Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 290421
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1221 AM EDT MON JUN 29 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 313 PM EDT SUN JUN 28 2015

AN UPPER TROUGH WILL REMAIN OVER THE GREAT LAKES THIS WEEK. THAT
MEANS COOLER THAN NORMAL TEMPERATURES AND CHANCES OF RAIN. WE/LL SEE
HIGHS IN THE 70S AND LOWS IN THE 50S.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 313 PM EDT SUN JUN 28 2015

A FAIRLY DEEP UPPER TROUGH WILL REMAIN ENTRENCHED OVER THE GREAT
LAKES FOR THE SEVERAL DAYS. AS IS USUALLY THE CASE...SEVERAL SHORT
WAVES WILL MOVE THROUGH THE FLOW AND INFLUENCE OUR WEATHER ACROSS
SOUTHWEST LOWER MICHIGAN.

LATEST SATELLITE IMAGERY SHOWS SCATTERED THUNDERSTORMS ALONG THE
MISSISSIPPI FROM MINNESOTA SOUTH TOWARD ST LOUIS. THIS CONVECTION IS
ASSOCIATED WITH LOW PRESSURE OVER IOWA. THIS LOW IS PROGD TO
CONTINUE THROUGH THE UPPER FLOW TO INDIANA BY MONDAY. THE BULK OF
THE PCPN WILL REMAIN JUST SOUTH OF THE MI/IN BORDER. HOWEVER SOME OF
IT WILL MAKE IT NORTH OF THE BORDER AND SO WE/LL HAVE LIKELY POPS
OVER THE SOUTHERN CWA. A STRONGER SHORT WAVE WILL ROTATE SOUTH
AROUND THE UPPER TROUGH TUESDAY AND THAT/S WHEN WE`LL HAVE OUR BEST
CHANCE FOR PCPN. INSTABILITY IS PRETTY WEAK THROUGHOUT THE PERIOD AS
WE/LL BE ON THE NORTH SIDE OF THE UPPER JET...SO CHANCES OF HEARING
THUNDER AREN`T GREAT BUT NOT ZERO.



.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 313 PM EDT SUN JUN 28 2015

DRY WEATHER IS EXPECTED WEDNESDAY WITH NORTHWEST FLOW ALOFT BEHIND
AN EXITING SHARP UPPER TROUGH. A STRONG UPPER PV ANOMALY SEEN ON
WATER VAPOR IMAGERY THIS AFTERNOON WELL OFF THE NW U.S. COAST AND
SOUTH OF THE ALEUTIAN ISLANDS IS FORECAST BY SEVERAL OF THE MEDIUM
RANGE MODELS TO CREST THE WESTERN U.S. RIDGE AND REACH THE WESTERN
GREAT LAKES BY FRIDAY MORNING. THIS IS WHEN WE HAVE THE GREATEST
CHANCES FOR SHOWERS...AND POSSIBLY THUNDERSTORMS...FOR THE ENTIRE
PERIOD.

THERE IS SOME QUESTION HOW QUICKLY RAIN EXITS FRIDAY NIGHT INTO
SATURDAY. THE GFS IS SLOWER IN DOING THIS THAN THE ECMWF...WHICH IS
TYPICAL. OFTEN IN THESE SITUATIONS WITH AN OPEN UPPER WAVE THE
FASTER SOLUTION WINS...SO WE MAY SEE DECREASING RAIN CHANCES FOR
SATURDAY WITH SUBSEQUENT MODEL RUNS.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1216 AM EDT MON JUN 29 2015

VFR CONDITIONS SHOULD PREVAIL OVERNIGHT AND LATER TODAY. WILL
HAVE TO MONITOR FOR POTENTIAL FOR BRIEF MVFR CONDITIONS TO DEVELOP
AFTER 12Z MONDAY MAINLY AT OUR SOUTHERN TERMINALS DUE TO LOWERING
CIGS AND SOME SHOWERS. HOWEVER NOT ENOUGH CONFIDENCE TO FORECAST
MVFR CONDITIONS AT THIS TIME SINCE CIGS SHOULD GENERALLY STAY UP
AROUND 3.5 TO 5 KFT AGL MONDAY. VFR CONDITIONS WILL THEN CONTINUE
THROUGH MONDAY EVENING. WIND SPEEDS THE NEXT 24 HRS SHOULD STAY
AOB 10 KTS.

&&

.MARINE...
ISSUED AT 313 PM EDT SUN JUN 28 2015

LOW PRESSURE NEAR THE GREAT LAKES WILL RESULT IN A WEAK PRESSURE
GRADIENT WHICH MEANS FAIRLY LIGHT WINDS AND LOW WAVES OVER THE
NEARSHORE FOR THE NEXT FEW DAYS.


&&

.HYDROLOGY...
ISSUED AT 200 PM EDT SUN JUN 28 2015

SEVERAL RIVER FLOOD ADVISORIES REMAIN IN THE GRAND AND KALAMAZOO
BASINS AS RIVERS ARE OUT OF THEIR BANKS IN SOME LOCATIONS. BASIN
AVERAGE RAINFALL OF A QUARTER INCH OR LESS MONDAY THROUGH TUESDAY
WILL HAVE A NEGLIGIBLE IMPACT ON RIVERS. SIGNIFICANT FLOODING IS
NOT EXPECTED THIS WEEK AS THE HEAVIEST RAIN PRODUCING SYSTEMS STAY
SOUTH AND EAST OF THE GREAT LAKES REGION.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...TJT
AVIATION...LAURENS
HYDROLOGY...CAS
MARINE...04


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