Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 012333
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
733 PM EDT SUN MAY 1 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT SUN MAY 1 2016

A WEAK LOW PRESSURE SYSTEM MOVING ACROSS THE OHIO VALLEY TONIGHT
WILL BRING RAIN SHOWERS TO SOUTHERN LOWER MICHIGAN. THE RAIN WILL
MOVE IN AFTER SUNSET AND SHOULD END BY DAYBREAK. HIGH PRESSURE WILL
THEN BRING DRY WEATHER FOR MONDAY AND TUESDAY. THE NEXT WEATHER
MAKER WILL BE A LOW PRESSURE SYSTEM THAT PIVOTS THROUGH THE GREAT
LAKES TUESDAY NIGHT INTO WEDNESDAY WHICH WILL DRAW COOLER AIR DOWN
FROM CANADA IN ITS WAKE. HIGHS WILL BE NEAR NORMAL MONDAY AND
TUESDAY AROUND 60...BUT WILL COOL BACK INTO THE 50S FOR WEDNESDAY
AND THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 330 PM EDT SUN MAY 1 2016

MAIN FORECAST FOCUS WAS ON CHANCES FOR RAIN TONIGHT AND AGAIN
TUESDAY NIGHT. MODELS ARE IN GOOD AGREEMENT IN BRINGING A SWATH OF
RAIN ACROSS THE SOUTH TONIGHT...ESSENTIALLY FROM I-96 SOUTHWARD. THE
HEAVIEST RAIN SHOULD BE TOWARDS I-94 WHERE A QUARTER TO A HALF INCH
IS POSSIBLE. IT WILL LIKELY REMAIN DRY ACROSS CENTRAL LOWER
MICHIGAN. CONSIDERED ADDING A CHANCE OF THUNDER IN THE SOUTH THIS
EVENING...BUT INSTABILITY IS REALLY WEAK...ON THE ORDER OF A 100
J/KG. LEFT IT OUT OF THE FORECAST FOR NOW.

WE SHOULD BE DRY MONDAY...MONDAY NIGHT AND MOST OF IF NOT ALL OF
TUESDAY AS A RIDGE OF HIGH PRESSURE SHIFTS THROUGH THE REGION.
CLOUDS LOOK TO LINGER ON MONDAY BEHIND THE SYSTEM WITH POTENTIALLY
A MOSTLY CLOUDY DAY ACROSS SOUTHERN LOWER MICHIGAN.

NEXT CHANCE FOR SHOWERS MOVES IN TUESDAY NIGHT ALONG A COLD FRONT.
LEFT THE MENTION OF A CHANCE OF THUNDER AS WELL GIVEN A LITTLE BIT
MORE IN THE WAY OF INSTABILITY. 850MB LI/S GO SLIGHTLY NEGATIVE IN
THE WEST TUESDAY NIGHT.

TEMPERATURES LOOK PRETTY CLOSE TO NORMALS IN THE SHORT TERM.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 330 PM EDT SUN MAY 1 2016

EVEN THOUGH THE SURFACE FEATURE WILL BE EXITING THE AREA EARLY
WEDNESDAY MORNING...THE UPPER TROUGH/LOW DOES NOT COME THROUGH UNTIL
AFTERNOON.  THIS WILL KEEP THE PCPN IN PLACE...SO I HAVE INCREASED
POPS. THIS WILL ALSO RESULT IN A COOL DAY HOLDING IN THE 50S.  THE
SYSTEM IS ONLY EXPECTED TO DRIFT SLOWLY TO THE EAST...SO SOME AREAS
WILL STILL SEE RAIN INTO WEDNESDAY NIGHT.

AS THE UPPER TROUGH/LOW MOVES FARTHER EAST WE WILL SEE AN UPPER
RIDGE MOVE IN LATE IN THE WEEK.  MODEL TRENDS ARE MUCH WARMER AS
THIS FEATURE MOVES IN AS THE PATTERN APPEARS MORE AMPLIFIED.  SOLID
WARM ADVECTION STARTS BY THURSDAY NIGHT.  THIS SHOULD LEAD TO A
PERIOD WITH ABOVE NORMAL TEMPS FOR FRIDAY AND SATURDAY ALONG WITH
SUNSHINE. H8 TEMPS JUMP TO AROUND +12C BY SATURDAY WHICH SHOULD HELP
TEMPS PUSH INTO THE 70S. SOME TIMING ISSUES IN THE MODELS THROUGH
THE WEEKEND...BUT AS IT APPEARS NOW WE SHOULD SEE A COLD FRONT COME
THROUGH SATURDAY NIGHT WITH THE RISK OF SHOWERS AND STORMS.  THIS
SHOULD BRING TEMPS BACK DOWN TO NORMAL RANGES BY SUNDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 719 PM EDT SUN MAY 1 2016

IFR CONDITIONS GENERALLY PREVAIL FOR ALL BUT KGRR AND KMKG AT
THIS TIME. WITH MORE RAIN MOVING IN...ESPECIALLY SOUTH AND EAST OF
KGRR...THE THOUGHT IS THAT THE IFR WILL CONTINUE. CONDITIONS
COULD TEMPORARILY IMPROVE TO MVFR...BUT WITH INCREASING SURFACE
HUMIDITY...THAT SHOULD ACT TO HOLD THE LOWER CLOUDS IN. AS FOR THE
THUNDER RISK TONIGHT...THE INSTABILITY IS FORECASTED TO STAY JUST
SOUTH OF KAZO...KBTL AND KJXN...SO I DID NOT INCLUDE THUNDER IN
THE TAFS.

AS FOR MONDAY...CONDITIONS ARE FORECASTED TO IMPROVE. THE RAIN
PULLS AWAY EARLY...BUT WITH A COOL NORTHEAST WIND...THE MIXING
WILL BE LIMITED. THUS IT LOOKS LIKE IT WILL TAKE TIL THE AFTERNOON
FOR ALL SITES IN SOUTHWEST LOWER MI TO IMPROVE TO VFR.

&&

.MARINE...
ISSUED AT 330 PM EDT SUN MAY 1 2016

WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH TUESDAY. NORTHEAST WINDS TONIGHT AT 10 TO 20 KNOTS WILL
DIMINISH TO 10 KNOTS OR LESS FOR MONDAY AND MONDAY NIGHT AS HIGH
PRESSURE BUILDS IN.

WINDS AND WAVES WILL BUILD INTO MID WEEK AS A LOW PRESSURE SYSTEM
DROPS SOUTH THROUGH THE GREAT LAKES REGION.


&&

.HYDROLOGY...
ISSUED AT 205 PM EDT SUN MAY 1 2016

FLOODING IS NOT EXPECTED. RECENT RAINS HAVE RESULTED IN MODEST RISES ON RIVERS
AND STREAMS... BUT SIGNIFICANT RISES ON MAIN STEM RIVERS ARE NOT EXPECTED.
ADDITIONAL RAINFALL IS EXPECTED TONIGHT ACROSS SOUTHERN LOWER MICHIGAN. A
QUARTER TO HALF INCH OF RAIN IS POSSIBLE THROUGH MONDAY MORNING ACROSS THE
KALAMAZOO RIVER BASIN AND THE UPPER GRAND BASIN.

&&

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

$$

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


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