Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 090727
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
327 AM EDT WED JUL 9 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 327 AM EDT WED JUL 9 2014

IT WILL REMAIN COOL THROUGH THE REST OF THE WORK WEEK.  NORMAL HIGH
TEMPERATURES ARE IN THE LOWER 80S...BUT WE WILL ONLY SEE HIGHS IN
THE 70S TODAY THROUGH FRIDAY.  OVERNIGHT LOWS WILL ALSO BE COOL...
MAINLY 50 TO 55.  WIDELY SCATTERED SHOWERS WILL BE POSSIBLE AGAIN
TODAY...MAINLY NORTH OF I-96.  THEN DRY WEATHER IS EXPECTED TONIGHT
THROUGH FRIDAY.

TEMPERATURE ARE EXPECTED TO RETURN TO NEAR NORMAL BY THE WEEKEND AND
INTO EARLY NEXT WEEK.  HOWEVER THERE WILL BE THE CHANCE FOR SHOWERS
AND STORMS SATURDAY THROUGH SUNDAY NIGHT.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 327 AM EDT WED JUL 9 2014

CYCLONIC UPPER FLOW WILL BE OVER THE REGION TODAY...WITH A TROUGH
AXIS COMING THROUGH THIS MORNING.  MOISTURE DEPTH IS MOST FAVORABLE
ACROSS THE NORTHERN CWA WHERE WE WILL SEE SCATTERED DIURNAL SHOWERS
AGAIN.  INSTABILITY IS LACKING THOUGH...SO KEEP THUNDER OUT OF THE
FORECAST.  QUITE COOL TODAY WITH MAX TEMPS ONLY REACHING AROUND 70
OR THE LOWER 70S.  CLIMATE DATA SHOWS THIS WOULD BE WITHIN THE TOP
10 COOLEST HIGHS EVER RECORDED FOR JULY 9TH.  AND DEPENDING ON THE
AMOUNT OF SUNSHINE...OR THE  LACK OF...TODAY COULD BE WITHIN THE TOP
5.

THE CYCLONIC NORTHWEST UPPER FLOW GRADUALLY RELAXES THROUGH THE
LATTER PORTION OF THE WORK WEEK.  AS A RESULT EXPECT MOSTLY DRY
WEATHER WITH A SLOW WARMUP.  REMOVED POPS FOR FRIDAY AS IT APPEARS A
SURFACE HIGH WILL NOT MOVE OFF TO THE EAST UNTIL LATE IN THE DAY.
THIS WILL DELAY THE MOISTURE ASSOCIATED WITH THE RETURN FLOW UNTIL
NIGHTFALL.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 327 AM EDT WED JUL 9 2014

THERE ARE TWO FEATURES TWO WATCH... THE POTENTIAL FOR CONVECTION
SATURDAY INTO MONDAY WHILE WE ARE STILL IN THE RELATIVELY WARM AIR
THEN A MAJOR COOL DOWN BEYOND THAT.

CURIOUSLY THE CONVECTION WE ARE EXPECTING THIS COMING WEEKEND AND
THE COOLING THAT FOLLOWS ARE LARGELY THE RESULT OF THE SAME SYSTEM.
THAT IS A CLOSED UPPER LOW OVER THE ARCTIC OCEAN NEAR 75N AND 120W
THIS MORNING. THIS SYSTEM DRIVES NEARLY DUE SOUTH TO NEAR GREAT
SLAVE LAKE BY FRIDAY EVENING AND FINALLY TO NORTHERN LAKE SUPERIOR
BY TUESDAY MORNING. THIS BRINGS THE 500 MB HEIGHTS TO MORE THAN 2
STANDARD DEVIATIONS FROM NORMAL BY THEN. ACTUALLY THERE IS ALSO A
SYSTEM THAT COMES IN FROM OFF THE BRITISH COLUMBIA COAST THAT MERGES
WITH THIS ARCTIC SYSTEM  BY SATURDAY.

