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000
FXUS63 KGRR 151945
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
345 PM EDT SAT JUN 15 2013

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

.SYNOPSIS...
ISSUED AT 345 PM EDT SAT JUN 15 2013

A LOW PRESSURE SYSTEM WILL MOVE THROUGH THE GREAT LAKES REGION
TONIGHT BRINGING SHOWERS AND THUNDERSTORMS. SEVERE WEATHER IS NOT
EXPECTED. THE RAIN WILL COME TO AN END ON SUNDAY FROM NORTH TO
SOUTH. ANOTHER LOW WILL MOVE THROUGH THE AREA ON MONDAY BRINGING
ADDITIONAL SHOWERS AND STORMS TO THE AREA. CONDITIONS WILL DRY OUT
MONDAY NIGHT AS HIGH PRESSURE SETTLES INTO THE REGION. DRY WEATHER
IS THEN FORECAST FROM MONDAY NIGHT THROUGH THURSDAY AS THE HIGH ONLY
SLOWLY MOVES THROUGH. HIGHS WILL TOP OUT AROUND 80 DEGREES SUNDAY
AND MONDAY....FALLING BACK INTO THE 70S FOR TUESDAY THROUGH THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 345 PM EDT SAT JUN 15 2013

MAIN FORECAST ISSUE WAS DETERMINING CHANCES FOR PRECIPITATION AS A
COUPLE OF WEAK LOW PRESSURE SYSTEMS MOVE THROUGH THE REGION.

AS FOR TONIGHT...SOME QUESTION AS TO HOW WIDESPREAD THE
PRECIPITATION IS GOING TO BE...BUT FELT LIKELY CHANCES (60/70 PCT)
FOR SHOWERS AND STORMS WERE STILL WARRANTED. THE 850MB LLJ INCREASES
OVERNIGHT...WITH WIND CONVERGENCE LOCATED RIGHT OVER THE CWA.
MOISTURE TRANSPORT CONTINUES AT 850MB/S TONIGHT...ALBEIT OF LIGHT TO
MODERATE VALUES. FEEL THE HEAVIER RAINS WILL FALL ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA. A WEAK COLD FRONT MAY HELP TO
FOCUS PRECIPITATION AS WELL...ALTHOUGH CONVERGENCE IS NOT
IMPRESSIVE. UPSTREAM VORT OVER MINNESOTA AND IOWA WILL LIKELY BE THE
MAIN FORCING MECHANISM. WEAK INSTABILITY SHOULD BE ENOUGH FOR SOME
EMBEDDED STORMS.

THE PRECIPITATION WILL LINGER INTO SUNDAY ESPECIALLY IN THE SOUTH
AND SOUTHEAST. BY EARLY TO MID AFTERNOON THE FINAL VESTIGES OF
PRECIPITATION SHOULD BE EXITING THE SOUTHEAST CWA TOWARDS JACKSON. A
DRYING WEST AND NORTHWEST WIND SHOULD TAKE SKIES MOSTLY SUNNY.

SUNDAY NIGHT CONTINUED THE DRY FORECAST DESPITE A WEAK FRONT NUDGING
DOWN FROM THE NORTH ACROSS NORTHERN LOWER MICHIGAN. FEEL
PRECIPITATION WITH THIS FRONT WILL HOLD OFF UNTIL MONDAY. SCATTERED
SHOWERS AND STORMS EXPECTED WITH THIS FRONT MONDAY INTO MONDAY
EVENING. CONDITIONS DRY OUT MONDAY NIGHT WITH HIGH PRESSURE BUILDING
IN.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 345 PM EDT SAT JUN 15 2013

A COOLER TREND WAS NOTED ON THE MEDIUM RANGE MODELS AS THE MONDAY
NIGHT SHORT WAVE CONTINUES TO DEEPEN AS IT HEADS TOWARD NEW
ENGLAND.  THIS WILL HELP DRAG DOWN COOL CANADIAN AIR FROM THE
CENTRAL CONTINENT.  H8 TEMPS DIP TO AROUND 8C SO LOWERED TEMPS FOR
TUESDAY THROUGH WEDNESDAY...WITH HIGHS MAINLY 70 TO 75 EACH DAY AND
TUESDAY NIGHT LOWS WERE DROPPED TO 45 TO 50.  A SIGNIFICANT WARM UP
IS EXPECTED INTO THURSDAY AND EVEN WARMER ON FRI/SAT AS H8 TEMPS ARE
PROGGED TO INCREASE TO AROUND 18C...BRINGING MAX TEMPS TO 80 TO 85
FOR FRI/SAT.

