Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 250540
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
140 AM EDT MON MAY 25 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 329 PM EDT SUN MAY 24 2015

WE WILL HAVE PERIODS OF RAIN ACROSS THE AREA TONIGHT INTO TUESDAY
NIGHT.  THE MOST WIDESPREAD RAINS SHOULD COME TONIGHT THROUGH MONDAY
MORNING.  THEN SHOWERS SHOULD BECOME SCATTERED MONDAY AFTERNOON AND
NIGHT.  ANOTHER ROUND OF STEADY RAINS IS EXPECTED TUESDAY AND
TUESDAY NIGHT.  A FEW RUMBLES OF THUNDER WILL ALSO BE POSSIBLE.
TEMPERATURES WILL REMAIN MILD WITH HIGHS MAINLY IN THE 70S AND LOWS
FROM 60 TO 65.

THE AREA SHOULD DRY OUT MID WEEK...THEN ANOTHER PERIOD OF SHOWERS
AND STORMS WILL BE POSSIBLE THURSDAY NIGHT THROUGH FRIDAY NIGHT.
DAYTIME TEMPERATURE SHOULD REMAIN MILD...MAINLY 75 TO 80.

&&

.UPDATE...
ISSUED AT 1034 PM EDT SUN MAY 24 2015

MAINTAINED SHOWERS IN THE FORECAST TONIGHT WITH ONLY A CHANCE OF
THUNDERSTORMS. HRRR MODEL RUNS CONTINUE TO INDICATE SHOWERS
GRADUALLY TAPERING OFF WITH LITTLE IN THE WAY OF THUNDERSTORM
ACTIVITY. THE NOTION OF LIMITED CONVECTIVE ACTIVITY IS BACKED BY
MODEL DATA INDICATING ONLY WEAK INSTABILITY TONIGHT DESPITE A
FORMIDABLE LOW LEVEL JET OF 40 KNOTS AND STRONG 850MB MOISTURE
TRANSPORT.

HAVE 60-80 PCT CHANCES FOR SHOWERS ACROSS CENTRAL LOWER TAPERING
TO 30-40 PCT CHANCES TOWARD INTERSTATE 94. DEEP LAYER WINDS ARE
OUT OF THE SOUTH-SOUTHWEST TONIGHT WHICH WILL TEND TO KEEP THE
PRECIPITATION TO THE WEST OF THE GRR FORECAST AREAS. THE NORTHWEST
CWA UP TOWARDS LUDINGTON STANDS THE BEST CHANCES FOR SHOWERS AND
AN EMBEDDED STORM. THE JACKSON AREA COULD BE DRY MOST OF THE
NIGHT.

TEMPERATURES WILL BE MILD IN THE 60S FOR THE MOST PART TONIGHT AS
A WARM FRONT WILL BE LIFTING NORTH THROUGH THE AREA. WINDS WILL
GRADUALLY BE PICKING UP TONIGHT IN RESPONSE TO A HIGH OFF THE EAST
COAST AND A LOW TRACKING THROUGH THE WESTERN GREAT LAKES. IT LOOKS
TO BECOME WINDY ON MEMORIAL DAY ESPECIALLY DURING THE MIDDAY AND
AFTERNOON HOURS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 329 PM EDT SUN MAY 24 2015

WILL HAVE LIKELY TO CATEGORICAL POPS ACROSS THE CWA TONIGHT INTO
MONDAY.  THEN WE WILL GET WITHIN A DRY SLOT MONDAY AFTERNOON WITH
SOME SUNSHINE DEVELOPING.  ANOTHER SURGE OF RAIN...POSSIBLY HEAVY...
MOVES IN TOWARD MID DAY TUESDAY AND LINGERS INTO TUESDAY NIGHT.

AN AREA OF UPPER DIVERGENCE WAS MOVING INTO THE CWA THIS AFTERNOON
AS WE ARE IN THE RIGHT ENTRANCE REGION OF THE UPPER JET.  THIS WILL
LINGER OVER THE REGION THROUGH 06Z BEFORE EXITING NE.  THEREFORE WITH
INCREASING MOISTURE AND LIFT EXPECT HIGH RAIN CHANCES EVERYWHERE.
THE BEST MOISTURE POOLS OVER THE NORTHERN CWA DUE TO THE ISENTROPIC
LIFT FROM THIS AFTERNOON.  SOME AREAS MAY SEE OVER A HALF INCH OF
RAIN NEAR HIGHWAY 10 TONIGHT.  MEANWHILE THE I-94 CORRIDOR SHOULD
ONLY SEE AROUND A TENTH OF AN INCH.  THERE MAY BE A FEW EMBEDDED
STORMS.

