Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 301653
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1253 PM EDT TUE JUN 30 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 329 AM EDT TUE JUN 30 2015

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ONCE AGAIN TODAY AS
A WEAK LOW PRESSURE SYSTEM MOVES EAST THROUGH THE GREAT LAKES
REGION. THERE MAY BE A BIT HIGHER CONCENTRATION OF SHOWERS AND
STORMS TODAY AS THEY WILL BE ASSOCIATED WITH THE LOW AND A FRONT.
JUST LIKE ON MONDAY SHOWERS AND STORMS WILL BE MOST NUMEROUS IN THE
AFTERNOON AND EVENING HOURS. WE WILL DRY OUT TONIGHT AS THE LOW
MOVES OFF TO THE EAST. AN ISOLATED SHOWER OR STORM CANNOT BE RULED
OUT TOWARDS LANSING AND JACKSON ON WEDNESDAY...BUT MOST AREAS SHOULD
STAY DRY. A PLEASANT AND DRY PERIOD IS FORECAST FOR THURSDAY THROUGH
THE FOURTH WEEKEND WITH HIGHS WARMING BACK INTO THE LOWER 80S FOR
THE FOURTH AND SUNDAY.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 329 AM EDT TUE JUN 30 2015

MAIN FOCUS OF THE SHORT TERM IS ON SHOWER AND STORM CHANCES TODAY
AND THE PREVALENCE OF LOW CLOUDS TONIGHT INTO WEDNESDAY.

AS FOR SHOWER AND STORM CHANCES TODAY...THEY ACTUALLY LOOK A BIT
BETTER THAN YESTERDAY DUE TO THE PRESENCE OF AN UPPER LEVEL
SHORTWAVE PUSHING IN. THE UPPER WAVE CAN CLEARLY BE SEEN IN WATER
VAPOR IMAGERY OVER THE WESTERN GREAT LAKES REGION. THERE IS EVEN A
SURFACE REFLECTION WITH A LOW CENTERED OVER THE U.P AND A TROUGH
EXTENDING SOUTH OVER EASTERN WISC AND ILL. THE TROUGH AND UPPER WAVE
WILL MOVE EAST THROUGH THE FORECAST AREA THROUGH THE COURSE OF THE
DAY. RAP GUIDANCE IS SUGGESTING MOST UNSTABLE CAPE VALUES WILL RISE
TO AROUND 1000 J/KG WHICH WILL BE SUFFICIENT FOR THUNDERSTORMS.
EXPECTING A DIURNAL FLARE ONCE AGAIN TO THE SHOWERS/STORMS WHICH IS
COMMON WITH SUMMER UPPER TROUGHS OF THIS MAGNITUDE. NOT EXPECTING
ANYTHING SEVERE...SMALL HAIL...LOCALLY HEAVY RAINS AND LIGHTNING.

THE SHOWERS AND STORMS SHOULD TAPER OFF/PRESS EASTWARD TOWARDS
SUNSET. MODELS ARE TRYING TO SUGGEST LOWER CLOUDS SETTLING INTO THE
AREA FROM THE NORTH AFTER THE PASSAGE OF THE SURFACE TROUGH TONIGHT.
THERE ARE SOME LOW CLOUDS IN THE WAKE OF THE LOW AT THE PRESENT TIME
AND ITS VERY PLAUSIBLE WE SEE THIS CLOUD COVER EXPAND ACROSS THE
REGION TONIGHT. GFS 950-900MB LAYER MOISTURE BEARS THIS OUT NICELY.

SOME OF THESE CLOUDS MAY LINGER ACROSS THE AREA ON WEDNESDAY. CANNOT
RULE OUT AN ISOLATED SHOWER OR STORM TOWARDS LAN/JXN ON
WEDNESDAY...ESPECIALLY IF WE CAN GET SOME BREAKS IN THE CLOUD COVER.

OTHERWISE...WEDNESDAY NIGHT AND THURSDAY LOOK DRY AS HIGH PRESSURE
SOLIDLY STARTS TO BUILD INTO THE AREA. A COOL NIGHT ACROSS CENTRAL
LOWER WED NIGHT WITH LOWS DIPPING INTO THE 40S.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 329 AM EDT TUE JUN 30 2015

A HIGH PRESSURE RIDGE WILL BRING FAIR WEATHER THURSDAY NIGHT THROUGH
MOST OF THE WEEKEND. TEMPERATURES WILL ALSO UNDERGO A GRADUAL
MODERATING TREND AND REACH THE LOWER TO PERHAPS MIDDLE 80S BY THE
WEEKEND.

