Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 292325
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
725 PM EDT WED JUL 29 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 PM EDT WED JUL 29 2015

A COLD FRONT IS MOVING ACROSS LOWER MICHIGAN THIS AFTERNOON. SHOWERS
AND THUNDERSTORMS HAVE ALREADY MOVED EAST OF SOUTHWEST LOWER
MICHIGAN. DRIER AIR IS NOW POISED TO MOVE OVER MICHIGAN AND PRODUCE
PARTLY CLOUDY SKIES FOR THE NEXT COUPLE OF DAYS. A WEAK AREA OF LOW
PRESSURE MAY GENERATE A SHOWER OR STORM FRIDAY NIGHT BUT THEN MUCH
OF THE WEEKEND WILL BE DRY.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 328 PM EDT WED JUL 29 2015

FORECAST CONCERNS DEAL WITH PCPN CHANCES FRIDAY NIGHT. NOW THAT THE
COLD FRONT AS MOVES ACROSS THE CWA...SKIES WILL CLEAR AND DEWPOINTS
WILL CONTINUE TO FALL. ALREADY DEWPOINTS IN THE LOWER TO MID 50S
HAVE MOVED OVER THE NW CWA. A COMFORTABLE COUPLE OF DAYS IS EXPECTED
WITH NW FLOW ALOFT AND A SFC HIGH NEARBY. HIGHS NEAR TO SLIGHTLY
ABOVE NORMAL ARE EXPECTED THURSDAY AND FRIDAY BEFORE A SHORT WAVE
MOVES ACROSS NORTHERN LOWER FRIDAY NIGHT. THIS WAVE MAY RESULT IN
SOME SCATTERED SHOWERS OR PERHAPS A STORM BUT IS NOT A BIG SYSTEM
AND SHOULD BE OUT OF THE CWA BY SATURDAY MORNING. THE LLJ FRIDAY
NIGHT IS WEAK AND PWATS ARE CLOSER TO AN INCH. MOST LOCATIONS WILL
BE DRY FRIDAY NIGHT.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 328 PM EDT WED JUL 29 2015

OUR OVERALL MESSAGE FOR THIS COMING WEEKEND INTO NEXT WEEK HAS
REALLY BEEN RATHER CONSISTANT. WE EXPECT THE WEATHER PATTERN TO
BECOME MORE ACTIVE AND TEMPERATURE WILL GRADUALLY COOL OVER TIME.
STILL THROUGH... AND WE ALSO HAVE BEEN SAYING THIS...WHILE WE WILL
LIKELY BE SEEING SOME RAINFALL IN THE SUNDAY THROUGH WEDNESDAY TIME
FRAME THE AMOUNT OF RAIN IN ANY ONE PLACE WILL BE LIGHT...THAT IS
LESS THAN A HALF INCH.

WE ALREADY HAVE THE CLOSED UPPER LOW OVER HUDSON BAY THAT WE HAVE
BEEN WRITING ABOUT FOR OVER A WEEK NOW. OVER TIME A SERIES OF
SHORTWAVES WILL SLOWLY DEEPEN THE EAST COAST TROUGH... EACH SHOTWAVE
BRING DOWN COLDER AIR THAN THE ONE BEFOR IT. FINALLY THE ECMWF AND
GFS ARE IN AGREEMENT THAT THE SYSTEM THAT COMES THROUGH IN THE
TUESDAY TIME FRAME WILL BE FOLLOWED BY THE COLDEST AIR WE HAVE SEEN
SINCE EARLY JULY.

AS FOR SOMETHING TO WATCH FOR BEYOND WEDNESDAY...WHICH WOULD MEAN
EVEN COLDER TEMPEATURES. THERE IS A CLOSED UPPER LOW NEAR THE NORTH
POLE (THIS MORNING)...JUST NORTH OF ALASKA. THIS SYSTEM SLOWLY
DEVELOPES SOUTHEAST OVER TIME... BY TUESDAY IT WILL BE APPROCHING
HUDSON BAY. IF THIS CAN COME DOWN A TOUCH FARTHER SOUTH... WE WILL
SEE THE COLDEST AIR WE HAVE SEEN IN SEVERAL MONTHS.

AS FOR THE DAILY WEATHER...THERE ARE CURRENTLY TWO SYSTEMS THAT WE
ARE WATCHING. THE FIRST ONE COMES THROUGH SUNDAY THEN THE MORE
SIGNIFCANT ONE ON TUESDAY. EACH ARE NORTHERN STREAM SHORTWAVES WITH
DECENT COLD FRONTS FOLLOWING THEM. EACH WILL HAVE SHOWERS AND
POSSIBLY THUNDERSTORMS WITH IT (BUT LIMITED RAINFALL) AND EACH WILL
HAVE COOLER AIR THEN THE PREVIOUS COLD FRONT BROUGHT. HIGHS WILL
FALL INTO THE 70S BY WEDNESDAY. AFTER ABOUT 2 WEEKS OF HIGHS IN THE
80S EACH DAY(AWAY FROM THE LAKE MICHIGAN SHORE)...THAT STREAK SHOULD
COME TO AN END BY WEDNESDAY.

BOTTOM LINE...THINK RAIN SHOWERS AND COOLER.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 725 PM EDT WED JUL 29 2015

VFR WEATHER IS EXPECTED THROUGH THURSDAY EVENING. CLEAR SKIES ARE
EXPECTED OVERNIGHT AND ON THURSDAY. WESTERLY WINDS AROUND 10 KTS
OCCASIONALLY GUSTING TO 15-20 KTS ARE EXPECTED EARLY THIS EVENING.
WINDS WILL SUBSIDE SOMEWHAT TOWARD SUNSET. WINDS SHOULD STAY UP
BETWEEN 5-10 KTS OVERNIGHT. WESTERLY WINDS WILL INCREASE ON
THURSDAY AFTER 13-14Z AND PEAK FROM AROUND NOON THROUGH THE
AFTERNOON. SUSTAINED WESTERLY WINDS AROUND 15 KTS WITH GUSTS TO 25
KTS ARE EXPECTED FROM LATE THURSDAY MORNING THROUGH THE AFTERNOON.

&&

.MARINE...
ISSUED AT 328 PM EDT WED JUL 29 2015

AS HIGH PRESSURE MOVES TOWARD LAKE MICHIGAN WEST WINDS WILL INCREASE
TO 15 TO 20 KNOTS TONIGHT AND WAVES WILL BUILD TO 2 TO 4 FEET. IT/S
POSSIBLE THAT WINDS MAY INCREASE TO 25 KNOTS WITH WAVES BUILDING TO
3 TO 5 FEET...BUT THAT WAS FAR FROM CERTAIN. SO A SCA WAS NOT
ISSUED...BUT IS SOMETHING TO KEEP AN EYE ON.


&&

.HYDROLOGY...
ISSUED AT 1151 AM EDT WED JUL 29 2015

RIVER LEVELS ARE FALLING AND WELL BELOW BANKFULL. THE MAIN CHANCE OF
RAIN IN THE NEXT 7 DAYS WOULD BE SUNDAY INTO MONDAY NIGHT. LOCALLY
HEAVY RAIN IS POSSIBLE... BUT ONLY PONDING OF WATER IS EXPECTED AWAY
FROM THE RIVERS. RIVERS MAY SHOW RISES... BUT SHOULD NOT REACH BANK
FULL LEVELS.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...WDM
AVIATION...EBW
HYDROLOGY...63
MARINE...04



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