Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 071740
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
140 PM EDT TUE JUL 7 2015

LATEST UPDATE...
AVIATION

.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.

&&

.UPDATE...
ISSUED AT 1203 PM EDT TUE JUL 7 2015

FORECAST GOING AS PLANNED...WITH SHOWERS AND LIGHT RAIN
PROGRESSING OFF TO THE SOUTH AND EAST. THE COLD FRONT HAS
PROGRESSED ALL THE WAY INTO JACKSON COUNTY AS OF 1130 AM. THE
BACK EDGE OF THE PRECIPITATION SHOULD BE OUT OF THE FORECAST AREA
BY 200 PM.

CLOUD FORECAST IS A BIT MORE OF AN ISSUE AS CUMULUS CLOUDS ARE
ALREADY FILLING IN WHERE SOME CLEARING AS TAKEN PLACE. CUMULUS
SCHEME AS WELL AS CYCLONIC FLOW LINGERING AT 850MB/S SUPPORTS
THIS. BASED ON MODEL GUIDANCE OF THESE FIELDS WE SHOULD SEE BROKEN
CUMULUS FILL IN OVER MUCH OF THE CWA THROUGH THE AFTERNOON. SO IN
GENERAL EXPECTING PARTLY CLOUDY SKIES ONCE THE LAYERED FRONTAL
CLOUDS CLEAR OUT TO THE EAST.

HIGHS WILL TOP OUT IN THE UPPER 60S TO LOWER 70S IN MOST
LOCATIONS.

&&

.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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 137 PM EDT TUE JUL 7 2015

INITIAL CONCERN FOR 18Z TAFS IS WITH CLEARING LOW CLOUDS.  SATELLITE
LOOPS AND METARS SHOW A CONTINUED PROGRESSION OF CLEARNING OF LOW
CLOUDS FROM NORTHWEST TO SOUTHEAST...AND EXPECT THESE TO EXIT KJXN
BY MID AFTERNOON. HOWEVER...AN AREA OF POST FRONTAL CUMULUS HAS
DEVELOPED OVER NORTHWEST LOWER MICHIGAN NEAR KCAD AND KRQB...AND
MODELS INDICATE THIS AREA SHOULD ADVECT/DEVELOP INTO CENTRAL
MICHIGAN THIS AFTERNOON. DO NOT EXPECT THESE CLOUDS TO AFFECT
KMKG...BUT OTHER TAF SITES SHOULD SEE AT LEAST SCATTERED CLOUDS
WITH THIS FEATURE. WILL KEEP CEILINGS IN PLACE AT KJXN UNTIL
AROUND MIDNIGHT AS A RESULT.

OTHER CONCERN FOR THIS TAF ISSUANCE IS THE POTENTIAL FOR FOG
DEVELOPMENT OVERNIGHT INTO EARLY WEDNESDAY MORNING. BUFKIT
SOUNDINGS SUGGEST THAT LOW LEVEL MOISTURE WILL BE PRESENT...BUT
SURFACE TEMPERATURES WILL NOT GET COOL ENOUGH TO CREATE DENSE FOG.
WITH PRECIPITATION OVER FOR ALL TAF SITES AND NORTH WINDS/AT LEAST
PARTIAL CLEARING EXPECTED THROUGH SUNSET...SOME OF THE SURFACE
MOISTURE WILL BE MIXED OUT AS WELL.

&&

.MARINE...
ISSUED AT 1203 PM EDT TUE JUL 7 2015

STRETCHED THE SMALL CRAFT ADVISORY AND THE BEACH HAZARD STATEMENT
FURTHER INTO THE NIGHT...THROUGH 5 AM...ACROSS THE SOUTHERN 3
MARINE ZONES. THE NORTH FLOW WILL KEEP WAVES UP IN THESE AREAS
DEEPER INTO THE NIGHT. SO...THE NORTHERN HALF ENDS AT 11
PM...WHILE THE SOUTH HEADLINES CONTINUE THROUGH 5 AM.

BEACH HAZARD/WAVE EVENT GOING DOWN AS EXPECTED...WITH LARGE WAVES
AFFECTING MOST BEACHES. THE SOUTHERN BUOYS AT SOUTH HAVEN AND OFF
OF BRIDGMAN HAVE HIT 7 FEET ALREADY. THE CORE OF WIND ACTUALLY
MOVES THROUGH THIS AFTERNOON...SO WINDS AND WAVES MAY INCREASE A
BIT AS WE MOVE THROUGH THE 200 PM TO 800 PM TIME FRAME. DANGEROUS
SWIMMING CONDITIONS ARE OCCURRING...ESPECIALLY IN THE SOUTHERN
MARINE ZONES. NORTH SIDES OF NORTH PIERS ARE DANGEROUS SPOTS TODAY
ESPECIALLY IN THE SOUTH AT HOLLAND STATE PARK AND NORTH BEACH IN
SOUTH HAVEN. WEBCAMS CONFIRM WAVES ROLLING UP AND OVER THE PIERS
THERE.

WINDS AND WAVES WILL SLOWLY SUBSIDE TONIGHT. WINDS WILL ALSO BE
TURNING OFFSHORE OUT OF THE NORTHEAST WHICH SHOULD LAY THE WAVES
DOWN FAIRLY QUICK OVERNIGHT.


&&

.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.

&&

$$

UPDATE...DUKE
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...04
AVIATION...MWS
HYDROLOGY...JAM
MARINE...DUKE



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