Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 071537
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1137 AM EDT TUE JUL 7 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 315 AM EDT TUE JUL 7 2015

A COLD FRONT WILL SWEEP ACROSS SOUTHWEST MICHIGAN DURING THE MID
MORNING HOURS OF TODAY. SHOWERS AND A FEW THUNDERSTORMS ARE
EXPECTED THIS MORNING AS THE FRONT MOVES THROUGH THE AREA. SKIES
WILL CLEAR DURING THE MID TO LATE AFTERNOON AS COOLER AND DRIER
AIR MOVES IN BEHIND THE FRONT. HIGH PRESSURE WILL BRING MOSTLY
SUNNY SKIES WEDNESDAY WITH HIGHS ONLY IN THE 70S. A WAVE ON THE
FRONT MAY BRING RAIN BACK TO THE AREAS NEAR AND SOUTH OF I-94
THURSDAY.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 315 AM EDT TUE JUL 7 2015

THE PRIMARY ISSUE TODAY IS THE COLD FRONTAL PRECIPITATION EVENT
ALREADY UNDERWAY AS I WRITE THIS. THE SECOND ISSUE THE THE WAVE ON
THE FRONT THAT PASSES SOUTH OF THE AREA ON THURSDAY.

THE RAIN BAND WITH THE FRONT SHOULD CLEAR THE AREA BY MID TO LATE
AFTERNOON. THE THREAT FOR SEVERE STORMS SEEMS RATHER LOW SINCE THE
FRONT IS COMING THROUGH MID MORNING AND THERE IS EXTENSIVE CLOUDS
AND SHOWERS AROUND. THAT WILL LIMIT THE INSTABILITY NEEDED FOR
STRONGER THUNDERSTORMS. THE EXTENSIVE AREA OF RAIN WITH THE FRONT
IS BEING HELPED BY THE DEEP LIFT CREATED BY THE ENTRANCE REGION
THE 95 KNOT POLAR JET...CROSSING LAKE SUPERIOR THIS MORNING. ONCE
THAT IS OUT OF THE WAY...SKIES SHOULD CLEAR FROM WEST TO EAST.

HIGH PRESSURE WILL KEEP WEDNESDAY MOSTLY SUNNY WITH AFTERNOON
TEMPERATURES MOSTLY IN THE 70S. THE NEXT WAVE ON THE FRONT NOW
LOOKS LIKE IT WILL MOSTLY TRACK JUST SOUTH OF STATE THURSDAY. THAT
SYSTEM IS A SOUTHERN STREAM WAVE THAT LIFTS NORTHEAST INTO
CONFLUENT FLOW FROM THE POLAR JET OVER MICHIGAN THURSDAY. THAT
SHOULD HELP KEEP THAT SYSTEM JUST SOUTH OF THIS AREA. STILL IT IS
NOT OUT OF THE QUESTION AREAS NEAR AND SOUTH OF I-94 COULD SEE A
LITTLE RAIN THURSDAY. IF NOTHING ELSE TEMPERATURES WILL BE ON THE
COOL SIDE OF NORMAL NOW FOR SEVERAL DAYS.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 315 AM EDT TUE JUL 7 2015

THE MAIN FOCUS OF THE LONG TERM WILL BE THE MOVEMENT OF A WARM FRONT
NORTH THROUGH THE CWA OVER THE WEEKEND. CONFIDENCE IS INCREASING
THAT PART OF THE WEEKEND WILL BE WET. BOTH THE ECMWF/GFS SHOW SFC
HIGH PRESSURE MOVING EAST AND A WARM FRONT OVER THE NORTHERN OHIO
VALLEY LIFTING NORTH THROUGH THE CWA SATURDAY/SATURDAY NIGHT. THERE
SHOULD BE A DECENT AMOUNT OF MOISTURE WITH THIS SYSTEM AS GULF
MOISTURE WILL GET WRAPPED AROUND THE WEST SIDE OF THE UPPER
RETROGRADING BERMUDA HIGH. PRECIPITABLE  WATER VALUES AROUND 2
INCHES SUGGESTS THAT HEAVY RAINFALL WILL BE POSSIBLE SATURDAY
NIGHT. SHEAR VALUES AROUND 35KTS COUPLED WITH LI/S AROUND -4C MAY
RESULT IN A FEW STRONG STORMS TOO. UPPER WAVES MOVING AROUND THE
TOP OF THE BERMUDA HIGH WILL NECESSITATE KEEPING POPS IN THE GRIDS
THROUGH MONDAY.

