Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 091930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EDT WED JUL 9 2014

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

.SYNOPSIS...
ISSUED AT 328 PM EDT WED JUL 9 2014

FAIR WEATHER WILL CONTINUE THROUGH FRIDAY THEN THUNDERSTORMS ARE
EXPECTED SATURDAY AND SUNDAY. TEMPERATURES WILL CONTINUE TO BE
COOLER THAN NORMAL THROUGH THE NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 328 PM EDT WED JUL 9 2014

ONLY FORECAST ISSUE IN THE NEAR TERM IS TIMING SHOWERS AND
THUNDERSTORMS IN LATE IN THE PERIOD. EXPECT MID LEVEL WARM
ADVECTION TO BEGIN LATE FRIDAY AND MOISTURE RETURN SHOULD BE
SUFFICIENT BY LATE FRIDAY NIGHT FOR SOME SCATTERED SHOWERS AND
POSSIBLY THUNDERSTORMS. INSTABILITY IS LIMITED BUT TOTAL TOTALS IN
THE MID 40S SUGGEST SOME ELEVATED STORMS ARE POSSIBLE...MOSTLY
ACROSS THE WESTERN FORECAST AREA WHERE MOISTURE IS DEEPEST.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 328 PM EDT WED JUL 9 2014

PRIMARY IMPACT WEATHER REVOLVES AROUND CHANCES FOR SHOWERS AND
THUNDERSTORMS THIS WEEKEND WITH PERHAPS SOME STRONGER THUNDERSTORMS
LATER SATURDAY NIGHT INTO SUNDAY MORNING.

THE THREAT FOR SHOWERS/STORMS DURING THE DAY SATURDAY APPEARS A BIT
LOWER THAN IN PAST MODEL RUNS...WITH THE EXCEPTION OF THE 12Z GFS
WHICH BRINGS A BAND OF MOSTLY SHOWERS WITH PERHAPS EMBEDDED THUNDER
INTO THE CWA BY 18Z SAT AND CONTINUING THRU THE AFTERNOON. THE ECWMF
AND GEM KEEP US MORE DRY THAN WET ON SATURDAY. ONE REASON THE GFS
BRINGS IN PRECIP QUICKER IS DUE TO A TIGHTER AND MORE PROGRESSIVE
VORT SIGNATURE AT 500 MB. WITH GFS FCST PW VALUES AROUND 2.00" ON
SATURDAY THAT WOULD INDICATE AREAS OF HEAVY RAIN. HOWEVER...NOT YET
SOLD ON THE QUICK GFS SOLUTION AS THE ECMWF AND GEM ARE IN ALIGNMENT
ON HOLDING OFF MORE SUBSTANTIAL PRECIP UNTIL 06Z SUNDAY OR
LATER...WHILE THE GFS EFFECTIVELY DRIES US OUT BY THAT POINT UNTIL
THE COLD FRONT ARRIVES ON MONDAY.

A PREFERENCE OF THE ECWMF/GEM BLEND IS SUGGESTED IN OUR GRIDS AT
THIS POINT WITH THE HIGHEST POPS FEATURED SATURDAY NIGHT AND SUNDAY
MORNING. HOWEVER...IT IS NOTED THAT THE GEM ALSO SEEMS TO BE
STRUGGLING WITH CONVECTIVE DEVELOPMENT WITH THE LIKELY EXCESSIVE 60
KT LLJ IT DEVELOPS ACROSS OUR CWA BY 12Z SUNDAY. THIS IS NOT
INDICATED BY THE ECMWF...SO SHOULD NOT EXPLICITLY FOLLOW THE GEM IN
THIS CASE. NEVERTHELESS A BLEND OF THE ECMWF/GEM SHOULD INDICATE THE
GENERAL TREND IN TIMING AND LOCATION OF PRECIP.

THE ECMWF HAS TRENDED FURTHER NORTH WITH CONVECTIVE DEVELOPMENT FOR
SATURDAY NIGHT MORE INTO THE HEART OF OUR CWA...WHICH THE GEM WAS
SUGGESTING WITH YESTERDAY`S 12Z RUN. WITH A STRONG ULJ MOVING IN FOR
MID JULY STANDARDS...COULD SEE SOME STRONGER WIND GUSTS MIX DOWN TO
THE SURFACE WITH THESE STORMS. SIGNIFICANT RAINFALL IS ALSO A THREAT
FROM 00Z SUN THRU 00Z MON BUT QPF GRIDS ARE CURRENTLY ON THE
CONSERVATIVE SIDE. EXPECTING AT LEAST SCATTERED SHOWERS/STORMS AHEAD
OF THE COLD FRONT ON MONDAY WITH GUSTY WINDS AGAIN A POTENTIAL
THREAT...ESPECIALLY WITH 60-70 KT WINDS AT 500 MB.

DEEP CLOSED 500 MB LOW SWINGS INTO NORTHERN LOWER MI BY 12Z TUESDAY
WITH 850 MB TEMPS CRASHING INTO THE 4-5C RANGE AT THAT TIME. WITH A
NW BREEZE ON TUESDAY...IT WILL FEEL MORE LIKE SEPTEMBER THAN JULY 15
WITH TEMPS MAINLY IN THE 60S TO NEAR 70. HEIGHT RISES ALREADY ENSUE
BY WEDNESDAY SO A MODERATION INTO THE 70S LOOKS LIKELY FOR WEDNESDAY
AND BEYOND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 121 PM EDT WED JUL 9 2014

MINIMAL IMPACTS TO AIR TRAVEL EXPECTED FOR THIS TAF PERIOD WITH
VFR CONDITIONS ANTICIPATED. THE ONLY THREAT THIS AFTERNOON WOULD
BE AN ISOLATED SHOWER THAT COULD POP UP AND/OR SURVIVE A TRIP
ACROSS LAKE MICHIGAN. PUT VCSH IN THE MKG TAF TO COVER THIS LOW
THREAT...BUT LIKE YESTERDAY IT IS POSSIBLE A SHOWER COULD CLIP THE
AIRPORT. OTHER THAN THIS...WINDS GO LARGELY CALM OVERNIGHT AND
SKIES CLEAR OUT.


&&

.MARINE...
ISSUED AT 314 PM EDT WED JUL 9 2014

WINDS AND WAVES WILL CONTINUE TO BE RELATIVELY LIGHT THE NEXT
COUPLE DAYS. SOUTH WINDS WILL PICK UP THIS WEEKEND AND
THUNDERSTORMS ARE EXPECTED SATURDAY AND SUNDAY.

&&

.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...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...HOVING
AVIATION...HOVING
HYDROLOGY...TJT
MARINE...OSTUNO






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