN WE COULD SEE SOME WET SNOW MIX IN WITH THE RAIN SHOWERS.
MINOR...LESS THAN AN INCH...ACCUMS SEEM POSSIBLE IN OSCEOLA/CLARE
COUNTIES TUESDAY NIGHT. THE UPPER LOW WILL BE VERY SLOW TO MOVE OUT
AND WE/LL SEE THE COOL SHOWERY PCPN CONTINUE WEDNESDAY AS A COUPLE
OF SHORT WAVES ROTATE AROUND THE UPPER LOW AND ACROSS LOWER MICHIGAN.

HIGHS WILL BE BELOW NORMAL THROUGH THE SHORT TERM RANGING FROM THE
MID 40S TO MID 50S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON APR 20 2015

THE COLD UPPER LOW REMAINS OVERHEAD THROUGH THURSDAY THEN MOVES INTO
NEW ENGLAND/SRN QUEBEC FOR THE WEEKEND. A SLIGHT CHANCE OF LIGHT
RAIN AND SNOW SHOWERS WILL LINGER THROUGH ABOUT THURSDAY NIGHT WHILE
H8 TEMPS AROUND -7C AND CYCLONIC FLOW ARE STILL PRESENT... OTHERWISE
DRY BUT CHILLY WEATHER IS EXPECTED WITH SFC HIGH PRESSURE MOVING IN.

THIS WEEKEND WE WILL STILL BE ON THE WRN PERIPHERY OF THE BROAD NEW
ENGLAND UPPER LOW. THE CONFLUENT/SHEARING UPPER LEVEL FLOW OVERHEAD
ASSOCIATED WITH THIS FEATURE HELPS TO FEND OFF RAIN ASSOCIATED WITH
A SYSTEM MOVING EAST FROM THE CENTRAL PLAINS. GUIDANCE SHOWS QPF
REMAINING TO OUR SOUTH WITH WEAK SURFACE RIDGING PREVAILING OVER THE
WEEKEND. TEMPERATURES WILL RECOVER A BIT AND HIGHS IN THE 50S ARE
EXPECTED SATURDAY AND SUNDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 752 AM EDT MON APR 20 2015

NUMEROUS IFR CIGS WILL PREVAIL THIS MORNING WITH PRIMARILY MVFR
CIGS EXPECTED THIS AFTERNOON. SCATTERED RAIN SHOWERS AND AREAS OF
DRIZZLE WILL OCCASIONALLY DROP VSBYS TO 3-5 MILES AND MKG WILL
EXPERIENCE SOME FOG OFF THE LAKE REDUCING VSBYS BELOW ONE MILE AT
TIMES THIS MORNING. CONDITIONS ARE EXPECTED TO IMPROVE TO VFR
TONIGHT.

SOUTHWEST TO WEST WINDS WILL BE STRONG TODAY WITH SUSTAINED SPEEDS
AROUND 20 KTS AND GUSTS TO 35 KTS. THE WINDS WILL DIMINISH A BIT
TONIGHT BUT WILL STILL GUST TO 25 KTS.

&&

.MARINE...
ISSUED AT 752 AM EDT MON APR 20 2015

ADDED AREAS OF DENSE FOG TO THE NEARSHORE FORECAST TODAY. DESPITE
GOOD MIXING... DEW POINTS IN THE 40S OVER THE COLD LAKE WATERS IS
PRODUCING FOG PER POST SUNRISE WEB CAMS AT MKG/HOLLAND.

LEFT THE SMALL CRAFT ADVISORY AS IS SOUTH OF WHITEHALL. AS THE LOW
MOVES FARTHER AWAY...WINDS WILL INCREASE FROM THE SOUTHWEST AND
WAVES WILL ALSO RESPOND. A SMALL CRAFT ADVISORY MAY ALSO BE NEEDED
NORTH OF WHITEHALL TONIGHT.

&&

.HYDROLOGY...
ISSUED AT 1114 AM EDT SUN APR 19 2015

PERIODS OF RAIN ARE EXPECTED TO DEVELOP LATE THIS AFTERNOON AND
AFFECT THE AREA OVER THE NEXT COUPLE OF DAYS. THE LIGHTER VARIETY OF
PRECIPITATION MAY EXTENT INTO MIDWEEK. THOUGH WE WILL SEE A DECENT
SOIL
SOAKING IT SHOULD NOT BE SUBSTANTIAL ENOUGH TO CREATE FLOODING
CONCERNS. GRADUAL BUT MINOR RISES ARE LIKELY...SUSPECTING THAT
THIS WOULD STAY WITHIN BANKS FOR MOST LOCATIONS. I WOULD NOT RULE
OUT A COUPLE OF SITES FLIRTING WITH ADVISORY STAGE AS WE GO INTO
TUESDAY...ESPECIALLY IF ANY MODERATE RAINFALL IS MORE PERSISTENT
WITH THE FIRST COUPLE OF ROUNDS OF MOISTURE. OTHERWISE...AREA
RIVERS ARE WELL BEHAVED THROUGH THE PERIOD.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT TUESDAY FOR LMZ844>847.

&&

$$

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






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