THE COOLISH MID WEEK WILL BE CURIOSITY OF CANADIAN HIGH PRESSURE
THAT SHOULD BE MOVING OVER THE CWA BY WED.  SOUTHERLY WINDS BEHIND
THE HIGH WILL RESULT IN THE WARMING TREND LATER IN THE WEEK.  DRY
WEATHER IS EXPECTED THROUGH THURSDAY NIGHT.  THEN BY FRI/SAT
INCREASING GULF MOISTURE AND A COUPLE OF WEAK SHORT WAVES SHOULD
CREATE THE CHANCE OF SHOWERS AND STORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 146 PM EDT SAT JUN 15 2013

AN AREA OF LIGHT SHOWERS AND VFR WEATHER WAS MOVING ACROSS THE TAF
SITES AS OF 1730Z. INSTABILITY GRADUALLY INCREASES TOWARD EVENING
AND A FEW THUNDERSTORMS WILL BE POSSIBLE MAINLY AFTER 21Z. IT
APPEARS THERE WILL BE TWO ROUNDS OF STORMS. ONE WITH THE WAVE
COMING ACROSS LAKE MICHIGAN THIS AFTERNOON...THEN A LULL AROUND
MIDNIGHT. THEN A SECOND ROUND OF STORMS SHOULD MOVE IN TOWARD
DAYBREAK SUNDAY.

LOW LEVEL MOISTURE INCREASES AS EACH ROUND OF STORMS PASSES...SO
I FIGURE MVFR CEILINGS WILL DEVELOP WITH THE SECOND ROUND OF
STORMS...EVEN PATCHY IFR IS NOT OUT OF THE QUESTION. SOME LIGHT
FOG SHOULD ALSO DEVELOP OVERNIGHT. CONDITIONS ARE EXPECTED TO
IMPROVE MID TO LATE SUNDAY MORNING AS THE STORMS EXIT AND CLEARING
MOVES IN.

&&

.MARINE...
ISSUED AT 345 PM EDT SAT JUN 15 2013

WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW ADVISORY CRITERIA THE
NEXT COUPLE OF DAYS. SOUTHWEST WINDS TODAY AND AGAIN SUNDAY NIGHT OF
10 TO 20 KNOTS WILL LIKELY BUMP WAVES UP INTO THE 1 TO 3 FOOT
CATEGORY. MONDAY NIGHT NORTHERLY WINDS WILL ELEVATE WAVES ONCE AGAIN
BEHIND A LOW PRESSURE SYSTEM...BUT A NORTHERLY FLOW MAY KEEP THE
HIGHEST WAVES OFF SHORE.

&&

.HYDROLOGY...
ISSUED AT 345 PM EDT SAT JUN 15 2013

4 RIVER ADVISORIES REMAIN FROM WEDNESDAY NIGHT/S RAIN. USGS PERCENT
OF NORMAL MAP ILLUSTRATES WELL THE AREA THAT RECEIVED THE HEAVY
RAIN...ESSENTIALLY THE MIDDLE OF THE FORECAST AREA THROUGH PORTIONS
OF THE GRAND BASIN. AREAS TO THE NORTH AND SOUTH REMAIN NEAR NORMAL
FLOWS. RAINFALL THE NEXT COUPLE DAYS SHOULD RANGE FROM AROUND A
QUARTER OF AN INCH ACROSS THE NORTH TO POSSIBLY AS MUCH AS THREE
QUARTERS OF AN INCH IN THE SOUTH. THIS RAINFALL MAY BUMP A FEW
ADDITIONAL SITES BACK INTO ADVISORY CATEGORY THAT ARE JUST BELOW
CRITERIA.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...JK
AVIATION...JK
HYDROLOGY...DUKE
MARINE...DUKE