Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 270725
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
325 AM EDT WED MAY 27 2015

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

.SYNOPSIS...
ISSUED AT 310 AM EDT WED MAY 27 2015

AN AREA OF LOW PRESSURE OVER LAKE SUPERIOR WILL TRACK AWAY FROM
THE REGION TODAY. THIS SYSTEM COULD STILL PRODUCE SOME SHOWERS AND
THUNDERSTORMS FOR THE REGION. TONIGHT AND THURSDAY A RIDGE OF HIGH
PRESSURE WILL BUILD IN FROM THE WEST. THIS SHOULD SUPPORT
RELATIVELY DRY AND WARM CONDITIONS. A SLOW MOVING COLD FRONT WILL
TRACK THROUGH THE GREAT LAKES REGION FRIDAY INTO SATURDAY CAUSING
SHOWERS AND THUNDERSTORMS FOR THE AREA.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 310 AM EDT WED MAY 27 2015

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR
THUNDERSTORMS TODAY.

MODELS SHOW THE ATMOSPHERE BECOMING UNSTABLE AGAIN
TODAY...PRIMARILY SOUTHEAST OF A HOLLAND TO MOUNT PLEASANT LINE.
NORTHWEST OF THIS LINE FORECAST SOUNDINGS THIS AFTERNOON DO NOT
SHOW MUCH CAPE ABOVE THE FREEING LEVEL. AS A RESULT I WILL
DOWNPLAY THE THUNDER RISK THERE. FURTHER SOUTHEAST SURFACE BASED
INSTABILITY LOWERS TO AT LEAST -3 DEG C AND SHOULD SUPPORT SOME
STORMS. DEEP LAYER SHEAR IS STILL FAVORABLE FOR ORGANIZED
CONVECTION...ESPECIALLY TOWARDS JACKSON. THUS AN ISOLATED SEVERE
STORM COULD OCCUR THERE.

I DO HAVE HIGHER POPS NORTHWEST OF GRAND RAPIDS...TOWARD
LUDINGTON. MODELS SUGGESTS THE TROWAL WILL PIVOT INTO THE
LUDINGTON REGION THIS AFTERNOON.

WILL MAINTAIN A MAINLY DRY FORECAST FOR TONIGHT THROUGH THURSDAY.
WILL NEED TO MONITOR THE POTENTIAL FOR AN ISOLATED STORM ON ANY
LAKE BREEZE THAT FORMS. SHOULD BE WARM GIVEN THE STRENGTHENING
WARM AIR ADVECTION THAT SHOWS UP IN THE AFTERNOON.

HIGH POPS WARRANTED FOR FRIDAY AS THE DEEPER MOISTURE ARRIVES FROM
THE WEST WITH A SLOW MOVING COLD FRONT APPROACHING. BETTER
INSTABILITY COULD SUPPORT SOME STRONGER STORMS



.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 310 AM EDT WED MAY 27 2015

A SLOW MOVING COLD FRONT WILL COMBINE WITH HIGH PRECIPITABLE WATER
VALUES AND STRONG LOW LEVEL CONVERGENCE TO BRING POTENTIAL FOR HEAVY
RAIN AND THUNDERSTORMS FRIDAY NIGHT. RAINFALL TOTALS OF AN INCH OR
TWO WITH LOCALLY HIGHER AMOUNTS ARE POSSIBLE.

A CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE CONTINUES TO INDICATE
HIGH PRESSURE WILL BUILD IN FROM THE NORTH AND BRING CLEARING SKIES
SATURDAY AND COOL AND FAIR WEATHER SATURDAY AFTERNOON THROUGH SUNDAY
INTO EARLY NEXT WEEK.

TEMPERATURES COULD DROP INTO THE 30S ACROSS COLDER LOCATIONS OF
ROUGHLY THE NORTHERN HALF OF OUR FORECAST AREA DURING THE EARLY
MORNING HOURS SUNDAY AND MONDAY. TEMPERATURES WILL THEN UNDERGO A
GRADUAL MODERATING TREND FOR THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY)
ISSUED AT 1155 PM EDT TUE MAY 26 2015

PRIMARILY VFR CONDITIONS WILL GRADUALLY DETERIORATE TO MAINLY MVFR
DURING THE EARLY TO MID MORNING HOURS WEDNESDAY DUE TO DEVELOPMENT
OF PATCHY FOG. CONDITIONS WILL GRADUALLY IMPROVE TO VFR LATE
WEDNESDAY MORNING BUT WINDS WILL VEER TO THE WSW AND INCREASE TO 15
TO 20 KTS WITH GUSTS TO 25 KTS BY LATE MORNING THROUGH WEDNESDAY
AFTERNOON. VFR CONDITIONS WILL CONTINUE THROUGH WEDNESDAY EVENING.


&&

.MARINE...
ISSUED AT 310 AM EDT WED MAY 27 2015

I SAW MANISTEE GUSTING OVER 30 KNOTS EARLIER AND LUDINGTON CLOSE
TO 30 KNOTS. THIS IS STRONGER THAN THE MODELS WERE SHOWING. GIVEN
THESE HIGHER WINDS...THE FORECAST FEATURES SMALL CRAFT WINDS AND
WAVES FOR MUCH OF THE REGION.

MODELS ALSO SUGGEST FOG COULD BE OVER THE LAKE TODAY. WILL HAVE
THAT IN THE FORECAST...ESPECIALLY WITH HIGH LOW LEVEL MOISTURE
VALUES ADVECTING IN FROM THE WEST.

&&

.HYDROLOGY...
ISSUED AT 113 PM EDT TUE MAY 26 2015

RIVER LEVELS ARE LOW AND STABLE. EXPECTING 1/2 TO 3/4 OF AN INCH OF
PRECIPITATION THROUGH WEDNESDAY. THIS SHOULD LEAD TO SLOWLY
INCREASING RIVER LEVELS BY WEDNESDAY. EXPECTING NO OR MINOR/NUISANCE
FLOODING BY WEEKS END.

A POTENTIAL FOR MORE RAIN FRIDAY INTO SUNDAY (OVER AN INCH) MAY PUSH
SOME STREAMS AND RIVERS ABOVE BANKFULL BY NEXT WEEK... IF THESE
AMOUNTS ARE REALIZED.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 11 AM EDT THIS MORNING FOR MIZ037-
     043-050-056-064.

LM...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR LMZ845>849.

&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...63
MARINE...MJS


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