WHAT CAUSES THE CONVECTION THIS WEEKEND IS THE UPPER LEVEL DIFFLUENT
FLOW THAT DEVELOPS OVER NORTHERN PLAINS AND GREAT LAKES AS THIS
SYSTEM MOVES SOUTH AND SOUTHEAST FROM NORTHERN CANADA INTO THE UPPER
GREAT LAKES. THE LEAD JET STREAK GIVES SOUTHWEST MICHIGAN JET EXIT
REGION DYNAMICS FRIDAY NIGHT... THEN THEN JET ENTRANCE REGION
DYNAMICS SATURDAY INTO SUNDAY. GIVEN THE STRENGTH OF THE UPPER JET
FORCING ALL OF THIS AND PROXIMITY TO THE UPPER SUBTROPICAL RIDGE
OVER THE SOUTHERN PLAINS THIS COULD RESULT IN SOME STRONG
THUNDERSTORMS AND LOCALLY HEAVY RAINFALL EVENTS AS THERE IS
DIFFLUENT THICKNESS AND PRECIPTABLE WATER VALUES NEAR 1.8 INCHES
WHICH IS NEARLY NEARLY DOUBLE NORMAL.  CURRENTLY THE BEST SET-UP FOR
STRONG CONVECTION WOULD BE SUNDAY. THE ECMWF AND CANADIAN GEM SHOW
SIGNIFICANT RAINFALL SATURDAY NIGHT INTO SUNDAY NIGHT AS THE PRIMARY
COLD FRONT COMES THROUGH.

THE SECONDARY COLD FRONT COMES THOUGH MONDAY. THAT IS FOLLOWED BY
THE UNSEASONABLY COLD WITH 850 TEMPERATURES 1 TO 2 STANDARD
DEVIATIONS FROM NORMAL AND 500 HEIGHTS SIMILARLY BELOW NORMAL. HIGHS
MAY ONLY BE IN THE 60S BY TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1203 AM EDT WED JUL 9 2014

MAINLY VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS. THERE IS A
CHANCE FOR SOME MVFR FOG TOWARDS MORNING AND INCLUDED THAT IN THE
TAFS. ALSO...SOME MVFR CEILINGS MAY TRY TO DRIFT INTO THE TAF
SITES FROM THE NORTH LATE TONIGHT BUT NOT CONFIDENT ENOUGH TO PUT
IN BROKEN CEILINGS AT THIS POINT.

SKIES ON WEDNESDAY WILL BE SCT-BKN CUMULUS WITH VFR BASES. WINDS
THROUGH THE PERIOD WILL BE FAIRLY LIGHT FOR AVIATION
PURPOSES...UNDER 12 KNOTS OR SO.

&&

.MARINE...
ISSUED AT 327 AM EDT WED JUL 9 2014

RATHER QUIET CONDITIONS EXPECTED ON THE LAKE THROUGH THE SHORT TERM.

WIND SPEEDS ARE EXPECTED TO REMAIN 15 KNOTS OR LESS.

&&

.HYDROLOGY...
ISSUED AT 330 PM EDT TUE JUL 8 2014

ADDITIONAL AREAL RAINFALL AMOUNTS YESTERDAY WERE GENERALLY AROUND
HALF AN INCH OVER THE HEADWATERS OF THE GRAND AND KALAMAZOO RIVERS.
THIS IS NOT ENOUGH TO SIGNIFICANTLY CHANGE FORECAST CRESTS ALONG THE
MAPLE RIVER AT MAPLE RAPIDS AND THE GRAND AT IONIA. THESE FORECAST
CRESTS ARE ONLY SLIGHTLY ABOVE CURRENT OBSERVED STAGES...SO WILL
STICK WITH THE CURRENT ADVISORIES.

DOWNGRADED THE FLOOD WARNING AT ALMA ON THE PINE RIVER TO AN
ADVISORY. OBSERVATIONS HAVE NOT BEEN AVAILABLE SINCE MONDAY
AFTERNOON. HOWEVER...STAGES WERE ALREADY DECREASING THEN AND
ADDITIONAL PRECIPITATION WAS MARGINAL.

PRECIPITATION WEDNESDAY IS EXPECTED TO STAY WELL UNDER A TENTH OF AN
INCH ON WEDNESDAY. THIS SHOULD HAVE LITTLE IMPACT ON RIVERS AND
ALLOW THEIR OVERALL SUBSIDING TRENDS TO CONTINUE.

&&

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

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...WDM
AVIATION...DUKE
HYDROLOGY...TJT
MARINE...JK









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