THE RIDGE WILL MOVE TO THE EAST COAST SUNDAY NIGHT AND ALLOW
SOUTHERLY RETURN FLOW TO DEVELOP WHICH WILL RESULT IN INCREASING
MOISTURE. A STRONG COLD FRONT WILL BRING A GOOD CHANCE OF SHOWERS
AND THUNDERSTORMS MONDAY THROUGH MONDAY NIGHT. MOST MEDIUM RANGE
GUIDANCE SHOWS POTENTIAL FOR A SIGNIFICANTLY COOLER AIRMASS TO MOVE
IN BEHIND THAT FRONT FOR THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1252 PM EDT TUE JUN 30 2015

EXTENSIVE IFR WITH LOW CEILINGS AND VISIBILITIES COVER THE WESTERN
TAF SITES WHICH ARE NEAR OR BEHIND THE COLD FRONT. MKG BEING BY
THE LAKE SHORE HAS BEEN AS LOW AS 1/4 MILE IN FOG INTO EARLY THIS
AFTERNOON. THE LOW CLOUDS AND LOWER VISIBILITIES ARE EXPECTED TO
SPREAD INTO THE OTHER TAF SITES AS THE COLF FRONT GETS CLOSER TO
THEM DURING THE MID AFTERNOON. LANING AND JACKSON MAY SEE A FEW
SHOWERS OR ISOLATED THUNDERSTORMS JUST AHEAD OF THE COLD
FRONT...TILL AROUND 21Z OR SO. THE LOW CLOUDS MAY BREIFLY CLEAR
BY MID EVEING BRING VFR TO MOST IF NOT ALL OF THE TAF SITES BUT AS
A SECOND AREA OF COOLER AIR MOVES IN AFTER MIDNIGHT THE LOW CLOUDS
RETURN... ALL TAF SITES SHOULD BE AT LEAST IFR FRIDAY MORNIG.

&&

.MARINE...
ISSUED AT 329 AM EDT TUE JUN 30 2015

WIND SPEEDS RAMP UP SOME THIS AFTERNOON AND ESPECIALLY TONIGHT OUT
OF THE NORTH. THIS IS DUE TO THE BRIEF TIGHTENING OF THE GRADIENT
BETWEEN A LOW MOVING EAST ACROSS THE LOWER PENINSULA AND AN
ADVANCING HIGH FROM THE LAKE SUPERIOR REGION. WINDS WILL NUDGE INTO
THE 15 TO 20 KNOT RANGE AND WAVES WILL LIKELY INCREASE INTO THE 2 TO
4 FOOT RANGE LATE THIS AFTERNOON AND TONIGHT. FEEL WE WILL STAY
BELOW SCA CRITERIA AS WELL AS BHS CRITERIA. BIGGEST TIME FRAME OF
CONCERN WILL BE FROM LATE AFTERNOON THROUGH TONIGHT. AFTER TONIGHT
EXPECTING WAVES IN THE 1 TO 3 FOOT RANGE INTO THURSDAY.


&&

.HYDROLOGY...
ISSUED AT 220 PM EDT MON JUN 29 2015

SEVERAL RIVER FLOOD ADVISORIES REMAIN AT SOME POINTS IN THE GRAND
AND KALAMAZOO RIVER BASINS. RIVER LEVELS AT MOST LOCATIONS ARE
FALLING. SHOWERS AND THUNDERSTORMS TODAY AND TUESDAY MAY PRODUCE
LOCALLY HEAVY RAINFALL... BUT BASIN AVERAGE RAINFALL AMOUNTS WILL
BE RATHER LOW AND SHOULD NOT IMPACT THE LARGER RIVERS. NO
WIDESPREAD HEAVY RAIN EVENTS ARE EXPECTED THIS WEEK.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...LAURENS
AVIATION...WDM
HYDROLOGY...CAS
MARINE...DUKE


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