HIGHS WILL MOSTLY BE IN THE 80S DURING THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 728 AM EDT TUE JUL 7 2015

AN AREA OF IFR CIGS FOLLOWS THE COLD FRONT WITH A PERIOD OF
SHOWERS. THE EXTENSIVE CLOUD COVER WILL PREVENT ANY SIGNIFICANT
THUNDERSTORMS FROM DEVELOPING BUT EVEN SO...DUE TO 2 INCHES OF
PRECIPITABLE WATER IN THE AIR...SOME OF THE SHOWERS WILL BE VERY
HEAVY...IF ONLY BRIEFLY SO. WITH THE COLD AIR COMING IN...EXPECT
GUSTY NORTH WINDS MOST OF THE DAY TIME HOURS AT ALL OF OUR TAF
SITES...ONCE THE FRONT GETS THROUGH. THAT MAY NOT BE TILL 15Z AT
JXN. CLEARING WILL FOLLOW QUICKLY THIS AFTERNOON...BY 21Z MOST OF
OUR TAF SITES SHOULD BE VFR. HIGH PRESSURE BUILDS IN TONIGHT SO
WINDS WILL BECOME LIGHT FROM THE NORTH.


&&

.MARINE...
ISSUED AT 315 AM EDT TUE JUL 7 2015

NOT MUCH CHANGE IN THE MARINE HEADLINES. NORTH WINDS OF 15 TO 25
KNOTS SHOULD BUILD WAVES TO 3 TO 5 FEET BY MID MORNING SO IT MAKES
SENSE TO KEEP THE HEADLINES JUST AS THEY ARE. I EXPUNGED THE FOG
FROM THE NEAR SHORE FORECAST AS IT DOES NOT LOOK THIS THIS WOULD
BE MUCH OF AN ISSUE GIVEN HOW COOL AND DRY THE FOLLOWING THE FRONT
REALLY IS.


&&

.HYDROLOGY...
ISSUED AT 1137 AM EDT TUE JUL 7 2015

LOCALLY HEAVY RAIN FELL IN THE PAST 12 HOURS OR SO AROUND AND
NORTH OF MUSKEGON. FURTHER SOUTHEAST ACROSS SOUTHWEST LOWER
MICHIGAN...HIGHER RAINFALL TOTALS WERE A BIT MORE SCATTERED. THIS
HAS RESULTED IN MINOR UPWARD TRENDS ON AREA RIVERS AND STREAMS.
THERE ARE NO IMMEDIATE CONCERNS FOR RIVER FLOODING. HOWEVER...THIS
MAY BECOME A CONCERN HEADING INTO NEXT WEEKEND.

DRY CONDITIONS ARE EXPECTED FOR THE NEXT 24 TO 36 HOURS BEFORE
ANOTHER ROUND OF PRECIPITATION REACHES THE SOUTHERN THIRD OF THE
FORECAST AREAS...MAINLY ALONG AND SOUTH OF I-94. SOME OF THE RAIN
MAY MAKE UP TO I-96 BUT IS EXPECTED TO BE LIGHTER ON THE TOTALS
ALONG THE NORTHERN FRINGES OF THE PRECIPITATION FIELD.

THE FRIDAY THROUGH SUNDAY TIMEFRAME IS STILL THE MAIN FOCUS WITH A
BOUNDARY THAT DRIFTS NORTHWARD LATE IN THE WEEK. PENDING BOUNDARY
PLACEMENT...ROUNDS OF SHOWERS AND THUNDERSTORMS COULD ADD UP TO
GENERAL TOTALS OF 1-2 INCHES. LOCALLY HIGHER AMOUNTS ARE CERTAINLY
POSSIBLE WITH THE GREATEST THREAT FOR HEAVY RAINFALL EXISTING
ACROSS THE SOUTHERN HALF OF THE CWA...ALONG I-96 AND SOUTH. GIVEN
RECENT RAINFALL AND PENDING WEDNESDAY NIGHT INTO THURSDAYS
ROUND...WEEKEND RAINFALL COULD ACT MORE AS RUNOFF AND LEAD TO
QUICKER RESPONSES ON RIVERS. RIVER FLOODING MAY BE SOMETHING WE
NEED TO MONITOR THROUGH THE WEEKEND.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH LATE TONIGHT FOR MIZ056-064-071.

     BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037-
     043-050.

LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ847>849.

     SMALL CRAFT ADVISORY UNTIL 5 AM EDT WEDNESDAY FOR LMZ844>846.

&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...04
AVIATION...WDM
HYDROLOGY...JAM
MARINE...WDM


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