THE WARM FRONT SWINGS THROUGH DURING THE FIRST HALF OF MONDAY.  THIS
WILL KEEP THE SHOWERS AND STORMS GOING.  HOWEVER DRIER AIR ARRIVES
BEHIND THE FRONT AND THE SHOWERS AND STORMS WILL BE REDUCED TO
ISOLATED FOR THE AFTERNOON.  WE SHOULD BREAK OUT INTO SOME SUNSHINE
THROUGH THE AFTERNOON AND EVENING.  THIS MAINLY DRY WARM SECTOR
SHOULD CONTINUE OVER SOUTHWEST MI MONDAY NIGHT.

THE FRONT STALLS ACROSS NORTHERN LOWER AND ANOTHER WAVE OF LOW
PRESSURE MOVES ALONG IT WILL BRING MORE RAIN.  PRECIPITABLE WATER
VALUES CLIMB WHICH MAY LEAD TO AREAS OF HEAVY RAIN TUESDAY AFTERNOON
AND EVENING.  RAMPED POPS TO CATEGORICAL FOR TUESDAY AFTERNOON.

OVERALL...MOST AREAS SHOULD SEE AROUND AN INCH OF RAIN WITH TONIGHT
THROUGH TUESDAY NIGHT.  BUT THERE IS THE THREAT OF LOCALIZED HEAVIER
RAINS.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 329 PM EDT SUN MAY 24 2015

AFTER TUESDAY NIGHT RAIN EVENT A WEAK SURFACE HIGH PRESSURE AREA
WITH SHORTWAVE RIDGING ALOFT BUILD OVERHEAD WED AFTERNOON INTO
THURSDAY. NEXT CHANCE OF RAINFALL STILL ON TRACK FOR FRIDAY INTO
SATURDAY AS ANOTHER FRONT PUSHES THROUGH THE REGION. LATEST NWP
TRENDING STRONGER WITH NORTHERN STREAM WHICH RESULTS IN A MORE
PROGRESSIVE SYSTEM WITH LESS HEAVY RAIN POTENTIAL AND A GOOD PUSH OF
SEASONABLY COOL CANADIAN AIR BY SUNDAY.

THERE ARE SOME DIFFERENCES BETWEEN ECMWF AND GFS ON THE EVOLUTION
AND EVENTUAL SHEARING OUT OF THE WEST U.S. SOUTHERN STREAM TROUGH
BUT THEY HAVE MORE IN COMMON THAN NOT SO CONFIDENCE IS A BIT HIGHER
TODAY THAN YESTERDAY.  EITHER SOLUTION WOULD RESULT IN A ROUND OF
FRONTAL THUNDERSTORMS WITH SOME SEVERE POTENTIAL FRIDAY AFTERNOON
(GFS) OR ON SATURDAY (ECMWF).  OVERALL ECMWF IS A BIT SLOWER WITH
MORE POTENTIAL OF HEAVY RAINFALL.  AS MENTIONED PREVIOUSLY...THERE
WILL BE GOOD MOISTURE ADVECTION AHEAD OF THE FRONT WITH PWATS ABOVE
1.5 INCHES.

SEVERE WEATHER WISE...SHEAR LOOKS TO BE A LIMITING FACTOR AT THIS
TIME WITH OVERALL RELATIVELY WEAK MID LEVEL FLOW AND A
UNIDIRECTIONAL PROFILE OVERALL. CAPE VALUES ARE A BIT BETTER WITH
500 TO 1500 J/KG DEPENDING ON AFTERNOON VERSUS MORNING FRONTAL
PASSAGE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 131 AM EDT MON MAY 25 2015

FOCUS CONTINUES TO BE ON STRONG S/SW WIND GUSTS FOR THE AFTERNOON
HOURS ESPECIALLY. MODELS CONTINUE TO INDICATE WIND GUSTS OF 25 TO
30 KNOTS WILL BE MIXED DOWN TO THE SFC AS THESE WINDS ARE NOT MORE
THAN 500 FT OFF THE GROUND. SHOULD THE CLOUDS CLEAR OUT SOON
ENOUGH THIS AFTERNOON...WIND GUSTS APPROACHING 40 KNOTS ARE NOT
OUT OF THE QUESTION. THESE WINDS WILL BE LOCATED ABOUT 2K FT OFF
THE GROUND AND THE POSSIBILITY EXISTS FOR SFC GUSTS TO BE THAT
HIGH IN THE 18Z-21Z TIME FRAME.

