Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 281730
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
130 PM EDT THU MAY 28 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 307 AM EDT THU MAY 28 2015

HIGH PRESSURE WILL DOMINATE THE WEATHER TODAY KEEPING THE WEATHER
MAINLY DRY AND WARM. AN ISOLATED THUNDERSTORM COULD POP UP AND
PRODUCE A BRIEF PERIOD OF RAIN. ON FRIDAY A COLD FRONT WILL SLOWLY
APPROACH THE GREAT LAKES REGION AND TRACK THROUGH MICHIGAN ON
SATURDAY. THIS SYSTEM WILL LEAD TO SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS. A COOLER AIRMASS MOVES IN BEHIND THE FRONT FOR THE
REMAINDER OF THE WEEKEND.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 307 AM EDT THU MAY 28 2015

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND
COVERAGE OF ANY SHOWERS AND THUNDERSTORMS.

TO START...IT LOOKS LIKE AN ISOLATED SHOWERS OR THUNDERSTORMS
COULD DEVELOP THIS AFTERNOON MAINLY ON THE LAKE BREEZE. IT BECOMES
UNSTABLE AND THE INCREASED CONVERGENCE COULD ALLOW FOR THIS TO
HAPPEN. THUS I ADDED A MENTION OF A THUNDERSTORM IN THE FORECAST.
UPON SUNSET...THE ATMOSPHERE SHOULD STABILIZE. EASTERLY FLOW
ESPECIALLY SOUTH OF GRAND RAPIDS SHOULD SUPPORT WARM
TEMPERATURES...ESPECIALLY ON THE LAKESHORE. TEMPERATURES WERE
INCREASED AS A RESULT WITH MOST LOCATIONS TOPPING OUT IN THE LOW
80S LIKELY.

MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED TO ARRIVE
BY FRIDAY NIGHT. THE COVERAGE ON FRIDAY MAY BE LIMITED DUE TO A
DELAY IN THE ARRIVAL OF THE DEEPER MOISTURE. HOWEVER AS THE DAY
EVOLVES WE SHOULD SEE THE ATMOSPHERE BECOMING UNSTABLE WHICH
SHOULD TRIGGER SCATTERED THUNDERSTORMS...ESPECIALLY INLAND. BY THE
END OF THE DAY...THE DEEPER MOISTURE WILL BE ARRIVING. THUS DURING
THE EVENING RATHER WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED.

THE RAIN WILL BE HEAVY IN PLACES FRIDAY NIGHT AND SATURDAY
MORNING. PRECIPITABLE WATER VALUES CLIMB TO OVER 1.5 INCHES AND
THE ATMOSPHERE WILL REMAIN UNSTABLE. LIFT ASSOCIATED WITH THE SLOW
MOVING FRONT WILL KEEP THE SHOWERS AND THUNDERSTORMS GOING. DEEP
LAYER SHEAR IS SHOWN TO BE ON THE LOW SIDE FRIDAY INTO EARLY
FRIDAY NIGHT. SO ANY STORMS THAT DO TRY TO BECOME SEVERE SHOULD BE
PULSE IN NATURE. BY SATURDAY MORNING STRONGER SHEAR MOVES IN WITH
THE FRONT. HOWEVER INSTABILITY WILL BE LIMITED. WILL NEED TO
MONITOR TRENDS CLOSELY. LOCALLY OVER AN INCH OF RAIN SHOULD FALL
IN A FEW LOCATIONS. I DID FEATURE A DIMINISHING TREND TO THE
SHOWERS AND THUNDERSTORMS SATURDAY AFTERNOON.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 307 AM EDT THU MAY 28 2015

HIGH PRESSURE WILL BUILD IN FROM THE NORTH SATURDAY NIGHT AND ALLOW
SKIES TO GRADUALLY CLEAR. THERE IS SOME POTENTIAL FOR PATCHY FROST
TO DEVELOP DURING THE EARLY MORNING HOURS SUNDAY MAINLY ACROSS OUR
FAR NORTH TO NE FCST AREA WHERE MIN TEMPS WILL FALL INTO THE 30S.
HOWEVER EASTERLY WINDS MAY STAY UP ENOUGH SATURDAY NIGHT TO INHIBIT
TEMPS FROM FALLING AS MUCH AS THEY POTENTIALLY COULD.

THE HIGH PRESSURE RIDGE WILL REMAIN IN CONTROL OF THE WX PATTERN
SUNDAY THROUGH EARLY NEXT WEEK AND RESULT IN FAIR AND COOL WEATHER.
THERE IS POTENTIAL FOR SOME PATCHY FROST TO DEVELOP ONCE AGAIN
DURING THE EARLY MORNING HOURS MONDAY ACROSS OUR FAR NNE FCST AREA.

SOUTHERLY RETURN FLOW ON THE BACK SIDE OF THE RIDGE WILL ALLOW TEMPS
TO MODERATE TUESDAY AND WEDNESDAY. THERE IS POTENTIAL FOR A FEW
SHOWERS AND STORMS TO DEVELOP BY WEDNESDAY AS WELL AS SOUTHERLY FLOW
RESULTS IN INCREASING MOISTURE IN AN AREA OF WEAK ISENTROPIC
UPGLIDE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 130 PM EDT THU MAY 28 2015

VFR CONDITIONS ARE EXPECTED THROUGH FRIDAY MORNING. THERE COULD BE
SOME SHALLOW FOG AT AZO AND JXN AGAIN TONIGHT BUT THIS WAS LEFT
OUT OF THE FORECAST FOR NOW. WINDS WILL BE SOUTH OR SOUTHWEST AOB
10 KNOTS THROUGH TONIGHT THEN INCREASE FRIDAY MORNING TO AOA 10
KTS WITH SOME GUSTS TO 20 KNOTS POSSIBLE BY EARLY AFTERNOON.
SHOWERS AND THUNDERSTORMS SHOULD HOLD OFF UNTIL AFTER 18Z.

&&

.MARINE...
ISSUED AT 307 AM EDT THU MAY 28 2015

THE PRESSURE GRADIENT REMAINS RELATIVELY WEEK TODAY...KEEPING
CONDITIONS WELL BELOW ADVISORY CRITERIA. WINDS WILL INCREASE
TONIGHT AS THE FRONT APPROACHES AND NEAR ADVISORY CRITERIA
CONDITIONS COULD DEVELOP...ESPECIALLY AROUND LITTLE AND BIG SABLE
POINTS. HAZARDOUS BOATING CONDITIONS ARE LIKELY FOR SATURDAY AS
THE WIND SHIFTS TO THE NORTH AND WAVES BUILD CONSIDERABLY.


&&

.HYDROLOGY...
ISSUED AT 1220 PM EDT THU MAY 28 2015

TOTAL QPF FRIDAY THROUGH SATURDAY WITH THE NEXT ROUND OF SHOWERS
AND THUNDERSTORMS CONTINUES TO TREND DOWNWARD AT AROUND AN INCH
OR LESS. GIVEN THAT BASE FLOWS ARE NEAR NORMAL IN THE GRAND RIVER
BASIN AND BELOW NORMAL IN THE KALAMAZOO BASIN...WE EXPECT MODEST
RISES WITH SOME SITES PERHAPS REACHING BANKFULL BUT NOTHING OF
GREAT SIGNIFICANCE. THE COMING WEEK LOOKS DRY WHICH SHOULD ALLOW
LEVELS TO FALL ONCE AGAIN.

&&

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

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...OSTUNO
HYDROLOGY...TJT
MARINE...MJS


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