THE CIGS/VIS ASSOCIATED WITH ANY SHOWERS TODAY DO NOT LOOK TO BE
CATEGORIZED AS IFR...BUT WILL HAVE TO WATCH OUT FOR AFTERNOON
T-STORM DEVELOPMENT FROM BTL TO LAN AND JXN WHERE GREATER HEATING
COMBINED WITH INSTABILITY WILL BE PRESENT.

&&

.MARINE...
ISSUED AT 329 PM EDT SUN MAY 24 2015

WILL GET AN ADVANCED NOTICE AND ISSUE MARINE HEADLINES FOR MEMORIAL
DAY.  SOUTH WINDS WILL RAMP UP LATE TONIGHT INTO MONDAY AND WAVES
WILL BUILD BY MID MORNING MONDAY.  WILL ALSO ISSUE A BEACH HAZARDS
STATEMENT FOR ANY WILLING TO GO OUT AND SWIM IN MID 40 DEGREE WATER
TEMPS.


&&

.HYDROLOGY...
ISSUED AT 204 PM EDT SUN MAY 24 2015

THREE MAIN ROUNDS OF RAIN ARE FORECAST FOR SOUTHWEST LOWER MICHIGAN
THROUGH NEXT WEEKEND...THE FIRST OF WHICH IS ARRIVING NOW. RAINFALL
TOTALS OF UP TO HALF AN INCH ARE POSSIBLE ACROSS CENTRAL LOWER
MICHIGAN THROUGH MONDAY AFTERNOON...MAINLY OVER THE UPPER MUSKEGON
BASIN AND PERE MARQUETTE BASINS. MONDAY AFTERNOON THROUGH MONDAY
NIGHT LOOKS FAIRLY DRY. A SECOND ROUND OF SHOWERS AND A FEW STORMS
WILL BE POSSIBLE TUESDAY AFTERNOON THROUGH TUESDAY NIGHT.

THE BIGGEST HYDRO CONCERN COULD BE THE THIRD ROUND ON FRIDAY AND
SATURDAY. A MORE UNSTABLE AND INCREASINGLY HUMID AIRMASS WILL BE
MORE CONDUCIVE TO STRONGER THUNDERSTORMS CAPABLE OF HEAVY RAINFALL
FRIDAY INTO SATURDAY. THE ECMWF EPS...GEM...AND GFS AGREE THAT 2 TO
3 INCHES OF WIDESPREAD RAINFALL IS POSSIBLE THROUGH SUNDAY...WITH
HIGHER AMOUNTS POSSIBLE IN STRONG THUNDERSTORMS. RIVER RISES ARE
EXPECTED THIS WEEK AND ESPECIALLY NEXT WEEKEND. THE MAIN IMMEDIATE
THREAT WILL BE MINOR NUISANCE FLOODING MIDWEEK WITH THE POSSIBILITY
OF HEAVY RAINFALL TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. THE
FLOODING RISK IS HIGHER NEXT WEEKEND...ESPECIALLY IN URBAN AREAS AND
ON SMALLER STREAMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT FROM 9 AM EDT THIS MORNING THROUGH LATE
     TONIGHT FOR MIZ056-064-071.

     BEACH HAZARDS STATEMENT FROM 9 AM EDT THIS MORNING THROUGH
     TUESDAY MORNING FOR MIZ037-043-050.

LM...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 8 AM EDT TUESDAY
     FOR LMZ847>849.

     SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 1 AM EDT TUESDAY
     FOR LMZ844>846.

&&

$$

UPDATE...DUKE
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...COBB
AVIATION...HOVING
HYDROLOGY...EBW
MARINE...JK



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